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Journal articles on the topic "Geology Granodiorites Granite Rocks"
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T, Aga, and Haruna A. I. "The field geology and petrography of the kofayi younger granite complex, central Nigeria." International Journal of Advanced Geosciences 7, no. 2 (2019): 95. http://dx.doi.org/10.14419/ijag.v7i2.29055.
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The Kofayi Younger Granite Complex is one of the several anorogenic alkaline Younger Granite Complexes that is located approximately 45 kilometres north east of Jos, Nigeria. The complex is found to comprise of felsic rocks like; biotite-granites, biotite microgranites and granodiorites. They are also found to be associated with mafic rocks like diorites which, at some portions have formed hybrid rocks. Quartz- feldspar- granites are the porphyritic rocks that found in the ring complex. The complex intrude the basement rocks of central Nigeria. Structural trends on these rocks suggest that they were controlled by some deep seated structures of the basement. Mineral suite identified include; fayalite, pyroxene, amphibole, k-feldspar, biotite, quartz, iron- oxide and accessory minerals like zircon, apatite, and allanite. Generally, the petrography of these rock samples reveal the presence of a mafic magma which has two pulses (a mafic and felsic pulse) of injection.
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Wolska, Anna. "Petrology and geochemistry of granitoids and their mafic micogranular enclaves (MME) in marginal part of the Małopolska Block (S Poland)." Mineralogia Polonica 43, no. 1-2 (2012): 3–127. http://dx.doi.org/10.2478/v10002-012-0003-5.
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AbstractGranitic plutons (the Dolina Będkowska valley and Pilica area) were found in a few boreholes in the Małopolska Block (MB). These granitic rocks may represent apical parts (apophyses) of a great magmatic bodies (batholiths) located in deeper level of the Ediacaran/Paleozoic basement. They are described as ‘stitching intrusions’, generated during/after collision in Carboniferous/Permian period (~300 Ma) between the Upper Silesian Block (USB) and the Małopolska Block (MB).These rocks are fresh, unaltered granodiorites that are pale grey in colour. They have holocrystalline, medium- to coarse-grained structure and massive texture. For the first time, several mafic microgranular enclaves (MME), varying in size and colour, were found in the granodioritic host (HG). The occurrence of MME in the host granodioritic rocks is evidence of a mingling process between mafic and felsic magmas.The MME are pale/dark grey in colour, fine-grained rocks with ‘porphyritic’ textures. They consist of large megacrysts/xenocrysts of plagioclase, quartz, alkali feldspars and the fine-grained groundmass of pseudo-doleritic textures (lath-shaped plagioclases, blade-shaped amphiboles/biotites). According to their modal/mineral composition, they represent Q-diorites and tonalites.The MME, similar to the host granodiorites (HG), are I-type rocks, exhibit high Na2O content >3.2 wt%; normative diopside or normative corundum occurs (mainly <1%). They are metaluminous to slightly peraluminous (ASI <1.1) and have calc-alkaline, medium-K to high-K character. They generally belong to magnesian series (#Mg=0.20-0.40) and have low agpaitic index (<0.87). They are low evolved magmatic rocks. The rocks studied are enriched in LREEs (La, Ce, Sm) compared to HREEs. The Eu* negative anomaly and high Sr contents point to varying degrees of plagioclase fractionation connected to the mixing process rather than simple fractional crystallization. Both rocks studied (HG and MME) are characterized by a high content of LILEs (K, Ba, Rb) in normalized patterns and a low HFS/LIL elements ratio (Ta, Nb)/(K, Rb, La). The projection points of the rocks studied plot in different fields of various petrochemical diagrams: mainly in the arc granites that are rare in the pre-collisional granites as well as the syn-subductional to post-collisional granites fields.For the first time, inner textures in rock-forming minerals related to mixing processes are described both in the granodioritic host (HG) and in the MME. Mantled boxy cellular plagioclase megacrysts with ‘old cores’ of labradorite composition, and amphibole aggregates with titanite and opaque minerals, represent peritectic rather than primary residual minerals. The plagioclase, quartz and alkali feldspar megacrysts/xenocrysts were mechanically transferred from the granodioritic host (HG) to MME. The presence of lath-shaped plagioclases, blade-shaped amphiboles/biotites and acicular-shaped apatites in the groundmass of the MME is evidence of undercooling of hot mafic blobs in a relatively cold granodioritic magma chamber. The MME were hybridized by leucocratic melt squeezed from the granodioritic magma in a later stage of the mixing process (quartz and alkali crystals in the interstices in the MME groundmass). In the granodiorites (HG), the spike and spongy cellular zones as well as biotite/amphibole zones in plagioclase megacrysts are connected to the mixing process.Both of the rocks studied are characterized by different amounts of major elements (SiO2, Na2O and K2O), trace elements (Ni, Cr, V, Ti and P), #Mg and modified alkali-lime index (MALI) that is related to their origins from different sources. On the other hand, they have similar chondrite-normalized patterns (for trace elements and REE), LILEs contents (Sr, Ba, Rb), aluminum saturation index (ASI) and isotopic signatures (high 86Sr/87Sr (0.079-0.713) and low 143Nd/144Nd (0.512) values but lower than in continental crust), which are evidence of the strong hybridisation of mafic enclaves by the granodioritic host magma. The parental rocks of both rocks studied have a similar mafic signature but were generated in different sources: the host granodiorites (HG) magma in lower continental crust rocks, and the MME magma in enriched upper mantle. The MME crystallized from strongly hybridized magma of intermediate compositions (Q-diorite, tonalite) rather than from primary mafic magma. The host granodiorites (HG) originated from completely homogenized crustal granodioritic magma which inherited its geochemical signature from ancient arc-rocks in a subduction-related setting
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FEELY, MARTIN, DAVID SELBY, JON HUNT, and JAMES CONLIFFE. "Long-lived granite-related molybdenite mineralization at Connemara, western Irish Caledonides." Geological Magazine 147, no. 6 (2010): 886–94. http://dx.doi.org/10.1017/s0016756810000324.
