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1
LaFlamme, Crystal, Christopher R. M. McFarlane, and David Corrigan. "Neoarchean Mantle-derived Magmatism within the Repulse Bay Block, Melville Peninsula, Nunavut: Implications for Archean Crustal Extraction and Cratonization." Geoscience Canada 42, no. 3 (2015): 305. http://dx.doi.org/10.12789/geocanj.2015.42.065.
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SUMMARYThe Repulse Bay block (RBb) of the southern Melville Peninsula, Nunavut, lies within the Rae craton and exposes a large (50,000 km2) area of middle to lower crust. The block is composed of ca. 2.86 Ga and 2.73–2.71 Ga tonalite-trondhjemite-granodiorite (TTG) and granitic gneiss that was derived from an older 3.25 and 3.10 Ga crustal substrate. This period of crustal generation was followed by the emplacement of ca. 2.69–2.66 Ga enderbite, charnockite, and granitoid intrusions with entrained websterite xenoliths. These voluminous batholith-scale bodies (dehydrated and hydrated intrusions), and the associated websterite xenoliths, have similar whole rock geochemical properties, including fractionated light rare earth element (LREE)–heavy (H)REE whole rock patterns and negative Nb, Ti, and Ta anomalies. Dehydrated intrusions and websterite xenoliths also contain similar mineralogy (two pyroxene, biotite, interstitial amphibole) and similar pyroxene trace element compositions. Based on geochemical and mineralogical properties, the two lithologies are interpreted to be related by fractional crystallization, and to be the product of a magmatic cumulate processes. Reworking of the crust in a ca. 2.72 Ga subduction zone setting was followed by ca. 2.69 Ga upwelling of the asthenospheric mantle and the intrusion of massif-type granitoid plutons. Based on a dramatic increase in FeO, Zr, Hf, and LREE content of the most evolved granitoid components from the 2.69–2.66 Ga cumulate intrusion, we propose that those granitoid plutons were in part derived from a metasomatized mantle source enriched by fluids from the subducting oceanic slab that underwent further hybridization (via assimilation) with the crust. Large-scale, mantle-derived Neoarchean sanukitoid-type magmatism played a role in the development of a depleted lower crust and residual sub-continental lithospheric mantle, a crucial element in the preservation of the RBb.RÉSUMÉLe bloc de Repulse Bay (RBb) dans le sud de la péninsule de Melville, au Nunavut, est situé dans le craton de Rae et expose une large zone (50 000 km2) de croûte moyenne à inférieur. Ce bloc est composé de tonalite-trondhjémite-granodiorite (TTG) daté à ca. 2,86 Ga et 2,73–2,71 Ga, et de gneiss granitique dérivé d’un substrat crustal plus ancien daté à 3,25 Ga et 3,10 Ga. Cette période de croissance crustale a été suivie par la mise en place entre ca. 2,69 et 2,66 Ga d’intrusions d’enderbite, charnockite et de granitoïde incluant des xénolites d’entraînement de websterite. Ces intrusions de taille batholitique (intrusions déshydratées et hydratées) ainsi que les xénolites d’entraînement de websterite associés, ont des propriétés géochimiques sur roche totale semblables notamment leurs profils de fractionnement des terres rares légers (LREE) et des terres rares lourds (HREE) ainsi que leurs anomalies négatives en Nb, Ti et Ta. Les intrusions déshydratées et les xénolites de websterite ont aussi des minéralogies similaires (deux pyroxènes, biotite, amphibole interstitielle) ainsi que des compositions semblables en éléments traces de leurs pyroxènes. Étant donné leurs propriétés géochimiques et minéralogiques, ces deux lithologies sont interprétées comme provenant d’une cristallisation fractionnée, et comme étant le produit de processus d'accumulations magmatiques. Le remaniement de la croûte dans un contexte de subduction vers ca. 2,72 Ga, a été suivi vers ca. 2,69 Ga d’une remontée du manteau asthénosphérique et de l’intrusion de granitoïdes de type massif. D'après l’importante augmentation en FeO, Zr, Hf et LREE dans les granitoïdes les plus évolués du magmatisme ayant pris place entre ca. 2,69 Ga et 2,66 Ga, nous proposons que ces plutons aient été en partie dérivés d’une source mantélique métasomatisée enrichies par des fluides d’une plaque océanique en subduction et qui a subi une hybridation supplémentaire (par assimilation) avec la croûte. Le magmatisme néo-archéen de type sanukitoïde, dérivé du manteau et de grande échelle, a joué un rôle dans le développement d’une croûte inférieure et d’un manteau lithosphérique continental résiduel appauvri, un élément déterminant pour la préservation du RBb.
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Najili, Ahmad, Purnama Sendjaja, Bambang Priadi, Verry Edi Setiawan, and Barry Majeed Hartono. "Petrogenesis of Pre-Tertiary A-Type Granitoid in Jambi Area and its Implications of Rare Earth Element Potential on Main Range Sumatra Belt." Indonesian Journal of Economic Geology 1, no. 1 (2021): 49–71. http://dx.doi.org/10.51835/ijeg.2021.1.1.342.
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Granitoid rocks are one of the main sources of rare earth elements (REE). This makes granitoid characterization become important in the early stages of REE exploration. Almost all granitoids in Indonesia have been mapped. However, more detailed granitoid studies in Indonesia are still focused on Bangka and Belitung granites (tin belt granite). In contrast to Bangka and Belitung granites, studies related to petrogenesis and granite characteristics on the mainland of Sumatra Island (Sumatra Main Range) are rarely done, such as granitoid in Jambi area. The aim of this study is to determine the characteristics of the Pre-Tertiary granitoids located in the Tigapuluh and Duabelas Mountains, Jambi. The Tanjungjabung Barat granitoid represent the Tigapuluh Mountains area while the Sarolangun granitoid represent the Duabelas Mountains area. These two granitoids interpreted to be Triassic to Jurassic in age. Granitoid characteristics include petrological and geochemical characters. This study also focuses on the petrogenesis of Pre-Tertiary granitoid and its implications for the abundance of REEs. Megascopic observation, petrographic, and geochemical analysis are done in this study. Geochemical analysis was done at the Center of Geological Survey Laboratory, Bandung using the ICP-MS Thermo Icap-Q and XRF ADVANT XP Thermo ARL9900 instruments. Based on megascopic and petrographic observations, both of the granitoids are classified as granite. Geochemically, these two granitoids show the character of A-type granite which is formed in the post-collision environment, and derived from the crustal melting with ferrous alkalic to alkali-calcic peraluminous affinities. This crustal melting happened due to the collision of the Sibumasu Block with Indochina resulting in crustal thickening and crustal melting. The magma then contaminated effectively in the rift environment due to the subduction roll-back of Meso-Tethys in the Late Triassic. Subduction in the West Sumatra also play roles in the genesis and it is shown by the geochemical character of the Sarolangun granitoid. Effective contamination derives the characteristics of A-type granite so that the REE content in both granites are abundant. The abundance of REE is indicated by the presence of the allanite, monazite, apatite, zircon, and titanite. The REE concentration of the Sarolangun granitoid reaches 330 ppm, while the Tanjungjabung Barat granitoid reaches 261 ppm. The REE concentrations of A-type granitoid in Jambi then compared with A-type granitoids from the world and showed relatively the same REE concentrations. The REE concentrations of these granitoids are also higher than the other type granitoids in Indonesia. However, the REE concentrations of Jambi granitoids are similar to the fractionated S-type granite in Bangka. With a recent study showing the presence of A-type granitoid in Sarudik (North Sumatra) and Bukit Batu (South Sumatra), the A-type granitoid in this study indicates the existence of A-type granitoid belt in the Sumatra Main Range. This belt will have a high abundance of REE concentrations and potentially become the source for REE deposits. The author hopes that this study could improve the understanding of tectonic in Sumatra and suggestion for REE exploration in the area.
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Dey, Sukanta, Sibani Kumari Nayak, Aniruddha Mitra, Keqing Zong, and Yongsheng Liu. "Mechanism of Paleoarchean continental crust formation as archived in granitoids from the northern part of Singhbhum Craton, eastern India." Geological Society, London, Special Publications 489, no. 1 (2020): 189–214. http://dx.doi.org/10.1144/sp489-2019-202.
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AbstractMany Paleoarchean cratons display a gradual change from early sodic tonalite–trondhjemite–granodiorite magmatism to late K-rich granitoid magmatism; the geodynamic significance of this change is debatable though. This contribution presents field, geochemical and zircon U–Pb age and Hf isotope results of four different 3.32–3.25 Ga granitoid bodies from the northern part of Singhbhum Craton to investigate their petrogenesis and role in crustal evolution. The granitoids range in composition from tonalites to trondhjemites, derived from intracrustal melting at low- to medium-pressure conditions. The source was mainly low-K mafic rock. The granitoids show intrasuite fractional crystallization. These sodic granitoids represent the last stage of granitoid magmatism in the Singhbhum Craton which formed contemporaneously with K-rich granitoids occurring in other parts of the craton. This fact suggests that, contrary to the popular notion (of only potassic granitoids), both sodic and potassic granitoids could form at the terminal phase of cratonization, implying reworking of heterogeneous (mafic to tonalite) crust. A combination of evidence from geochemical data, secular change in granitoid composition, structural pattern and rock association of the Singhbhum Craton reflects that recurring mantle plume-related mafic–ultramafic magma emplacement in an oceanic plateau setting and attendant crustal melting can explain the Paleoarchean crustal evolution pattern.
