Letteratura scientifica selezionata sul tema "I-type granite"
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Articoli di riviste sul tema "I-type granite"
1
Mustafa, Moch Akrom, e Ediar Usman. "ANALISIS PERBANDINGAN GEOKIMIA GRANIT DAN SEDIMEN DASAR LAUT DI PULAU SINGKEP BAGIAN TIMUR, PROVINSI KEPULAUAN RIAU". JURNAL GEOLOGI KELAUTAN 11, n. 3 (16 febbraio 2016): 131. http://dx.doi.org/10.32693/jgk.11.3.2013.237.
Testo completoAbstract (sommario):
Hasil analisis kimia secara umum menunjukkan kesamaan antara granit dan sedimen permukaan dasar laut. Perbedaan hanya pada dua unsur, yaitu Al2O3 dan Fe2O3; kandungan Al2O3 pada granit antara 12,63 - 15,58% dan Fe2O3 antara 1,26 - 1,78%, sedangkan sedimen permukaan dasar laut Al2O3 berkisar antara 2,10 - 3,29% dan Fe2O3 antara 7,57 - 12,88%. Hasil analisis pada Diagram Harker menunjukkan penyebaran granit dan sedimen dasar laut membentuk pola searah, mengiindikasikan pola ko-magmatik.
Selanjutnya, untuk menentukan tipe granit di P. Singkep dalam kaitannya dengan kandungan timah, dua diagram SiO2 vs FeOtot/MgO dan ACF telah digunakan. Hasilnya menunjukkan bahwa granit Singkep termasuk daerah transisi antara tipe A dan tipe I&S dan tipe S yang kaya ilmenit dan berassosiasi dengan konsentrat timah.
Kata kunci: granit, sedimen dasar laut, kimia, tipe I&S, tipe S, timah, Pulau Singkep
Results of chemical analyses generally show the similarities between the granites and the seafloor sediments. The difference is only in the two elements, namely Al2O3 and Fe2O3; Al2O3 contents. In the granite ranges between 12.63 to 15.58% and the Fe2O3 ranges between 1.26 to 1.78%; while the seafloor sediment shows Al2O3 between 2.10 to 3, 29% and Fe2O3 between 7.57 to 12.88%. Results of the analysis on the Harker Diagram shows the distribution of the granites and the seafloors sediments form the unidirectional pattern, indicates the co-magmatic pattern.
Furthermore, to determine the type of granite in Singkep Island in relation with the tin content two diagram of SiO2 vs FeOtot/MgO and ACF are used. The result shows that the Singkep granite belong to the the transition area between the A and I&S and the S type which rich of ilmenite and associated with tin concentrate.
Keywords: granite, sea floor sediments, chemicals, I&S type, S type, tin, Singkep Island
2
Chappell, B. W., e W. E. Stephens. "Origin of infracrustal (I-type) granite magmas". Earth and Environmental Science Transactions of the Royal Society of Edinburgh 79, n. 2-3 (1988): 71–86. http://dx.doi.org/10.1017/s0263593300014139.
Testo completoAbstract (sommario):
ABSTRACTI-type granites are produced by partial melting of older igneous rocks that are metaluminous and hence have not undergone any significant amount of chemical weathering. In the Lachlan Fold Belt of southeastern Australia and the Caledonian Fold Belt of Britain and Ireland there was a major magmatic event close to 400 Ma ago involving a massive introduction of heat into the crust. In both areas, that Caledonian-age event produced large volumes of I-type granite and related volcanic rocks. Granites of these two areas are not identical in character but they do show many similarities and are markedly different from many of the granites found in Mesozoic and younger fold belts. These younger, dominantly tonalitic, granites have compositions similar to those of the more felsic volcanic rocks forming at the present time above subduction zones. The Palaeozoic granites show little evidence of such a direct relationship to subduction. Within both the Caledonian and Lachlan belts there are some granites with a composition close to the younger tonalites. A particularly interesting case is that of the Tuross Head Tonalite of the Lachlan Fold Belt, which can be shown to have formed from slightly older source rocks by a process that we refer to as remagmatisation which has caused no significant change in composition. Since remagmatisation has reproduced the former source composition in the younger rocks, the wrong inference would result from the use of that composition to deduce the tectonic conditions at the time of formation of the tonalite. Granites, particularly the more mafic ones, will generally have compositions reflecting the compositions of their source rocks, and attempts to use granite compositions to reconstruct the tectonic environment at the time of formation of the granite may be looking instead at an older event. This is probably also the case for some andesites formed at continental margins.Several arguments can be presented in favour of a general model for the production of I-type granite sources by underplating the crust, so that the source rocks are infracrustal. Such sources may contain a component of subducted sediments with the consequence that some of the compositional characteristics of sedimentary rocks may be present in I-type source rocks and in the granites derived from them. The small bodies of mafic granite and gabbro associated with island arc volcanism have an origin that can be related to the partial melting of subducted oceanic crust or of mantle material overlying such slabs and can be referred to as M-type. These rocks have compositions indistinguishable from those of the related volcanic rocks, except for a small component of cumulative material. The tonalitic I-type granites characteristic of the Cordillera are probably derived from such M-type rocks of basaltic to andesitic composition, which had been underplated beneath the crust. Some of the more mafic tonalites of the Caledonian-age fold belts may also have had a similar origin. More commonly, however, the plutonic rocks of the older belts are granodioritic and these probably represent the products of partial melting of older tonalitic I-type source rocks in the deep crust, these having compositions and origins analogous to the tonalites of the Cordillera. In this way, multiple episodes of partial melting, accompanied by fractionation of the magmas, can produce quite felsic rocks from original source rocks in the mantle or mantle wedge. These are essential processes in the evolution of the crust, since the first stages in this process produce new crust and the later magmatic events redistribute this material vertically without the addition of significant amounts of new crust.
3
Blevin, Phillip L., e Bruce W. Chappell. "The role of magma sources, oxidation states and fractionation in determining the granite metallogeny of eastern Australia". Earth and Environmental Science Transactions of the Royal Society of Edinburgh 83, n. 1-2 (1992): 305–16. http://dx.doi.org/10.1017/s0263593300007987.
Testo completoAbstract (sommario):
ABSTRACTThe ore-element associations of granite-related ore deposits in the eastern Australian Palaeozoic fold belts can be related to the inferred relative oxidation state, halogen content and degree of fractional crystallisation within the associated granite suites. Sn mineralisation is associated with both S- and I-type granites that are reduced and have undergone fractional crystallisation. Cu and Au are associated with magnetite- and/or sphene-bearing, oxidised, intermediate I-type suites. Mo is associated with similar granites that are more fractionated and oxidised. W is associated with a variety of granite types and shows little dependence on inferred magma redox state. The observed ore deposit-granite type distribution in eastern Australia, and the behaviour of ore elements during fractionation, is consistent with models of ore element sequestering by sulphides and Fe-Ti phases (e.g. pyrrhotite, ilmenite, sphene, magnetite) whose stability is nominally fO2-dependent. Fractional crystallisation acts to amplify this process through the progressive removal of compatible elements and the concentration of incompatible elements into decreasing melt volumes. The halogen content is also important. S-type granites are poorer in Cl than I-types. Cl decreases and F increases in both S- and I-type granites with fractional crystallisation. Low Cl contents combined with low magma fO2 in themselves seem to provide an adequate explanation for the rarity of Mo, Cu, Pb and Zn type mineralisation with S-type granites. Although such properties of granite suites seem adequately to predict the associated ore-element assemblage to be expected in associated mineral deposits, additional factors determine whether or not there is associated economic mineralisation.
4
Regelous, Anette, Lars Scharfenberg e Helga De Wall. "Origin of S-, A- and I-Type Granites: Petrogenetic Evidence from Whole Rock Th/U Ratio Variations". Minerals 11, n. 7 (24 giugno 2021): 672. http://dx.doi.org/10.3390/min11070672.
Testo completoAbstract (sommario):
The origin and evolution of granites remain a matter of debate and several approaches have been made to distinguish between different granite types. Overall, granite classification schemes based on element concentrations and ratios, tectonic settings or the source rocks (I-, A-, S-type) are widely used, but so far, no systematic large-scale study on Th/U ratio variations in granites based on their source or tectonic setting has been carried out, even though these elements show very similar behavior during melting and subsequent processes. We therefore present a compiled study, demonstrating an easy approach to differentiate between S-, A- and I-type granites using Th and U concentrations and ratios measured with a portable gamma ray spectrometer. Th and U concentrations from 472 measurements in S- and I-type granites from the Variscan West-Bohemian Massif, Germany, and 78 measurements from Neoproterozoic A-type Malani granites, India, are evaluated. Our compendium shows significant differences in the average Th/U ratios of A-, I- and S-type granites and thus gives information about the source rock and can be used as an easy classification scheme. Considering all data from the studied A-, I- and S-type granites, Th/U ratios increase with rising Th concentrations. A-type granites have the highest Th/U ratios and high Th concentrations, followed by I-type granites. Th/U ratios in S- to I-type granites are lower than in A-type and I-type granites, but higher than in S-type granites. The variation of Th/U ratios in all three types of granite cannot be explained by fractional crystallization of monazite, zircon and other Th and U bearing minerals alone, but are mainly due to source heterogeneities and uranium mobilization processes.
5
Williams, Ian S., e Kenton S. W. Campbell. "Bruce William Chappell 1936–2012". Historical Records of Australian Science 28, n. 2 (2017): 146. http://dx.doi.org/10.1071/hr17012.
Testo completoAbstract (sommario):
Bruce Chappell was one of the most distinguished geologists of his generation whose contributions to understanding the origins of granites are both insightful and profound. A pioneer in the application of X-ray fluorescence spectrography to the analysis of geological materials, his radical ideas about magma genesis, still the subject of vigorous debate, have dominated and largely determined the global directions of subsequent research on granites. His restite model, the recognition that most granite magmas move bodily away from their source regions as a mixture of melt and solid residual material, the progressive separation of which determines the magma composition, underlies his tenet that granites are images of their source. His consequent recognition, with Allan White, that there are two fundamentally different types of granite magma, I-type (derived from igneous sources) and S-type (derived from weathered sedimentary sources), each with its distinctive evolutionary path and associated mineralization, continues to underpin research into granites worldwide, and the search for granite-related mineral deposits.
6
Nguyen, Tai Minh, Hoa Xuan Tran, Giang Thi Truong Nguyen, Cuong Chi Truong e Minh Pham. "U-Pb zircon and Hf composition of granite Song Ma block". Science and Technology Development Journal - Natural Sciences 2, n. 4 (14 agosto 2019): 167–75. http://dx.doi.org/10.32508/stdjns.v2i4.825.
Testo completoAbstract (sommario):
The granite of the Song Ma block mainly consists of two types of granite: biotite granite and hornblende-biotite granite. Biotite granites have the percent of plagioclase (35– 45%), K-feldspar (25–35%), quartz (~20%) and biotite (~10%). Biotite-hornblende granite with the content of plagioclase (40–50%), Kfeldspar (10–15%), hornblende (5–10%) and biotite (5%). Zircon crystals were selected from the granite of Song Ma block are V0741, V0856 and V1006 samples with the LA-ICPMS U-Pb analyses gave concordant ages concentrated at 257±4Ma, 262±3Ma and 241±6Ma (weighted mean). Those ages are older than the results of the previous research. The mineral assemblages and geochemical characteristics show the typical of I-type granites. The results of Hf isotope composition analysis give the value of εHf(t) from +7.3 to +13.9, which is proven the sources of the granite Song Ma block similar to the granite of Phan Si Pan zone, NW Viet Nam during the period from late Permian to early Triassic.
7
Semblano, Flávio Robson Dias, Moacir José Buenano Macambira e Marcelo Lacerda Vasquez. "Petrography, geochemistry and Sm-Nd isotopes of the granites from eastern of the Tapajós Domain, Pará state". Brazilian Journal of Geology 46, n. 4 (dicembre 2016): 509–29. http://dx.doi.org/10.1590/2317-4889201620160059.
Testo completoAbstract (sommario):
ABSTRACT: The Tapajós Domain, located in the southern portion of the Amazonian Craton, is a tectonic domain of the Tapajós-Parima Province, a Paleoproterozoic orogenic belt adjacent to a reworked Archean crust, the Central Amazonian Province. This domain has been interpreted as the product of an assemblage of successive magmatic arcs followed by post-orogenic A-type magmatism formed ca. 1880 Ma-old granites of the Maloquinha Intrusive Suite. The study presented here was carried out in four granitic bodies of this suite (Igarapé Tabuleiro, Dalpaiz, Mamoal and Serra Alta) from the eastern part of the Tapajós Domain, as well as an I-type granite (Igarapé Salustiano) related to the Parauari Intrusive Suite. The A-type granites are syenogranites and monzogranites, and alkali feldspar granites and quartz syenites occur subordinately. These rocks are ferroan, alkalic-calcic to alkalic and dominantly peraluminous, with negative anomalies of Ba, Sr, P and Ti and high rare earth elements (REE) contents with pronounced negative Eu anomaly. This set of features is typical of A-type granites. The Igarapé Salustiano granite encompasses monzogranites and quartz monzonites, which are magnesian, calcic to calc-alkalic, high-K and mainly metaluminous, with high Ba and Sr contents and depleted pattern in high field strength elements (HFSE) and heavy rare earth elements (HREE), characteristic of I-type granites. The source of magma of these A-type granites is similar to post-collisional granites, while the I-type granite keeps syn-collisional signature. Most of the studied granites have εNd (-3.85 to -0.76) and Nd TDM model ages (2.22 to 2.46 Ga) compatible with the Paleoproterozoic crust of the Tapajós Domain. We conclude that the Archean crust source (εNd of -5.01 and Nd TDM of 2.6 Ga) was local for these A-type granites.