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AbstractNew Re–Os age determinations from the Galway Granite (samples: KMG = 402.2 ± 1.1 Ma, LLG = 399.5 ± 1.7 Ma and GBM = 383.3 ± 1.1 Ma) show that in south Connemara, late Caledonian granite-related molybdenite mineralization extended from c. 423 Ma to c. 380 Ma. These events overlap and are in excellent agreement with the published granite emplacement history determined by U–Pb zircon geochronology. The spatial distribution of the late-Caledonian Connemara granites indicates that initial emplacement and molybdenite mineralization occurred at c. 420 Ma (that is, the Omey Granite and probably the Inish, Leterfrack and Roundstone granites) to the N and NW of the Skird Rocks Fault, an extension of the orogen-parallel Southern Uplands Fault in western Ireland. A generally southern and eastward progression of granite emplacement (and molybdenite mineralization) sited along the Skird Rocks Fault then followed, at c. 410 Ma (Roundstone Murvey and Carna granites), at c. 400 Ma (Errisbeg Townland Granite, Megacrystic Granite, Mingling Mixing Zone Granodiorite, Lough Lurgan Granite and Kilkieran Murvey Granite) and at c. 380 Ma (Costelloe Murvey Granite, Shannapheasteen and Knock granites). The duration of granite magmatism and mineralization in Connemara is similar to other sectors of the Appalachian–Caledonian orogeny and several tectonic processes (e.g. slab-breakoff, asthenospheric flow, transtension and decompression) may account for the duration and variety of granite magmatism of the western Irish Caledonides.
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Broska, Igor, and Igor Petrík. "Variscan thrusting in I- and S-type granitic rocks of the Tribeč Mountains, Western Carpathians (Slovakia): evidence from mineral compositions and monazite dating." Geologica Carpathica 66, no. 6 (2015): 455–71. http://dx.doi.org/10.1515/geoca-2015-0038.
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AbstractThe Tribeč granitic core (Tatric Superunit, Western Carpathians, Slovakia) is formed by Devonian/Lower Carboniferous, calc-alkaline I- and S-type granitic rocks and their altered equivalents, which provide a rare opportunity to study the Variscan magmatic, post-magmatic and tectonic evolution. The calculatedP-T-Xpath of I-type granitic rocks, based on Fe-Ti oxides, hornblende, titanite and mica-bearing equilibria, illustrates changes in redox evolution. There is a transition from magmatic stage atTca. 800–850 °C and moderate oxygen fugacity (FMQ buffer) to an oxidation event at 600 °C between HM and NNO up to the oxidation peak at 480 °C and HM buffer, to the final reduction at ca. 470 °C at ΔNN= 3.3. Thus, the post-magmatic Variscan history recorded in I-type tonalites shows at early stage pronounced oxidation and low temperature shift back to reduction. The S-type granites originated at temperature 700–750 °C at lower water activity and temperature. TheP-Tconditions of mineral reactions in altered granitoids at Variscan time (both I and S-types) correspond to greenschist facies involving formation of secondary biotite. The Tribeč granite pluton recently shows horizontal and vertical zoning: from the west side toward the east S-type granodiorites replace I-type tonalites and these medium/coarse-grained granitoids are vertically overlain by their altered equivalents in greenschist facies. Along the Tribeč mountain ridge, younger undeformed leucocratic granite dykes in age 342±4.4 Ma cut these metasomatically altered granitic rocks and thus post-date the alteration process. The overlaying sheet of the altered granites is in a low-angle superposition on undeformed granitoids and forms “a granite duplex” within Alpine Tatric Superunit, which resulted from a syn-collisional Variscan thrusting event and melt formation ~340 Ma. The process of alteration may have been responsible for shifting the oxidation trend to the observed partial reduction.
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ESSAIFI, ABDERRAHIM, SCOTT SAMSON, and KATHRYN GOODENOUGH. "Geochemical and Sr–Nd isotopic constraints on the petrogenesis and geodynamic significance of the Jebilet magmatism (Variscan Belt, Morocco)." Geological Magazine 151, no. 4 (2013): 666–91. http://dx.doi.org/10.1017/s0016756813000654.
