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Dissertations / Theses on the topic 'Granite Geology, Stratigraphic Geochemistry'
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1
Wong, Ping-mei Jean. "Geochemistry, U-Pb and Sr-Nd-Hf isotopes of the Baijuhuajian A-type granites in Zhejiang Province evidence for a continuous extensional regime in the mid and late mesozoic /." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39557297.
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王冰媚 and Ping-mei Jean Wong. "Geochemistry, U-Pb and Sr-Nd-Hf isotopes of the Baijuhuajian A-type granites in Zhejiang Province: evidence for acontinuous extensional regime in the mid and late mesozoic." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39557297.
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Ghosh, Amiya Kumar. "Reconnaissance U-Pb geochronology of Precambrian crystalline rocks from the northern Black Hills, South Dakota: Implications for regional thermotectonic history." [Kent, Ohio] : Kent State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=kent1240007954.
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Thesis (M.S.)--Kent State University, 2009.Title from PDF t.p. (viewed Feb. 12, 2010). Advisor: Peter Dahl. Keywords: Black Hills; Crook Mountain granite; Homestake gold mine; gold mineralization; magmatism; metamorphism; metapelite; g monazite; zircon; titanite; geochronology; thermotectonism Includes bibliographical references (p. 97-106).
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Liu, Mian. "Migmatization and volcanic petrogenesis in the La Grande greenstone belt, Quebec." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63353.
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Oak, Keith Alan. "The geology and geochemistry of Closepet granite, Karnataka, South India." Thesis, Oxford Brookes University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278897.
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The Archaean craton of southern India has four main components. The multi-phase Peninsular gneiss, with ages from 3360-2900 Ma, is spatially dominant and grades from granulite facies in the south to greenschist facies in the north. Ages for the Peninsular gneiss range from 3360-2900 Ma. Within the craton are two suites of Greenstone Belts and supracrustal rocks. The older, high-grade Sargur type occur as enclaves in the Peninsular gneiss and are in places older than 3360 Ma. The younger, lower-grade type occur occasionally have unconformable bases with the Peninsular gneiss and have been dated from 3100-2605 Ma. Granitoids form the last major component with the Closepet granite being the largest, ages for the emplacement of the Closepet granite and many of the other granitoids cluster around 2500 Ma. The Closepet granite outcrops from Kabbal Durge in the south to the Deccan Plateau in the north, a distance of some 450 km. A 320 km section from Kabbal Durga to Hospet in the north exposes a linear trending granite. The granite outcrop varies from one of essentially partial melting and melt extraction in the south to a zone of melt accumulation in the central zone to a zone of high level intrusion of large granite bodies. Related to these changes in primary processes are changes in the granite phases, size, shape and intrusive style. The petrography of the granite phases is described. These studies help to constrain phase relationships. The petrography also provides evidence to suggest that the K-feldspar megacrysts are in fact phenocrysts. Analyses of major and trace elements utilised standard X.R.F. methods. However, the analyses of REE on selected samples involved the setting up of the department's "ICP for routine operation. This procedure is outlined. The geochemistry of the granite's is described melting and crystallization models being used to explain their petrogenesis. Harker diagrams indicate that plagioclase, sphene and apatite have strong controls on major element composition and that biotite was a residual or fractionating phase. The removal of restite biotite as granite magmas intrude is thought to be a significant process.Evidence from the petrography agrees with the equilibrium phase diagram at PH2 0 ~ 5 kbar. Plots of Peninsular gneiss in the granite phase diagram have a range of compositions which could provide minimum and non-minimum melts capable of producing the Closepet granite trend. Predicted fractional crystallization would produce a sequence of magma compositions comparable to those of the Closepet granite with an order of phase crystallization that agrees with petrographic evidence. The phase relationships further constrain subsequent melting and crystallization models utilising trace elements and REE.
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Wong, Lai-man Kennis. "Geochemistry of mafic dykes from the Discovery Bay granitic pluton, Hong Kong." Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/hkuto/record/B42577688.
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Curtis, David. "Variations in nappe related fabric orientations during Paleopropterozoic ductile reworking of Archean basement, central Laramie Mountains, southeastern Wyoming /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1421128.
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Fedo, Christopher M. "Geologic evolution of the Archean Buhwa Greenstone Belt and surrounding granite-gneiss terrane, southcentral Zimbabwe." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-164845/.
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Hildebrand, Alan Russell. "Geochemistry and stratigraphy of the Cretaceous/Tertiary boundary impact ejecta." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/186109.
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An array of stratigraphic, chemical, isotopic, and mineralogical evidence indicates that an impact terminated the Cretaceous Period. The 180-km-diameter Chicxulub crater, which now lies buried on the Yucatan peninsula of Mexico, was probably formed by the impact. The impactor was probably a long-period comet. Shock devolatization of the thick carbonate/evaporite sequence impacted at Chicxulub probably led to a severe and long-lasting greenhouse warming and a prompt pulse of sulfuric acid rain. The fallout of crater ejecta formed two layers: a lower layer which varies in thickness following a power-law relation based on distance from the Chicxulub crater and an upper, globally-distributed, uniformly ∼3-mm-thick layer. The upper layer probably represents the fallout of condensates and entrained solid and liquid particles which were distributed globally by the impact fireball. The lower layer consists of brecciated rock and impact melt near the crater and largely altered tektites far from the crater. The clasts of this layer were probably ballistically transported. The Raton, New Mexico K/T boundary section preserves the fireball and ejecta layers in a coal-free nonmarine environment. Siderophile, chalcophile, and lithophile trace element anomalies occur similar to those found at marine K/T boundary localities. Soot occurs peaking in the 3-mm-thick fireball layer and the immediately overlying 3 mm of sediment, implying prompt burning of the Cretaceous forests. The Brazos River, Texas continental-shelf K/T sections preserve coarse boundary sediments which were probably produced by impact waves. Siderophile and chalcophile trace-element anomalies occur suggesting that the fireball layer and possibly part of the ejecta layer are interbedded with the coarse boundary sediments. The Beloc, Haiti deep-sea K/T sections preserve a thick ejecta sequence including altered and unaltered tektites and shocked minerals capped by the fireball layer. The thick K/T ejecta preserved at this and other nearby K/T localities require a source crater of Chicxulub's size and location. The composition of the tektites and shocked grains require an impact into recently extracted continental crust with a carbonate/evaporite component as found at the Chicxulub crater.
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Lazar, Ovidiu Remus. "Redefinition of the New Albany Shale of the Illinois basin an integrated, stratigraphic, sedimentologic, and geochemical study /." [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3252777.
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Thesis (Ph.D.)--Indiana University, Dept. of Geological Studies, 2007.Title from PDF t.p. (viewed Nov. 19, 2008). Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 0846. Adviser: Juergen Schieber.
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Elders, Christopher Frank. "Caledonian tectonics from stratigraphy and isotope geochemistry of lower palaeozoic successions." Thesis, University of Oxford, 1987. http://ora.ox.ac.uk/objects/uuid:bf48a950-7ffb-4b58-bae3-915a2f7b5a94.