8
Zhu, Xinxiang, Markus B. Raschke e Yan Liu. "Tourmaline as a Recorder of Ore-Forming Processes in the Xuebaoding W-Sn-Be Deposit, Sichuan Province, China: Evidence from the Chemical Composition of Tourmaline". Minerals 10, n. 5 (14 maggio 2020): 438. http://dx.doi.org/10.3390/min10050438.
Testo completoAbstract (sommario):
The Xuebaoding W-Sn-Be deposit located in the Songpan-Ganze Orogenic Belt (Sichuan Province, China) is a hydrothermal deposit with less developed pegmatite stage. The deposit is famous for the coarse-grained crystals of beryl, scheelite, cassiterite, apatite, fluorite, muscovite, and others. The orebody is spatially associated with the Pankou and Pukouling granites hosted in Triassic marbles and schists. The highly fractionated granites are peraluminous, Li-Rb-Cs-rich, and related to W-Sn-Be mineralization. The mineralization can chiefly be classified based on the wallrock and mineral assemblages as muscovite and beryl in granite (Zone I), then beryl, cassiterite and muscovite at the transition from granite to triassic strata (Zone II), and the main mineralized veins composed of an assemblage of beryl, cassiterite, scheelite, fluorite, and apatite hosted in metasedimentary rock units of marble and schist (Zone III). Due to the stability of tourmaline over a wide range of temperature and pressure conditions, its compositional variability can reflect the evolution of the ore-forming fluids. Tourmaline is an important gangue mineral in the Xuebaoding deposit and occurs in the late-magmatic to early-hydrothermal stage, and can thus be used as a proxy for the fluid evolution. Three types of tourmalines can be distinguished: tourmaline disseminations within the granite (type I), tourmaline clusters at the margin of the granite (type II), and tourmalines occurring in the mineralized veins (type III). Based on their chemical composition, both type I and II tourmalines belong to the alkali group and to the dravite-schorl solid solution. Type III tourmaline which is higher in X-site vacancy corresponds to foitite and schorl. It is proposed that the weakly zoned type I tourmalines result from an immiscible boron-rich aqueous fluid in the latest stage of granite crystallization, that the type II tourmalines showing skeletal texture directly formed from the undercooled melts, and that type III tourmalines occurring in the mineralized veins formed directly from the magmatic hydrothermal fluids. Both type I and type II tourmalines show similar compositional variations reflecting the highly fractionated Pankou and Pukouling granites. The higher Ca, Mg, and Fe contents of type III tourmaline are buffered by the composition of the metasedimentary host rocks. The decreasing Na content (<0.8 atoms per formula unit (apfu)) and increasing Fe3+/Fe2+ ratios of all tourmaline samples suggest that they precipitated from oxidized, low-salinity fluids. The decreasing trend of Al content from type I (5.60–6.36 apfu) and type II (6.01–6.43 apfu) to type III (5.58–5.87 apfu) tourmalines, and associated decrease in Na, may be caused by the crystallization of albite and muscovite. The combined petrographic, mineralogical, and chemical characteristics of the three types of tourmalines thus reflect the late-magmatic to early-hydrothermal evolution of the ore-forming fluids, and could be used as a geochemical fingerprint for prospecting W-Sn-Be mineralization in the Xuebaoding district.
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Sandeman, Hamish A., e John Malpas. "Epizonal I- and A-type granites and associated ash-flow tuffs, Fogo Island, northeast Newfoundland". Canadian Journal of Earth Sciences 32, n. 11 (1 novembre 1995): 1835–44. http://dx.doi.org/10.1139/e95-141.
Testo completoAbstract (sommario):
Magmatic activity of Silurian–Devonian age is widespread in the Appalachian–Caledonian Orogen. A marked characteristic of this magmatism is the composite nature of the igneous suites, which range from peridotite to granodiorite in single plutonic bodies. The origin of these suites is still enigmatic, and the assumption that all are the same not proven. Such a suite of intrusive rocks, ranging in composition from minor peridotite to granodiorite, intrudes an openly folded sequence of Silurian volcanogenic sandstones and ash-flow tuffs on Fogo Island, northeast Newfoundland. Two units, the Rogers Cove and Hare Bay microgranites, consist of fine-grained hastingsite granites with spherulitic and flow-banded textures, and exhibit drusy cavities and microfractures that contain the mineral assemblage hastingsitic hornblende + plagioclase + magnetite + zircon. These rocks are characterized by elevated high field strength element contents (e.g., Zr = 74–672 and Y = 21–103 ppm), very high FeO*/MgO ratios (FeO*/MgO = 2.4–93.5), and 10 000 Ga/Al ratios of 1.67–10.52, indicating an A-type granitoid affinity. A third and the most voluminous granitic unit, the Shoal Bay granite, is an alkali-feldspar-phyric, medium-grained, equigranular biotite–hastingsite granite with hastingsite and annitic biotite interstitial to euhedral plagioclase, anhedral quartz, and perthite crystals. The Shoal Bay granite exhibits mineral parageneses similar to the microgranites, but chemical characteristics more typical of calc-alkaline, I-type granitoids. Volcanic–sedimentary sequences spatially associated with the granitic rocks include dense, welded, high-silica, hastingsite-bearing ash-flow tuffs with compositions that suggest they represent erupted equivalents of fractionated end members of the Shoal Bay granite. The rocks making up the Fogo Island batholith have been directly equated with the bimodal, calc-alkaline Mount Peyton batholith of northeast Newfoundland, but the specialized A-type nature of the Fogo granites suggests differing source conditions for the two suites.
10
Clemens, J. D., e G. Stevens. "S- to I- to A-type magmatic cycles in granitic terranes are not globally recurring progressions. The cases of the Cape Granite Suite of Southern Africa and central Victoria in southeastern Australia". South African Journal of Geology 124, n. 3 (1 settembre 2021): 565–74. http://dx.doi.org/10.25131/sajg.124.0007.
Testo completoAbstract (sommario):
Abstract Recurring progression from S- to I- to A-type granites has been proposed for a subset of granitic rocks in eastern Australia. The wider applicability and the validity of this idea is explored using the Cape Granite Suite (CGS) of South Africa and the granitic and silicic volcanic rocks of central Victoria, in southeastern Australia. Within the CGS there is presently little justification for the notion that there is a clear temporal progression from early S-type, through I-type to late A-type magmatism. The I- and S-type rocks are certainly spatially separated. However, apart from a single slightly older pluton (the Hoedjiespunt Granite) there is no indication that the S- and I-type granites are temporally distinct. One dated A-type granitic sample and a syenite have poorly constrained dates that overlap with those of the youngest S-type granites. In central Victoria, the granitic magma types display neither a spatial separation nor a temporal progression from one type to another. All magma varieties are present together and were emplaced within a far narrower time window than in the CGS. Thus, a progression may or may not exist in a particular region, and the occurrence of such a progression does not hold true even in a part of southeastern Australia, which afforded the type example. Thus, the idea that, globally, there should be a progression from S- to I- to A-type magmatism is unjustified. The critical factor in determining the temporal relationship between granitic magmas of different types is probably the compositional structure of the deep crust in a particular region, a reflection of how the individual orogen was assembled. In turn, this must reflect significant differences in the tectonic settings.
Tesi sul tema "I-type granite"
1
Ng, Wai Pan. "Petrogenesis, U-Pb zircon geochronology and tectonic evolution of the Malaysian granite provinces in the Southeast Asian tin belt". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:0f2f3942-6d64-4a17-b194-08672107aeb2.
Testo completoAbstract (sommario):
The Malaysian granitoids form the backbone of the Malay Peninsula and have long been recognized as composed of two distinct granitic provinces separated by the Bentong-Raub suture zone:
2
Spicer, Esme M. (Esme Marelien). "Apatite, allanite, titanite and monazite characteristics in S-, I- A-type Cape Granites". Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52120.
Testo completoAbstract (sommario):
Thesis (MSc)--Stellenbosch University, 2001.ENGLISH ABSTRACT: This study focussed on the comparison of accessory mineral chemistry and paragenesis in the S-, I- and A-type granites of the Cape Granite Suite. The objective of the study was to use differences in accessory mineral chemistry and petrography to give insight in the evolution, recycling and formation of continental crust as affected by the Cape Granite Suite. Because of the high partition coefficients of the REE and trace elements into accessory minerals these minerals play an important role to explain granite evolution. The accessory mineral features are used as discriminators between barren and mineralized S-, I- and A-type granites in the suite. The petrography of the suite reflects the allanite-monazite dichtonomy with allanite and titanite occurring in the I -type granites while monazite occurs in S-type granites. Monazite becomes unstable in high Ca melts such as I-type granites. Apatite occurs in all the plutons which reflects its stability over a wide range of geological conditions. Rounded crystal habits of apatite and monazite in S-type granites indicate they are relics of sedimentary source rocks. Concentric growth- and sectoral zoning, as observed with CL and SEM, are common features in minerals that crystallized in barren plutons. The overprinting of magmatic textures reflects secondary processes, such as those that occurred in mineralized plutons, by "patchy" zoning and irregular alteration rims (coronas) in the mineralized plutons' accessory minerals. CL and SEM observations revealed that REE are redistributed into these coronas. Mineral chemistry of the accessory minerals reflects mostly the whole rock chemistry and physical conditions of the magmas. (Al~ Fe) substitution in titanite is controlled by P-T conditions, together with Ca, Mn and Mg substitution which is controlled by whole-rock chemistry, are good discriminators in S- and I-type granites. LREE and Sr content in allanite discriminate between the plutons and reflect the whole-rock chemistry. Apatite, because it occurs in all the plutons, is the most useful accessory mineral for discriminating between the plutons. From previous studies it is known that ASI controls the two main substitutions in apatite: Ca+P~Si+REE and Na+REE~2Ca, Fe and Mn content in apatite (0,1 pfu Mn and 0,05 pfu Fe contents are the cut-off between S-and Itype granites) are controlled by oxidation state of the magma and Sr, REE and Mg reflect whole-rock chemistry. The content of these elements in apatite can be used as discriminators between the plutons as their ASI, oxidation states and whole-rock chemistry differ. REE patterns of monazite and allanite are LREE enriched without exception, while apatite and titanite REE patterns are mostly birdwing profiles with occurrences of LREE or HREE enrichment. These patterns are influenced by crystallization of coexisting REE-bearing phases, fractionation history of the pluton and by crystallization sequence of the accessory minerals. Phase relationships were investigated experimentally for monazite and allanite under magmatic conditions (870 °C, 1,8 kbar) in peraluminous to metaluminous granitic melts. Monazite became unstable when aqueous CaCh solutions of 0.7-7 g CaCh/10cc H20 where added to peraluminous melts (ASI> 1 ). Monazite broke down to Cl-apatite and corona textures were observed. Allanite was tested in peraluminous (ASI> 1) and metaluminous (ASI=1) melts with different P20 5 (0.08 - 0.25 wt%) concentrations. Allanite became unstable at high phosphorus and peraluminous melt conditions and broke down to LREE-P± Al, Ca, K phases. Corona (kelyphitic) textures were observed. It is also clear that phosphorus played an important role, with Al, in the melt structure as can be seen from the absence or presence of crystals in the glasses of the different melts. This is possible because adding of phosphorus to the melt results in a depression of the T of the granitic melts' liquidus. Because of an interaction of phosphorus with Si networks and formation of complexes it also depolymerize aluminosilicate melts. The solubility of monazite was also tested in aqueous solutions under atmospheric conditions and low T (100-350 °C) to investigate low TIP alteration. Solutions ofCaCb +NaCl (1:1) chlorides were very reactive and dissolved the monazite completely, while solutions of CaCb were less reactive and only partly dissolved the monazite. These experiments demonstrate the concentrations required in hydrothermal solutions to destabilize monazite and explain textures found in natural rocks. Accessory minerals are useful discriminators between S-, I- and A-type granites and also their mineralized counterparts. Discrimination does depend on what accessory minerals are present and therefore apatite is the best mineral because it occurs in all the plutons. Petrography of these minerals is an indicator of primary or secondary processes.