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AbstractIn the Variscan fold belt of Morocco, the Jebilet massif is characterized by Palaeozoic metasedimentary rocks intruded by syntectonic magmatism that includes an ultramafic–granitoid bimodal association and peraluminous granodiorites emplacedc. 330 Ma, intruded by younger leucogranitesc. 300 Ma. The mafic–ultramafic rocks belong to a tholeiitic series, and display chemical and isotopic signatures consistent with mixing between mantle-derived and crust-derived magmas or assimilation and fractional crystallization. The granites within the bimodal association are mainly metaluminous to weakly peraluminous microgranites that show characteristics of A2-type granites. The peraluminous, calc-alkaline series consists mainly of cordierite-bearing granodiorites enclosing magmatic microgranular enclaves and pelitic xenoliths. Detailed element and isotope data suggest that the alkaline and the peraluminous granitoids were formed in the shallow crust (<30 km) by partial melting of tonalitic sources at high temperatures (up to 900°C) and by partial melting of metasedimentary protoliths at relatively low temperatures (c. 750°C), respectively. Mixing between the coeval mantle-derived and crust-derived magmas contributed to the large variation of initial εNdvalues and initial Sr isotopic ratios observed in the granitoids. Further contamination occurred by wall-rock assimilation during ascent of the granodioritic plutons to the upper crust. The ultramafic–granitoid association has been intruded by leucogranites that have high initial Sr isotopic ratios and low initial εNdvalues, indicating a purely crustal origin. The heating events that caused emplacement of the Jebilet magmatism are related to cessation of continental subduction and convective erosion/thinning of the lithospheric mantle during plate convergence.
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Dunning, G. R., D. H. C. Wilton, and R. K. Herd. "Geology, geochemistry and geochronology of a taconic batholith, southwestern Newfoundland." Transactions of the Royal Society of Edinburgh: Earth Sciences 80, no. 2 (1989): 159–68. http://dx.doi.org/10.1017/s0263593300014449.
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ABSTRACTFoliated to massive hornblende and biotite-bearing tonalite, trondhjemite and granodiorite comprise a terrane of batholithic dimensions in southwestern to central Newfoundland. These rocks intrude and include Ordovician ophiolite fragments and metasedimentary rocks of Fleur de Lys type, and are cut by a suite of Silurian gabbro-diorite and norite and Siluro-Devonian (?) granite intrusions.A U/Pb (zircon, sphene) age of 456 ± 3 Ma (2σ) and a K/Ar (hornblende) age of 455 ± 14 Ma (previously reported) for a representative least-deformed tonalite of the Southwest Brook Complex indicate that it crystallised and cooled in Caradoc time. A less precise U/Pb (zircon) age of 428 ± 41 Ma (2σ) is measured for tonalitic Cape Ray Granite in southern Newfoundland. On discrimination diagrams which use Rb, Nb and Y contents to infer tectonic setting, these rocks fall in the field of volcanic arc granites. The occurrence of zircon cores with average ages of 1430 + 18/–17 and 1541 ± 173 Ma (2σ) also indicate that the magmas formed in part by partial melting of Proterozoic crust, or sediments derived from such crust. It is suggested that the tonalitic magmas were generated during the Taconic Orogeny in an arc: continent collision zone at the ancient margin of eastern North America.Tonalitic rocks in western Newfoundland broadly correlative in age and chemistry with the batholith include the Burlington Granodiorite and Hungry Mountain Complex, as well as allochthonous slices of foliated tonalite emplaced over Ordovician platform carbonates W of Grand Lake.
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Boerboom, Terrence J., and Robert E. Zartman. "Geology, geochemistry, and geochronology of the central Giants Range batholith, northeastern Minnesota." Canadian Journal of Earth Sciences 30, no. 12 (1993): 2510–22. http://dx.doi.org/10.1139/e93-217.
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The Giants Range batholith is a large composite granitoid body that intrudes deformed supracrustal rocks in the western part of the Wawa Subprovince of the Archean Superior Province. Peak fabric development in the supracrustal rocks coincides with D2 deformation, the product of regional transpression across the southern Superior Province. U–Pb zircon ages on two phases of the Giants Range batholith bracket D2 deformation to an interval between 2685 and 2669 Ma. Two well-exposed components of the central part of the Giants Range batholith are the pre- to syn-D2 Britt granodiorite, which contains a linear D2 metamorphic fabric, and the syn- to post-D2 Shannon Lake granite, which cuts deformation fabrics in the Britt granodiorite and the supracrustal rocks. Geochemical discrimination plots imply emplacement of the Britt granodiorite in an arc environment and the Shannon Lake granite in a collision setting. Zircons yield U–Pb ages of 2681 ± 4 and 2685 ± 4 Ma for the Britt granodiorite and 2674 ± 5 and 2674 ± 27 Ma for the Shannon Lake granite. Timing of D2 deformation near the Giants Range batholith corresponds well with similar rocks exposed along strike 170 km to the east near Shebandowan Lake, Ontario, where the end of D2 deformation has been bracketed between 2692 and 2681 Ma. The slightly younger ages for D2 deformation in Minnesota reflect later volcanic-arc development and associated plutonism than at Shebandowan Lake, possibly due to oblique convergence along a westward-migrating tectonic front.
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Mao, Qigui, Jingbin Wang, Wenjiao Xiao, et al. "From Ordovician nascent to early Permian mature arc in the southern Altaids: Insights from the Kalatage inlier in the Eastern Tianshan, NW China." Geosphere 17, no. 2 (2021): 647–83. http://dx.doi.org/10.1130/ges02232.1.