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K. Agbenyezi, Theophilus, Gordon Foli, and Simon K. Y. Gawu. "GEOCHEMICAL CHARACTERISTICS OF GOLD-BEARING GRANITOIDS AT AYANFURI IN THE KUMASI BASIN, SOUTHWESTERN GHANA: IMPLICATIONS FOR THE OROGENIC RELATED GOLD SYSTEMS." Earth Science Malaysia 4, no. 2 (2020): 127–34. http://dx.doi.org/10.26480/esmy.02.2020.127.134.
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This study investigates auriferous granitoids from the Esuajah and Fobinso pits within the Ayanfuri environment in the Paleoproterozoic Kumasi basin. The aim is to establish the geochemical characteristics of the granitoid gold ores and the possible deposit type which may influence mineral project development. 13 major and 51 trace elements were analyzed using XRF and ICP-MS devices, respectively. The granitoids are mainly classified as granodiorite that crystallized from a calc-alkaline magma series. The Fobinso granodiorite derived from the partial melting of the Birimian metasedimentary rocks, while the Esuajah granitoid derived from igneous rock melts. The granitoid are linked to magma source depleted in mantle material that contains crustal components through subduction processes. Major oxides of the granitoid vary lowly from the average background values derived for basin type granitoid in such terrains. Generally, the granitoid are enriched in Large Ion Lithophile Elements (LILE), while High Field Strength Elements (HFSE) and base metals are within background values when compared to Primitive Mantle (PM) values. Gold mineralisation is associated with Ag, As, Bi, Sb, Te, Pb and S in the peraluminous granitoids. Geochemical characteristics and field observations identify the deposit style as an orogenic related gold deposit type.
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Halla, Jaana. "Highlights on Geochemical Changes in Archaean Granitoids and Their Implications for Early Earth Geodynamics." Geosciences 8, no. 9 (2018): 353. http://dx.doi.org/10.3390/geosciences8090353.
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The Archaean (4.0–2.5 Ga) continental crust is mainly composed of granitoids, whose geochemical characteristics are a function of their formation mechanisms and components, as well as physical conditions of their source. Therefore, revealing changes in Archaean geodynamic processes requires understanding of geochemical changes in Archaean granitoids. This paper compares key geochemical signatures in granitoid occurrences from the Eoarchaean to Neoarchaean Eras and aims to highlight changes or variations in their geochemical signatures. The study is performed by exploring and comparing geochemical and geochronological datasets of Archaean granitoids compiled from literature. The results show that two end-members of sodic TTGs (tonalite–trondhjemite–granodiorite) occur throughout the Archaean: low- and high-HREE (heavy rare earth elements) types. A profound change in granitoid geochemistry occurred between 3.0 and 2.5 Ga when multi-source high-K calc-alkaline granitoid batholiths emerged, possibly indicating the onset of modern-type plate tectonics.
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Bahajroy, Mojtaba, and Saeed Taki. "Study of the mineralization potential of the intrusives around Valis (Tarom-Iran)." Earth Sciences Research Journal 18, no. 2 (2015): 123–29. http://dx.doi.org/10.15446/esrj.v18n2.44799.
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<p>The study area is located in northwestern Iran in the central Iran zone, specifically the western Alborz sub-zone south of the Tarom-Hashtjin metallogenic zone. The exposed rock units in this area generally include Eocene volcanic rocks (lava flows and pyroclasts belonging to the Karaj formation) and Oligocene granitoid intrusive bodies. The intrusive bodies in the area have a petrographic composition of granite, syenite and monzonite and are mostly metaluminous. The dual characteristics of these intrusives (for example, the behavior of elements such as Rb, P, Ga/Al, Y/Nb, K/Na, and FeO/Fe2O3, the Rb/Nb ratios, the A/CNK molar ratios and the ACF and A/CNK-Fe2O3+FeO diagrams), some of which are consistent with the I nature and others with the S and A natures, show that the rocks are among hybrid granitoids and, in terms of the tectonic setting, lie within the WPG range. According to the Rb/Sr, Zr/Hf, K/Rb ratios, the granite melts that form the aforementioned bodies are not extremely evolved and have not undergone post magmatic activity, which would lead to mineralization. The Sm/Eu and Rb/Ba ratios and the behavior of Rb, Ba and Sr within the aforementioned granitoids show that the rocks are similar to average granitoids unrelated to Li, Be, Sn, W and Ta deposits; they fall within the range of barren granitoids but are partially fertile in Cu.</p><p> </p><p><strong>Resumen</strong></p><p>El área de este estudio está localizada en el noroeste de la zona central de Irán, específicamente en el oeste de la subzona de Alborz y al sur de la zona metalogénica de Tarom-Hashtjin. Las unidades de roca expuesta en esta área se clasifican generalmente como rocas volcánicas del Eoceno (flujos de lava y piroclastos pertenecientes a la formación Karaj) y como cuerpos granitoides intrusivos del Oligoceno. Los cuerpos intrusivos en el área tienen una composición petrográfica de granito, sienita y monzonita mayormente metaluminosa. Las características duales de estas intrusiones (por ejemplo, el comportamiento de de elementos como Rb, P, Ga/ Al, Y/Nb, K/Na, y Feo/Fe2O3, los índice de Rb/Nb, la proporción molar de los A/CNK y los diagramas ACF y A/CNK-Fe2O3+FeO), algunas de las cuales son consistentes con la índole I y otras con las índoles S y A, muestran que las rocas son granitoides híbridos y, en términos de orden tectónico, subyacen en la cadena WPG. De acuerdo con los índices Rb/Sr, Zr/Hf, K/Rb, los granitos fundieron la forma de los cuerpos sin desarrollarse completamente y sin registrar actividad magmática posterior, lo que llevó a la mineralización. Los índices Sm/Eu y Rb/Ba y el comportamiento del Rb, Ba y Sr al interior de los granitoides mencionados muestran que las rocas son similares al promedio de los granitoides no relacionados con los depósitos de Li, Be, Sn, W y Ta; estos incluyen en el rango de granitoides estériles, pero son parcialemente fértiles en Cu.</p><p><strong><br /></strong></p>
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Nguyen, Chien Dong, Hong Son Duong, Dinh Cong Bui, Huu Hieu Ho, and Thi Hoang Linh Nguyen. "Relations between phia oac granitoids and uranium in Nguyen Binh area - Cao Bang province." Nuclear Science and Technology 3, no. 4 (2013): 40–48. http://dx.doi.org/10.53747/nst.v3i4.326.
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After reviewing the trace metals (Sn, W, Mo)-bearing granitoid deposits in the world, theauthors recognized that some deposits in Sweden (e.g. Nozzboten, Vasterbotten, Hotagen, Bergslagen, Bohus, Gosthenburg, Gotemar, Blekinge) contain not only trace metals (Sn, W, Mo), but also F, Li, U,Th, etc… which are similar to the Phia Oac granitoids. The correlation chart with the T. Carlsson (1982)’s criteria helps to determine the uranium-bearing granitoids. Initially, we constructed some correlation charts of granitoid fields in Northern Vietnam and concluded that some granitoid fields certainly related to uranium are Phia Oac, Xom Giau, Phu Sa Phin, and some granitoid fields possibly related to uranium are Ye Yen Sun, Muong Lat, Ban Chieng, and Song Chay (based on data from the Geology of Vietnam, Part II, Magma Section). This issue needs to be further studied.
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Yamashita, Katsuyuki, Robert A. Creaser, James U. Stemler, and Tony W. Zimaro. "Geochemical and Nd-Pb isotopic systematics of late Archean granitoids, southwestern Slave Province, Canada: constraints for granitoid origin and crustal isotopic structure." Canadian Journal of Earth Sciences 36, no. 7 (1999): 1131–47. http://dx.doi.org/10.1139/e98-047.
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New geochemical and Nd-Pb isotopic data for ~ 2.62-2.59 Ga granitoids from the southwest Slave Province are used to determine the source(s) of granitoid magmas, to evaluate the role of pre-2.8 Ga basement during this magmatism, and to refine the existing Nd-Pb isotopic structure of the western Slave Province. The Pb isotopic data require crust older than ~3.2 Ga as a granitoid protolith, whereas the Nd isotopic data require input from juvenile crustal material. This discrepancy is explained if the granitoid protoliths are mixtures of ancient basement and ~2.7 Ga juvenile crust in varying proportions. Specifically, granitoids from the southwestern Slave Province require 10-30% basement, whereas granitoids from other parts of the western Slave Province require >50%. Incorporation of basement as a protolith may be achieved indirectly, by assimilation of basement during juvenile ~2.7 Ga magmatism, or directly during ~2.62-2.59 Ga magmatism. The granitoid isotopic data suggest that indirect basement input was important on a regional scale, but direct input may have also taken place in some areas of the western Slave Province, particularly along the ~111°W "isotopic boundary" zone previously recognized. The geochemical characteristics of these granitoids are compatible with an origin by partial melting of dominantly amphibolite and metasedimentary rocks to produce the ~2.61 Ga and ~2.59 Ga magmatism, respectively; partial melting occurred in response to regional crustal thickening at this time.
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Boyadjiev, Stefan. "Comparative petrologic-geochemical eharacterization of the Pre-Mesozoic granitoids of the Sredna Gora zone." Geologica Balcanica 21, no. 3 (1991): 35–74. http://dx.doi.org/10.52321/geolbalc.21.3.35.