AFRIKAANSE OPSOMMING: Die fokus van hierdie studie was om die mineraalchemie en paragenese van bykomstige minerale in S-, 1- en A-tipe graniete van die Kaapse Graniet Suite te vergelyk. Die doelwit van hierdie studie was om die verskille in chemie en petrografie van bykomstige minerale te gebruik as insig in die evolusie, herwinning en ontstaan van kontinentale kors soos geaffekteer deur die Kaapse Graniet Suite. Omdat SAE en spoorelemente hoe partisiekoeffisiente het vir bykomstige minerale speel hierdie minerale 'n belangrike rol om graniet evolusie te verklaar. Genoemde kenmerke van bykomstige minerale is ook gebruik om te onderskei tussen ongemineraliseerde en gemineraliseerde S-, 1- en A-tipe graniete in die suite. Die petrografie van die Kaapse Graniet Suite weerspieel die tweeledigheid van allanietmonasiet deurdat allaniet en titaniet in 1-tipe graniete en monasiet in S-tipe graniete voorkom. Monasiet word dus onstabiel in hoe Ca, 1-tipe, graniete. Apatiet kom in al drie tipes voor wat die mineraal se stabiliteit in verskeie geologiese omgewings weerspieel. Geronde kristalvorme , of reliekteksture, van apatiet en monasiet in S-tipe graniete weerspieel die sedimentere oorsprong van hierdie graniete. Konsentriese groei - en sektorale sonering kom algemeen voor in bykomstige minerale in ongemineraliseerde plutone. Sekondere veranderings rande (koronas) en onreelmatige sonering in gemineraliseerde plutone se bykomstige minerale is 'n aanduiding dat primere teksture gedeeltelik vemietig is deur sekondere prosesse. Katodeluminisensie en skandeerelektron mikroskopie ondersoeke het bewys dat SAE gehermobiliseer word na die koronas. Heelrotschemie en fisiese toestande van die magma word weerspieel in die mineraalchemie van bykomstige minerale. (Al~Fe) substitusie in titaniet word beheer deur P-T toestande en is, saam met Ca, Mn en Mg inhoud wat heelrotschemie weerspieel, goeie diskriminators in S- en 1-tipe graniete. LSAE en Sr inhoud in allaniet onderskei goed tussen plutone omdat hierdie elemente die heelrotschemie weerspieel. Omdat apatiet in al die plutone voorkom is dit die bruikbaarste mineraal om as diskriminant te gebruik. V anuit vorige werk is dit bekend dat die aluminium versadigings indeks die twee hoofsubstitusies: Ca+P~Si+SAE en Na+SAE~2Ca beheer, Fe en Mn inhoud in apatiet (0,1 pfu Mn en 0,05 pfu Fe is die afsnypunt tussen S- en 1-tipe graniete) weerspieel die oksidasietoestand van die magma en Sr, SAE en Mg weerspieel heelrotschemie. Saam kan hierdie elemente dus gebruik word as diskriminatore tussen die verskillende plutone. SAE patrone van allaniet en monasiet is sonder uitsondering verryk in die LSAE, terwyl apatiet en titaniet meestal "birdwing" profiele wys, maar kan ook verryk wees in LSAE of SSAE. Hierdie patrone word beinvloed deur kristallisasie van ander SAE-draende minerale, fraksionering van minerale uit die magma en die kristallisasie volgorde van die mineral e. Faseverwantskappe is eksperimenteel getoets tussen monasiet en allaniet in magmatiese toestande (780 °C en 1,8 kbar). Monasiet word onstabiel in 'n peralumineuse smelt (Aluminium versadigingsindeks >1) as waterig oplossings met konsentrasies van 0.7-7 g CaCh/1 0 cc H20 bygevoeg word. Cl-apatiet vorm as veranderingsproduk om die rande (koronas ). Allaniet is getoets in peralumineuse (Aluminium versadigingsindeks > 1) en metalumineuse smelte (Aluminium versadigingsindeks =1) met wisselende konsentrasies P20s (0.08 - 0.25 wt%). Allaniet het onstabiel geraak in peralumineuse smelte en hoe fosfor konsentrasies en het afgebreek na fases van LSAE+P± Ca, Al, K. Korona (kelifitiese) teksture is waargeneem. Hierdie eksperimente bewys dat fosfor, saam met Al, 'n belangrike rol speel in smeltstruktuur. Dit kan gesien word in die teenwoordig- of afwesigheid van kristalle in die glas. Dit is moontlik deurdat die byvoeging van fosfor 'n verlaging in die graniet likwidus temperatuur veroorsaak. Fosfor depolimeriseer ook aluminiumsilikaat smelte deur interaksie en kompleksvorming tussen fosfor en silika netwerke. Die oplosbaarheid van monasiet is ook getoets in waterige oplossings onder atmosferiese toestande en lae T (100-350 °C) om lae PIT veranderinge te ondersoek. 'n Versadigde oplossing van CaCh en NaCl (1:1) chloried het monasiet heeltemal opgelos terwyl 'n versadigde oplossing van CaCh monasiet net gedeeltelik opgelos het. Hierdie eksperimente dui op die konsentrasies nodig vir hidrotermale vloeistowwe waar bykomstige minerale onstabiel raak en verklaar teksture in natuurlike rotse. Bykomstige minerale kan dus gebruik word as diskriminators tussen ongemineraliseerde en gemineraliseerde plutone en ook tussen S-, I- en A-tipe graniete. Hulle kan egter net gebruik word as hulle teenwoordig is en daarom is apatiet die beste omdat dit in al die plutone aanwesig is. Petrografie is 'n aanduiding van magmatiese of sekondere prosesse.
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Silva, Rafael Fernandes e. "O granito capão do leão: magmatismo Tipo-I altamente fracionado no sudeste do Cinturão Dom Feliciano, RS". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/133640.
Testo completoAbstract (sommario):
No SE do domínio oriental do Cinturão Dom Feliciano (CDF) o Granito Capão do Leão (GCL) ocorre como dois corpos, norte e sul, encaixados em rochas Pré-Cambrianas do Complexo Pinheiro Machado (CPM) e nos granitos Chasqueiro (GCH) e Arroio Grande (GAG). Os corpos do GCL, tanto o norte quanto o sul, possuem formas elípticas e ocupam áreas de, respectivamente, 200 km2 e 100 km2, apresentando orientação ENE-WSW, sendo dominantemente uma rocha maciça, a qual preserva suas características magmáticas. Zonas centimétricas a métricas de deformação dúctil, principalmente no corpo sul, são observadas gerando rochas miloníticas subverticais, apresentando plano de foliação com mergulho maior que 70° e direção NE-SW que podem refletir reativações da Zona de Cisalhamento Arroio Grande (ZCAG). Petrograficamente é um granito equigranular, médio a grosso, com textura hipidiomórfica predominante, de composição sieno a monzogranítica, apresentando, por vezes, cavidades miarolíticas centimétricas, as quais sugerem um posicionamento final em condições rasas (epizonal) e indicam a presença de fluidos até os estágios finais da cristalização, além de raros enclaves máficos, de composição micácea, os quais podem representar um material de origem mantélica fonte do granito, uma rocha encaixante fundida e assimilada pelo magma ou a ocorrência de uma mistura de magmas. Apresenta injeções centimétricas de veios ou bolsões tardios de aplitos. A assembleia mineral do GCL é constituída de quartzo, feldspato alcalino e plagioclásio do tipo albita. Como varietais ocorrem biotitas, dos tipos siderofilita e anita, granadas, com predomínio de membros finais em almandina e espessartina, e, subordinadamente, anfibólio cálcico do tipo ferro-pargasita. Seus minerais acessórios são apatita, titanita, zircão e opacos. O GCL é uma rocha de composição ácida, tem afinidade geoquímica subalcalina, metaluminosa a fracamente peraluminosa, com tendência cálcio-alcalina alto-K, apresentando elevados teores de SiO2, entre 71,60 e 75,95 %, teores de Al2O3 entre 11,00 e 15,00 %, teores em álcalis elevados, com valores de Na2O oscilando entre 1,76 à 4,61 % e 3,8 até 7,36 % para o K2O, baixos teores em CaO, MgO e MnO, menores que 1% e teores extremamente baixos de P2O5, menores que 0,03 %. A ocorrência de granada sugere um caráter altamente diferenciado, decorrente de longa cristalização fracionada. Os diagramas multielementares mostram enriquecimento em Rb, Pb, Th, U e K, e depleção nos elementos Ba, Nb, Sr, P, Eu e Ti , assim como enriquecimento de ETR leves em relação aos ETR pesados e acentuada anomalia negativa em Ba, Sr, Ti e Eu. O GCL apresenta características de magmatismo tipo-I, com alto fracionamento, de ambiente pós-colisional, apresentando padrões geoquímicos semelhantes ao GCH, os quais permitem correlacioná-los como líquidos segregados de uma mesma fonte, diferenciados por mecanismos petrológicos, tais como assimilação de material encaixante e cristalização fracionada. O líquido magmático dos granitos Capão do Leão, Chasqueiro e Arroio Grande, podem ter sua gênese relacionada a eventos de movimentação da Zona de Cisalhamento Arroio Grande, a qual pode ter causado a fusão da base da crosta, por adição de material mantélico, sendo, portanto, a responsável tanto pelo processo de extração, colocação e da referida segregação dos líquidos do GCL e do GCH, como pela geração e emplaçamento do líquido do GAG.In the SE of the eastern domain of Dom Feliciano Belt (CDF) the Capão do Leão Granite (GCL) forms two bodies, northern and southern, embedded in Precambrian rocks of the Pinheiro Machado Complex (CPM), Chasqueiro Granite (GCH) and Arroio Grande Granite (GAG). The GCL bodies are elliptically shaped predominantly massive rocks, which preserve their magmatic features, and cover areas of respectively 200 km2 and 100 km2, with ENE-WSW orientation. Centimetric to metric ductile deformation zones, mainly in the south body, are observed causing sub-vertical mylonitic rocks, with foliation plan whose dip is greater than 70° and orientation is NE-SW, which may reflect reactivation of Arroio Grande Shear Zone (ZCAG). Petrographically it is an equigranular medium to large granite, predominantly hypidiomorphic consisting of sieno to monzogranitic, sometimes presenting miarolitic centimetric cavities, which suggest a final positioning in shallow conditions (epizonal) and indicate the presence of fluids to the final stages of crystallization, in addition to rare mafic micaceous enclaves, which may represent a mantle-originated and source of granite material, a molten host rock assimilated by magma or the occurrence of a mixture of magmas. The GCL presents centimetric injections of veins or late albite pockets. The mineral assembly of GCL consists of quartz, alkali feldspar and albite-rich plagioclase. Varieties also occur such as siderophyllite and annite types of biotites, garnets with a prevalence of end-members in almandine and spessartine and subordinate calcic type Fe-pargasite amphibole. Its accessory minerals are apatite, titanite, zircon and opaques. GCL is a rock with acid composition, has metaluminous to weakly peraluminous subalkaline geochemical affinity, with calc-alkaline high-K trend, with high SiO2 level, between 71.60 and 75.95 %, Al2O3 level between 11.00 and 15.00 %, high contents of alkalis, with Na2O values ranging from 1.76 to 4.61 % and 3.8 to 7.36 % and of K2O, low contents of CaO, MgO and MnO, below 1 % and extremely low levels of P2O5, lower than 0.03 %. The occurrence of garnet suggests a highly distinctive character as a result of long fractional crystallization. The multi-element diagrams show enrichment in Rb, Pb, Th, U and K, and depletion in Ba, Nb, Sr, P, Eu and Ti, as well as enrichment of light REE in comparison to heavy REE and a pronounced anomaly in Ba, Sr, Ti and Eu. GCL has I-type highly fractionated magmatism characteristics, from a post-collisional environment, presenting geochemical patterns similar to those of GCH, which allows a correlation between them as segregated liquids from the same source, differentiated by petrological mechanisms such as host rock material assimilation, and fractional crystallization. The magmatic liquid of Capão do Leão, Chasqueiro and Arroio Grande granites, may have its genesis related to the movement of Arroio Grande Shear Zone, which may have caused the lower crust to melt, by adding mantle material and, therefore, being responsible for both the extraction and placing processes and for the referred GCL and GCH's liquids segregation, as for the petrogenesis and emplacement of GAG's liquid.
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Halliday, Jennifer M. "Magnetic characterisation and palaeointensity analysis of rocks from selected I-type granitic plutons". Thesis, Kingston University, 2008. http://eprints.kingston.ac.uk/20395/.