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Abstract The Kalatage inlier in the Dananhu-Haerlik arc is one of the most important arcs in the Eastern Tianshan, southern Altaids (or Central Asian orogenic belt). Based on outcrop maps and core logs, we report 16 new U-Pb dates in order to reconstruct the stratigraphic framework of the Dananhu-Haerlik arc. The new U-Pb ages reveal that the volcanic and intrusive rocks formed in the interval from the Ordovician to early Permian (445–299 Ma), with the oldest diorite dike at 445 ± 3 Ma and the youngest rhyolite at 299 ± 2 Ma. These results constrain the ages of the oldest basaltic and volcaniclastic rocks of the Ordovician Huangchaopo Group, which were intruded by granite-granodiorite-diorite plutons in the Late Ordovician to middle Silurian (445–426 Ma). The second oldest components are intermediate volcanic and volcaniclastic rocks of the early Silurian Hongliuxia Formation (S1h), which lies unconformably on the Huangchaopo Group and is unconformably overlain by Early Devonian volcanic rocks (416 Ma). From the mid- to late Silurian (S2-3), all the rocks were exhumed, eroded, and overlain by polymictic pyroclastic deposits. Following subaerial to shallow subaqueous burial at 416–300 Ma by intermediate to felsic volcanic and volcaniclastics rocks, the succession was intruded by diorites, granodiorites, and granites (390–314 Ma). The arc volcanic and intrusive rocks are characterized by potassium enrichment, when they evolved from mafic to felsic and from tholeiitic via transitional and calc-alkaline to final high-K calc-alkaline compositions with relatively low initial Sr values, (87Sr/86Sr)i = 0.70391–0.70567, and positive εNd(t) values, +4.1 to +9.2. These new data suggest that the Dananhu-Haerlik arc is a long-lived arc that consequently requires a new evolutionary model. It began as a nascent (immature) intra-oceanic arc in the Ordovician to early Silurian, and it evolved into a mature island arc in the middle Silurian to early Permian. The results suggest that the construction of a juvenile-to-mature arc, in combination with its lateral attachment to an incoming arc or continent, was an important crustal growth mechanism in the southern Altaids.
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GRENNE, T., R. B. PEDERSEN, T. BJERKGÅRD, A. BRAATHEN, M. G. SELASSIE, and T. WORKU. "Neoproterozoic evolution of Western Ethiopia: igneous geochemistry, isotope systematics and U–Pb ages." Geological Magazine 140, no. 4 (2003): 373–95. http://dx.doi.org/10.1017/s001675680300801x.
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New geochemical, isotopic and age data from igneous rocks complement earlier models of a long-lived and complex accretionary history for East African Orogen lithologies north of the Blue Nile in western Ethiopia, but throw doubt on the paradigm that ultramafic complexes of the region represent ophiolites and suture zones. Early magmatism is represented by a metavolcanic sequence dominated by pyroclastic deposits of predominantly basaltic andesite composition, which give a Rb–Sr whole-rock errorchron of 873±82 Ma. Steep REE patterns and strong enrichments of highly incompatible trace elements are similar to Andean-type, high-K to medium-K calc-alkaline rocks; εNd values between 4.0 and 6.8 reflect a young, thin continental edge. Interlayered basaltic flows are transitional to MORB and compare with mafic rocks formed in extensional, back-arc or inter-arc regimes. The data point to the significance of continental margin magmatism already at the earliest stages of plate convergence, in contrast with previous models for the East African Orogen. The metavolcanites overlap compositionally with the Kilaj intrusive complex dated at 866±20 Ma (U–Pb zircon) and a related suite of dykes that intrude thick carbonate-psammite sequences of supposedly pre-arc, continental shelf origin. Ultramafic complexes are akin to the Kilaj intrusion and the sediment-hosted dykes, and probably represent solitary intrusions formed in response to arc extension. Synkinematic composite plutons give crystallization ages of 699±2 Ma (Duksi, U–Pb zircon) and 651±5 Ma (Dogi, U–Pb titanite) and testify to a prolonged period of major (D1) contractional deformation during continental collision and closure of the ‘Mozambique Ocean’. The plutons are characterized by moderately peraluminous granodiorites and granites with εNd values of 1.0–2.0. They were coeval with shoshonitic, latitic, trachytic and rare trachybasaltic intrusions with very strong enrichments of highly incompatible trace elements and εNd of 0.4–8.0. The mafic end-member is ascribed to partial melting of enriched sub-continental mantle that carried a subduction component inherited from pre-collision subduction. Contemporaneous granodiorite and granite formation was related to crustal underplating of the mafic magmas and consequent melting of lower crustal material derived from the previously accreted, juvenile arc terranes of the East African Orogen.
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Li, Dapeng, Yuelong Chen, Guoliang Xue, et al. "Initiation of modern-style subduction in the Neoarchean: From plume to subduction with frequent slab break-off." GSA Bulletin 132, no. 9-10 (2020): 2119–34. http://dx.doi.org/10.1130/b35522.1.