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Pre-Hercynian (Late Proterozoic!) and Hercynian (South Bulgarian) types of granitoids are described. Grounds are given for their palingenetic origin and crustal level of magma generation. On the basis of the analysis performed, the South Bulgarian granitoids are determined as a bimodal superformation, respectively presented by: a) Formation of basic and ultrabasic rocks of a probable Precambrian age- mainly embedded in single layers among the Precambrian crystalline complex; regarding them as a single gabbro-granite formation is not grounded. b) Formation of the batholitic granitoid complex which is distinguished for its polyphase-polyfacies structure. It is presented by three temporarily and laterally defined granitoid phases (impulses): first - marginal facies built by contaminated (a result of assimilation of basic and ultrabasic rocks) rocks which are gradually and centripetally transformed into granitoids up to granites; second – predominantly medium- up to coarse-grained, porphyroid biotite to two-mica granites, partially to granodiorite; third – medium-grained, predominantly biotite to two-mica granites, rarely granodiorites. On the basis of the relationships presented and on the basis of geochemical criteria as well, the development of a fourth granitoid phase - aplite-pegmatoid biotite to two-mica subalkaline granites to leucogranites of not elucidated, probably Alpine age - is grounded. The granitoids are referred·to the K-Na series. They are characterized by a very high aluminity, weak ferreous and magnesium properties, which determine the low content of mafites and the strongly expressed leuco-rate frequency of rocks. Ba, B, Pb, Th have contents above the clarke, while the other elements studied have contents about or under the clarke; the granitoids of fourth phase are enriched in So, W, Mo, Ag which determines their metallogenic specialization. They are characterized by a deficiency of REE, Eu and a negative europium anomaly; in the fourth granitoid phase REE is two times higher. A complete petrologic and phase-facies analogy is established between the pre-Mezozoic granitoids from the Sredna Gora zone and from the Rhodope Massif.
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Luchitskaya, М. V., М. V. Gertseva, and I. V. Sysoyev. "Geodynamics and Early Cretaceous Magmatism of the Northern Volcanic-Plutonic Belt of Verkhoyan-Kolyma Fold Area (Northeastern Russia)." Геотектоника, no. 5 (September 1, 2023): 96–120. http://dx.doi.org/10.31857/s0016853x23050053.
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New data on the geological position, U‒Pb SIMS zircon ages, petro-geochemical features, Sr‒Nd isotopic composition and geodynamic setting of the granitoids and volcanites of the Northern volcanic-plutonic belt, Verkhoyan-Kolyma fold area, are presented. Magmatites of the belt include granitoids of Elikchan, Kuranakh, Bakyn plutons, composed of elikchansky granite-granodiorite complex, and volcanites of predominantly intermediate-felsic Tumusskaya sequence with subvolcanic bodies of the same composition. They form single Early Cretaceous (127–121 Ma) volcanic-plutonic assemblage. Granitoid plutons are elongated in sub-latitudinal-northwestern direction and are discordant to main fold and thrust structures. Granitoids intrude and metamorphose Jurassic terrigenous and Early Cretaceous volcanites of Tumusskaya sequence and are cut by younger Late Cretaceous subvolcanic bodies. Granitoids of Bakyn, Elikchan and Kuranakh plutons combine petro-geochemical features of I-, S- and A-type granites. Such diversity of petro-geochemical granitoid types as well as interrelations of major (\({\text{F}}{{{\text{e}}}_{{\text{2}}}}{\text{O}}_{3}^{{{\text{tot}}}}\)–TiO2–MgO) and rare (Ba/La–Nb × 5–Yb × 10) elements in granitoids and the same age volcanites of Tumusskaya sequence allow to refer them to magmatites of transform margin or plates translation boundaries. Collision between Chukotka microcontinent and Siberian continent with earlier accreted Kolyma-Omolon microcontinent in Barremian-Aptian time changed to post-collisional extension and formation of volcanic-plutonic assemblage of the Northern volcanic-plutonic belt. Post-collisional extension took place in the regime of plates translation boundaries. Sr–Nd isotopic characteristics of granitoids of all plutons indicate the interrelation of mantle and crustal sources of granitoid melts in this process.
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Tugareva, A. V., M. L. Moroz, G. A. Chernova, and E. V. Belova. "THE GRANITOID MAGMATISM IN THE TERRITORY OF FROLOVSKAYA MEGADEPRESSION OF WESTERN SIBERIA." Oil and Gas Studies, no. 6 (January 20, 2019): 33–40. http://dx.doi.org/10.31660/0445-0108-2018-6-33-40.
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The article deals with the granitoid magmatism in the territory of Frolovskaya megadepression. Granite massifs are usually confined to erosion-tectonic ledges of the foundation, located in tectonically active zones, usually with increased heat flux. The detection of such massifs allows to predict the development of improved reservoirs in the zone of contact with sedimentary cover rocks. The age of granitoids is the Middle-Late Paleozoic. We clarify the boundaries of granitoid massifs and distinguish new massifs based on new information on geology and seismic survey. Also we analyses the connection of temperature, productivity with granitoids and foundation blocks.
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Breemen, O. van, W. J. Davis, and J. E. King. "Temporal distribution of granitoid plutonic rocks in the Archean Slave Province, northwest Canadian Shield." Canadian Journal of Earth Sciences 29, no. 10 (1992): 2186–99. http://dx.doi.org/10.1139/e92-173.
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Granitoid rocks in the Slave Province consist of 4.0–2.8 Ga granitoid gneisses that predate the 2.71–2.65 Ga volcanic and turbiditic rocks of the Yellowknife Supergroup and 2.70–2.58 Ga granitoid plutons that intrude the Yellowknife Supergroup. U–Pb zircon ages and Nd and Pb isotopic data indicate that the older granitoids are restricted to the western part of the Slave Province. Granitoid gneisses in the eastern Slave Province, previously suspected to predate the Yellowknife Supergroup, are similar in age to the volcanic rocks.In this paper, the results of a detailed geochronological study of plutonic rocks of the Contwoyto Lake – Nose Lake area of the northcentral Slave Province are reviewed and integrated with the available age data base for plutonic rocks elsewhere in the Slave Province. The data indicate that the timing of the later (<2.7 Ga) plutonism is bimodal, consisting of two distinct magmatic periods separated by approximately 20 Ma of apparent magmatic quiescence. The first period was synvolcanic, dating from 2695 to 2650 Ma. The second period, during which more than 80% of the granitoids presently exposed in the Slave Province were intruded, lasted from 2625 to 2580 Ma, spanning the major Archean deformation events, Syndeformation granitoids, with ages between 2625 and 2595 Ma, are dominantly diorite and tonalité in composition. Late- to post-deformation granitoid rocks, with ages between 2605 and 2580 Ma, range in composition from megacrystic biotite granodiorite to two-mica granite. In general terms, the compositions of the granitoid plutons vary in time from dominantly metaluminous to more strongly peraluminous.Present data show no obvious regional age variation among the younger granitoid rocks across the province. This apparent absence of diachroneity has important implications for models interpreting the magmatism as having evolved in a continental-margin setting, because the extent of contemporaneous plutonism is more than 400 km across strike, considerably broader than in most Mesozoic continental-margin batholiths.
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Mamtani, Manish A., Sandeep Bhatt, Virendra Rana, Koushik Sen, and Tridib K. Mondal. "Application of anisotropy of magnetic susceptibility (AMS) in understanding regional deformation, fabric development and granite emplacement: examples from Indian cratons." Geological Society, London, Special Publications 489, no. 1 (2019): 275–92. http://dx.doi.org/10.1144/sp489-2019-292.
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AbstractIn this paper the authors review various applications of analysing fabric in granites from Indian cratons using anisotropy of magnetic susceptibility (AMS). First the general importance of AMS in identifying the internal fabric in massive granitoids devoid of visible foliations/lineations is highlighted. Subsequently, three important applications of AMS in granitoids are discussed. (a) The case of Godhra Granite (southern parts of the Aravalli Mountain Belt) is presented as an example of the robustness of AMS in working out the time relationship between emplacement/fabric development and regional deformation by integrating field, microstructural and magnetic data. (b) AMS orientation data from Chakradharpur Granitoid (eastern India) are compared with field-based information from the vicinity of the Singhbhum Shear Zone to highlight the use of AMS in kinematic analysis and vorticity quantification of syntectonic granitoids. (c) Magnetic fabric orientations from the Mulgund Granite (Dharwar Craton) are presented to document the application of AMS in recognizing superposed deformation in granitoids. Moreover, AMS data from Mulgund Granite are also compared with data from another pluton of similar age (c. 2.5 Ga) from the Dharwar Craton (Koppal Granitoid; syenitic composition). This highlights the use of AMS from granitoids of similar absolute ages in constraining the age of regional superposed deformation.
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Fernández, F. J., and S. Llana-Fúnez. "Deformación asociada a la falla de Valdoviño (Noroeste del Macizo Ibérico) Deformation related to the Valdoviño fault (Northwest Iberian Massif)." Trabajos de Geología 36, no. 36 (2018): 95. http://dx.doi.org/10.17811/tdg.36.2016.95-118.