Testo completoAbstract (sommario):
Absolute palaeointensity data are crucial to investigating the behaviour of the geomagnetic field. Long-term global palaeomagnetic databases are compiled with the aim of documenting the evolution of the geomagnetic field. However the temporal and spatial distribution remains limited, partly due to a lack of 'suitable' material in critical time windows, or poor magnetic behaviour of these rocks during experiments. Therefore it would be useful to have other potential sources of palaeointensity data in the surface rock record. Granitic intrusions occur frequently throughout the geological record, are often well exposed and well dated. However, granitic rocks have not previously been fully exploited in palaeointensity studies, due to their perceived lower primary magnetic content and problems associated with the stability of their magnetic signatures. Plutons show an internal grain-size variation and contain mafic enclaves, xenoliths and sheets derived from the primary melt. Therefore a range of magnetic behaviour, and hence a range of potential suitability for palaeointensity work can be expected within a single pluton. To our knowledge, there are no recorded rock magnetic or palaeomagnetic investigations addressing the question of whether granites are generically unsuitable, for palaeointensity work. To test this hypothesis, three I-type granitic plutons were characterised in terms of their magnetic suitability for palaeointensity analysis - including the Ross of Mull Pluton and Loch Doon Complex, SW Scotland and selected intrusions from the Coastal Batholith, Peru. Characterisation was achieved though extensive rock magnetic, palaeomagnetic and SEM analysis which enabled the magnetic properties of the samples to be determined. 180 samples were investigated using the Coe-modified Thellier technique to determine whether reliable palaeointensity data can be obtained. Magnetic characterisation and SEM analysis reveal that the magnetic mineralogy of the granitic intrusions is dominated by multidomain (MD) Ti-poor titanomagnetite. Exsolution textures observed in the Fe-Ti oxide grains are responsible for creating grains with SD-MD grain sizes. Stable univectoral remanences are usually accompanied by narrow unblocking temperatures where most NRM is lost between 560- 580°C. This makes obtaining acceptable PI data difficult, but by no means impossible. PI experiments were of variable success. Experiments including pTRM and pTRM tail checks and standard acceptance criteria were used to assess the quality of the results. The Ross of Mull rocks yielded no PI determinations. However, the Loch Doon Complex and intrusions from the Coastal Batholith were more triumphant with success rates of 28% and 57% respectively. The Loch Doon pluton (408Ma) is calculated to have a pluton average 8.2[mu]T with standard deviation 4[mu]T. The main reasons for failure of PI experiments are weak NRM, alteration and unstable MD behaviour. Experimental success correlates with the perceived geological complexity at each field area, where it is observed that simpler intrusions with less complicated cooling histories yield rocks with a: more stable magnetic signature and allow PI data to be derived. Results indicate that the more mafic rocks sampled in each pluton produced the best quality PI data. PI estimates were made on samples from Peruvian intrusives. The Anta ring dyke and Chasquitambo pluton give a site average of 15[mu]T with standard deviation 13.5[mu]T. Large deviation is caused by a single estimate, which at 46.7±18.4[mu]T is significantly different from the values found from other sites. Remaining sites have PI within error, however it should be noted that according to the K-Ar dates (Wilson, 1975) emplacement of the two separate intrusions occurred millions of years apart, 70.7±1.6Ma and 61±0.7Ma respectively. Samples from the Sayan pluton (61.2±0.4Ma) yield an average PI 25.4[mu]T ±7.7[mu]T. Arai plots are dominated by curvature, pTRM checks and rock magnetic experiments indicate that curvature is not caused by alteration and can be attributed to MD phenomena. PI estimates are made using the end-point method and from linear segments were possible, consistency between the two methods was demonstrated. This research reveals the potential of I-type plutons to provide reliable palaeointensity data.However, the PI data presented here must be considered as preliminary as no cooling rate or anistropy corrections have been applied.
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Hutton, Laurie James. "Petrogenesis of I- and S-type Granites in the Cape River - Lolworth area, northeastern Queensland - Their contribution to an understanding of the Early Palaeozoic Geological History of northeastern Queensland". Thesis, Queensland University of Technology, 2004. https://eprints.qut.edu.au/15858/1/Laurie_Hutton_Thesis.pdf.
Testo completoAbstract (sommario):
The geological history of the Early Palaeozoic in eastern Australia is not known precisely. The eastern margin of the outcropping Precambrian Craton 'Tasman Line' is poorly understood. The Thomson Orogen, which underlies much of eastern Queensland, lies to the east of the Tasman Line. Basement to the Tasman Orogenic Zone is poorly understood, but knowledge of this basement is critical to our understanding to the processes that formed the eastern margin of the Precambrian craton.
The Lolworth-Ravenswood Province lies to the east of the Tasman Line in northeast Queensland. A study of basement terranes in the Lolworth-Ravenswood Province will therefore provide some insights as to the nature of crust beneath this area, and therefore to the basement to the Thomson Orogen.
The Fat Hen Creek Complex comprises para-authchthonous bodies of granitoid within middle to upper amphibolite facies metamorphic rocks. Data contained herein demonstrate that the composition and geochemistry of the granitoid are compatible with the generation of the granitoid by partial anatexis of the metamorphic rocks that are part of the Cape River Metamorphics. Temperature and pressure of anatexis is determined to be between 800-850OC and 5-9kb. Under these conditions, experimental data indicate that meta-pelite and meta-greywacke will produce between 5-10% melt coexisting with biotite, cordierite, garnet and plagioclase. The mineralogy of the granitoid bodies in the Fat Hen Creek Complex is consistent with partial anatexis of meta-greywacke at these temperatures and pressures. 5-10% melt is generally insufficient to allow efficient separation of melt and restite. The granitoids of the Fat Hen Creek Complex are interpreted as being a closed system with melt generated during high-grade metamorphism not separating from the residium.
U/Pb dating of zircon from the Fat Hen Creek Complex indicate two distinct periods of zircon growth. The older episode occurred during the Late Cambrian to Early Ordovician. A second episode is dated as Middle Ordovician. This younger age coincides with the onset of regional compression, and may be related to exhumation of a mid-crustal layer during thrusting.
The Lolworth Batholith is one of three granite batholiths in the Lolworth-Ravenswood Province. It comprises mainly muscovite-biotite granite, with smaller areas of hornblende-biotite granite to granodiorite. Sills and dykes of muscovite and garnet-muscovite leucogranite extensively intrude both of these types.
The hornblende-biotite granite to granodiorite is metaluminous, with petrographic and geochemical characteristics similar to the adjacent Ravenswood Batholith. U-Pb SHRIMP ages also overlap with those from the Ravenswood Batholith. ENd(tc) values of ~-3 suggest a significant crustal contribution in the magma. Zircon populations determined using the SHRIMP suggest some inheritance from a Neoproterozoic source.
The two-mica granites make up over 80% of the batholith and show little variation throughout. Aluminium Saturation indices range dominantly from 1-1.1, in keeping with the muscovite-bearing nature of the granites. U-Pb ages are significantly younger than the hornblende-biotite granitoids. ENd(tc) is ~-10, suggesting a greater role for crustal material in these granites than in the hornblende-bearing varieties. Previously, these granites were interpreted as S-types, mainly on the basis of the presence of muscovite. Low Na/Ca and Na greater than K are both considered as indicators of source compositions and both are characteristic of a mafic igneous rather than a meta-sedimentary source. Anatexis of mafic igneous rocks at temperatures less than~1000OC are found experimentally to produce peraluminous melts similar to those which produced the two-mica granites.
The third major rock-type in the Lolworth Batholith is muscovite leucogranite, which occurs as sills and dykes intruding older granites and basement. The age of the leucogranite was not determined, but it has sharp contacts with the two-mica granite suggesting that the latter had cooled prior to intrusion of the former. The leucogranite is strongly peraluminous and is deemed to have been derived from anatexis of a supra-crustal (meta-sedimentary) source.
The batholith is therefore deemed to comprise three different elements. The hornblende-biotite granitoids are the western extension of the adjacent Ravenswood Batholith. The two-mica granite and muscovite leucogranite are derived from different sources, but may be part of the same crustal anatexis event.
During the Early Palaeozoic, the Lolworth-Ravenswood Province saw the intrusion of three granite batholiths into a basement of Late Neoproterozoic to Cambrian meta-sedimentary rocks. Also, Late Cambrian to Early Ordovician and Middle Ordovician high-grade metamorphism accompanied by partial anatexis is recorded at several sites across northeast Queensland. Although this metamorphism is restricted to these sites, they are widespread across the area suggestive of a widespread metamorphic event at these times. Similar metamorphism is recorded in the Arunta Inlier in Central Australia increasing the possible extent of this event.
The geochemistry, isotopic characteristics and zircon populations of granites in the Lolworth-Ravenswood Province are used to characterise their source rocks; and thus the basement to the Province. Precambrian basement is indicated to underlie the entire province. However, the source rocks for the eastern part of the Province (Ravenswood and into the Lolworth Batholiths) are different to source rocks for the western part of the Province. Georgetown-type crust extends eastwards from the outcropping area, extending under the western Lolworth-Ravenswood Province.
Late Mesoproterozoic rocks are recorded from the Cape River area adjacent to the Lolworth Batholith. They are also indicated as source-rocks for granites in the Ravenswood Batholith. Rocks of this age are characteristic of Grenvillian-age mobile belts in the United States. Their presence in north Qeensland has implications for the breakup of Rodinia, the Mesoproterozoic-age super continent that broke up during the Neoproterozoic.
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Hutton, Laurie James. "Petrogenesis of I- and S-type Granites in the Cape River - Lolworth area, northeastern Queensland - Their contribution to an understanding of the Early Palaeozoic Geological History of northeastern Queensland". Queensland University of Technology, 2004. http://eprints.qut.edu.au/15858/.
Testo completoAbstract (sommario):
The geological history of the Early Palaeozoic in eastern Australia is not known precisely. The eastern margin of the outcropping Precambrian Craton 'Tasman Line' is poorly understood. The Thomson Orogen, which underlies much of eastern Queensland, lies to the east of the Tasman Line. Basement to the Tasman Orogenic Zone is poorly understood, but knowledge of this basement is critical to our understanding to the processes that formed the eastern margin of the Precambrian craton. The Lolworth-Ravenswood Province lies to the east of the Tasman Line in northeast Queensland. A study of basement terranes in the Lolworth-Ravenswood Province will therefore provide some insights as to the nature of crust beneath this area, and therefore to the basement to the Thomson Orogen. The Fat Hen Creek Complex comprises para-authchthonous bodies of granitoid within middle to upper amphibolite facies metamorphic rocks. Data contained herein demonstrate that the composition and geochemistry of the granitoid are compatible with the generation of the granitoid by partial anatexis of the metamorphic rocks that are part of the Cape River Metamorphics. Temperature and pressure of anatexis is determined to be between 800-850OC and 5-9kb. Under these conditions, experimental data indicate that meta-pelite and meta-greywacke will produce between 5-10% melt coexisting with biotite, cordierite, garnet and plagioclase. The mineralogy of the granitoid bodies in the Fat Hen Creek Complex is consistent with partial anatexis of meta-greywacke at these temperatures and pressures. 5-10% melt is generally insufficient to allow efficient separation of melt and restite. The granitoids of the Fat Hen Creek Complex are interpreted as being a closed system with melt generated during high-grade metamorphism not separating from the residium. U/Pb dating of zircon from the Fat Hen Creek Complex indicate two distinct periods of zircon growth. The older episode occurred during the Late Cambrian to Early Ordovician. A second episode is dated as Middle Ordovician. This younger age coincides with the onset of regional compression, and may be related to exhumation of a mid-crustal layer during thrusting. The Lolworth Batholith is one of three granite batholiths in the Lolworth-Ravenswood Province. It comprises mainly muscovite-biotite granite, with smaller areas of hornblende-biotite granite to granodiorite. Sills and dykes of muscovite and garnet-muscovite leucogranite extensively intrude both of these types. The hornblende-biotite granite to granodiorite is metaluminous, with petrographic and geochemical characteristics similar to the adjacent Ravenswood Batholith. U-Pb SHRIMP ages also overlap with those from the Ravenswood Batholith. ENd(tc) values of ~-3 suggest a significant crustal contribution in the magma. Zircon populations determined using the SHRIMP suggest some inheritance from a Neoproterozoic source. The two-mica granites make up over 80% of the batholith and show little variation throughout. Aluminium Saturation indices range dominantly from 1-1.1, in keeping with the muscovite-bearing nature of the granites. U-Pb ages are significantly younger than the hornblende-biotite granitoids. ENd(tc) is ~-10, suggesting a greater role for crustal material in these granites than in the hornblende-bearing varieties. Previously, these granites were interpreted as S-types, mainly on the basis of the presence of muscovite. Low Na/Ca and Na greater than K are both considered as indicators of source compositions and both are characteristic of a mafic igneous rather than a meta-sedimentary source. Anatexis of mafic igneous rocks at temperatures less than~1000OC are found experimentally to produce peraluminous melts similar to those which produced the two-mica granites. The third major rock-type in the Lolworth Batholith is muscovite leucogranite, which occurs as sills and dykes intruding older granites and basement. The age of the leucogranite was not determined, but it has sharp contacts with the two-mica granite suggesting that the latter had cooled prior to intrusion of the former. The leucogranite is strongly peraluminous and is deemed to have been derived from anatexis of a supra-crustal (meta-sedimentary) source. The batholith is therefore deemed to comprise three different elements. The hornblende-biotite granitoids are the western extension of the adjacent Ravenswood Batholith. The two-mica granite and muscovite leucogranite are derived from different sources, but may be part of the same crustal anatexis event. During the Early Palaeozoic, the Lolworth-Ravenswood Province saw the intrusion of three granite batholiths into a basement of Late Neoproterozoic to Cambrian meta-sedimentary rocks. Also, Late Cambrian to Early Ordovician and Middle Ordovician high-grade metamorphism accompanied by partial anatexis is recorded at several sites across northeast Queensland. Although this metamorphism is restricted to these sites, they are widespread across the area suggestive of a widespread metamorphic event at these times. Similar metamorphism is recorded in the Arunta Inlier in Central Australia increasing the possible extent of this event. The geochemistry, isotopic characteristics and zircon populations of granites in the Lolworth-Ravenswood Province are used to characterise their source rocks; and thus the basement to the Province. Precambrian basement is indicated to underlie the entire province. However, the source rocks for the eastern part of the Province (Ravenswood and into the Lolworth Batholiths) are different to source rocks for the western part of the Province. Georgetown-type crust extends eastwards from the outcropping area, extending under the western Lolworth-Ravenswood Province. Late Mesoproterozoic rocks are recorded from the Cape River area adjacent to the Lolworth Batholith. They are also indicated as source-rocks for granites in the Ravenswood Batholith. Rocks of this age are characteristic of Grenvillian-age mobile belts in the United States. Their presence in north Qeensland has implications for the breakup of Rodinia, the Mesoproterozoic-age super continent that broke up during the Neoproterozoic.
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Payne, J. L. "The Poodla Granite in the Olary Domain, South Australia: Intrusive relationships, alteration and implications for Cu-Au mineralisation". Thesis, 2003. http://hdl.handle.net/2440/112941.