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The Southern Uplands of Scotland is interpreted as a Lower Palaeozoic accretionary complex which formed on the northern margin of the Iapetus Ocean. Seven conglomerates which contain detritus derived from the north-west, from sources on the Laurentian continental margin, were studied. Granite clasts in five of the conglomerates have distinct petrographic and geochemical characteristics which indicate that separate source areas supplied detritus to the Southern Uplands at different times. The Llandeilo Corsewall Point and Caradoc Glen Afton conglomerates, which occur in Tracts 1 and 2 of the Northern Belt, contain granite clasts that yield similar Rb-Sr whole-rock isochron ages (c. 1,200 Ma, 600-660 Ma and c. 475 Ma) and similar Sm-Nd model ages. This suggests that the clasts in the two conglomerates were derived from related sources. Some of the granite clasts in the early Ashgill Shinnel Formation conglomerate, which occurs in Tract 3 of the Northern Belt, resemble those in the Corsewall Point conglomerate, but most are petrographically and geochemically distinct, and yield younger Sm-Nd model ages. The lower Llandovery Pinstane Hill conglomerate occurs in Tract 4 of the Central Belt, and contains granitic detritus which yields a Rb-Sr whole-rock isochron age of 458 ± 26 Ma and has similar characteristics to the clasts in the Shinnel Formation conglomerate. The granite clasts in the Corsewall Point and Glen Afton conglomerates are of a different age to the granite intrusions of northern Scotland, and are unlikely to have been derived from this region. Conglomerates in the Midland Valley contain granite clasts with different petrographic and isotopic characteristics to those supplied to the Southern Uplands during the Llandeilo and Caradoc. However, north-west Newfoundland has a similar igneous history to that recorded by the Southern Uplands clasts, which could be derived from this region. The clasts supplied to the Shinnel Formation and Pinstane Hill conglomerates during the Ashgill and Llandovery have more in common with the granitic detritus in the Midland Valley. Thus, the Southern Uplands form a distinct Caledonian terrane which was south-east of Newfoundland in the Llandeilo, and was affected by sinistral strike-slip displacements during and after accretion.
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Leung, Ho-sun. "Geochemistry of the paleozoic Xiadong mafic-ultramafic complex, Eastern Xinjiang, NW China." Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B44143850.
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Dilliard, Kelly Ann. "Sequence stratigraphy and chemostratigraphy of the Lower Cambrian Sekwi Formation, Northwest Territories, Canada." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/Spring2006/K%5FDilliard%5F042406.pdf.
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Zhao, Junhong. "Geochemistry of neoproterozoic arc-related plutons in the Western margin of the Yangtze Block, South China." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/b40203748.
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Li, Longming, and 李龙明. "The crustal evolutionary history of the Cathaysia Block from the paleoproterozoic to mesozoic." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45693596.
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Wolf, David Eny. "The Burntside Lake and Shagawa/Knife Lake shear zones : deformation kinematics, geochemistry and geochronology; Wawa Subprovince, Ontario, Canada." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Thesis/Fall2006/d_wolf_010807.pdf.
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Buick, Ian S. "The petrology and geochemistry of granitic rocks from the Entia domal structure, Harts Range, eastern Arunta Block, Central Australia /." Title page, contents and abstract only, 1985. http://web4.library.adelaide.edu.au/theses/09SM/09smb932.pdf.
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Ames, Doreen E. "Geology and regional hydrothermal alteration of the crater-fill, onaping formation : association with Zn-Pb-Cu mineralization, Sudbury Structure, Canada." Ottawa, 1999.
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Sun, Weihua. "The neoproterozoic Yanbian group and associated plutons in the western Yangtze block, SW China." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B41897158.
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Korotkikh, Elena. "A High Resolution Record of the Eemian Interglacial and Transition to the Next Glacial Period from Mount Moulton (West Antarctica)." Fogler Library, University of Maine, 2009. http://www.library.umaine.edu/theses/pdf/KorotkikhE2009.pdf.
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Zhao, Jian-xin. "The geology, geochemistry and geochronology of the Atnarpa Igneous Complex, SE Arunta Inlier, northern Australia : implications for early to middle proterozoic tectonism and crustal evolution." Title page, contents and abstract only, 1989. http://web4.library.adelaide.edu.au/theses/09SM/09smz63.pdf.
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Singh, Updesh. "Late Precambrian and Cambrian carbonates of the Adelaidean in the Flinders Ranges, South Australia : a petrographic, electron microprobe and stable isotope study /." Title page, abstract and contents only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phs1792.pdf.
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Swanson, Rodney Duane. "A stratigraphic-geochemical study of the Troutdale Formation and Sandy River Mudstone in the Portland basin and lower Columbia River Gorge." PDXScholar, 1986. https://pdxscholar.library.pdx.edu/open_access_etds/3720.
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Hyaloclastic sediment forms an identifiable stratigraphic interval within the Troutdale Formation that can be traced from the Bridal Veil channel to the Portland basin. Hyaloclastic sediment composed chiefly vitric sands is found interbedded with muds, sandy muds and gravels penetrated by wells in northeast Portland are correlated with the upper member of the Troutdale Formation. These beds are characteristic of the informal upper member of the Troutdale Formation in the Bridal Veil channel of the ancestral Columbia River (Tolan and Beeson, 1984) and the type area of the Troutdale Formation exposed along the Sandy River (Trimble, 1963). Fluvially deposited hyaloclastic beds within the upper Troutdale Formation are interpreted to be the result of interaction of Cascadian basaltic lavas with an ancestral Columbia River (Tolan and Beeson, 1984; Trimble, 1963). Glass clasts taken from well and outcrop samples have nearly identical trace and minor element geochemical content as determined by instrumental neutron activation analysis.
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Zhao, Junhong, and 趙軍紅. "Geochemistry of neoproterozoic arc-related plutons in the Western margin of the Yangtze Block, South China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40203748.
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He, Yanhong. "Ages and geochemistry of the Xiong'er volcanic rocks along the southern margin of the North China Craton implications for the outgrowths of the paleo-mesoproterozoic supercontinent Columbia (Nuna) /." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B4163424X.
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Wang, Wei, and 王伟. "Sedimentology, geochronology and geochemistry of the proterozoic sedimentary rocks in the Yangtze Block, South China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196033.
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The South China Craton comprises the Yangtze Block in the northwest and Cathaysia Block in the southeast. Located in the southeastern Yangtze Block, the Jiangnan Orogen formed through the amalgamation between the Yangtze and Cathaysia Blocks. The Yangtze Block has sporadically exposed Archean rocks in the north, Paleoproterozoic to Mesoproterozoic volcano-sedimentary sequences in the southwest and widespread Neoproterozoic sedimentary sequences accompanied by syn-sedimentary igneous rocks on the western and southeastern margins.
The late Paleoproterozoic to early Mesoproterozoic Dongchuan, Dahongshan and Hekou groups in the southwestern Yangtze Block formed in a series of fault-controlled, rift-related basins associated with the fragmentation of the supercontinent Columbia. These sedimentary sequences were deposited between 1742 and 1503 Ma, and recorded continuous deposition from alluvial fan and fluvial sedimentation during the initial rifting to deep marine sedimentation in a passive margin setting. Sedimentation during initial rifting received felsic detritus mainly from adjacent continents, whereas sedimentation in a passive margin basin received detritus from felsic to intermediate rocks of the Yangtze Block. Paleoproterozoic to Mesoproterozoic rift basins in the southwestern Yangtze Block are remarkably similar to those of north Australia and northwestern Laurentia in their lower part (1742-1600 Ma), but significantly different after ca. 1600 Ma. The southwestern Yangtze Block was likely connected with the north Australia and northwestern Laurentia in Columbia but drifted away from these continents after ca. 1600 Ma.