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Abstract Fundamental geodynamic changes from vertical tectonics to lateral subduction occurred during the Neoarchean, yet detailed processes related to this transition and initiation of modern-style subduction remain enigmatic. Successive Neoarchean magmatic rocks including both plume-derived komatiites and subduction-related supracrustal and intrusive rocks appeared and preserved key information on the late Archean geodynamic changes in the Western Shandong Province granite-greenstone belt (WSP), North China Craton. In this study, whole-rock geochemical and Sm-Nd isotopic data and zircon U-Pb and Lu-Hf isotopes are reported for early Neoarchean supracrustal and intrusive rocks for the WSP. Temporally, the early Neoarchean magmatic movements in the WSP can be subdivided into two stages, including the early stage (2.77–2.69 Ga) and the late stage (2.69–2.60 Ga). Spatially, from southwest to northeast, intrusive rocks with similar ages define three belts (A, B, and C). Early stage tholeiitic and enriched meta-basalts were plume-related, representing oceanic crust opening from a pre-early Neoarchean continent. Slab subduction at least initiated at ca. 2.74 Ga and generated various Neoarchean tonalite-trondhjemite-granodiorites, quartz diorites, and arc-related volcanic rocks and mafic intrusions. Episodic emergence of meta-basaltic rocks and/or mafic intrusions with depleted εHf(t) values and low (La/Yb)N ratios indicates frequent slab break-offs during ca. 2.70–2.68 Ga, 2.66–2.64 Ga, and 2.62–2.60 Ga due to a relatively hotter mantle and regional heating by mantle plume. Secular geochemical changes of mafic and felsic rocks in this study outline roles of slab subduction in contributions of cooling the mantle, secular mantle refertilization, and crustal growth.
Dissertations / Theses on the topic "Geology Granodiorites Granite Rocks"
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Pett, Teresa K. "Garnetites of the Cardigan Pluton - Evidence for Restite and Implications for Source Rock Compositions." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/1099.
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The Cardigan pluton, located in the southern half of New Hampshire, is a strongly peraluminous, S-type granite which is granodioritic in composition. It is inferred to have been emplaced rapidly, thrust up along west-verging nappes during the Acadian orogeny. Distinctive pods, consisting of 50 to 70 percent modal garnet, are found throughout the pluton in assemblages of garnet + sillimanite + biotite + plagioclase + quartz. These garnetite rocks present an intriguing case for restite. Textural features of the garnetite rocks, such as fibrolitic sillimanite mats and flat, unzoned major and trace-element garnet grain profiles, provide evidence for biotite dehydration melting with single-stage garnet growth from the reaction: bio + plag + qtz + kspar = gar + sill + liq. Temperatures calculated using garnet-biotite (GB) thermometry and garnet-aluminum silicate-quartz-plagioclase (GASP) barometry yield estimates between 662-714ºC and 3.8 kbars. These low calculated temperatures are most likely the result of biotite compositions which have been altered by retrograde exchange reactions. The dominant source rock for the Cardigan magmas was likely calc-pelitic to greywacke in composition. Major element modeling suggests that ~70% melting of a calc-pelitic metasediment from the Central Maine trough could have generated a granodioritic melt similar to the average granodiorite of the Cardigan pluton. However, most of the Cardigan garnetite rocks appear to have been derived from pelites, as they are too poor in CaO and Na2O. Hence, though the majority of garnetite rocks cannot represent the dominant restite of the source rocks that produced the Cardigan pluton, they do appear to be the melt-depleted residue of an unidentified pelitic source. Comparison of Nd and Sr isotopic data from garnetite and Central Maine trough metasediments permit an interpretation that the Lower Rangeley Formation, from the Central Maine trough, could be the source rock of the Cardigan magmas. However, one feldspar Pb isotopic analysis in the literature (Moench and Allienikoff, 2002) and rare monazite chemical ages near 600 Ma suggest that the Cardigan pluton does not have a Laurentian source (i.e. Lower Rangeley Formation or other Central Maine trough metasediments), whereas an inferred peri-Gondwanan basement source is permissible.
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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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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.<br>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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Beard, Linda Sue. "Precambrian Geology of the Cottonwood Cliffs Area, Mohave County, Arizona." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/244095.
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A belt of Early Proterozoic rocks crops out in the Cottonwood Cliffs area, northwest Arizona. The belt contains an eastern and a western assemblage separated by the Slate Mountain fault. The western assemblage consists of mafic to felsic metavolcanic rocks, metapelites, and metaconglomerates. The eastern assemblage consists of phyllites, felsic to intermediate metavolcanic rocks, metagraywackes, and metagabbro bodies. The belt is bounded to the east by foliated granodiorite. The Valentine granite intruded the belt on the west and north. Steeply-plunging lineations and fold axes, and northeast-trending vertical foliation dominate the structural fabric. The regional elongation direction is near-vertical, as indicated by mineral and pebble lineations, and is parallel to fold axes. Although only one deformational event is evident, the intensity of that event may have obliterated evidence of any earlier deformation. Tertiary basalts and the Peach Springs Tuff locally overly the metamorphic rocks. Cenozoic normal faults in the area are mostly of minor displacement.
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Costarella, René. "Le complexe annulaire alcalin de Combeynot ( Massifs cristallins externes, Alpes françaises), témoin d'un magmatisme en régime distensif. Pétrogéochimie et signification géodynamique." Phd thesis, Grenoble 1, 1987. http://tel.archives-ouvertes.fr/tel-00539879.