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Resumen: La sección costera de la falla de Valdoviño expone rocas de falla deformadas en las proximidades de la base de la zona sismogénica de la corteza Ibérica Varisca, en la que estructuras frágiles discretas afectan una zona de deformación predominantemente dúctil. El núcleo de la falla contiene rocas ultramáficas, rocas máficas con granate, anfibolitas, neises cuarzo-feldespáticos y metavulcanitas básicas entre las facies deformadas del granitoide Varisco de A Espenuca. Este artículo describe la deformación y microestructuras relacionadas con la falla desarrolladas en el granitoides. La composición y características tectonometamórficas del resto de rocas presentes en el núcleo de la falla sugieren que las estructuras asociadas a la falla se superpusieron a fábricas tectónicas previas, similares a las que presentan las rocas de los complejos alóctonos del NO del Macizo Ibérico.Palabras clave: microestructura, rocas de falla, corteza continental, EBSD, Orógeno Varisco.Abstract: The coastal section across the Valdoviño fault exposes fault-related rocks deformed at the base of the seismogenic zone of the Iberian Variscan crust. Discrete brittle structures are superimposed over previous predominant ductile deformation fabrics in most rocks. The core of the fault contains ultramafic rocks, garnet-bearing mafic rocks, amphibolites, quartzo-feldspathic gneisses and basic metavulcanites, in between the deformed facies of the A Espenuca Variscan granitoid. We show the deformation and microstructures related to the fault developed in the Variscan granitoid. The composition and tectonometamorphic features of the rest of the related rocks at the core of the fault suggest that deformation structures are superposed onto earlier tectonic fabrics, similar to those present in the rocks of the allochthonous complexes of the NW Iberian Massif.Keywords: microstructure, fault-related rocks, continental crust, SEM-EBSD, Variscan Orogeny.
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CAGGIANELLI, A., and G. PROSSER. "Modelling the thermal perturbation of the continental crust after intraplating of thick granitoid sheets: a comparison with the crustal sections in Calabria (Italy)." Geological Magazine 139, no. 6 (2002): 699–706. http://dx.doi.org/10.1017/s0016756802006817.
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Thick granitoid sheets represent a considerable percentage of Palaeozoic crustal sections exposed in Calabria. High thermal gradients are recorded in upper and lower crustal regional metamorphic rocks lying at the roof and base of the granitoids. Ages of peak metamorphism and emplacement of granitoids are mostly overlapping, suggesting a connection between magma intrusion and low-pressure metamorphism. To analyse this relationship, thermal perturbation following granitoid emplacement has been modelled. The simulation indicates that, in the upper crust, the thermal perturbation is short-lived. In contrast, in the lower crust temperatures greater than 700°C are maintained for 12 Ma, explaining granulite formation, anatexis and the following nearly isobaric cooling. An even longer perturbation can be achieved introducing the effect of mantle lithosphere thinning into the model.
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Ariani, Rizky Putri, and Hari Wiki Utama. "Petrogenesis and Geological Structure of Tantan Granitoid in Sungai Manau District, Merangin Regency, Jambi Province." EKSPLORIUM 43, no. 2 (2023): 79. http://dx.doi.org/10.17146/eksplorium.2022.43.2.6415.
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Tantan granitoids are Late Triassic–Early Jurassic age intrusive rocks that are quite extensive and can be partially found in Sungai Manau Sub-district, Merangin Regency, Jambi Province. Tantan granitoids are found in the Barisan Hills physiography, a magmatic arc line on Sumatra Island. Tantan granitoids are interesting to observe to explain rock formation. The petrographic and XRF analyses can provide insight into the intrusive rock type, its relationship to the tectonic framework, and magmatism. The trend of potential mineral resources can be interpreted based on the granitoid-type approach. The Tantan Granitoid Intrusion has two types of rocks: granite and quartz monzodiorite. Granite and quartz monzodiorite are sub-alkaline magma types, with the granitoid type being I-type metaluminous, which tends to have potential with base metal minerals associated with hornblende minerals from observations or petrographic analysis. Based on the TAS diagram of Na2O+K2O vs. SiO2 shows that the sub-alkaline magma type is a calc-alkaline series type in the K2O vs. SiO2 diagram and a calc-alkaline type in the AFM diagram. This data analysis shows that the tectonic formation of the Tantan Granitoid magma was formed from orogenic results in the form of a Continental Arc. This type can be associated with Meso-Thetic subduction activities against the West Sumatra Sundablock during the Late Triassic–Early Jurassic. Structures in the study area include northwest-southeast trending horizontal faults, including Batang Tantan Fault, Tiangko Fault, Sei Tengko Fault, and Serik Fault, then northeast–southwest trending regional faults, and relatively downward trending faults, namely Serik Fault and Betung Fault. The formation of fault structures is believed to result from subduction tectonic processes during this period.
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KADIOĞLU, Y. K., A. ATEŞ, and N. GÜLEÇ. "Structural interpretation of gabbroic rocks in Ağaçören Granitoid, central Turkey: field observations and aeromagnetic data." Geological Magazine 135, no. 2 (1998): 245–54. http://dx.doi.org/10.1017/s001675689800836x.
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Gabbroic rocks crop out commonly in different localities of the Central Anatolian Crystalline Complex and are interpreted by many researchers as the remnants of a Neotethyan ophiolitic suite now observed as roof-pendants in the granitoids of the complex. In this study, the structural position of the gabbroic rocks within one of the granitoids of the Central Anatolian Crystalline Complex, namely the Ağaçören Granitoid, is determined by geological and aeromagnetic data from the central part of the pluton. The gabbroic rocks have sinuous contacts with the Ağaçören Granitoid and they display a gradual change in composition and texture from gabbro at the top of the hills to diorite at the foot of the hills towards the contact with granitoid. Power spectra, high- and low-pass filtered aeromagnetic and pseudogravimetric anomalies were produced using geophysical methods. A two-dimensional model constructed from the high pass-filtered anomalies, with the control of the in situ susceptibility data and the low-pass filtered anomaly, suggests existence of a shallow conical-shaped and deeply buried gabbroic body. The deep body extends down to deeper levels of the upper crust and, given the textural and compositional features which suggest magma mixing, is interpreted as an intrusion coeval with the Ağaçören Granitoid.
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Li, Shan, Calvin F. Miller, Wang Tao, Wenjiao Xiao, and David Chew. "Role of sediment in generating contemporaneous, diverse “type” granitoid magmas." Geology 50, no. 4 (2021): 427–31. http://dx.doi.org/10.1130/g49509.1.
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Abstract Granite typology categorizes granitoid rocks based upon distinguishing characteristics that are interpreted to indicate sources, conditions of generation, and, by implication, tectonic setting. Complexities of elemental and isotopic geochemistry, however, commonly preclude simple typological interpretation and suggest more complex petrogenetic histories. Granitoids from the Songpan-Ganzi terrane in the eastern Tibetan Plateau were emplaced within a short interval (~15 m.y.). They display mineralogical and geochemical characteristics that are consistent with a wide range of proposed typologies (I-, S-, and A-type; high Ba-Sr and adakitic variants). Despite their close spatial and temporal association, these granitoids exhibit diversity in geochemical characteristics that indicates a broad spectrum of contributing sources. Radiogenic isotope data reveal a continuum from primitive to evolved crustal compositions; i.e., 87Sr/86Sr(t) = 0.704–0.715 and εNd(t) = +2 to −11. All granitoid “types” have variable but commonly high zircon δ18O (+4.1‰ to +11.6‰) and low whole-rock Li-B-Mg isotopic ratios compared to mantle and/or seawater (δ7Li = +5.1‰ to −3.2‰; δ11B = −10.7‰ to −16.5‰; δ26Mg = −0.23‰ to −0.59‰). These stable isotopic compositions suggest that the Songpan-Ganzi granitic magmas of all “types” had contributions from sediment, ranging from minor to dominant. The highly variable isotopic compositions of the granitoids rule out a single homogeneous source for these diverse yet contemporaneous granitoids. Their compositional variability may have been significantly influenced by sedimentary contributions, and these results demonstrate the difficulty of straightforward assignment and interpretation of granitoids using conventional typology.
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Luchitskaya, M. V., B. V. Belyatsky, E. A. Belousova, and L. M. Natapov. "Sr-Nd-Pb-Hf isotopic composition of late paleozoic granitoids of Central Chukotka." Доклады Академии наук 485, no. 1 (2019): 58–62. http://dx.doi.org/10.31857/s0869-5652485158-62.
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Results of the study of Sr–Nd–Pb–Hf isotopic composition of Late Paleozoic granitoids of Central Chukotka are represented on the example of Kibera and Kuekvun plutons. The age of granitoids of these plutons and granites from pebbles in conglomerates in the base of overlying Lower Carboniferous deposits is 351–363 Ma (U–Pb zircon, TIMS, SIMS, LA–ICP–MS). Thus, granitoid magmatism corresponds in time to tectonic events of Elsmerian orogeny in Arctic region. Sr–Nd–Pb–Hf isotopic composition of granitoids indicate participation of mantle and crustal components in the source of granite melts. Granitoids formation probably occurred in geodynamic setting of Andean type continental margin during the interaction between mantle melts, forming at the mantle wedge melting in suprasubduction conditions, and continental crust.
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Chugaev, A. V., O. Yu Plotinskaya, E. O. Dubinina та ін. "Crustal Source of Pb and S at the Yubileynoe Porphyry Gold Deposit (Southern Urals, Kazakhstan): High Precision Pb–Pb and δ34S Data". Geology of Ore Deposits 63, № 3 (2021): 173–84. http://dx.doi.org/10.1134/s107570152103003x.
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Abstract The Yubileinoe large gold deposit, located at the southern end of the Magnitogorsk megazone, is the only known representative of the Au–porphyry systems in the Southern Urals. It is genetically related to granitoids formed in a suprasubduction setting under mature oceanic island arc environment/setting. The obtained isotope (Pb–Pb and δ34S) data indicate the input of mineral-forming components into the Au–porphyry system of the deposit, mainly from granitoid melts, confirming a common source of ore material and ore-bearing granitoids. The geochemical and isotopic characteristics of granitoids indicate the leading role in their genesis of the crustal source, which is considered Late Precambrian continental crust.