Traditionally thought Mesoproterozoic sedimentary sequences in the southeastern Yangtze Block are now confirmed to be Neoproterozoic in age and include the 835-830 Ma Sibao, Fanjingshan and Lengjiaxi groups, and 831-815 Ma Shuangqiaoshan and Xikou groups. These sequences are unconformably overlain by the ~810-730 Ma Danzhou, Xiajiang, Banxi, Heshangzheng, Luokedong and Likou groups. The regional unconformity likely marked the amalgamation between the Yangtze and Cathaysia Blocks and thus occurred at ~815-810 Ma. The lower sequences (835-815 Ma) received dominant Neoproterozoic (~980-820) felsic to intermediate materials in an active tectonic setting related to continental arc and orogenic collision, whereas the upper sequences represent sedimentation in an extensional setting with input of dominant Neoproterozoic granitic to dioritic materials (~740-900 Ma). The upper
parts of the Shuangqiaoshan and Xikou groups, uncomfortably underlain by lower units, are molasse-type assemblages with additional input of pre-Neoproterozoic detritus, representing accumulation of sediments in a retro-arc foreland basin associated with the formation of the Jiangnan Orogen. Stratigraphic correlation, similarly low-δ18O and tectonic affinity of igneous rocks from different continents suggest that the Yangtze Block should be placed in the periphery of Rodinia probably adjacent to northern India. Paleoproterozoic (~2480 Ma and ~2000 Ma) and Early Neoproterozoic (711-997 Ma) were the most important periods of crustal and magmatic events of the southeastern Yangtze Block, but there is a lack of significant Grenvillian magmatism. Early Neoproterozoic magmatism highlights the contribution from both juvenile materials and pre-existing old crust, whereas ~2480 Ma and ~2000 Ma events are marked by reworking of pre-existing continental crust. Magmatism at 1600-1900 Ma was dominated by reworking of pre-existing crust, whereas the 1400-1600 Ma magmatic event recorded some addition of juvenile materials.published_or_final_version
Earth Sciences
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Doctor of Philosophy
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Beasley, Justin M. "Geochemistry and fluid evolution of a carboniferous-hosted sphalerite breccia deposit, Isle of Man." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/6524.
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Thesis (M.S.)--University of Missouri-Columbia, 2008.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed July 14, 2009). Includes bibliographical references.
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Wong, Lai-man Kennis, and 王麗敏. "Geochemistry of mafic dykes from the Discovery Bay granitic pluton, Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B42577688.
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Van, Boening Angela M. "Petrogenesis and tectonic implications of mafic rocks in the Precambrian core of the Black Hills, South Dakota." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4995.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on November 6, 2007) Includes bibliographical references.
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Abdel-Rahman, Abdel-Fattah Mostafa. "Plutonism and tectonic evolution of the Ras Gharib segment of the northern nubian shield, Egypt." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=73998.
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Sun, Weihua, and 孙卫华. "The neoproterozoic Yanbian group and associated plutons in the westernYangtze block, SW China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B41897158.
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Boudreaux, Andrew P. "Mineralogy and geochemistry of the Erongo Granite and interior quartz-tourmaline orbicules and NYF-type miarolitic pegmatites, Namibia." ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1854.
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The early Cretaceous anorogenic Erongo Granite of Namibia is known to host abundant boron mineralization in rounded, quartz-tourmaline clusters and in NYF-type miarolitic, pegmatitic cavities. Rock and mineral samples were taken from the bulk granite, tourmaline nests, and miarolitic cavities and analyzed using a variety of modern analytical techniques. Geochemical and mineralogical data suggest substantial input from the metasedimentary rocks of the Damara orogen was important in the genesis of the Erongo Granite magma. The geochemical signature of the Damara orogen is most evident in the tourmaline clusters and miarolitic cavities, where fractional crystallization accumulated volatile and incompatible elements enough to exsolve a second fluid phase and induce drastic textural and mineralogical changes. As a result, the geochemical character of the pegmatitic cavities is far removed from that of classic NYF-type systems, where boron mineralization is usually not observed.
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Roche, Richard Louis. "Stratigraphic and geochemical evolution of the Glass Buttes complex, Oregon." PDXScholar, 1987. https://pdxscholar.library.pdx.edu/open_access_etds/3748.
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Glass Buttes complex lies at the northern margin of the Basin and Range province in central Oregon and is cut by the northwest-trending Brothers fault zone. An older acrystalline volcanic sequence of high-silica rhyolites (>75% SiO2) forms a broad platform composed of domes and flows with minor pyroclastic deposits. The high-silica rhyolite sequence is divided on the basis of texture into 1) zoned flows and domes, 2) obsidian flows, 3) felsite flows, and 4) biotite-phyric flows and domes.
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Zhao, Xinfu. "Paleoproterozoic crustal evolution and Fe-Cu metallogeny of the western Yangtze Block, SW China." Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B43572261.
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Crous, Stephanus Philippus. "The geology, geochemistry and stratigraphic correlations of the farm Rietfontein 70 JS on the south -eastern flank of the Dennilton Dome, Transvaal, South Africa." Thesis, Rhodes University, 1996. http://hdl.handle.net/10962/d1005572.
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The study area is located between Loskop Dam and the town of Groblersdal, on the southeastern flank of the Dennilton dome, and is underlain by lithologies of the Pretoria Group, Bushveld Complex mafics and ultramafics and acid lavas that resort under the Rooiberg felsites. Field work comprised of geological mapping, soil-, hard-rock- and stream sediment geochemistry, various geophysical techniques and diamond drilling. The rocktypes that resembles the Rustenburg Layered Suite on the farm Rietfontein 70JS is subdivided into a Mixed Zone, Critical Zone and Main Zone, on grounds of geochemical and certain geophysical attributes. The Mixed Zone that overlies the Bushveld Complex floor-rocks, is furthermore separated into an i) Lower-, ii) Middle- and, iii) Upper Unit. The Lower Unit of the Mixed Zone consists primarily of magnetite-gabbros, iron-rich pegmatites, harzburgites and feldspathic pyroxenites. The Fe-rich constituents of this stratigraphic horizon generates a pronounced magnetic anomaly within the study area. On the basis of; amongst other parameters, Zr/Rb and Sr/Al₂0₃ ratios, the magnetite-gabbros are postulated to conform to lithotypes in the vicinity of magnetite layers 8 to 14 of Upper Zone Subzone B in a normal Bushveld Complex stratigraphical scenario. Similarly, it is argued that the feldspathic pyroxenites and norites that display elevated chromium values are analogues to normal Critical Zone rocktypes of the Rustenburg Layered Snite. A more elaborate and precise stratigraphic correlation for the Critical zone was, however, not possible. It is advocated that a volume imbalance was created by the hot, ascending mafic magmas of the intruding Bushveld Complex, resulting in the updoming of certain prevailing basement features such as the Dennilton Dome. In addition to this ideology, it is proposed that the Mineral Range Fragment is in fact a large xenolith underlain by mafics, after being detached from the Dennilton Dome during the intrusion event. Evidence generated by this study unequivocally indicate that the potential for viable PGE's, Ni, Cu and Au within a Merensky Reef- type configuration or a Plat Reef-type scenario under a relatively thin veneer of acid Bushveld Complex roof-rocks on the eastern flank of the Dennilton Dome, appears feasible.