Testo completoAbstract (sommario):
This item is only available electronically.The Palaeoproterozoic Poodla Granite within the Olary Domain, Curnamona Province, South Australia, has been suggested as a direct contributor to Cu-Au mineralisation within the region on the basis of age correlations. Alteration present within the Poodla Granite consists of four styles that have been interpreted as two events. The first event includes pervasive potassic alteration followed by pervasive Na-Ca alteration. Sm/Nd isotope analysis indicates fluids for this event were sourced from the Willyama Supergroup sediments. The second event consists of fracture-controlled sodic and Ca-Na-Si alteration with associated actinolite/clinopyroxene brecciation. Utilisation of magmatic major element trends obtained from a natural analogue (Mt Angelay Complex, Cloncurry District) has allowed greater accuracy in chemical characterisation of alteration. Fluid inclusion analysis has identified two distinct fluids involved in the later fracture-controlled sodic and Ca-Na-Si alteration event. Namely, a low salinity (18-26wt% NaCl equivalent) and a high salinity (35-45wt% NaCl equivalent) fluid. A later fluid mobilisation event related to the Palaeozoic Delamerian Orogeny is indicated by re-equilibration of the Rb/Sr isotopic system. New age constraints from other granites in the I-type suite, to which Poodla Granite belongs, suggest the Poodla Granite did not have direct hydrothermal input into regional Cu-Au mineralisation. Analysis of alteration chemistry suggests that Cu and Au mobilisation occurred during the first alteration event. These results offer evidence for previously untested Cu-Au mineralising models within the region and may encourage exploration for Cu-Au resources.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2003
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Quelhas, Pedro Moniz. "Petrology and geochemistry of the igneous rocks from Macao (South China) : Tectono-magmatic implications". Doctoral thesis, 2019. http://hdl.handle.net/10451/44158.
Testo completoAbstract (sommario):
The territory of Macao is composed of several granitic intrusions belonging to one of the biggest granite provinces in the world, the Southeast China Magmatic Belt (SCMB), located in the southeast (SE) area of the Cathaysia Block. The SCMB is known by the occurrence of large volumes of Mesozoic magmatic rocks (over 90% are granitic rocks and equivalent volcanic rocks with minor basalts), occupying a total outcrop area of nearly 200.000 km2. The geology of Macao (~30 Km2) is dominated by granitic rocks displaying a wide range of textural, mineralogical and chemical features, making it an ideal region to study these rocks and the petrogenetic processes responsible for their diversity.
This study employed a wide range of research methodologies, namely field studies, petrography, zircon geochronology, mineral chemistry, whole-rock elemental and isotopic geochemistry to determine the nature of the source, the petrogenetic processes and the tectonic regimes of the Mesozoic magmatism in this region. Thus, the data collected along this study aims to provide new knowledge on the tectono-magmatic evolution of Macao, in particular, and of SE China, in general.
The results obtained from the high-precision U–Pb zircon geochronology, acquired through isotope dilution thermal ionization mass spectrometry (ID-TIMS) and in-situ laser ablation multi-collector inductively coupled mass spectrometry (LA-MC-ICPMS), revealed different ages for Macao granites. Despite its relatively small area, the determined ages tightly constrain the Macao granitic magmatism to two periods, ranging from 164.5 ± 0.6 to 162.9 ± 0.7 Ma (MGI – Macao Group I granites) and 156.6 ± 0.2 to 155.5 ± 0.8 Ma (MGII – Macao Group II granites). In addition, younger dacitic rocks were dated at 150.6 ± 0.6 Ma and <120 Ma. The existence of two proximal but distinct granitic pulses, spanning for a time of about 9 Ma and separated by ca. 6 Ma, in the Macao granitic suite suggests that it was incrementally assembled. This hypothesis is also extendable to the neighbouring Hong Kong region, where the magmatic activity occurred in four major pulses spanning for about 24 Ma. However, the MGII granites indicate the occurrence, on the Pearl River Delta region, of a magmatic pulse between those defined in Hong Kong at the origin of Lamma Suite (165–160 Ma) and the Kwai Chung Suite (148–146 Ma). In addition, Rare Element Earth (REE) ratios suggest that this pulse may only occur in Macao area, while MGI granites show evolving trends of REE ratios similar to those of Jurassic granites outcropping in vast areas of the Cathaysia Block (SE China). Inheritance patterns in the zircon U–Pb data indicate the presence of a population of antecrysts (165–180 Ma) crystallized from earlier magmatic pulses and a population of inherited zircons, from Precambrian to Phanerozoic sources, incorporated into the magmas during melting and/or ascent/emplacement at crustal levels. The oldest inherited ages (2.4 Ga and possibly 2.9 Ga) suggest contribution of Proterozoic and possibly of late Archaean crustal sources for the Macao magmatism.
The granitic rocks of Macao are mainly high-K calc-alkaline metaluminous to weakly peraluminous I-type granites with variable degrees of fractionation. Fractional crystallization played an important role in the evolution of these granites, though the fractionation paths differ for the highly fractionated facies of both groups mainly due to distinct accessory fractionating phases. Such difference is evident by distinct REE evolution trends: while MGI magmas seem to have evolved by gradual enrichment in heavy REE relatively to light REE, originating progressively flatter REE patterns, magmas from MGII are marked by depletion of middle REE, leading to progressively concave upward REE patterns. However, while most of the geochemical variation of the MGII granites can be explained by fractional crystallization, the same is not true for MGI granites. The MGI highly fractionated granites show evidence for the REE tetrad effect and are characterized by non-CHArge-and-RAdius-Controlled (non-CHARAC) behaviour of trace elements, suggesting late-stage melt/fluid interactions involving F-rich fluids. The stage of evolution represented by the MGI highly fractionated granites corresponds to the onset of fluid/melt interaction in a highly evolved granitic system, which may have led to enhanced hydrothermal activity in more evolved stages, as those represented in neighbouring areas in SE China. Significant differences in isotopic composition were also observed, with the MGII being characterized by a much narrow range of initial 87Sr/86Sr ratios and εNd(t) and εHf(t) values than MGI. Based on these differences, the MGII granites are considered to be part of a comagmatic suite that has evolved in closed system, contrasting with what can be inferred for MGI. The increase in initial 87Sr/86Sr ratios with degree of evolution, the presence of metasedimentary enclaves and the high percentage of inherited zircon with Paleozoic ages in MGI, suggest the occurrence of an assimilation fractionation crystallization (AFC) process. The AFC processes were a major cause for the I-S transitional characteristics of the MGI highly fractionated granites and possibly of the other similar Jurassic biotite granites in SE China. The observed decoupling of Sr, Nd and Hf isotope systems might have resulted from magma mixing between the granitic and more mafic magmas, which caused the homogenization of Sr isotope ratios but not of the Nd and Hf ones. Such process is also supported by the occurrence of Microgranular Mafic Enclaves (MME) hosted by the granites.
Isotope and major element compositions together with model ages strongly suggest that Macao granitic magmas were generated by partial melting of infracrustal medium-to-high K basaltic Paleo-Proterozoic to Mesoproterozoic protoliths heated by, and mixed to some degree with mantle-derived magmas. The temporal and spatial association of Macao and SE China Jurassic I-type granites with basaltic/gabbroic rocks, syenites and A-type granites, displaying typical intraplate chemical features, indicates an extensional regime rather than an active margin for the origin of these rocks. It also points to an important role of mantle-derived magmas in the production of SE China Jurassic granites. Adiabatic decompression melting of the asthenospheric mantle produced mafic magmas, which underplated at the base of the crust (Moho), subsequently triggering partial melting of the lower crust to generate the granitic magmas. The Jurassic Macao granites are interpreted as being produced in an intraplate extensional setting related to the break-off and foundering of a previously flat-slab (Paleo-Pacific plate) beneath the Eurasian plate.
The boundary between east and west Cathaysia blocks is roughly along the Zhenghe-Dapu Fault (ZDF), which intersects the SE China coast near Hong Kong and is thought to have played a major role for the Mesozoic magmatic activity in this region. The stronger isotopic affinities of Macao granites with the other granitic rocks and lower crustal xenoliths from the western Cathaysia Block suggest that the ZDF is likely to pass south of Macao, a fact that has not been mentioned before.
In addition to the Early Yanshanian (Jurassic) granitic magmatism in Macao, the younger ages obtained for the dacite dykes indicate that the territory was also affected, to a lesser degree, by Late Yanshanian (Cretaceous) magmatism. The transition from granitic to dacitic magmatism most likely corresponds to a change in the regional tectonic regime, which induced a significant change in the magma genesis processes. In contrast with the intraplate features of Macao and SE China Jurassic granites and coeval mafic rocks, the geochemical features of the Macao dacite dykes (e.g. high LILE/HFSE ratios and negative anomalies of Nb, Ta and Ti) are identical to those characterizing arc-like subduction-related magmas. These dacites are most likely evolved products of arc-like magmatism and may testify the reestablishment of a normal subduction system in this area of SE China.
Libri sul tema "I-type granite"
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Allende, Isabel. Retrato en sepia. Waterville, Maine: Thorndike Press, 2002.
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Allende, Isabel. Portrait in sepia: A novel. New York: HarperCollins, 2001.
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Allende, Isabel. Retrato en sepia: Una novella. Madrid, España: Plaza & Janes Editores, S.A., 2000.
Cerca il testo completoCapitoli di libri sul tema "I-type granite"
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Stern, Charles R., e Peter J. Wyllie. "Phase Relationships of I-Type Granite With H20 to 35 Kilobars: The Dinkey Lakes Biotite-Granite From the Sierra Nevada Batholith". In 1989, Granites and Rhyolites, 10412–22. Washington, DC: American Geophysical Union, 2013. http://dx.doi.org/10.1002/9781118782057.ch17.
Testo completo
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Toma, Stefánia. "Counteracting the Schools’ Demon: Local Social Changes and Their Effects on the Participation of Roma Children in School Education". In Social and Economic Vulnerability of Roma People, 117–33. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-52588-0_8.
Testo completoAbstract (sommario):
AbstractThe aim of the article (The empirical material leading to the present chapter results from the research effort “MigRom—The Immigration of Romanian Roma to Western Europe: Causes, effects, and future engagement strategies”, a project funded by the European Union’s Seventh Framework Programme under the call “Dealing with diversity and cohesion: the case of the Roma in the European Union” (GA319901). I also used the results and experiences of earlier fieldworks starting with 2000 in Bighal (the name of the localities were changed in order to respect the identities of the people) that were financed through Open Society Institute, Visegrad Funds, CERGE-EI through GDN and WIIW, respectively Inclusion 2007 through PHARE 2004. Earlier version of the article was presented at the GLS Conference in Nicosia (Cyprus) in 2017. The article was finalized in the framework of a visiting research programme at TARKI-POLC receiving funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 730998, “InGRID-2—Integrating Research Infrastructure for European expertise on Inclusive Growth from data to policy”.) is to inquire into the interconnectedness of large number of factors that carry the opportunity and possibility of improving school participation of Roma children in Romania.I argue that the inherent deficiencies of the educational system, starting with the structural constraints and ending with the psycho-social context in which Roma (or minoritized, marginalized, vulnerable) children learn, can be and are challenged by initiatives, strategies or processes that fall out of the immediate range of the strict framework of the educational system. Bourdieu used the Maxwell’s demon as a metaphor to illustrate the reproduction of socio-economic inequalities in the framework of school system. But this ‘demon’ might be challenged with more or less success if we step out and look for possible ‘tools’ to counteract this demon. Two such cases are presented in this chapter. One is a project implemented with and by the local Roma community using external financing and the other one is the participation of the members of the communities in international migration and use of remittances. I will emphasize that independently of the type and amount of the mobilized resources the individuals and/or communities are able to create and proactively make good use of path-departing opportunities through mechanisms of redefining and changing contextual constraints thus improvements can be observed in the school participation of the Roma children (PS. PS. The article was written before the COVID-19 pandemic hit the world. Its effects seems to neutralize the positive impact of the above mentioned processes: the slow steps taken in improving the socio-economic situation of the Roma seems to be stopped; prejudices and ethnic hatred seems to be stronger; access to services for Roma communities get more difficult, including to education: in this context, a further research question is how on-line schooling changed or will change the participation of Roma children?).
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Miedema, Frank. "Science in Transition How Science Goes Wrong and What to Do About It". In Open Science: the Very Idea, 67–108. Dordrecht: Springer Netherlands, 2021. http://dx.doi.org/10.1007/978-94-024-2115-6_3.