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Ntieche, Benjamin, Wokwenmendam Nguet Pauline, Eric José Messi Ottou, et al. "FIELD AND PETROGRAPHIC EVIDENCES OF GRANITOIDS AND MAFIC MAGMAS INTERACTION IN THE NEOPROTEROZOIC CENTRAL AFRICAN FOLD BELT IN CAMEROON (MAKENENE AREA)." Earth Sciences Pakistan 6, no. 1 (2022): 07–16. http://dx.doi.org/10.26480/esp.01.2022.07.16.
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Field and petrographic studies of the Makenene area in the Central African Fold Belt in Cameroon reveals several features testifying the mafic and felsic magmas interactions and their coeval nature. They are: (1) the Mafic Magmatic Enclaves (MMEs) scattered throughout the Makenene granitoid pluton and displaying sub-rounded shape and back veining, (2) flow structures consisting of schlierens at the tails of MMEs, folded MMEs along with felsic host granitoids with hinge indicating the flow direction, (3) irregular or cuspate boundary between MMEs and host granitoids, (4) quenching of apatite and biotites minerals, (5) MMEs enclosing other MMEs or felsic host granitoids. The mafic magma injection operated during at least four stages (from early to late crystallization state of the host magma) leading respectively to the formation of homogenized granitoid; sub-spherical MMEs scattered in the pluton; dismembered dyke and undisturbed synplutonic mafic dyke. The Makenene area registered four deformation phases (D1 to D4). The first two deformation phases occurred before the magmatism and migmatization events. The third phase is coeval to the magmatism and the migmatization period (at the Eburnean orogeny (2.08-2.07 Ga)). The fourth phase is related to the Panafrican orogeny.
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Alekseev, Viktor. "Deep structure and geodynamic conditions of granitoid magmatism in the Eastern Russia." Journal of Mining Institute 243 (June 14, 2020): 259. http://dx.doi.org/10.31897/pmi.2020.3.259.
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We investigated the deep structure of the lithosphere and the geodynamic conditions of granitoid magmatism in the Eastern Russia within the borders of the Far Eastern Federal District. The relevance of the work is determined by the need to establish the geotectonic and geodynamic conditions of the granitoids petrogenesis and ore genesis in the Russian sector of the Pacific Ore Belt. The purpose of the article is to study the deep structure of the lithosphere and determine the geodynamic conditions of granitoid magmatism in the East of Russia. The author's data on the magmatism of ore regions, regional granitoids correlations, archive and published State Geological Map data, survey mapping, deep seismic sounding of the earth's crust, gravimetric survey, geothermal exploration, and other geophysical data obtained along geotraverses. The magma-controlling concentric geostructures of the region are distinguished and their deep structure is studied. The connection of plume magmatism with deep structures is traced. The chain of concentric geostructures of Eastern Russia controls the trans-regional zone of leucocratization of the earth's crust with a width of more than 1000 km, which includes the Far Eastern zone of Li-F granites. Magmacontrolling concentric geostructures are concentrated in three granitoid provinces: Novosibirsk-Chukotka, Yano-Kolyma, and Sikhote-Alin. The driving force of geodynamic processes and granitoid magmatism was mantle heat fluxes in the reduced zones of the lithospheric slab. The distribution of slab windows along the Pacific mobile belt's strike determines the location of concentric geostructures and the magnitude of granitoid magmatism in the regional provinces. Mantle diapirs are the cores of granitoid ore-magmatic systems. The location of the most important ore regions of the Eastern Russia in concentric geostructures surrounded by annuli of negative gravity anomalies is the most important regional metallogenic pattern reflecting the correlation between ore content and deep structure of the earth's crust.
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Sato, K., S. V. Kovalenko, N. P. Romanovsky, M. Nedachi, N. V. Berdnikov, and T. Ishihara. "Crustal control on the redox state of granitoid magmas: tectonic implications from the granitoid and metallogenic provinces in the circum-Japan Sea Region." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 95, no. 1-2 (2004): 319–37. http://dx.doi.org/10.1017/s0263593300001103.
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ABSTRACTFelsic magmatism has occurred over a large region of East Asia since Jurassic times and has provided important mineral resources such as tin, tungsten, base metals and gold. The circum-Japan Sea region preserves various geological records of active continental margins, including Jurassic to Early Tertiary magmatic arcs and subduction zones and pre-Jurassic continental basements, which were separated by the opening of the Japan Sea during the Miocene. The felsic magmatism in this region shows a wide variation in terms of redox state and related mineralisation, encompassing east–west contrasts around the Pacific Ocean. A review of granitoids and associated ore deposits in this region indicates that the character of the crust, sedimentary versus igneous, is an essential factor to control the redox state, and a tectonic setting may be an additional factor in some cases.The reduced-type granitoids, characterised by tin mineralisation, were generated in carbonbearing sedimentary crust which was composed mainly of accretionary complex material and not influenced by previous magmatism. Involvement of sedimentary materials is corroborated by oxygen, sulphur and strontium isotope data. The oxidised-type granitoids, characterised by gold or molybdenum mineralisation, were generated in igneous crust which was depleted in reducing agents as a result of previous magmatism. Granitoid magmatism in a given area tends to become more oxidised with time.Jurassic accretionary complexes in East Asia are thought to have been largely displaced from the original place of accretion and stacked up against the northeastern margin in the Khingan and Sikhote–Alin Mountains. This region, dominated by sedimentary crust, was subsequently subjected to Cretaceous felsic magmatism and converted to a large province of reduced-type granitoids and tin–tungsten mineralisation. Diverse geodynamic processes, including the change of the arc-trench system, the creation and collapse of the back-arc basin and the collision of continents, may have prepared many favourable sites for the generation of reduced-type granitoids in northeast Asia. These processes may have resulted in a remarkable contrast with the Pacific margin of North America, where repeated arc magmatism during the Mesozoic formed granitoid batholiths of the oxidised-type.The granitoid types may also be controlled by the tectonic setting and mode of magma emplacement. In the northern Kitakami area of Northeast Japan, Early Cretaceous episodic magmatism occurred in a Jurassic accretionary complex, and formed the oxidised-type granitoids accompanied by submarine bimodal volcanism associated with kuroko mineralisation. Granitoids of fissure-filling type emplaced under extensional environments may be oxidised, irrespective of basement geology, because of insignificant crustal input.
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Prasetya, Yogi Adi, Lamganda Nainggolan, and Bilal Al Farishi. "PETROLOGI GRANITOID KAPUR DI KOMPLEKS GRANITOID PADEAN." Jurnal Geofisika Eksplorasi 8, no. 2 (2022): 127–36. http://dx.doi.org/10.23960/jge.v8i2.201.
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Batuan granitoid di Provinsi Lampung dapat ditemukan di peta geologi regional lembar Kota Agung dan Lembar Tanjungkarang. Masih sedikitnya penelitian tentang batuan granitoid Formasi Granit Kapur di Lampung mendasari penelitian ini. Tujuan penelitian adalah untuk mengidentifikasi jenis batuan granitoid dan melihat komposisi mineral batuan granitoid Formasi Granit Kapur. Metode yang digunakan adalah observasi lapangan untuk deskripsi petrologi dan pengambilan sampel batuan dan dengan metode pengamatan petrografi. Dari hasil observasi lapangan didapatkan 3 jenis batuan granitoid di lokasi penelitian dengan warna, komposisi mineral dan ukuran kristal yang berbeda, 3 batuan tersebut adalah Tonalit, Granodiorit dan Monzogranit, komposisi mineral utama dari batuan granitoid di lokasi penelitian antara lain, plagioklas, potassium feldspar, kuarsa, hornblende dan biotit, dengan komposisi mineral sekunder antara lain klorit, apatit, muskovit, titanit, turmalin dan opak. Dari hasil penelitian dapat diinterpretasikan jika batuan granitoid di lokasi penelitian berasal dari satu magma yang sama dan hasil proses diferensiasi magma dimana tonalit membeku terlebih dulu dan monzogranit yang memiliki ukuran kristal paling besar dan diinterpretasikan merupakan hasil kristalisasi di tahap akhir dari pembekuan magma. Dari data kelimpahan mineral dapat diklasifikasikan jika batuan granitoid di daerah penelitian merupakan tipe KCG (K-rich and K-feldspar porphyritic Calc-alkaline Granitoids).
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Campos, José C. S., Maurício A. Carneiro, and Miguel A. S. Basei. "U-Pb evidence for late Neoarchean crustal reworking in the Southern São Francisco Craton (Minas Gerais, Brazil)." Anais da Academia Brasileira de Ciências 75, no. 4 (2003): 497–511. http://dx.doi.org/10.1590/s0001-37652003000400008.
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The Passa Tempo Metamorphic Complex is one of several metamorphic complexes that form the Archean sialic crust of the southern São Francisco Craton. It encompasses hypersthene-bearing gneissic rocks, with subordinateNW- or EW-trending mafic-ultramafic bodies and granodioritic to alkali-granitic, weakly foliated, and light-colored granitoids. These granitoids are the product of generalized migmatization that followed granulite-facies metamorphism. To determine the ages of the granulite-facies metamorphism and granitoid genesis, we obtained U-Pb ages on zircon extracted from the mesosome and leucosome of the migmatitic gneisses. For the mesosome, a discordia that intercepts Concordia at 2622 ± 18 Ma is interpreted as a minimum age for granulite-facies metamorphism. For the leucosome, the upper intercept of discordia at 2599 ± 45 Ma corresponds to migmatization and granitoid genesis. Contemporaneous metamorphism and magmatism have been documented elsewhere in the São Francisco Craton, especially in the southern portion, demonstrating vast and vigorous reworking of sialic crust by the end of the Neoarchean.