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Johnson, Geoffrey I. "The petrology, geochemistry and geochronology of the felsic alkaline suite of the eastern Yilgarn Block, Western Australia /." Title page, contents and abstract only, 1991. http://web4.library.adelaide.edu.au/theses/09PH/09phj67.pdf.
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Thesis (Ph. D.)--Dept. of Geology and Geophysics, University of Adelaide, 1992.Typescript (Photocopy). Includes copies of 4 papers by the author as appendix 4 (v. 1). Errata slip inserted. Includes bibliographical references (leaves 170-192 (v. 1)).
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Bergström, Sara. "Fluid inclusions and geochemistry of the Peña del Seo W-deposit, northwest Spain : Controlling mechanisms for tungsten deposition." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-78194.
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The Peña del Seo tungsten deposit in northwestern Spain is situated in the tin (Sn)-tungsten (W) metallogenic province of Europe − one of the richest tin-tungsten (tantalum-lithium) mineral provinces in the world. The European Union’s current goal is to become self-sufficient of these commodities in the near future and the iTARG3T project was launched in order to improve the understanding and provide innovative exploration methods of these types of deposits. This master thesis will contribute to the iTARG3T project. The aim was to determine which physico-chemical conditions (temperature, pressure, salinity) that prevailed during the emplacement of the Peña del Seo deposit. A geochemical study was done consisting of a fluid inclusion study on the quartz veins from the deposit, and a whole-rock geochemistry analyse of the granitic rock. Homogenisation temperatures ranged between 97,6° C to 325,6° C and salinities (NaCl % equiv.) between 0,2% to 21,3%. The fluid was determined to consist of a two-component system of H2O and NaCl based on eutectic temperature. Based on its geochemical classification the granitic rock was considered to be an alkali granite, strongly peraluminous with S-type characteristics. At least two different types of fluids were present during the emplacement of the Peña del Seo deposit, one that was hot and with a moderate salinity, and one that had a lower temperature than the other fluid and a lower salinity, possibly meteoric water. The depositional mechanism of tungsten is thought to be caused by a combination between mixing between two fluids and cooling of the fluids, with the main depositional mechanism being cooling since the change in salinity was not of such magnitude that it would change the fluid chemical composition, while the decrease in temperature was. It is uncertain whether the granitic rock found at Peña del Seo is part of the granitic cupola of the greisen system. The granitic rock has similar characteristics as the leucogranites of the West Asturian-Leonese Zone and based on quartz vein morphology, which cut the D2 foliation, time of emplacement of the deposit could be linked to the syntectonic event at 320-310 Ma. If the relation between the granitic rock and the greisen system can be determined the time of emplacement would be possible.
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Stremtan, Ciprian Cosmin. "Mantle-crust Interaction in Granite Petrogenesis in Post-collisional Settings: Insights from the Danubian Variscan Plutons of the Romanian Southern Carpathians." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5624.
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The issue of granite petrogenesis plays a key role in our overall understanding of the growth and differentiation of continents, as well as in our ability to unravel the tectonic histories of orogenic belts. Granites are ubiquitous magmatic products found in almost all tectonic settings: oceanic and continental rifts (i.e., plagiogranites - extreme basalt differentiates), active continental margins (e.g,. the granitic batholiths of central and southern Andes), continent-continent collision zones (e.g., the orogenic batholiths of the Himalayas, Western Anatolia), post-collisional settings (e.g., the Variscan provinces of Europe), complex within-plates settings (e.g., Limmo massif, Afar, Ethiopia). Furthermore, granitoids are characterized by considerable petrological and geochemical heterogeneity, as they can form from a vast array of sources: sediments (e.g., pelites, arkoses, psammites), metamorphic rocks (e.g., (mica)schists, gneisses, etc.), and igneous rocks (e.g. andesites, dacites, tonalites, etc.). Aside from fertile sources (i.e., protoliths), granite petrogenesis is dependent upon two critical parameters: temperature (to promote melting of the protoliths) and water availability - either as freely available aqueous solutions/vapors (e.g., water input in subduction zones); or water released via dehydration melting of hydrous minerals (e.g., micas, amphiboles). The presence of water in protoliths depresses the melting temperature of mineral components and provides the environment for redistribution of chemical components.
Understanding the origins of granitic rocks presents unique challenges, given that in many of the tectonic settings where granites are encountered, it is clear that their modes of formation can involve a spectrum of igneous and metamorphic processes that are not readily accessible for examination, either through the study of modern environments or via analogy to "classical" localities. The petrogenesis and emplacement of granites in post-collisional tectonic settings is one of the thornier challenges, as these rocks appear to be derived via thermal and magmatic processes within highly deformed and compositionally diverse continental crust for which we lack a clear understanding. A number of unconventional and difficult-to-test mechanisms have been posited to drive crustal heating, melting, and subsequent pluton post-collisional emplacement. Although large volumes of granitic magmas have been emplaced in post-collisional settings, the complexities of the processes active in such settings make it challenging to put forward testable models that effectively combine available geochemical, petrologic, and geophysical data. Models for granite genesis away from plate margins (by means of crustal thickening, thermal blanketing, and internal heating from radioactive decay of 40K, 230Th, 235U, and 238U; delamination of the crustal lithosphere and juxtaposition of hot mantle melts at the base of the crust; underplating of mantle melts; or slab brake-off and upwelling of mantle melts) have been successfully applied in comparatively young orogenic regions, such as the Himalayas, the Carpathians, and Turkey. These models have proven challenging to employ in older orogenic belts, given their sometimes intricate tectonic and metamorphic histories, and the loss of pertinent evidence due to the effects of post-emplacement tectonic reworking, and often extensive alteration and erosion.
A series of ancient but fresh, age-correlative granitic plutons are exposed in Alpine nappes on the flanks of the Carpathians Mountains in southwestern Romania. These granites, all mapped as intruding the Neoproterozoic basement of the Danubian tectonic terrane, were emplaced during the post-collisional stages of two world-scale orogenies: an older, Pan-African event (~600 Ma) and a younger, Variscan event (~330- 280 Ma). My dissertation is focused on the study of late Variscan post-collisional plutons and associated sub-volcanic dykes, as they are tremendous tools for understanding and quantifying the mantle-crust interaction in post-collisional environments and the overall evolution of the continental crust during the Variscan orogeny.