Testo completoAbstract (sommario):
AbstractScience in Transition, which started in 2013, is a small-scale Dutch initiative that presented a systems approach, comprised of analyses and suggested actions, based on experience in academia. It was built on writings by early science watchers and most recent theoretical developments in philosophy, history and sociology of science and STS on the practice and politics of science. This chapter will include my personal experiences as one of the four Dutch founders of Science in Transition. I will discuss the message and the various forms of reception over the past 6 years by the different actors in the field, including administrators in university, academic societies and Ministries of Higher Education, Economic Affairs and Public Health but also from leadership in the private sector. I will report on my personal experience of how these myths and ideologies play out in the daily practice of 40 years of biomedical research in policy and decision making in lab meetings, at departments, at grant review committees of funders and in the Board rooms and the rooms of Deans, Vice Chancellors and Rectors.It has in the previous chapters become clear that the ideology and ideals that we are brought up with are not valid, are not practiced despite that even in 2020 they are still somehow ‘believed’ by most scientists and even by many science watchers, journalists and used in political correct rhetoric and policy making by science’s leadership. In that way these ideologies and beliefs mostly implicitly but sometimes even explicitly determine debates regarding the internal policy of science and science policy in the public arena. These include all time classic themes like the uniqueness of science compared to any other societal activity; ethical superiority of science and scientists based on Mertonian norms; the vocational disinterested search for truth, autonomy; values and moral (political) neutrality, dominance of internal epistemic values and unpredictability regards impact. These ideas have influenced debates about the ideal and hegemony of natural science, the hierarchy of basic over applied science; theoretical over technological research and at a higher level in academic institutions and at the funders the widely held supremacy of STEM over SSH. This has directly determined the attitudes of scientists in the interaction with peers within the field, but also shaped the politics of science within science but also with policy makers and stakeholders from the public and private sector and with interactions with popular media.Science it was concluded was suboptimal because of growing problems with the quality and reproducibility of its published products due to failing quality control at several levels. Because of too little interactions with society during the phases of agenda setting and the actual process of knowledge production, its societal impact was limited which also relates to the lack of inclusiveness, multidisciplinarity and diversity in academia. Production of robust and significant results aiming at real world problems are mainly secondary to academic output relevant for an internally driven incentive and reward system steering for academic career advancement at the individual level. Similarly, at the higher organizational and national level this reward system is skewed to types of output and impact focused on positions on international ranking lists. This incentive and reward system, with flawed use of metrics, drives a hyper-competitive social system in academia which results in a widely felt lack of alignment and little shared value in the academic community. Empirical data, most of it from within science and academia, showing these problems in different academic disciplines, countries and continents are published on virtually a weekly basis since 2014. These critiques focus on the practices of scholarly publishing including Open Access and open data, the adverse effects of the incentive and reward system, in particular its flawed use of metrics. Images, ideologies and politics of science were exposed that insulate academia and science from society and its stakeholders, which distort the research agenda and subsequentially its societal and economic impact.
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A. El Bahariya, Gaafar. "An Overview on the Classification and Tectonic Setting of Neoproterozoic Granites of the Nubian Shield, Eastern Desert, Egypt". In Geochemistry. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95904.
Testo completoAbstract (sommario):
Granites constitute the main rock components of the Earth’s continental crust, which suggested to be formed in variable geodynamics environments. The different types of granitic rocks, their compositional characteristics, tectonic settings and magma sources are outlined. Mineralogical classification of granites includes four rock types: tonalites, granodiorites, granite (monzogranite and syenogranites) and alkali-feldspar granites. Alphabetical classification subdivided granites into: I-type, S-type, A-type and M-type granites. Moreover, formation of granitic magmas requires distinctive geodynamic settings such as: volcanic arc granite (Cordilleran); collision-related granites (leucogranites); intra-plate and ocean ridge granites. The Eastern Desert of Egypt (ED) forms the northern part of Nubian Shield. Both older and younger granites are widely exposed in the ED. Old granites (OG) comprise tonalites and granodiorites of syn- to late-orogenic granitoid assemblages. They are calcalkaline, I-type, metaluminous and display island arc tectonic setting. Younger granites (YG) on the other hand, include granites, alkali-feldspar granites and minor granodiorites. They are of I- and A-type granites and of post-orogenic to anorogenic tectonic settings. The majority of the YG are alkaline, A-type granite and of within-plate tectonic setting (WPG). The A-type granites are subdivided into: A2-type postorogenic granites and A1-type anorogenic granites. Granite magma genesis involves: (a) fractional crystallization of mafic mantle-derived magmas; (b) anatexis or assimilation of old, upper crustal rocks (c) re - melting of juvenile mafic mantle – derived rocks underplating the continental crust. Generally, older I-type granitoids were interpreted to result from melting of mafic crust and dated at approximately 760–650 Ma, whereas younger granites suggested to be formed as a result of partial melting of a juvenile Neoproterozoic mantle source. Moreover, they formed from anatectic melts of various crustal sources that emplaced between 600 and 475 Ma.
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René, Miloš. "Investigation of Accessory Minerals from the Blatná Granodiorite Suite, Bohemian Massif, Czech Republic". In Mineralogy [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.102628.
Testo completoAbstract (sommario):
The Central Bohemian magmatic complex belongs to the Central European Variscan belt. The granitic rocks of this plutonic complex are formed by several suites of granites, granodiorites, and tonalites, together with small bodies of gabbros, gabbro diorites, and diorites. The granodiorites of the Blatná suite are high-K, calc-alkaline to shoshonitic, and metaluminous to slightly peraluminous granitic rocks. Compared to the common I-type granites, granodiorites of the Blatná suite are enriched in Mg (1.0–3.4 wt.% MgO), Ba (838–2560 ppm), Sr. (257–506 ppm), and Zr (81–236 ppm). For granodiorites of the Blatná suite is assemblage of apatite, zircon, titanite, and allanite significant. Zircon contains low Hf concentrations (1.1–1.7 wt.% HfO2). The composition of titanite ranges from 83 to 92 mol.% titanite end-member. Allanite is relatively Al-poor and displays Feox. ratio 0.2–0.5.
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Chappell, B. W., e A. J. R. White. "I- and S-type granites in the Lachlan Fold Belt". In Geological Society of America Special Papers, 1–26. Geological Society of America, 1992. http://dx.doi.org/10.1130/spe272-p1.
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Champion, David C., e Bruce W. Chappell. "Petrogenesis of felsic I-type granites: an example from northern Queensland". In Geological Society of America Special Papers, 115–26. Geological Society of America, 1992. http://dx.doi.org/10.1130/spe272-p115.
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Chen, Cheng-Hong, Wayne Lin, Hsueh-Yu Lu, Chi-Yu Lee, Jung-Li Tien e Yi-Hsin Lai. "Cretaceous fractionated I-type granitoids and metaluminous A-type granites in SE China: the Late Yanshanian post-orogenic magmatism". In The Fourth Hutton Symposium on the Origin of Granites and Related Rocks. Geological Society of America, 2000. http://dx.doi.org/10.1130/0-8137-2350-7.195.
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Sawka, W. N., M. T. Heizler, R. W. Kistler e B. W. Chappell. "Geochemistry of highly fractionated I- and S-type granites from the tin-tungsten province of western Tasmania". In Geological Society of America Special Papers, 161–80. Geological Society of America, 1990. http://dx.doi.org/10.1130/spe246-p161.
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Grubb, Philip W., Peter R. Thomsen, Tom Hoxie e Gordon Wright. "The Nature and Origins of Patent Rights". In Patents for Chemicals, Pharmaceuticals, and Biotechnology. Oxford University Press, 2016. http://dx.doi.org/10.1093/oso/9780199684731.003.0002.
Testo completoAbstract (sommario):
This chapter begins by setting out the definition of a patent, covering issues such as exclusionary right, property right, and limited duration. It then traces the early history of patents in England. During the reign of Queen Elizabeth I, monopolies in commodities such as salt, coal, playing cards, and many others were frequently granted by letters patent either to raise revenue, or to reward royal favourites at the public expense. The first English patent granted to an inventor in the modern sense of the word appears to have been that to Giacopo Acontio in 1565 for a new type of furnace. The remainder of the chapter discusses the early histories of patents in Continental Europe (Venice, Germany, France, and the Netherlands) and North America.
Atti di convegni sul tema "I-type granite"
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Li, Haiquan, Wenxiao Zhou e Youye Zheng. "Triassic intraplate I-type granite in eastern Tianshan, NW China: partial melting of low crust during asthenosphere underplating with crustal reworking". In Goldschmidt2022. France: European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.8491.
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Castro, Antonio, e Daniel Gómez-Frutos. "Sanukitoids and the Origin of Secondary I-Type Granites". In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.336.
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Qin, Zhengwei, e Wolfgang Siebel. "The source nature, magma evolution of I-type granites revealed by zircon morphology and grain-scale Hf-O isotopes". In Goldschmidt2022. France: European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.13180.
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Stirling, Jack, Anthony Kemp, Steven Denyszyn e Malcolm McCulloch. "Generation of granites and continental growth in eastern Australia: An analysis of compositional variation in the ‘I-type’ Siluro-Devonian Bega Batholith". In Goldschmidt2022. France: European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.10817.
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Cempel, Czesław, e Dariusz Pleban. "VIBROACOUSTIC HAZARD IN THE ENVIRONMENT". In 18th International Conference Noise Control 2019. Centralny Instytut Ochrony Pracy – Państwowy Instytut Badawczy, 2019. http://dx.doi.org/10.54215/noisecontrol2019_cempel_pleban.
Testo completoAbstract (sommario):
Jednym z procesów fizycznych w naturze, środowisku pracy i życia człowieka są zjawiska akustyczne polegające na propagacji ruchu oscylacyjnego (wibracyjnego) w otoczeniu: gazowym (np. powietrze), ciekłym (np. woda), stałym (np. grunt, materiały konstrukcyjne). W gospodarce i technice niezamierzona generacja zjawisk akustycznych przybiera nieraz znaczne poziomy, na granicy bólu dla słuchu (120-130 dBA), lub innego typu szkodliwego oddziaływania, czyli zagrożenia zdrowia czy nawet życia. W pracy przedstawiono w skrótowej formie współczesne myślenie o zagrożeniach wibroakustycznych w środowisku naturalnym oraz w środowisku pracy i życia człowieka.
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Savion, N., A. Gamliel e N. Farzame. "THROMBIN INTERACTION WITH CULTURED AORTIC AND CAPILLARY ENDOTHELIAL CELLS: BINDING, INTERNALIZATION, DEGRADATION AND RELEASE OF PROTEASE NEXINS". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644734.
Testo completoAbstract (sommario):
Thrombin (Th) binds specifically to confluent cultures of bovine aortic (ABAE) and brain capillary (BBC) endothelial cells. Saturation of 125I-Th binding is observed after 1 h exposure to the ligand and at an extracellular concentration of 0.5 and 1.0 µg/ml for ABAE and BBC cells, respectively. Under optimal conditions both ABAE and BBC cultures bind about 2 to 5 ng/106 cells, which represents about 20% of Th binding.to bovine corneal endothelial (BCE) cells. The cell associated 125I-Th in ABAE and BBC cells is internalized and degraded as described in BCE cells. The nature of the cell associated radioactivity is analyzed on SDS-polyacrylamide -gel electrophoresis and in ABAE and BBC cells about 30% of the I-Th appears in a complex with protease nexin I (PN I) while in BCE cells about 70% of the binding is mediated by PN I. ABAE cells possess 3 types of complexes, one which appears only on the cell surface with a molecular weight of 78 kDa, and two other complexes which appear only in the conditioned medium (CM) with molecular weights of 84 and 85 kDa. BBC and BCE cells demonstrate only one type of complex with a molecular weight of 77 kDa which appears both on the cell surface and in the CM. Preincubation of BCE cultures in the presence of Th is known to up-regulate the amount of PN I on the cell surface and in the CM, but this Th induced up-regulation effect is not observed in ABAE or BBC cells.The results described above indicate a difference between ABAE and BBC cells although both cell types growunder similar conditins and demonstrate similar morphological appearance. However, in both vascular endothelial cell types the total amount of PN I and its metabolism is relatively small compared to corneal endothelial cells. It, therefore, may indicate the lower capacity of vascular endothelial cells to control serine proteases activity at or near their cell surfaces as compared to corneal endothelial cells. This research was supported by a grant from the NationalCouncil for Research and Development, Israel and G.S.F. Munchen, Germany
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Rendu, F., T. Hovig, P. Marche, M. Lebret, D. Tenza, J. Maclouf, J. P. Caen e S. Levy-Toledano. "MEMBRANE SIGNAL TRANSDUCTION IN PLATELETS WITH ALTERED RELEASE REACTION". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644746.
Testo completoAbstract (sommario):
The process of signal transduction during thrombin-induced activation was studied in pathological platelets characterized by a defect in a specific storage granule, i.e. from Hermansky-Pudlak syndrome (HPS) and from Grey-Platelet Syndrome (GPS). HPS platelets exhibited an apparently normal ultrastructure except for a decreased number of dense bodies. Grey platelets showed marked vacuolization and an almost total absence of alpha-granules. During thrombin stimulation both types of platelets showed the same tendency of centralization of the organelles present indicating that neither type of granule is a prerequisite for this ring-like structure.However this granule centralization was clearly delayed in GPS where it occurred 15 sec after thrombin addition instead of 5 sec in normal platelets. The transducing system involving phosphoinositides specific phospholipase C was observed in platelets lacking dense bodies (HPS) but the phosphatidyl 4,5 bisphosphate(PIP2 )breakdown in 32P-prelabelled platelets was measurable at 202 sec instead of 10 sec in normal platelets. No ch activity was detectable at any time in grey platelets. 32P-phosphatidate (PA) formation was subnormal in HPS platelets and normal in grey platelets. Phosphorylation pattern of myosin light chain (P20) and of 43K protein (P43) were normal in HPS platelets and markedly reduced in grey platelets, being less than half of the normal during the first 15 sec and remaining subnormal even after complete aggregation. The release of constituents from the present granules and the thromboxane formation were lower than in normal platelets in all cases. In conclusions, (i) alpha-granules but not dense bodies may play a key role in the activation of the PIP2 specific phospholipase C,(ii) PA formation does not always correlate with phosphoinositide metabolism and could originate from another pool of diacylglycerol,(iii) complete phosphorylations of both P20 and P43 may not be sufficient to stimulate a normal release, and (iv) end products such as thromboxanes and released ADP accelerate and reinforce platelet responses.