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Dey, S., and J. F. Moyen. "About this title - Archean Granitoids of India: Windows into Early Earth Tectonics." Geological Society, London, Special Publications 489, no. 1 (2020): NP. http://dx.doi.org/10.1144/sp489.
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Granitoids form the bulk of the Archean continental crust and preserve key information on early Earth evolution. India hosts five main Archean cratonic blocks (Aravalli, Bundelkhand, Singhbhum, Bastar and Dharwar). This book summarizes the available information on Archean granitoids of Indian cratons. The chapters cover a broad spectrum of themes related to granitoid typology, emplacement mechanism, petrogenesis, phase-equilibria modelling, temporal distribution, tectonic setting, and their roles in fluid evolution, metal delivery and mineralizations. The book presents a broader picture incorporating regional- to cratons-scale comparisons, implications for Archean geodynamic processes, and temporal changes thereof. This synthesis work, integrating modern concepts on granite petrology and crustal evolution, offers an irreplaceable body of reference information for any geologist interested in Archean Indian granitoids.
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Brodnikova, E. A., E. V. Vetrov, E. F. Letnikova, A. V. Ivanov, and S. N. Rudnev. "Early Ediacaran and Middle Ediacaran Granitoids in the Provenances of Early Cambrian Coarse-Grained Rocks of the Bayan-Kol Formation of the Systyg-Khem Depression (Tuva)." Russian Geology and Geophysics 63, no. 6 (2022): 649–63. http://dx.doi.org/10.2113/rgg20214208.
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Abstract —The Tuva segment of the Central Asian Orogenic Belt is characterized by the ubiquitous presence of conglomerates few tens of meters to a kilometer in thickness in early Paleozoic volcanosedimentary sequences. We present the first results of geochemical, isotopegeochemical (Sm–Nd and Rb–Sr), and U–Pb geochronological studies of granitoid boulders and pebbles from the conglomerate sequence of the early Cambrian Bayan-Kol Formation of the Systyg-Khem depression. These studies made it possible to establish several sources of clastic material as a result of the destruction of granitoids of different ages and isotope-geochemical compositions. At least two complexes of granitoids were denuded in the pre-Ediacaran tectonic block in the early Cambrian: (1) middle Ediacaran (~590 Ma) and (2) early Ediacaran (~630 Ma); the latter resulted from the melting of pre-Ediacaran island arc crust formed from a depleted mantle source (εNd(T) = +8.0 to +8.6). At present, no granitoids of this age and with such isotope-geochemical characteristics have been found within the Tuva segment. Probably, the granitoid complexes reconstructed from the results of study of clastic conglomerates are eroded or buried beneath younger deposits and do not expose. Thus, the study of clastic conglomerates from the Bayan-Kol Formation provided the first information about the Precambrian history of the tectonic block whose destruction led to the accumulation of this terrigenous sequence.
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Aykol, A., and S. Tokel. "The geochemistry and tectonic setting of the Demirköy pluton of the Srednogorie–Istranca granitoid chain, NW Turkey." Mineralogical Magazine 55, no. 379 (1991): 249–56. http://dx.doi.org/10.1180/minmag.1991.055.379.13.
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AbstractThe chain of Late Subhercynian granitoids can be traced along the Srednogorie-Istranca-Pontid belt. The Demirköy pluton outcrops in the Istranca segment. The rocks of the pluton range from diorite through grandiorite to perthite granite with granodiorite predominating. On the basis of 25 chemical analyses, the intrusive setting of the granitoid has been investigated. Calcic to calc-alkaline and peraluminous to metaluminous character indicate a subduction-related origin. Low to moderate concentrations of the large-ion lithophiles (LIL), high field strength elements (HFS), light rare earth elements (La, Ce) and low HFS/LIL ratios indicate a mantle-derived magma with subduction-related enrichment. Trace element discrimination diagrams such as Rb/Zr-Nb, Rb/Zr-Y, Rb-SiO2 and Rb-(Nb + Y), are particularly indicative of normal arc-setting for the samples.The Demirköy granitoid is chemically indistinguishable from the Upper Cretaceous granitoids of Strednogorie to the west and the Pontids to the east. This extensive maximum of plutonism can be considered as a time marker in the northern Tethys subduction system.
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Johansson, Å., D. G. Gee, L. Björklund, and P. Witt-Nilsson. "Isotope studies of granitoids from the Bangenhuk Formation, Ny Friesland Caledonides, Svalbard." Geological Magazine 132, no. 3 (1995): 303–20. http://dx.doi.org/10.1017/s0016756800013625.
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AbstractThe Caledonian Hecla Hoek succession in Ny Friesland, eastern Svalbard has been interpreted, for many decades, to be a continuous stratigraphic sequence. Early Palaeozoic and Neoproterozoic strata in its upper parts pass more or less conformably down into amphibolite facies rocks (Stubendorffbreen Supergroup) at depth. Recent isotopic age-determination and structural studies have indicated that the Stubendorffbreen succession is tectonostratigraphic and made up of at least three major thrust sheets. This paper provides new data from two meta-igneous units within the succession, the Bangenhuk and Instrumentberget gneisses. Both are granitoid sheets, consisting mainly of red, strongly lineated gneisses of monzogranitic composition; the Bangenhuk unit also contains some lenses of little deformed granitoids, as well as cross-cutting aplite dykes, amphibolitized dolerites and subordinate metasedimentary rocks. The latter are locally cut by granitoids. U—Pb zircon dating of six samples of variably deformed Bangenhuk granitoids, including one cross-cutting aplitic dyke, has yielded ages between 1720 and 1770 Ma, the higher values generally from the less deformed samples. The Instrumentberget gneissic granite yielded an age of 1737+46−41 Ma. These ages are interpreted to date the time of intrusion of the granitoids at around 1750 Ma; the younger ages may have been slightly lowered by Caledonian deformation, particularly those from specimens located close to a major fracture (the Billefjorden Fault Zone) in Wijdefjorden—Austfjorden. U—Pb dating of titanite from the least deformed granitoid also yields comparable Palaeoproterozoic ages; in the more deformed rocks, however, titanites give evidence of Caledonian ductile deformation at c. 410 Ma. The Rb—Sr system of the corresponding whole rock samples has been disturbed and yields an errorchron age of about 1650 Ma and, for some samples, an impossibly low initial Sr ratio. The Sm—Nd system may be more intact and yields initial εNd values of −2 to −3, suggesting some contribution from older crustal material to the granitoid magmas. The results indicate the presence of extensive units of Palaeoproterozoic granitic basement within the Lower Hecla Hoek succession of Ny Friesland, supporting the hypothesis that the latter is composed of tectonically intercalated basement and cover units.
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Zaitsev, Albert I., Valery Yu Fridovsky, and Maxim V. Kudrin. "Granitoids of the Ergelyakh Intrusion-Related Gold–Bismuth Deposit (Kular-Nera Slate Belt, Northeast Russia): Petrology, Physicochemical Parameters of Formation, and Ore Potential." Minerals 9, no. 5 (2019): 297. http://dx.doi.org/10.3390/min9050297.
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This paper describes features of petrographic and chemical compositions and isotopic dating of the Ergelyakh and Sokh plutons, located within the Kular-Nera slate belt, Verkhoyansk-Kolyma folded region (VKFR), Northeast Russia. Intrusion of the massifs took place approximately 145–150 million years ago. Different isotopic systems on the whole rock samples and mineral separates record at least two stages of later tectono-magmatic activity 130–120 and 110–100 million years ago. Granitoid magmas for the Ergelyakh and Sokh plutons were formed at high temperatures (950–1060 °C) within the amphibolitic lower crust of an island arc setting. The ages of crustal protoliths for granitoids of the Ergelyakh intrusion-related gold–bismuth deposit, calculated on Rb–Sr and Sm–Nd two-stage models, are 1109–1383 and 1199–1322 million years, respectively. Formation of the Ergelyakh and Sokh plutons took place within a significant temperature interval (<450 to 901 °C) and, with regard to the superposition of later events, lasted for a long time. During the cooling process of granitoid melts, at the time of biotite crystallization in both massifs, a significant increase of oxygen fugacity was registered. The ore potential of granitoids of both massifs seems to be similar, but due to some differences in the physicochemical parameters of their formation (redox conditions), it was partially realized only within the Ergelyakh massif with the generation of several minor intrusion-related gold–bismuth deposits. Granitoid melts of the Ergelyakh massif were formed in relatively heterogeneous and oxidizing conditions (∆Ni–NiO = +3.26 to –3.60). Granitoid melts for the Sokh massif (∆Ni–NiO = –2.88 to –9.27) were formed in reducing conditions.
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Bónová, Katarína, Igor Broska, and Igor Petrík. "Biotite from Čierna hora Mountains granitoids (Western Carpathians, Slovakia) and estimation of water contents in granitoid melts." Geologica Carpathica 61, no. 1 (2010): 3–17. http://dx.doi.org/10.2478/v10096-009-0040-1.