Originally believed to be Proterozoic in age, zircon U/Pb dating showed that the plutons are much younger (Chapter 1 - Post-collisional Late Variscan magmatism in the Danubian domain (South Carpathians, Romania) documented by zircon U/Pb LA-ICP-MS) and correspond to the latest stages of the Variscan orogeny, as recorded elsewhere in the European Variscan provinces. The granitic plutons are relatively small and are generally concordant with the structures preserved by the country rocks. The extraordinary petrological and geochemical heterogeneities, even at pluton scale (Chapter 2 - Petrology and geochemistry of the Late Variscan post-collisional Furătura granitic pluton South. Carpathian Mts. (Romania)) argue against unique protoliths and simple evolutionary processes (e.g., closed-system fractional crystallization; anatexis). Trace elemental data for the Furătura pluton shows that the melts were formed in equilibrium with a garnet-amphibole restite, under pressure-temperature conditions deeper than the plagioclase stability field, implying that the melting took place at depths in excess of 40 km in the continental crust. Stable and radiogenic isotope data suggest that a protolith was of (possibly enriched) mantle affinities, and that the melts were subsequently contaminated in various degrees by deep crustal lithologies. In comparison, other post-collisional Variscan plutons from the Danubian domain (Chapter 4 - The role of the continental crust and lithospheric mantle in Variscan post-collisional magmatism - insights from Muntele Mic, Ogradena, Cherbelezu, Sfârdinu, and Culmea Cernei plutons (Romanian Southern Carpathians)) have trace elemental compositions that suggest they were formed at different levels in the crust, under P-T conditions corresponding to both garnet-amphibole and plagioclase stability fields. Some of the plutons lack mantle geochemical signatures and their isotopic compositions are indicative of substantial involvement of both lower- and upper-crustal rocks in their formation and subsequent evolution. On the other hand, plutons emplaced during the same time interval and most likely in close geographical proximity have trace elemental and isotopic compositions indicating strong input from previously enriched mantle components which experienced various degrees of assimilation fractionation-crystallization and/or assimilation of continental crust material during their evolution. This variability in both protoliths and processes responsible for the formation of the granites, coupled with the presence of mantle signatures in late-orogenic post-collisional melts are strong evidence to support delamination as means of providing both the mantle-derived input and energy required for generation of granitoids in the crust. The pronounced variation in petrological and chemical compositions of synchronous plutons suggests that delamination in the Danubian domain was not a single, large scale event that affected the entire crust, but rather a collection of disparate, spatially and chronologically limited event, that affected the Variscan crust during the latest stages of the orogeny.
This hypothesis is further tested on a series of sub-volcanic dykes (the Motru Dyke Swarm) crosscutting the entire Danubian basement (Chapter 3 - Post-collisional magmatism associated with Variscan orogeny in the Danubian Domain (Romanian Southern Carpathians): the Motru Dyke Swarm). Initially, the emplacement age of these dykes was assumed as "pre-Silurian" but our mapping has showed that they intrude components of the Danubian domain that shared a documented common history not earlier than the Carboniferous. Furthermore, the dykes are in intrusive relationship with two of the Danubian Variscan plutons, thus arguing for an early Permian emplacement age. Geochemical data show extraordinary heterogeneities in the dykes' composition and record both mantle and crust involvement in their formation. The dykes were emplaced at much shallower depths in the crust, as compared with the granitic plutons. Still, their isotopic compositions clearly indicate that they sampled both lower- and upper-crustal compositions during their evolution. This means that after the crustal thickening episodes that define continent-continent collisions, during the latest stages of the Variscan orogeny, the crust became progressively thinner, as a way to compensate for its metastable state. Thinning of the crust is greatly favored by delamination of the lithosphere. A delamination event, which usually postdates the cessation of continental collision or prolonged crustal shortening, involves the geologically rapid foundering of negatively buoyant lithosphere comprised of mantle and (potentially) lower crust into underlying hotter and less dense asthenosphere. Such a process will remove the lithospheric mantle (and potentially segments of the lower crust) along pre-existing lineaments or mechanical flaws, and juxtapose hot upwelling asthenosphere against the base of the crust, leading to partial melting.
Field, petrological, and geochemical data presented in my dissertation document pronounced variations in the overall composition of synchronous plutons and dykes, and further suggest that delamination in the Danubian domain was an active process. This bears great importance in our understanding of the evolution of the crust and argues that mantle-crust interactions are responsible for the generation of continental crust even in the latest stages of an orogen.
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Moukhsil, Abdelali. "Géochimie, pétrologie structurale et mode de mise en place du pluton de Father, zone volcanique nord, sous-province de l'Abitibi, Canada /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1996. http://theses.uqac.ca.
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Claassen, Debbie. "A geoscientific framework for the proposed site of South Africa's second nuclear power plant: Thyspunt, Eastern Cape." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/d1021182.
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This study describes the bedrock lithologies and structure of the Ordovician to early Devonian (485-419 Ma) Table Mountain Group (TMG), the Devonian (419-358 Ma) lower Bokkeveld Group, and the Miocene to Holocene (<23 Ma) overburden sediments of the Algoa Group within an area identified by Eskom for the potential construction of South Africa’s second proposed nuclear power plant (NPP), ‘Nuclear-1’. The study area is located along the southern coastal margin of the Eastern Cape Province, South Africa, between Oyster Bay and St. Francis (approximately 88 km west of Port Elizabeth), and encompasses the Thyspunt site where the proposed NPP will be built. The study aims to supplement existing information about the Thyspunt area, related to the geoscientific topic ‘Geological Setting’, as outlined in section 2.5.1.1 of the US Nuclear Regulatory Commission (USNRC) Standard Review Plan NUREG-800, which details the geological information required for review of a proposed NPP. The results obtained from geoscientific studies are used to determine geological factors that may potentially affect site specific design. Factors considered include: bedrock lithology, stratigraphic bedrock contacts, bedrock palaeotopography, thickness of overburden sediments and structural geology. Work by previous authors is combined with new data to create a GIS based 2½D model of the study area’s geology (geomodel) and on which future research or interpretations can be based. Field mapping and petrographic analyses of the TMG, comprising the Peninsula, Cedarberg, Goudini, Skurweberg and Baviaanskloof Formations as well as the lower undifferentiated Bokkeveld Group were undertaken to define the study area’s lithologies and structure. Interpretation of geophysical results and the integration of existing borehole data aided in defining the variability in overburden sediments, the identification of contacts between TMG formations beneath overburden, and the palaeotopography of bedrock. Borehole data indicates a clear N-S trend in the thickness distribution of Algoa Group aeolian and marine related sediments. Four coast-parallel trending thickness zones (zones A – D) are recognized within the study area. At Thyspunt overburden thickness reaches a maximum of 61 m, approximately 1200 m from the coastline, in areas underlain by the argillaceous Goudini and Cedarberg Formations. Overburden thickness is influenced by a combination of dune relief, bedrock lithology, palaeotopography and the area’s sediment supply. Interpolation of bedrock elevation points and detailed cross sections across bedrock reveals four NW-SE trending palaeovalleys at Thyspunt, Tony’s Bay, Cape St. Francis and St. Francis, where bedrock relief (beneath overburden) is formed to be below present day sea-level. Approximately 450 m NW of Thys Bay, a 1050 m2 (area below sea-level) palaeovalley, gently sloping SE to a depth of -15.5 m asl, is cut into strata of the Goudini Formation resulting in thicker overburden fill in that area. Structural analysis of the TMG confirms that NE-SW striking strata form part of the regional SE plunging, north verging Cape St. Francis anticline. Bedding inclination is controlled by the distance away from the fold axis, varying from a 5° SE dip along the broad fold hinge to 65° along its moderately steeper SE limb. Folds within the study area plunge gently southeastward at shallow angles, with axial planes dipping steeply SW or NE. Fold axes orientated perpendicular to the fold axis of the Cape St. Francis anticline indicate a secondary stress orientation oblique to the main palaeostress direction. The previously identified 40 km long, NW-SE trending Cape St. Francis fault occurring offshore within 17.5 km of Thyspunt show no onshore continuation within the bounds of the study area. Late jointing is pervasive within the study area and four joint systems are identified. The dominant joint set J1, trends N-S to NNE - SSW; perpendicular to bedding and has a subvertical dip. Normal right-lateral and left-lateral micro-faults dip subvertically, with a displacement that ranges from a few centimetres to <3 m. Micro-faults trend parallel to joints sets J1 and J4 (ESE-WSW). Inferred faults, identified by the Atomic Energy Co-operation (AEC), are interpreted as zones of closely spaced jointing (shatter zones), and show little to no recognizable displacement. Faults and joints do not extend into the younger cover deposits of the Algoa Group and are therefore older than 23 Ma years.