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Sylvestre Nguo, Kanouo, Kouske Patrice Arnaud, Lentz Richard David e Yongue Fouateu Rose. "Zircon Textural Analyses, Th/U and Geochronology, Tools to Understand Neoproterozoic to Cretaceous Events Registered by I-Type Anatectic Granitic Basement in the Mamfe Basin (SW Cameroon, Centra Africa)". In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.2518.
Testo completo
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Belloc, F., P. Hourdille, M. Boisseau e A. T. Nurden. "FIBRINOGEN SYNTHESIS BUT DEFECTIVE STORAGE IN THE PLATELETS OF A PATIENT WITH GLANZMANN’S THROMBASTHENIA". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644739.
Testo completoAbstract (sommario):
Patient A.M. has a lifelong history of bleeding episodes and platelet function defects typical of type I Glanzmann's thrombasthenia. Analysis of platelet membrane glycoproteins (GP) by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) or by studying the binding of monoclonal antibodies to intact platelets, confirmed the presence of only trace amounts of GP lib and GP Ilia. SDS-PAGE also revealed a severe deficiency of the alpha-granule pool of platelet fibrinogen although an immunoblot performed using a monospecific rabbit anti-fibrinogen antibody showed the presence of residual amounts of fibrinogen. This was estimated to be approximately 10 % of the normal range by an ELISA procedure. Incubation of washed platelets from A.M. with (35S) methionine for 3 h at 37°C resulted in the incorporation of radioactivity into multiple protein bands as revealed by SDS-PAGE followed by fluorography. Immunoprecipitation experiments with affinity purified anti-fibrinogen IgG bound to ultrogel confirmed the synthesis of fibrinogen. The amounts of radioactivity obtained were similar to those immunoprecipitated from control platelet extracts under the same conditions. However, unlike for control platelets, the neosynthesized fibrinogen in A.M. platelets was no longer detected after a 18 h cold chase. In contrast, neosynthesized thrombospondin of the patient was normally preserved during the same chase period. When the fate of the neosynthesized fibrinogen in A.M. platelets was studied it was found to be lost at a faster rate than in normal platelets. Immunoblotting experiments confirmed that cytoplasmic proteases may degrade fibrinogen when exposed to the protein. Our results suggest that the fibrinogen deficiency in the platelets of patients with type I thrombasthenia may be related to a storage abnormality in megakaryocytes or platelets and not from a synthesis defect.
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Chung, D. W., R. Asakai e E. W. Davie. "THE ORGANIZATION OF THE HUMAN FACTOR XI GENE: CORRELATION OF INTRON AND EXON LOCATIONS WITH STRUCTURAL DOMAINS". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1642802.
Testo completoAbstract (sommario):
Factor XI (plasma thromboplastin antecedent) is a plasma glycoprotein that participates in the contact activation of blood coagulation. In the present study, the organization of the gene for human factor XI has been elucidated. The gene for human factor XI has been isolated from two independent human genomic λ phage libraries using a full length cDNA for human factor XI as a hybridization probe. Four overlapping recombinant λ phage containing the human factor XI gene have been isolated and characterized. Restriction mapping, Southern blotting and hybridization studies indicate that the entire gene for human factor XI is 25 kilobases in length. Overlapping regions of the gene have been subcloned and the DNA sequence of selective regions has been determined. These results show that the gene for factor XI is composed of 15 exons and 14 introns. Exon I codes for the 5′ noncoding sequences and exon II codes for the signal peptide of 18 amino acid residues. The four tandem repeats that constitute the heavy chain of factor XIa are each encoded by two consecutive exons (exons III and IV, V and VI, VII and VIII, IX and X). The location of the introns and the junction type among these four tandem repeats are strictly conserved. Exon XI, XII, XIII, XIV and XV code for the light chain of factor XIa that contains the serine protease part of the molecule. The location of the introns and the junction types in this region of the gene are identical to those in the corresponding regions of the genes for human tissue plasminogen activator and porcine urokinase. These results show that gene duplication and exon shuffling play a significant role in the evolution of the human factor XI gene. (Supported in part by NIH Grant HL 16919 and AHA Grant 82-221.)
Rapporti di organizzazioni sul tema "I-type granite"
1
Henderson, Tim, Vincent Santucci, Tim Connors e Justin Tweet. National Park Service geologic type section inventory: Sonoran Desert Inventory & Monitoring Network. National Park Service, settembre 2022. http://dx.doi.org/10.36967/2294374.
Testo completoAbstract (sommario):
Type sections are one of several kinds of stratotype. A stratotype is the standard (original or subsequently designated), accessible, and specific sequence of rock for a named geologic unit that forms the basis for the definition, recognition, and comparison of that unit elsewhere. Geologists designate stratotypes for rock exposures that are illustrative and representative of the map unit being defined. Stratotypes ideally should remain accessible for examination and study by others. In this sense, geologic stratotypes are similar in concept to biological type specimens; however, they remain in situ as rock exposures rather than curated in a repository. Therefore, managing stratotypes requires inventory and monitoring like other geologic heritage resources in parks. In addition to type sections, stratotypes also include type localities, type areas, reference sections, and lithodemes, all of which are defined in this report. The goal of this project is to consolidate information pertaining to stratotypes that occur within NPS-administered areas, in order that this information is available throughout the NPS to inform park managers and to promote the preservation and protection of these important geologic heritage resources. This effort identified six stratotypes designated within four park units of the Sonoran Desert Inventory & Monitoring Network (SODN): Chiricahua National Monument (CHIR) has three type areas; Coronado National Memorial (CORO) has one type area; Gila Cliff Dwellings National Monument (GICL) has one type area; and Saguaro National Park (SAGU) has one type area. Table 1 provides information regarding the six stratotypes currently identified within SODN parks. There are currently no designated stratotypes within Casa Grande Ruins National Monument (CAGR), Fort Bowie National Historic Site (FOBO), Montezuma Castle National Monument (MOCA), Organ Pipe Cactus National Monument (ORPI), Tonto National Monument (TONT), Tumacácori National Historical Park (TUMA), or Tuzigoot National Monument (TUZI). However, CHIR, MOCA, SAGU, and TUZI contain important rock exposures that could be considered for formal stratotype designation as discussed in the “Recommendations” section. The inventory of geologic stratotypes across the NPS is an important effort in documenting these locations so that NPS staff may recognize and protect these areas for future studies. The focus adopted for completing the baseline inventories throughout the NPS has centered on the 32 inventory and monitoring (I&M) networks established during the late 1990s. Adopting a network-based approach to inventories worked well when the NPS undertook paleontological resource inventories for the 32 I&M networks and was therefore adopted for the stratotype inventory. The Greater Yellowstone I&M Network (GRYN) was the pilot network for initiating this project (Henderson et al. 2020). Methodologies and reporting strategies adopted for the GRYN have been used in the development of this report for the SODN. This report includes a recommendation section that addresses outstanding issues and future steps regarding park unit stratotypes. These recommendations will hopefully guide decision-making and help ensure that these geoheritage resources are properly protected and that proposed park activities or development will not adversely impact the stability and condition of these geologic exposures.
2
Kerber, Steve, Daniel Madrzykowski, James Dalton e Robert Backstrom. Improving Fire Safety by Understanding the Fire Performance of Engineered Floor Systems and Providing the Fire Service with Information for Tactical Decision Making. UL Firefighter Safety Research Institute, marzo 2012. http://dx.doi.org/10.54206/102376/zcoq6988.
Testo completoAbstract (sommario):
This research project was a collaboration of several research organizations, product manufacturers and fire service representatives to examine hazards associated with residential flooring systems to improve firefighter safety. Funding for this project was provided through the National Institute of Standards and Technology’s American Recovery and Reinvestment Act Grant Program. The main objective of this study was to improve firefighter safety by increasing the level of knowledge on the response of residential flooring systems to fire. Several types (or series) of experiments were conducted and analyzed to expand the body of knowledge on the impact of fire on residential flooring systems. The results of the study have been prepared to provide tactical considerations for the fire service to enable improved decision making on the fire scene. Experiments were conducted to examine several types of floor joists including, dimensional lumber, engineered I-joists, metal plate connected wood trusses, steel C-joists, castellated I-joists and hybrid trusses. Experiments were performed at multiple scales to examine single floor system joists in a laboratory up through a full floor system in an acquired structure. Applied load, ventilation, fuel load, span and protection methods were altered to provide important information about the impact of these variables to structural stability and firefighter safety. There are several tactical considerations that result from this research that firefighters can use immediately to improve their understanding, safety and decision making when sizing up a fire in a one or two family home. This report summarizes the results from each of the experimental series and provides discussion and conclusions of the results.
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Morin, Shai, Gregory Walker, Linda Walling e Asaph Aharoni. Identifying Arabidopsis thaliana Defense Genes to Phloem-feeding Insects. United States Department of Agriculture, febbraio 2013. http://dx.doi.org/10.32747/2013.7699836.bard.
Testo completoAbstract (sommario):
The whitefly (Bemisia tabaci) is a serious agricultural pest that afflicts a wide variety of ornamental and vegetable crop species. To enable survival on a great diversity of host plants, whiteflies must have the ability to avoid or detoxify numerous different plant defensive chemicals. Such toxins include a group of insect-deterrent molecules called glucosinolates (GSs), which also provide the pungent taste of Brassica vegetables such as radish and cabbage. In our BARD grant, we used the whitefly B. tabaci and Arabidopsis (a Brassica plant model) defense mutants and transgenic lines, to gain comprehensive understanding both on plant defense pathways against whiteflies and whitefly defense strategies against plants. Our major focus was on GSs. We produced transgenic Arabidopsis plants accumulating high levels of GSs. At the first step, we examined how exposure to high levels of GSs affects decision making and performance of whiteflies when provided plants with normal levels or high levels of GSs. Our major conclusions can be divided into three: (I) exposure to plants accumulating high levels of GSs, negatively affected the performance of both whitefly adult females and immature; (II) whitefly adult females are likely to be capable of sensing different levels of GSs in their host plants and are able to choose, for oviposition, the host plant on which their offspring survive and develop better (preference-performance relationship); (III) the dual presence of plants with normal levels and high levels of GSs, confused whitefly adult females, and led to difficulties in making a choice between the different host plants. These findings have an applicative perspective. Whiteflies are known as a serious pest of Brassica cropping systems. If the differences found here on adjacent small plants translate to field situations, intercropping with closely-related Brassica cultivars could negatively influence whitefly population build-up. At the second step, we characterized the defensive mechanisms whiteflies use to detoxify GSs and other plant toxins. We identified five detoxification genes, which can be considered as putative "key" general induced detoxifiers because their expression-levels responded to several unrelated plant toxic compounds. This knowledge is currently used (using new funding) to develop a new technology that will allow the production of pestresistant crops capable of protecting themselves from whiteflies by silencing insect detoxification genes without which successful host utilization can not occur. Finally, we made an effort to identify defense genes that deter whitefly performance, by infesting with whiteflies, wild-type and defense mutated Arabidopsis plants. The infested plants were used to construct deep-sequencing expression libraries. The 30- 50 million sequence reads per library, provide an unbiased and quantitative assessment of gene expression and contain sequences from both Arabidopsis and whiteflies. Therefore, the libraries give us sequence data that can be mined for both the plant and insect gene expression responses. An intensive analysis of these datasets is underway. We also conducted electrical penetration graph (EPG) recordings of whiteflies feeding on Arabidopsis wild-type and defense mutant plants in order to determine the time-point and feeding behavior in which plant-defense genes are expressed. We are in the process of analyzing the recordings and calculating 125 feeding behavior parameters for each whitefly. From the analyses conducted so far we conclude that the Arabidopsis defense mutants do not affect adult feeding behavior in the same manner that they affect immatures development. Analysis of the immatures feeding behavior is not yet completed, but if it shows the same disconnect between feeding behavior data and developmental rate data, we would conclude that the differences in the defense mutants are due to a qualitative effect based on the chemical constituency of the phloem sap.
4
Bacharach, Eran, e Sagar Goyal. Generation of Avian Pneumovirus Modified Clones for the Development of Attenuated Vaccines. United States Department of Agriculture, novembre 2008. http://dx.doi.org/10.32747/2008.7696541.bard.