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Le massif de Combeynot, sur la bordure nord-orientale du massif du Haut-Dauphiné (massifs cristallins externes, Alpes Françaises) est constitué de deux unités fondamentales (1) un socle, déformé et métamorphisé, représenté par un ensemble migmatitique et un orthogneiss oeillé ; ce socle se rattache aux formations du noyau du massif du Haut-Dauphiné, (2) un complexe annulaire subvolcanique, intrusif dans le socle, composé de formations volcaniques et volcano-détritiques, d'un réseau filonien microgranitique et rhyolitique très dense, de deux unités granitiques disposées de manière concentrique et de filons doléritiques tardifs terminant l'épisode magmatique. Une étude comparative sur la pétrographie, la structure, la typologie des zircons et la géochimie des éléments majeurs, en traces (Y, Nb, Zr, Rb, Sr, U, Th, Hf, Sc, Cs et Ta) et Terres Rares du complexe de Combeynot ont permis de retracer l'histoire magmatique de la série et de tester sa signification géodynamique. Le magmatisme de Combeynot est de nature alcaline intraplaque et traduit un environnement géotectonique de distension. Il trouve son origine dans le manteau à partir duquel plusieurs magmas subcontemporains s'individualisent par des taux de fusion partielle différents et conduisent aux unités acides par cristallisation fractionnée. Leur mise en place superficielle dans une zone orogénique encore non consolidée, riche en fluides et la participation des phases fluides juvéniles et/ou des eaux météoriques conditionnent la nature pétrographique acide, sursaturée et subsolvus des unités granitiques du complexe ainsi que les processus d'altération hydrothermale post- et tardi- magmatiques.
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Dupont, Pierre-Luc. "Pétrologie et géochimie des ensembles magmatiques pharusien I et II, dans le rameau oriental de la chaîne pharusienne (Hoggar, Algérie) : Implications géodynamiques pour l'évolution d'une chaîne mobile au protérozoïque supérieur." Nancy 1, 1987. http://www.theses.fr/1987NAN10332.
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Au pharusien I, la série de timesselarsine révèle l'épanchement de basaltes, d'affinité transitionnelle a faiblement alcaline dont le site géodynamique serait celui d'un "rift" en domaine continental. Vient ensuite une série ultrabasique/basique dont le site le plus probable est celui d'arc insulaire ou de bassin marginal. Le troisième épisode est représenté par deux ensembles : un lié à un domaine de type arc insulaire, l'autre montrant une évolution vers une marge continentale active. Au pharusien II, la série d'anded est intrudée par des dolérites et des roches volcaniques en liaison avec un site de type arc insulaire. La série d'Irrellouchem est liée à un site d'arc insulaire ou de marge continentale active. Les données isotopiques du strontium obtenues sur ces deux séries impliquent une contribution mantellique importante. Le dernier épisode pharusien est représenté par les roches du batholite de Tin Tekadiouit
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Schneider, Richard C. "Stratigraphy and depositional environments of the Mississippian Rocks, Garnet Range-Bearmouth area, Granite County, western Montana /." 1988. http://hdl.handle.net/1957/14497.
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Thesis (M.S.)--Oregon State University, 1988.<br>Typescript (photocopy). Mounted photographs. 2 folded plates in pocket. Includes bibliographical references (leaves 131-140). Also available on the World Wide Web.
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Freeman, Lauren Anne. "The nature of hydrothermal fluids associated with granite-hosted, polymetallic mineralisation in the Eastern lobe of the bushveld complex." Thesis, 1998. https://hdl.handle.net/10539/24747.
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A thesis submitted in fulfilment of the requirements for the degree of PhD in Geology< University of the Witwatersrand.<br>Numerous small base-metal deposits occur in the acidic rocks of the Bushveld Complex, and modern exploration programs are currently re-examining this metallotect in an attempt to refine the current working hypothesis for mineralisation in these granites. The hypothesis proposed for the origin of mineralisation is multifaceted, encompassing both spatial and temporal relationships between at least three episodes of ore formation. The first episode of mineralisation (typified by the Zaaiplaats tin deposit) occurred at relatively high temperatures (>600'C to 4000' C), and resulted in the formation of orthomagmatic cassiterite, scheelite and an early generation of fluorite. At lower temperatures (200°C<T<400°C), where processes were essentially fluid dominated, a mesothermal Cu-Pb-Zn-As-Ag-Au assemblage was deposited (exemplified by the Spoedwel, Boschhoek and Albert copper and silver deposits). A third episode of mineralisation resulted in the formation of an Fe-U-F assemblage and is recognised at several, but not necessanly all, of the deposits examined (for example, the Albert silver deposit). The extended nature of this three-stage paragenetic sequence is considered to reflect widespread mixing between an early fluid derived by H20-saturation of the granitic magma and an external meteoric/connate fluid, circulation of which was stimulated by the long-lived high heat-productive capacity of the Bushveld granites, as well as exhumation of the metallotect; The early high-temperature Sn/W assemblage was precipitated while magmatic fluids dominated the system. With time, the pluton cooled and was subject to regional uplift. Fractures developed, acting as conduits for external fluids of meteoric and/or connate origin. The late magmatic fluids, enriched in incompatible metals (and volatiles), interacted with the latter fluid, resulting in the localised precipitation of a secondary, lower-temperature mineral assemblage (Cu-Pb-Zn) in the zone of fluid mixing. As the external fluid component became progressively more dominant, the paragenesis changed, forming the :final Fe-U-F assemblage. The formation of these three different, temporally separate assemblages is adequately explained in terms of a fluid mixing model, wherein the concentration ofmetaIs and localisation of ore deposits are controlled by lithology and structure.<br>Andrew Chakane 2018
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Byars, Heather E. "Tectonic evolution of the west-central portion of the Newton window, North Carolina Inner Piedmont timing and implications for the emplacement of the Paleozoic Vale charnockite, Walker Top Granite, and mafic complexes /." 2010. http://trace.tennessee.edu/utk_gradthes/607.