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Polteau, Stéphane. "Stratigraphy and geochemistry of the Makganyene formation, Transvaal supergroup, Northern Cape, South Africa." Thesis, Rhodes University, 2001. http://hdl.handle.net/10962/d1005616.
Full textAbstract:
The Makganyene Formation forms the base of the Postmasburg Group in the Transvaal Supergroup of the Northern Cape Province. The Makganyene Formation has diamictite as the main rock type, but siltstone, sandstone, shale, and iron-formations are also present. A glacial origin has been proposed in the past due to the presence of dropstones, faceted and striated pebbles. Typically, the Makganyene Formation contains banded iron-formations interbedded with clastic rocks (shale, siltstone, sandstone and diamictites) at the contact with the underlying iron-formations. This transitional zone is generally overlain by massive or layered diamictites which contain poorly sorted clasts (mainly chert) within a shaly matrix. Striated pebbles have been found during field work, and dropstones have been observed in diamictites and banded iron-formations during the study. The top of the Makganyene Formation contains graded cycles interbedded with diamictites and thin layers of andesitic lavas from the Ongeluk Formation. The basal contact of the Makganyene Formation with the underlying Koegas Subgroup was described as unconformable by previous workers. However field work localised in the Rooinekke area shows a broadly conformable and interbedded contact with the underlying Koegas Subgroup. As described above, banded iron-formations are interbedded with the clastic rocks of the Makganyene Formation. Moreover, boreholes from the Sishen area display the same interbedding at the base of the Makganyene Formation. This suggests that no significant time gap is present in the whole succession between the Ghaap and Postmasburg Group. The Transvaal Supergroup in the Northern Cape displays the following succession : carbonates-BIFs-diamictites/ lava-BIFs-carbonates. The Makganyene Formation is thus at the centre of a symmetrical lithologic succession. Bulk rock compositions show that the diamictites have a similar composition to banded iron-formation with regard to their major element contents. Banded iron-formations acted as a source for the diamictites with carbonates and igneous rocks representing minor components. Differences in bulk composition between the Sishen and Matsap areas emphasize that the source of the diamictite was very localised. The Chemical Index of Alteration (CIA) has been calculated, but since the source dominant rock was iron-formation, this index cannot be usefully applied to the diamictites. ACN, A-CN-K, and A-CNK-FM diagrams confer a major importance in sorting processes due to the separation between the fine and coarse diamictites. The interbedded iron-formations display little clastic contamination indicating deposition in clear water conditions. However, dropstones are present in one borehole from the Matsap area, indicating that iron-formation took place under ice cover, or at least under icebergs. Stable isotope studies show that the iron-formations, interbedded towards the base of the Makganyene Formation, have similar values to the iron-formations of the Koegas Subgroup. As a result of the above observations, new correlations are proposed in this study, relating the different Transvaal Supergroup basins located on the Kaapvaal Craton. The Pretoria Group of the Transvaal Basin has no correlative in the Griqualand West Basin, and the Postmasburg Group of the Northern Cape Basin has no lateral equivalent in the Transvaal Basin. These changes have been made to overcome problems present in the current correlations between those two basins. The Makganyene Formation correlates with the Huronian glaciations which occurred between 2.4 and 2.2 Ga ago in North America. Another Precambrian glaciation is the worldwide and well-studied Neoproterozoic glaciation (640 Ma). At each of these glaciations, major banded iron-formation deposition took place with associated deposition of sedimentary manganese in post-glacial positions. The central position of the Makganyene Formation within the Transvaal Supergroup in the Northern Cape emphasizes this glacial climatic dependence of paleoproterozoic banded iron-formation and manganese deposition. However these two Precambrian glaciations are interpreted in paleomagnetic studies as having occurred near to the equator. The controversial theory of the Snowball Earth has been proposed which proposes that the Earth was entirely frozen from pole to pole. Results from field work, sedimentology, petrography and geochemistry were integrated in a proposed depositional model of the Makganyene Formation occurring at the symmetrical centre of the lithologic succession of the Transvaal Supergroup. At the beginning of the Makganyene glaciation, a regression occurred and glacial advance took place. The diamictites are mostly interpreted as being deposited from wet-based glaciers, probably tidewater glaciers, where significant slumping and debris flows occurred. Any transgression would cause a glacial retreat by rapid calving, re-establishing the chemical sedimentation of banded iron-formations. These sea-level variations are responsible for the interbedding of these different types of rocks (clastic and chemical). The end of the Makganyene glacial event is characterised by subaerial eruptions of andesitic lava of the Ongeluk Formation bringing ashes into the basin. Banded iron-formation and associated manganese accumulations are climate-dependant. Glacial events are responsible for the build up of metallic ions such as iron and manganese in solution in deep waters. A warmer climate would induce a transgression and precipitation of these metallic ions when Eh conditions are favourable. In the Transvaal Supergroup, the climatic variations from warm to cold, and cold to warm are expressed by the lithologic succession. The warm climates are represented by carbonates. Cold climates are represented by banded iron-formations and the peak in cold climate represented by the diamictites of the Makganyene Formation. These changes in climate are gradual, which contradict the dramatic Snowball Earth event: a rapid spread of glaciated areas over low-latitudes freezing the Earth from pole-to-pole. Therefore, to explain low-latitude glaciations at sea-level, a high obliquity of the ecliptic is most likely to have occurred. This high obliquity of the ecliptic was acquired at 4.5 Ga when a giant impactor collided into the Earth to form the Moon. Above the critical value of 54° of the obliquity of the ecliptic, normal climatic zonation reverts, and glaciations will take place preferentially at low-latitudes only when favourable conditions are gathered (relative position ofthe continents and PC02 in the atmosphere).
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Grajales-Nishimura, Jose Manuel 1953. "Geology, geochronology, geochemistry and tectonic implications of the Juchatengo Green Rock Sequence, state of Oaxaca, southern Mexico." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/558094.