Testo completoAbstract (sommario):
Abstract (one page maximum, single spaced), include: List the original objectives, as defined in the approved proposal, and any revisions made at the beginning or during the course of project: The main goal described in our original proposal has been the development of a molecular infectious clone of the avian metapneumovirus subtype B (aMPV-B) and the modification of this clone to create mutated viruses for the development of attenuated vaccines. The Achievements and Appendix/Part I sections of this report describes the accomplishments in creating such a molecular clone. These sections also contain the results of a longitudinal study that we made in Israel, demonstrating the infiltration of field strains of aMPV into vaccinated flocks and emphasizing the need for the development of better vaccines. We also describe our unexpected findings regarding the ability of aMPV to establish persistent infection in cell cultures. Although this direction of research was not described in the original proposal we feel that it is highly important for the understanding of aMPV pathogenesis. For example, this direction has provided us with evidence showing that aMPV replication can augment influenza replication. Moreover, we observed that viruses that were produced from chronically-infected cells show reduced ciliostasis. Accordingly, we carried vaccination trials using such viruses. In the original grant proposal we also offered that the American lab will clone and express immunomodulators in the context of an aMPV -based replicon that the Israeli lab has generated. However, as we reported in our annual reports, further analysis of this replicon by the Israeli lab has revealed that the level of expression achieved by this vehicle is relatively poor; thus, the American lab has focused on sequencing the genomes of different aMPV-C isolates that differ in their virulence (including vaccine strains). Achievements and Appendix/Part II sections of this report include the summary of this effort. Background to the topic: The aMPVs belong to the paramyxoviridae family and cause mild to severe respiratory tract diseases mainly in turkeys and also in chickens. Four aMPV subgroups, A, B, C and D, have been characterized; in Israel aMPV-A and B are the common subtypes while in the USA type C is the prevalent one. Although vaccine strains do exist for aMPVs, they do not always provide full protection against virulent strains and the vaccines themselves may induce disease to some extent. Improved vaccines against aMPV are needed, to achieve better protection of the poultry industry against this pathogen. Major conclusions, solutions, achievements: We isolated aMPV-B from a diseased flock and accomplished the sequencing and cloning of its full-genome. In addition, we cloned the four genes encoding the viral replicase. These should serve as the platform for generation of modified aMPV-Bs from molecular clones. We also identified aMPVs that are attenuated in respect to their ciliostatic activity and accordingly showed the potential of such viruses as vaccine strains. For aMPV-C, the different mutations scattered along the genome of different isolates with varied virulence have been determined. Implications, both scientific and agricultural: The newly identified pattern of mutations in attenuated strains will allow better understanding of the pathogenicity of aMPV and the generation of aMPV molecular clones, together with isolation of strains with attenuated ciliostatic activity should generate improved vaccine strains Abstract (one page maximum, single spaced), include: List the original objectives, as defined in the approved proposal, and any revisions made at the beginning or during the course of project: The main goal described in our original proposal has been the development of a molecular infectious clone of the avian metapneumovirus subtype B (aMPV-B) and the modification of this clone to create mutated viruses for the development of attenuated vaccines. The Achievements and Appendix/Part I sections of this report describes the accomplishments in creating such a molecular clone. These sections also contain the results of a longitudinal study that we made in Israel, demonstrating the infiltration of field strains of aMPV into vaccinated flocks and emphasizing the need for the development of better vaccines. We also describe our unexpected findings regarding the ability of aMPV to establish persistent infection in cell cultures. Although this direction of research was not described in the original proposal we feel that it is highly important for the understanding of aMPV pathogenesis. For example, this direction has provided us with evidence showing that aMPV replication can augment influenza replication. Moreover, we observed that viruses that were produced from chronically-infected cells show reduced ciliostasis. Accordingly, we carried vaccination trials using such viruses. In the original grant proposal we also offered that the American lab will clone and express immunomodulators in the context of an aMPV -based replicon that the Israeli lab has generated. However, as we reported in our annual reports, further analysis of this replicon by the Israeli lab has revealed that the level of expression achieved by this vehicle is relatively poor; thus, the American lab has focused on sequencing the genomes of different aMPV-C isolates that differ in their virulence (including vaccine strains). Achievements and Appendix/Part II sections of this report include the summary of this effort. Background to the topic: The aMPVs belong to the paramyxoviridae family and cause mild to severe respiratory tract diseases mainly in turkeys and also in chickens. Four aMPV subgroups, A, B, C and D, have been characterized; in Israel aMPV-A and B are the common subtypes while in the USA type C is the prevalent one. Although vaccine strains do exist for aMPVs, they do not always provide full protection against virulent strains and the vaccines themselves may induce disease to some extent. Improved vaccines against aMPV are needed, to achieve better protection of the poultry industry against this pathogen. Major conclusions, solutions, achievements: We isolated aMPV-B from a diseased flock and accomplished the sequencing and cloning of its full-genome. In addition, we cloned the four genes encoding the viral replicase. These should serve as the platform for generation of modified aMPV-Bs from molecular clones. We also identified aMPVs that are attenuated in respect to their ciliostatic activity and accordingly showed the potential of such viruses as vaccine strains. For aMPV-C, the different mutations scattered along the genome of different isolates with varied virulence have been determined. Implications, both scientific and agricultural: The newly identified pattern of mutations in attenuated strains will allow better understanding of the pathogenicity of aMPV and the generation of aMPV molecular clones, together with isolation of strains with attenuated ciliostatic activity should generate improved vaccine strains.
5
Morrison, Mark, Joshuah Miron, Edward A. Bayer e Raphael Lamed. Molecular Analysis of Cellulosome Organization in Ruminococcus Albus and Fibrobacter Intestinalis for Optimization of Fiber Digestibility in Ruminants. United States Department of Agriculture, marzo 2004. http://dx.doi.org/10.32747/2004.7586475.bard.
Testo completoAbstract (sommario):
Improving plant cell wall (fiber) degradation remains one of the highest priority research goals for all ruminant enterprises dependent on forages, hay, silage, or other fibrous byproducts as energy sources, because it governs the provision of energy-yielding nutrients to the host animal. Although the predominant species of microbes responsible for ruminal fiber degradation are culturable, the enzymology and genetics underpinning the process are poorly defined. In that context, there were two broad objectives for this proposal. The first objective was to identify the key cellulosomal components in Ruminococcus albus and to characterize their structural features as well as regulation of their expression, in response to polysaccharides and (or) P AA/PPA. The second objective was to evaluate the similarities in the structure and architecture of cellulosomal components between R. albus and other ruminal and non-ruminal cellulolytic bacteria. The cooperation among the investigators resulted in the identification of two glycoside hydrolases rate-limiting to cellulose degradation by Ruminococcus albus (Cel48A and CeI9B) and our demonstration that these enzymes possess a novel modular architecture specific to this bacterium (Devillard et al. 2004). We have now shown that the novel X-domains in Cel48A and Cel9B represent a new type of carbohydrate binding module, and the enzymes are not part of a ceiluiosome-like complex (CBM37, Xu et al. 2004). Both Cel48A and Cel9B are conditionally expressed in response to P AA/PPA, explaining why cellulose degradation in this bacterium is affected by the availability of these compounds, but additional studies have shown for the first time that neither PAA nor PPA influence xylan degradation by R. albus (Reveneau et al. 2003). Additionally, the R. albus genome sequencing project, led by the PI. Morrison, has supported our identification of many dockerin containing proteins. However, the identification of gene(s) encoding a scaffoldin has been more elusive, and recombinant proteins encoding candidate cohesin modules are now being used in Israel to verify the existence of dockerin-cohesin interactions and cellulosome production by R. albus. The Israeli partners have also conducted virtually all of the studies specific to the second Objective of the proposal. Comparative blotting studies have been conducted using specific antibodies prepare against purified recombinant cohesins and X-domains, derived from cellulosomal scaffoldins of R. flavefaciens 17, a Clostridium thermocellum mutant-preabsorbed antibody preparation, or against CbpC (fimbrial protein) of R. albus 8. The data also suggest that additional cellulolytic bacteria including Fibrobacter succinogenes S85, F. intestinalis DR7 and Butyrivibrio fibrisolvens Dl may also employ cellulosomal modules similar to those of R. flavefaciens 17. Collectively, our work during the grant period has shown that R. albus and other ruminal bacteria employ several novel mechanisms for their adhesion to plant surfaces, and produce both cellulosomal and non-cellulosomal forms of glycoside hydrolases underpinning plant fiber degradation. These improvements in our mechanistic understanding of bacterial adhesion and enzyme regulation now offers the potential to: i) optimize ruminal and hindgut conditions by dietary additives to maximize fiber degradation (e.g. by the addition of select enzymes or PAA/PPA); ii) identify plant-borne influences on adhesion and fiber-degradation, which might be overcome (or improved) by conventional breeding or transgenic plant technologies and; iii) engineer or select microbes with improved adhesion capabilities, cellulosome assembly and fiber degradation. The potential benefits associated with this research proposal are likely to be realized in the medium term (5-10 years).
6
Altstein, Miriam, e Ronald J. Nachman. Rational Design of Insect Control Agent Prototypes Based on Pyrokinin/PBAN Neuropeptide Antagonists. United States Department of Agriculture, agosto 2013. http://dx.doi.org/10.32747/2013.7593398.bard.
Testo completoAbstract (sommario):
The general objective of this study was to develop rationally designed mimetic antagonists (and agonists) of the PK/PBAN Np class with enhanced bio-stability and bioavailability as prototypes for effective and environmentally friendly pest insect management agents. The PK/PBAN family is a multifunctional group of Nps that mediates key functions in insects (sex pheromone biosynthesis, cuticular melanization, myotropic activity, diapause and pupal development) and is, therefore, of high scientific and applied interest. The objectives of the current study were: (i) to identify an antagonist biophores (ii) to develop an arsenal of amphiphilic topically active PK/PBAN antagonists with an array of different time-release profiles based on the previously developed prototype analog; (iii) to develop rationally designed non-peptide SMLs based on the antagonist biophore determined in (i) and evaluate them in cloned receptor microplate binding assays and by pheromonotropic, melanotropic and pupariation in vivo assays. (iv) to clone PK/PBAN receptors (PK/PBAN-Rs) for further understanding of receptor-ligand interactions; (v) to develop microplate binding assays for screening the above SMLs. In the course of the granting period A series of amphiphilic PK/PBAN analogs based on a linear lead antagonist from the previous BARD grant was synthesized that incorporated a diverse array of hydrophobic groups (HR-Suc-A[dF]PRLa). Others were synthesized via the attachment of polyethylene glycol (PEG) polymers. A hydrophobic, biostablePK/PBAN/DH analog DH-2Abf-K prevented the onset of the protective state of diapause in H. zea pupae [EC50=7 pmol/larva] following injection into the preceding larval stage. It effectively induces the crop pest to commit a form of ‘ecological suicide’. Evaluation of a set of amphiphilic PK analogs with a diverse array of hydrophobic groups of the formula HR-Suc-FTPRLa led to the identification of analog T-63 (HR=Decyl) that increased the extent of diapause termination by a factor of 70% when applied topically to newly emerged pupae. Another biostablePK analog PK-Oic-1 featured anti-feedant and aphicidal properties that matched the potency of some commercial aphicides. Native PK showed no significant activity. The aphicidal effects were blocked by a new PEGylated PK antagonist analog PK-dF-PEG4, suggesting that the activity is mediated by a PK/PBAN receptor and therefore indicative of a novel and selective mode-of-action. Using a novel transPro mimetic motif (dihydroimidazole; ‘Jones’) developed in previous BARD-sponsored work, the first antagonist for the diapause hormone (DH), DH-Jo, was developed and shown to block over 50% of H. zea pupal diapause termination activity of native DH. This novel antagonist development strategy may be applicable to other invertebrate and vertebrate hormones that feature a transPro in the active core. The research identifies a critical component of the antagonist biophore for this PK/PBAN receptor subtype, i.e. a trans-oriented Pro. Additional work led to the molecular cloning and functional characterization of the DH receptor from H. zea, allowing for the discovery of three other DH antagonist analogs: Drosophila ETH, a β-AA analog, and a dF analog. The receptor experiments identified an agonist (DH-2Abf-dA) with a maximal response greater than native DH. ‘Deconvolution’ of a rationally-designed nonpeptide heterocyclic combinatorial library with a cyclic bis-guanidino (BG) scaffold led to discovery of several members that elicited activity in a pupariation acceleration assay, and one that also showed activity in an H. zea diapause termination assay, eliciting a maximal response of 90%. Molecular cloning and functional characterization of a CAP2b antidiuretic receptor from the kissing bug (R. prolixus) as well as the first CAP2b and PK receptors from a tick was also achieved. Notably, the PK/PBAN-like receptor from the cattle fever tick is unique among known PK/PBAN and CAP2b receptors in that it can interact with both ligand types, providing further evidence for an evolutionary relationship between these two NP families. In the course of the granting period we also managed to clone the PK/PBAN-R of H. peltigera, to express it and the S. littoralis-R Sf-9 cells and to evaluate their interaction with a variety of PK/PBAN ligands. In addition, three functional microplate assays in a HTS format have been developed: a cell-membrane competitive ligand binding assay; a Ca flux assay and a whole cell cAMP ELISA. The Ca flux assay has been used for receptor characterization due to its extremely high sensitivity. Computer homology studies were carried out to predict both receptor’s SAR and based on this analysis 8 mutants have been generated. The bioavailability of small linear antagonistic peptides has been evaluated and was found to be highly effective as sex pheromone biosynthesis inhibitors. The activity of 11 new amphiphilic analogs has also been evaluated. Unfortunately, due to a problem with the Heliothis moth colony we were unable to select those with pheromonotropic antagonistic activity and further check their bioavailability. Six peptides exhibited some melanotropic antagonistic activity but due to the low inhibitory effect the peptides were not further tested for bioavailability in S. littoralis larvae. Despite the fact that no new antagonistic peptides were discovered in the course of this granting period the results contribute to a better understanding of the interaction of the PK/PBAN family of Nps with their receptors, provided several HT assays for screening of libraries of various origin for presence of PK/PBAN-Ragonists and antagonists and provided important practical information for the further design of new, peptide-based insecticide prototypes aimed at the disruption of key neuroendocrine physiological functions in pest insects.