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Biotite from Čierna hora Mountains granitoids (Western Carpathians, Slovakia) and estimation of water contents in granitoid meltsBiotite is the dominant ferromagnesian mineral in different granites from the Čierna hora Mountains, in the Western Carpathians (Slovakia). A higher content of Fe3+(up to 20 %) is characteristic for the biotites from I-type Sokoľ and Sopotnica granitoid bodies in contrast to the biotites from S-type Ťahanovce granitoids showing decreased Fe3+amount (around 5 %). The Fe/(Fe + Mg) ratio in biotites from the Sokoľ and Sopotnica massifs between 0.47 and 0.54 is rather low with respect to that in biotite from the Ťahanovce [Fe/(Fe + Mg) = 0.55-0.63] and Miklušovce [Fe/(Fe + Mg) = 0.73-0.81] granite body. Water fugacities and contents calculated using Wones' (1981) calibration of biotite stability equation and Burnham's (1994) water dissolution model yield relatively similar values of 4-5 wt. % in remaining melts at 400 MPa and various levels of fo2and activities of annite for magnetite-bearing assemblages. This suggests an effective buffering role of biotite in both oxygen and water fugacities. Comparison of the peraluminosity index (A/CNK) of biotite with the same index in whole-rock shows distinctly higher A/CNK values for biotite indicating its aluminous character and important role as a significant aluminium carrier. The biotite composition indicates that granitoids in the Čierna hora Mts can be primarily derived from the lower crust; their protolith was influenced by mixing and/or assimilation process.
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Fiannacca, Patrizia, Damiano Russo, Eugenio Fazio, Rosolino Cirrincione, and Manish A. Mamtani. "Fabric Analysis in Upper Crustal Post-Collisional Granitoids from the Serre Batholith (Southern Italy): Results from Microstructural and AMS Investigations." Geosciences 11, no. 10 (2021): 414. http://dx.doi.org/10.3390/geosciences11100414.
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The Serre Batholith in Central Calabria (southern Italy) represents the intermediate portion of a continuous cross-section of late Variscan continental crust. The various granitoid units of the batholith were emplaced at depths between 23 and 6 km through an overaccretion mechanism that, at its upper levels, was marked by the emplacement of two-mica granodiorites and granites (MBG) at c. 295 Ma, followed by weakly peraluminous granodiorites (BAG) at c. 292 Ma. These upper crustal granitoid rocks have recorded tectonic stresses, which affected the batholith during cooling of the magmatic bodies, exhibiting a range of deformation microstructures from submagmatic to low-temperature subsolidus conditions, but without developing an evident meso/micro-structural fabric. Anisotropy of magnetic susceptibility (AMS) was employed to identify a possible “internal” fabric of the Serre upper crustal granitoids, revealing a magnetic foliation represented by a mainly oblate AMS ellipsoid. Magnetic foliations and lineations are consistent with a stress field characterized by a shortening axis roughly oriented NW–SE. Further studies are in progress to investigate more in depth the relationships between regional tectonic structures and the emplacement of the late-Variscan Serre Batholith granitoids.
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Can, Pham Ngoc, Tran Tuan Anh, Tran Trong Hoa, Vu Hoang Ly, Pham Thi Phuong Lien, and Ngo Thi Huong. "Chemical compositions of amphiboles and their references to formation conditions of granitoids from Nam Rom and Song Ma massifs, Northwest Vietnam." VIETNAM JOURNAL OF EARTH SCIENCES 42, no. 1 (2020): 80–92. http://dx.doi.org/10.15625/0866-7187/42/1/14760.
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In this paper, the mineralogical and geochemical characteristics of amphiboles and plagioclases of granitoids from the Nam Rom and Song Ma massifs have been investigated to understand their formation conditions. The Nam Rom amphibole and plagioclase are subhedral to euhedral fine- to medium-grained crystals. Whereas, the Song Ma amphibole and plagioclase are anhedral to subhedral fine-grained crystals. Geochemical compositions of amphiboles suggest that Nam Rom and Song Ma amphiboles are edenite and ferro-edenite, respectively. Nam Rom edenite has higher contents of basic constituents (Mg and Ca) and lower contents of felsic constituents (Na and K) compared with the Song Ma ferro-edenite. On the other hand, Si-(Na+K) and Si-Ca apfu ratios of the Nam Rom edenite and the Song Ma ferro-edenite and Al/(Na+K)-Al/(Ca+Na+K) atom per formula unit (apfu) ratios of the Nam Rom edenite and andesine and the Song Ma ferro-edenite, andesine and oligoclase are similar. Formation conditions of the Nam Rom and Song Ma granitoids were calculated using amphibole-plagioclase geobarometer. The Nam Rom granitoid was formed at 3.07-5.32 kbar (10.1-17.6 km under paleo-surface) and 750-785°C. The Song Ma granitoid was formed at 1.04-3.08 kbar (3.4-10.2 km under paleo-surface) and 715-745°C. Therefore, Nam Rom and Song Ma granitoids are thought to be crystallized from the same magma. The former was formed from the immature and more basic stage of magma; the latter was formed from the mature and more felsic stage of magma.
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Chacko, Thomas, Suman K. De, Robert A. Creaser, and Karlis Muehlenbachs. "Tectonic setting of the Taltson magmatic zone at 1.92.0 Ga: a granitoid-based perspective." Canadian Journal of Earth Sciences 37, no. 11 (2000): 1597–609. http://dx.doi.org/10.1139/e00-029.
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The Paleoproterozoic Taltson magmatic zone is one of the key tectonic features of western Laurentia. The existing tectonic model for the belt envisions its formation by subduction of oceanic crust beneath a continental margin, followed by direct collision between formerly separate crustal blocks. We tested this model by comparing the large geochemical and isotopic database available for Taltson magmatic zone granitoids with similar databases for Phanerozoic granitoid suites from different tectonic environments. The comparison reveals that the early granitoid suite of the Taltson magmatic zone, which had been ascribed to the subduction phase of orogenesis, lacks the mantle signature apparent in granitoids of Phanerozoic continental-margin arc settings. Instead, both early and late suites appear to have an intracrustal origin, similar to Mesozoic and Cenozoic granitoids of the Cordilleran interior of western North America, which formed in the distant hinterland of a convergent plate margin. In light of these findings, we propose an alternative tectonic model, which envisions formation of the Taltson magmatic zone in a plate-interior rather than a plate-margin setting. Modern-day examples of this setting are found in the mountain belts of central Asia, such as the Tian Shan, which are located many hundreds of kilometres away from the plate margin. The critical feature of these belts that make them an appealing analogue for the Taltson magmatic zone is that there is no subduction zone closely associated with their formation. Rather, magmatism occurs in response to thickening of crust in the continental interior.
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Whalen, Joseph B., George A. Jenner, Ernst Hegner, Clément Gariépy, and Frederick J. Longstaffe. "Geochemical and isotopic (Nd, O, and Pb) constraints on granite sources in the Humber and Dunnage zones, Gaspésie, Quebec, and New Brunswick: implications for tectonics and crustal structure." Canadian Journal of Earth Sciences 31, no. 2 (1994): 323–40. http://dx.doi.org/10.1139/e94-030.
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Siluro–Devonian granitoids span a wide compositional range (~50–76% SiO2) and can be subdivided into two groups: (i) monzonitic or incompatible element enriched with affinities to within-plate magmatism (WPG); and (ii) calc-alkalic or incompatible element depleted with supra-subduction zone affinities (VAG). Granitoid εNd(T = 0.4 Ga) values range from −1 to +5.5; most lie between +3 and +5.5. 207Pb/204Pb isotopic compositions range from 15.52 to 15.61; most fall between ~15.55 and 15.59. Most δ18O values lie between +5.5 and +8‰. No well-established trends exist between SiO2 and isotopic composition, and isotopic compositions do not differ between the two trace element defined granitoid groups.Though Pb isotopic data are consistent with a major contribution to the granitoids from Proterozoic-aged Laurentian plate rocks (i.e., Grenville basement), Nd and O isotopic data are not. These isotopic data are consistent with major source components derived from early Paleozoic depleted or supra-subduction zone affected mantle and (or) crustal rocks derived from the early Paleozoic mantle(s). These protoliths would not have seen significant interaction with time-integrated old crustal material or surficial processes. Granitoid Pb isotopic data can be reconciled with an early Paleozoic mantle–crust origin, but it may also be that the Pb isotopes are decoupled from other isotopic systems. In either case, Nd and O isotopic data clearly prohibit the involvement of significant amounts of Grenville crust and suggest that seismic-reflection data do not define crustal blocks, or at least not blocks having a tectonic and geologic history easily related to the surface geology.
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Murphy, Finbarr C. "Late Caledonian granitoids and timing of deformation in the Iapetus suture zone of eastern Ireland." Geological Magazine 124, no. 2 (1987): 135–42. http://dx.doi.org/10.1017/s0016756800015946.
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AbstractLate Caledonian granitoids, (c. 400 Ma) in the zone of the Iapetus suture provide a datum against which current models for the relative timing of deformation can be tested. One such granitoid adjacent to the proposed suture ‘line’ in eastern Ireland is now buried by an Upper Palaeozoic cover. It is identified geophysically by a negative Bouguer anomaly with no magnetic signature, and geologically by a hypabyssal dyke swarm and hornfels metamorphism. The timing of intrusion of the granitoid is shown to have occurred during the continuing end-Silurian/early-Devonian deformation. Other members of this widespread suite in Ireland show features consistent with diapiric intrusion during the later stages of the deformation. This evidence brackets the age of regional deformation as continuing during granite emplacement and cooling (c. 400 Ma). The unifying characteristics of the straddling granitoid suite, coupled with a sinistrally transpressive deformation, in this broad suture zone are interpreted in terms of a continental collision which climaxed in late-Silurian/early-Devonian time.
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Caldevilla Domínguez, Pablo, Luis González-Menéndez, Alba Lozano, Fernando Gómez-Fernández, and Ana María Castañón. "Petrology and geochemical modeling (Ba-W-Sn) of the Peña do Seo granitoids (West Asturian-Leonese Zone, León, Spain)." Geogaceta 74 (December 18, 2023): 43–46. http://dx.doi.org/10.55407/geogaceta98144.