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Adriaans, Luke. "Geology, geochemistry and Sr-Nd isotope analysis of the Vredenburg Batholith and Cape Columbine Granites Paternoster/Vredenburg, South Africa: Implications on their petrogenesis, tectonic setting, and sources." University of the Western Cape, 2018. http://hdl.handle.net/11394/6527.
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>Magister Scientiae - MScThe late− to post−collisional Cape Granite Suite (CGS) located in the southwest of South Africa is comprised of S−, I−, and A−type granites, mafic intrusives, and volcanic flows. The CGS is interpreted to have formed during the closing of the Adamastor Ocean during the Late−Proterozoic to Early−Cambrian. Recently, the S−type granites have received much attention concerning their petrogenesis and sources. However, the I− and A−type granites remain poorly understood and little studied. Therefore, with new geochemical and isotopic data the petrogenesis, sources, and tectonic settings of I− (Vredenburg Batholith) and A−type (Cape Columbine) granites of the CGS form the focus for this study. The major and trace element data presented in this thesis show that the granites from the Vredenburg Batholith are weakly peraluminous to metaluminous, ferroan, and alkali−calcic. Associated with the granites are metaluminous, magnesian, and calc−alkalic igneous enclaves. Formerly, the granites have been interpreted to have formed by fractionation. However, with new geochemical analyses and reassessment of such models, it can be shown that such processes are incompatible with accounting for the chemical variation displayed by the granites and their enclaves. Moreover, the I−type granites and enclaves exhibit positive linear trends between whole−rock major and trace elements vs. maficity (Fe + Mg), which can be explained by co−entrainment of peritectic and accessory phases. The lithogeochemical characteristics of the enclaves and host granite reflect melting of a heterogeneous source. Moreover, the granite and enclave's εNd(t) values reflect melting of Paleoproterozoic-aged crustal sources. Finally, with tectonomagmatic discrimination diagrams, it can be shown that the tectonic setting of the granites indicates a transition from a collisional to extensional regime which corroborates the inferences of previous studies. The Cape Columbine Granites lithogeochemical characteristics are ferroan, calc−alkalic and weakly peraluminous. They show typical A−type granite characteristics in having high silica content, high Na + K values, REE enrichment as compared to S− and I−type granites and strong negative Eu anomalies. For this thesis, it can be shown that anatexis of quartzofeldspathic protolith in an extensional regime produced the chemical variation of the Cape Columbine Granite. Moreover, their isotope ratios are typically radiogenic, indicative of a crustal origin. With this new geochemical data evidence is provided against and in support of previous inferences made about the petrogenesis of the I− and A−type granites of the CGS. This also betters our understanding of the magmatic processes involved in the construction of the CGS over time.
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Slabber, Nina. "The geology and geochemistry of the Bridgetown Formation of the Malmesbury Group, Western Cape Province." Thesis, Stellenbosch : Stellenbosch University, 1995. http://hdl.handle.net/10019.1/54889.
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Thesis (MSc) -- Stellenbosch University , 1995.ENGLISH ABSTRACT: A number of small greenstone bodies of the Bridgetown Formation are exposed as elongated lenses and dykes within metasediments of the Malmesbury Group in the Western Cape Province, South Africa. The Malmesbury Group is part of the Neoproterozoic to Cambrian (Namibian) Saldania Subprovince which is the southern continuation of a Pan-African mobile belt system. A detailed geological and geochemical study was conducted on the largest outcrop of the Bridgetown Formation, situated 20km east of the town Moorreesburg. The Bridgetown Formation consists of a meta-volcano-sedimentary sequence that experienced polyphase deformation and metamorphism up to the lower greenschist facies. Tectonically, the Bridgetown Formation is included in the Boland tectonic domain, east of the Piketberg-Wel lington fault zone that is suggested to run Skm west of Heuningberg and subparallel to the Berg River. This agrees with Rabie's (1974) original subdivision of the tectonic domains. The Bridgetown Formation consists of: i) A basal unit of poorly differentiated alkaline metabasalt with a within-plate tectonomagmatic fingerprint. ii) An intermediate unit of poorly differentiated tholeiitic metabasalt, intruded by a younger tholeiitic metabasite with a low degree of differentiation. Both members of the intermediate unit have ocean-floor basalt (P-type MORB) and island arc basalt fingerprints. iii) An upper unit of poorly differentiated as well as more evolved alkaline metabasalts, interlayered with metatuff with an alkaline basaltic composition, metasedimentary rocks with a marine origin, and graphitic schists and muscovitequartz schists, both with a continental crust provenance. iv) An overlying metasedimentary sequence including dolomite, massive and oolitic chert, jasper and jaspilite. The Bridgetown Formation probably also comprises a lower metamorphosed ultramafic unit, indicated by the association of Ni- and Cr-rich talc bodies, Ni-and errich banded chert, chlorite schist and small dolomite-talc-chlorite bodies at Spitskop, situated directly northwest of the main greenstone body. The sequence of eruptive stages and the geochemistry of the metavolcanics resemble Hawaiian volcanism , indicated by an initial deep water stage of alkaline magmatism, followed by main tholeiitic edifice and post-caldera alkaline magmatism. Post-caldera alkaline magmatism occurred contemporaneously with deposition . of sediments and chemical precipitates (carbonates and cherts). The Bridgetown metavolcanics have no magmatic association with either the Bloubergstrand volcanics or mafic and intermediate plutonic rocks in the Malmesbury Group. However, some physical and geochemical similarities exist between the Bridgetown Formation and the age related Grootderm Formation of the Marmora Terrane (Gariep Supergroup) which is considered to represent ophiolitic material. The Bridgetown Formation probably represents segments of oceanic crust, including seamounts of oceanic islands, which were tectonically emplaced in an accretionary prism zone during subduction of oceanic crust underneath the Kalahari Craton, 600 to 700 Ma ago. This resulted in the present spatial configuration of various small greenstone bodies in the Malmesbury Group. To date no exploitable mineral deposits have been found 1n the Bridgetown Formation. However, Au and As anomalies in stream sediment and soil samples, taken in the Spitskop area, require further attention. lt is suggested that the gold and arsenic is hosted in brittle deformed clear to milky quartz veins which developed at zones of competency contrasts in all the li tholog ies in the Spitskop area.