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Gower, David Patrick. "Geology and genesis of uranium mineralization in subaerial felsic volcanic rocks of the Byers Brook formation and the comagatic [sic] Hart Lake Granite, Wentworth area, Cobequid Highlands, Nova Scotia /." 1988. http://collections.mun.ca/u?/theses,124296.
Full textBooks on the topic "Geology Granodiorites Granite Rocks"
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Witt, W. K. Geology and geochemistry of granitoid rocks in the southwest Eastern Goldfields Province. Geological Survey of Western Australia, 1997.
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John, David A. Granitic rocks in the Triassic-Jurassic magmatic arc of western Nevada and eastern California. U.S. Dept. of the Interior, U.S. Geological Survey, 1994.
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Lidke, David J. Rocks and structure of the north-central part of the Anaconda Range, Deer Lodge and Granite counties, Montana. U.S. G.P.O., 1992.
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Dodds, C. J. Potassium-argon ages of mainly intrusive rocks in the Saint Elias Mountains, Yukon and British Columbia. Energy, Mines and Resources Canada, 1988.
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Tensile fracturing in rocks: Tectonofractographic and electromagnetic radiation methods. Springer, 2005.
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Loen, Jeffrey S. Gold placer deposits and a molybdenum anomaly in the Miners Gulch area, Granite County, Montana. U.S. Govt. Print. Off., 1989.
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Hutton Symposium on the Origin of Granites and Related Rocks (5th 2003 Toyohashi-shi, Japan). Fifth Hutton Symposium: The origin of granites and related rocks : proceedings of a symposium held in Toyohashi, Japan, 2-6 September 2003. RSE Scotland Foundation, 2004.
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Hutton, Symposium on the Origin of Granites and Related Rocks (5th 2003 Toyohashi-shi Japan). Fifth Hutton Symposium: The origin of granites and related rocks : proceedings of a symposium held in Toyohashi, Japan, 2-6 September 2003. Royal Society of Edinburgh, 2005.
Find full textBook chapters on the topic "Geology Granodiorites Granite Rocks"
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Bouchez, Jean Luc. "Granite is Never Isotropic: An Introduction to AMS Studies of Granitic Rocks." In Petrology and Structural Geology. Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-017-1717-5_6.
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Anhaeusser, Carl R. "Palaeo- Meso- and Neoarchaean Granite-Greenstone Basement Geology and Related Rocks of the Central and Western Kaapvaal Craton, South Africa." In Regional Geology Reviews. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-78652-0_3.
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Kisvarsanyi, Eva B. "Precambrian rocks and ore deposits in the St. Francois Mountains, southeast Missouri: A Middle Proterozoic terrane of granite ring complexes and associated rhyolites." In Precambrian and Paleozoic Geology and Ore Deposits in the Midcontinent Region: Rosiclare, Illinois to Ironton and Viburnum, Missouri: June 30–July 8, 1989. American Geophysical Union, 1989. http://dx.doi.org/10.1029/ft147p0037.
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Migon, Piotr. "Geology of Granite." In Granite Landscapes of the World. Oxford University Press, 2006. http://dx.doi.org/10.1093/oso/9780199273683.003.0009.
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The unifying theme for granite landscapes of the world is the granite itself, hence it is logical to start with a brief account of granite geology. For obvious reasons of space and relevance, this chapter cannot provide a comprehensive and extensive treatment of granite as a rock. Rather, its aim is to provide background information on those aspects of granite geology which are relevant to geomorphology and may help to explain the variety of landforms and landscapes supported by granite. The survey of literature about the geomorphology of granite areas reveals that in too many studies the lithology of granite and the structure of their intrusive bodies have not received adequate attention, especially if a ruling paradigm was one of climatic, or climato-genetic geomorphology. Granites were usually described in terms of their average grain size, but much less often of their geochemistry, fabric, or physical properties. Even the usage of the very term ‘granite’ may have lacked accuracy, and many landforms described as supported by granite may in fact have developed in granodiorite. On the other hand, it is true that granite may give way to granodiorites without an accompanying change in scenery. In the Yosemite National Park, Sierra Nevada, California, these two variants occur side by side and both support deeply incised valleys, precipitous slopes and the famous Sierran domes. Likewise, wider structural relationships within plutons and batholiths, and with respect to the country rock, have been considered in detail rather seldom. In analyses of discontinuities, long demonstrated to be highly significant for geomorphology, terms such as ‘joints’, ‘faults’, and ‘fractures’ have not been used with sufficient rigour. But it has to be noted in defence of many such geologically poorly based studies that adequate geological data were either hardly available or restricted to a few specific localities within extensive areas, therefore of limited use for any spatial analysis of granite landforms. Notwithstanding the above, there exist a number of studies in which landforms have been carefully analysed in their relationships to various aspects of the lithology, structure, and tectonics of granite intrusions.