AFRIKAANSE OPSOMMING: 'n Aantal klein groenskisliggame van die Bridgetown Formasie is blootgestel as verlengde lense en gange binne metasedimente van die Malmesbury Groep in die Wes-Kaap Provinsie, Suid-Afrika. Die Malmesbury Groep is deel van die Neoproterozo·iese tot Kambriese (Namibiese) Saldania Subprovinsie wat die suidelike voortsetting is van 'n Pan-Afrikaanse mobiele gordel sisteem. 'n Gedetaileerde geologiese en geochemiese studie is gedoen op die grootste dagsoom van die Bridgetown Formasie, gelee 20km oos van die dorp Moorreesburg. Die Bridgetown Formasie bestaan uit 'n metavulkanies-sedimentere opeenvolging wat pol ifase vervorming en metamorfisme tot en met die laer groenskis fasies ondergaan het. Die Bridgetown Formasie word hier in die Boland tektoniese domein ingedeel deur die Piketberg-Wellington verskuiwingsone 5km wes van Heuningberg, subparallel a an die Bergrivier, te plaas. Dit stem ooreen met Rabie ( 197 4) se oorspronkl ike verdeling van die tektoniese domeine. Die Bridgetown Formasie bestaan uit: i) 'n Basale eenheid wat hoofsaaklik bestaan uit min gedifferens ieerde alkali-metabasalte met binneplaat tektonomagmatiese eienskappe. ii) 'n lntermediere eenheid wat bestaan uit min gedifferensieerde tholeiitiese metabasalt en 'n jonger intrusiewe tholeiitiese metabasiet wat 'n lae graad van differensias ie ondergaan het. Beide intermediere eenhede het oseaanvloer-basalt (P-t ipe MORB) en eilandboog basaltiese eienskappe. iii) 'n Boonste eenheid wat bestaan uit min gedifferensieerde asook meer gedifferensieerde alkal i-metabasalte, tussengelaagd met metatuf met 'n alka libasaltiese samestelling; metasedimentere gesteentes met 'n mariene oorsprong, en grafitiese ski ste en kwarts-muskoviet skiste, beide met 'n kontinentale kors oorsprong . iv) 'n Oorliggende metasedimentere opeenvolging wat dolomiet, massiewe en ooli tiese chert, jaspis en jaspiliet insluit. Die Bridgetown Formasie slu it moontlik ook 'n onderliggende gemetamorfiseerde ultramafiese eenheid in; aangedui deur die assosiasie van Ni- en Cr-ryke ta lkl iggame, Ni- en Cr-ryke gebande chert, chlorietskis en klein dolomiet-talk-chloriet liggame by Spitskop, gelee direk noordwes van die hoof groensteenliggaam. Die opeenvolg ing van magmatisme en die geochemie van die metavulkaniese gesteentes stem ooreen met Hawaiiese vulkanisme, naamlik 'n diepwater stadium, gekarakteriseer deur alkaliese magmatisme, gevolg deur 'n hoof tholeiitiese opbouing en post-kaldera alkaliese magmatisme. Die post-kaldera alkaliese magmatisme het gelyktydig plaasgevind met afsetting van sedimente en chemiese presipitate (karbonate en cherte ). Die Bridgetown metavulkaniese gesteentes het geen magmatiese assosiasie met 6f die Bloubergstrand vulkaniese gesteentes 6f mafiese en intermediere plutoniese gesteentes in die Malmesbury Groep nie. Fisiese en geochemiese ooreenkomste bestaan egter tussen die Bridgetown Formasie en die Grootderm Formasie van die Marmora Terrein (Gariep Supergroep) wat beskou word as ofiolitiese materiaal. Die Bridgetown Formasie verteenwoordig moontlik segmente van oseaankors, insluitende oseaan-eilande, wat tektonies in 'n melange sone ingeplaas is tydens subduksie van oseaankors onder die Kalahari Kraton in (600 tot 700 Mj gelede). Dit verklaar die huidige ruimte like verspreiding van verske ie klein groensteenliggame in die Malmesbury Groep. Tot en met hede is geen ontginbare mineraalafsettings in die Bridgetown Formasie ontdek nie. Au en As anomalie in stroomsediment- en grondmonsters, geneem in die Spitskop area, behoort egter verdere aandag te geniet. Daar is voorgestel dat die goud en arseen voorkom in brosvervormde helder tot melkerige kwartsare wat ontwikkel het in swak sones in al die litologie in die Spitskop area.
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Pollock, J. Michael. "Geology and geochemistry of hydrothermal alteration, eastern portion of the North Santiam mining area." PDXScholar, 1985. https://pdxscholar.library.pdx.edu/open_access_etds/3582.
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The Ruth Mine is a base-metal vein deposit near the eastern margin of a reported porphyry copper deposit in the Western Cascade Range in Oregon. Uplift of the Western Cascade Range has resulted in a deeply dissected terrain in which more than a kilometer of the stratigraphy overlying the porphyry-style mineralization is preserved and exposed. The stratigraphic units, which are middle Tertiary in age, have been given arbitrary letter designations beginning with the lowest unit (Unit A) through the uppermost unit (Unit D).
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Leung, Ho-sun, and 梁灝燊. "Geochemistry of the paleozoic Xiadong mafic-ultramafic complex, Eastern Xinjiang, NW China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44143850.
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Scott, Clinton Thomas. "Biogeochemical signatures in Precambrian black shales window into the co-evolution of ocean chemistry and life on Earth /." Diss., [Riverside, Calif.] : University of California, Riverside, 2009. http://proquest.umi.com/pqdweb?index=0&did=1957331771&SrchMode=2&sid=3&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1268856729&clientId=48051.
Full textAbstract:
Thesis (Ph. D.)--University of California, Riverside, 2009.Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 16, 2010). Includes bibliographical references. Also issued in print.
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LaMaskin, Todd Allen. "Stratigraphy, provenance, and tectonic evolution of Mesozoic basins in the Blue Mountains Province, eastern Oregon and western Idaho /." Connect to title online (ProQuest), 2009. http://proquest.umi.com/pqdweb?did=1790314181&sid=2&Fmt=2&clientId=11238&RQT=309&VName=PQD.
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Carter, James Edward. "Structure, stratigraphy, and geochemistry of the Upper Ordovician Lawrence Harbour Formation, Exploits Subzone, Newfoundland." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0028/MQ36103.pdf.
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Johnson, Christopher M., and Daalen Christopher M. Van. "Mineralogy and geochemistry of Late Archean and Paleoproterozoic granites and pegmatites in the Northern Penokean terrane of Marquette and Dickinson Counties, Michigan." ScholarWorks@UNO, 2015. http://scholarworks.uno.edu/td/2088.
Full textAbstract:
This thesis focuses on mineralogy, geochemistry, and origin of eight pegmatites and two spatially associated granites of Late Archean and Paleoproterozoic ages located in Marquette and Dickinson Counties, Michigan. Biotite geochemistry reveals that both granites and all pegmatites are peraluminous and have an orogenic signature. However, bulk composition reveals the Humboldt granite is a peraluminous A-type granite and the Bell Creek granite is a peraluminous mix between I-, S-, and A-type granites. The Republic Mine pegmatite appears to be geochemically similar to the Bell Creek granite and Grizzly pegmatite. The Crockley pegmatite is genetically related to the Humboldt granite. The Groveland Mine, Sturgeon River, and Hwy69 pegmatites appear to be a product of the Peavy Pond Complex being contaminated with the Marquette Range Super Group. Contamination and anatexis have made classification of the granites and pegmatites problematic. The Grizzly should be classified as a primitive LCT-type even though this pegmatite lacks characteristic enrichment associated with LCT pegmatites. Mineralogical geochemistry reveals that the Republic Mine is relatively more primitive than other pegmatites and should be classified as a primitive Mixed-type pegmatite. Groveland Mine has mineralogy and geochemistry not normally associated with NYF-type pegmatites and should be classified as Mixed. The Crockley pegmatite should be classified as NYF-type with a primitive LCT overprint. Dolfin, Hwy69, Sturgeon River, and Black River pegmatites should be classified as Rare Element, REE, NYF-type, although the Black River has slight tantalum enrichment expressed in columbite group minerals.