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Kemp, A. I. S. "IGNEOUS ROCKS | Granite." In Encyclopedia of Geology. Elsevier, 2005. http://dx.doi.org/10.1016/b0-12-369396-9/00301-4.
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Jacob, Jean-Baptiste, and Jean-François Moyen. "Granite and Related Rocks." In Encyclopedia of Geology. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-409548-9.12501-1.
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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.
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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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Karlstrom, Karl E., Bradley R. Ilg, David Hawkins, et al. "Vishnu basement rocks of the Upper Granite Gorge: Continent formation 1.84 to 1.66 billion years ago." In Grand Canyon Geology: Two Billion Years of Earth's History. Geological Society of America, 2012. http://dx.doi.org/10.1130/2012.2489(01).
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Herz, Norman, and Ervan G. Garrison. "Archaeological Materials :Rocks and Minerals." In Geological Methods for Archaeology. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780195090246.003.0016.
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This chapter is only a brief introduction to lithic archaeological materials. Archaeologists with but little knowledge of rocks and rock-forming minerals are urged to learn about them in greater detail than that presented here. Lithic resources are abundant in almost every archaeological site, and lithic artifacts are invariably the best preserved of any remains. Early societies learned how to exploit these resources, and the use and production of lithics go back to the earliest known sites, at least 1.5 million years. In fact, the earliest cultures are distinguished on the basis of their lithic industries and lithic artifacts. Horror stories in misidentification of lithics abound. Not only have misidentified artifacts proven embarrassing to the archaeologist, but also they have made it difficult to make meaningful comparisons of different societies using published descriptions. In addition, conservation strategies for historical monuments cannot be developed without an understanding of the nature of the material used in their construction. Some egregious examples of ignorance of the rocks and minerals from our personal experience include the following: 1. An archaeologist asked if a quartzite scraper was either flint or chert. When told that it was neither, he asked, "Well then, which is it more like?" (answer, still neither). 2. Egyptian basalt statues have been called limestone in publications (and several other rock types). 3. Sources for alabaster were searched to explain a trading link between a site and elsewhere when the geological map showed the site was adjacent to a mountain of gypsum, the mineral component of alabaster (the gypsum may have merely rolled down the hillside to the workshops, where it became the more salable alabaster). 4. Conservators searched for methods to preserve an allegedly granitic historic monument, or so it had been identified. Chemical analysis revealed only abundant Ca, Mg, and carbonate. Fossils were also abundant in the "granite," which dissolved easily in hydrochloric acid (the "granite" was clearly limestone). Petrology is the branch of geology that deals with the occurrence, origin, and history of rocks. Petrography is concerned with descriptions of rocks, their mineralogy, structures, and textures.
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Alexander, Earl B., Roger G. Coleman, Todd Keeler-Wolfe, and Susan P. Harrison. "Baja California, Domain 1." In Serpentine Geoecology of Western North America. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780195165081.003.0019.
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Ophiolites occur in Baja California along the outer coast from San Benito and Cedros Islands through the Vizcaíno Peninsula to Magdalena and Santa Margarita Islands. This is a mountainous region with altitudes up to 920 m (3018 ft) on the Vizcaíno Peninsula, >300 m (∼1000 ft.) on Magdalena Island, and about 550 m (∼1800 ft) on Santa Margarita Island. The ophiolite of Calmalli, which is geologically distinct from ophiolites on the outer coast, is in low hills (mostly <500 m, or 1640 ft) near El Arco, about midway from Guerrero Negro to the Gulf of California. Ophiolites of the outer coast are in the Cochimí terrane, whereas the ophiolite of Calmalli is in the Alisitos terrane (Sedlock et al. 1993, Sedlock 2003). Mafic rocks of the Peninsular Ranges batholith that extends from California into Baja California are included in this domain. A major feature of the Peninsular Ranges is this batholith with plutons that range in composition from granite to gabbro, with tonalite the most common composition. Also, gabbro is common in the “western zone” of the batholith (Sedlock 2003). This zone is mostly southwest of the Elsinore fault zone in the California and north of the Agua Blanca fault in Baja California. All the ophiolites are in desert areas. Mean annual temperatures are about 20°C, and mean annual precipitation is about 10 cm on Cedros Island and along the outer coast of Baja California Sur and about 15 cm in the ophiolite of Calmalli locality (Hastings and Turner 1965). The precipitation falls mostly in winter in the Cedros Island and Puerto Nuevo localities, in September in the Magdalena–Margarita locality, and in both September and in winter in the Calmalli locality. Fog and dew are common along the outer coast around Santa Margarita and Magdalena Islands. Drought persists for most of each year at all the localities (Hastings and Humphrey 1969; fig 13-3). The gabbro belt in the northern part of the Peninsular Ranges has been added to this domain. Descriptions of the geology, climate, soils, and vegetation of the gabbroic plutons are given in section 13.8, describing the Los Pinos locality.
Reports on the topic "Geology Granodiorites Granite Rocks"
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Dickson, W. L., P. W. Delaney, and J. C. Poole. Geology of the burgeo granite and associated rocks in the Ramea [11P/11] and La Hune [11P/10] map areas, southern Newfoundland. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1985. http://dx.doi.org/10.4095/121074.
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