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The Cadafresnas granites and granitoid breccias (Peña do Seo, W of León) are small post-tectonic stocks of Variscan age related to W-Sn mineralizations. According to their mineralogical geochemical characteristics, they are classified as granites-syenogranites, granodiorites and granitoids rich in quartz, of peraluminous/metaluminous composition. The Rb-Ba-Sr relationships allow assigning a metapelitic source for the granites and a metagreywacke source for the granitoid breccias. Using geochemical modeling (partial melting), the contribution of these sources to explain the Ba, W and Sn contents of the granites and granite breccias is investigated. The results indicate that the partial melting of these lithologies explains part of the content of these elements in the studied rocks, requiring additional processes of fractional crystallization and/or hydrothermal injections.
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Artemenko, G. V., L. M. Stepanyuk, L. S. Dovbysh, and B. V. Borodynya. "GRANITOIDS OF THE ZACHATIVKA-FEDORIVKA ANTICLINE IN THE MANGUSH SYNCLINORIUM: GEOCHEMICAL FEATURES, ORIGIN, AND AGE (AZOV DOMAIN OF THE UKRAINIAN SHIELD)." Mineralogical Journal 44, no. 2 (2022): 48–59. http://dx.doi.org/10.15407/mineraljournal.44.01.048.
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The Paleoproterozoic crust formation in the Azov domain remains underexplored. In the Neoarchean-Paleoproterozoic, the Azov segment of the Archean crust was fragmented by large rift structures. This stage is associated with the formation of Neoarchean-Paleoproterozoic sedimentary-volcanic complexes of the Central Azov Series (2.76-2.22 Ga) and extensive granitoid magmatism. The research aimed at studying granitoid intrusions in the Zachativka-Fedorivka anticline in the Mangush synclinorium of the Central Azov region from the geochemical perspective. Granitoids of the Zachativka-Fedorivka anticline in the Mangush synclinorium include granitoids and later pegmatoidal granites. Plagiogranitoids are moderate-potassium rocks of the K-Na series, with predominance of Na2O over K2O and low Rb/Sr ratio (0.03). They are divided into plagiogranites with low contents of HFS elements and positive europium anomalies and granodiorites with higher contents of HFS elements and predominantly negative europium anomalies. The U-Pb age of titanite from granodiorites is 2028±47 Ma. This age corresponds to the closure of the U-Pb isotope system of titanite and thus reflects the minimum age of granodiorite. The 207Pb/206Pb age of zircon from granites is 2.07-2.09 Ga. The formation of the Paleoproterozoic granitoids of the Central Azov may be related to the activization of the mantle beneath the Azov domain during the formation of the East Sarmatian orogen at ca. 2.1 Ga. They could have formed because of partial melting of the lower crust because of underplating of mafic melts. The 2.05 Ga old vein bodies of pegmatoidal subalkaline granites, were probably formed at the stage of collision of the Sarmatia and Volga-Ural continents.
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Artemenko, G. V., L. M. Stepanyuk, L. S. Dovbysh, and B. V. Borodynya. "GRANITOIDS OF THE ZACHATIVKA-FEDORIVKA ANTICLINE IN THE MANGUSH SYNCLINORIUM: GEOCHEMICAL FEATURES, ORIGIN, AND AGE (AZOV DOMAIN OF THE UKRAINIAN SHIELD)." Mineralogical Journal 44, no. 2 (2022): 48–59. http://dx.doi.org/10.15407/mineraljournal.44.02.048.
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The Paleoproterozoic crust formation in the Azov domain remains underexplored. In the Neoarchean-Paleoproterozoic, the Azov segment of the Archean crust was fragmented by large rift structures. This stage is associated with the formation of Neoarchean-Paleoproterozoic sedimentary-volcanic complexes of the Central Azov Series (2.76-2.22 Ga) and extensive granitoid magmatism. The research aimed at studying granitoid intrusions in the Zachativka-Fedorivka anticline in the Mangush synclinorium of the Central Azov region from the geochemical perspective. Granitoids of the Zachativka-Fedorivka anticline in the Mangush synclinorium include granitoids and later pegmatoidal granites. Plagiogranitoids are moderate-potassium rocks of the K-Na series, with predominance of Na2O over K2O and low Rb/Sr ratio (0.03). They are divided into plagiogranites with low contents of HFS elements and positive europium anomalies and granodiorites with higher contents of HFS elements and predominantly negative europium anomalies. The U-Pb age of titanite from granodiorites is 2028±47 Ma. This age corresponds to the closure of the U-Pb isotope system of titanite and thus reflects the minimum age of granodiorite. The 207Pb/206Pb age of zircon from granites is 2.07-2.09 Ga. The formation of the Paleoproterozoic granitoids of the Central Azov may be related to the activization of the mantle beneath the Azov domain during the formation of the East Sarmatian orogen at ca. 2.1 Ga. They could have formed because of partial melting of the lower crust because of underplating of mafic melts. The 2.05 Ga old vein bodies of pegmatoidal subalkaline granites, were probably formed at the stage of collision of the Sarmatia and Volga-Ural continents.
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Oljira, Temesgen, Olugbenga Akindeji Okunlola, Akinade Shadrach Olatunji, Dereje Ayalew, and Bekele Ayele Bedada. "Petrogenesis of the Neoproterozoic rocks of Megele area, Asosa, Western Ethiopia." Earth Sciences Research Journal 26, no. 2 (2022): 157–72. http://dx.doi.org/10.15446/esrj.v26n2.98451.
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The Western Ethiopian Shield is underlain by volcano-sedimentary terranes, gneissic terranes, and ophiolitic rocks intruded by different granitoid bodies. The Megele area is part of Western Ethiopian Shield and consist of a low-grade volcano-sedimentary zone that has been intruded by mafic (dolerite dyke) and granitoid intrusions (granodiorite, diorite, granite gneiss). To establish the origin of the distinctive lithologies of the locality and evaluate its mineral potential, petrological, petrographical, and geochemical characterization of these rocks were carried out. Hence, the lithological, geochemical, and petrogenetic features of the Neoproterozoic granitoid intrusives and associated metavolcanic, were illustrated through a combination of field mapping, petrological, and geochemical analysis. The petrological result obtained from the thin section analysis of the granitoids and metabasalt from Megele area indicates that, these rocks has been metamorphosed from lower green-schist facies to lower amphibolite facies as denoted by mineral assemblages such as albite + muscovite + prehnite+ quartz and actinolite + hornblende + epidote + garnet. The major and trace element geochemical analysis of granodiorite, diorite, and granite gneiss revealed that the rocks in the studied area were mainly calc-alkaline and peraluminous in nature in the SiO2 versus Na2O+K2O and A/NK versus A/CNK, the details of the results on the major and rare elements are stated in the result section respectively. The granitoids are S-type granites revealed silica saturated rock formed at the volcanic arc subduction (VAG) to syn-collisional (syn-COLD) tectonic setting by fractionation of LREE-enriched, HREE-depleted basaltic magma with considerable crustal input. This basaltic magma seems to be generated from the LREE-enriched, HREE-depleted mantle. In conclusion, the metabasalt is sub-alkaline (tholeiitic), metaluminous bodies generated at mid-oceanic ridge tectonic setting by partially melting of HREE-depleted and LREE-enriched basaltic magma. The magma sources are associated with the reworked sediment-laden crustal slabs from the subduction zone and resulted in S-type granitoid.
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Syaifullah, Mulyadi, and Hari Wiki Utama. "Petrogenesis Intrusi Granitoid Langkup di Desa Rantau Kermas dan Sekitarnya, Kecamatan Jangkat, Kabupaten Merangin, Provinsi Jambi." Jurnal Geosains dan Remote Sensing 2, no. 1 (2021): 41–48. http://dx.doi.org/10.23960/jgrs.2021.v2i1.59.
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Granitoid Langkup tersingkap baik di Desa Rantau Kermas, dikarenakan keberadaannya tepat tersingkap di bagian Perbukitan Barisan yang merupakan jalur busur magmatik Sunda-Banda berumur Miosen Akhir-Pliosen. Penelitian karakteristik mineralogi Granitoid Langkup menjadi penting dan menarik untuk dapat menjelaskan pembentukan batuan, dengan menggunakan analisis petrografi sehingga hasilnya dapat memberikan gambaran mengenai tipe Granitoid yang terdapat di Formasi Langkup, hubungan antara kegiatan magmatisme, serta keberadaan sumberdaya mineral dan energi. Pada metode penelitian tahap awal dilakukan pengamatan Citra Model Elevasi Digital (DEM) dengan menggunakan perangkat lunak Arcgis 10.5.1 format UTM dengan skala peta 1:25.000. Tahap selanjutnya berupa survey di lapangan dengan pengamatan geomorfologi, pengamatan singkapan, pengukuran struktur geologi, dan stratigrafi terukur. Untuk mengetahui karakteristik batuan, serta tipe Granitod dilakukan analisis petrografi pada sampel batuan dengan klasifikasi batuan beku IUGS. Magma yang mengandung unsur gas dan bersifat bergerak (mobile) dengan temperatur tinggi dan tekanan yang tinggi bergerak menuju tekanan yang lebih rendah. Pergerakan magma yang menerobos naik dipengaruhi oleh pengangkatan dan struktur geologi berupa sesar yang menyebabkan terbentuknya intrusi batuan. Pada saat magma naik menginjeksi batuan samping terjadi proses silisifikasi yang mengakibatkan peningkatan derajat keasaman magma membentuk batuan granit. Pengelompokan tipe granitoid berdasarkan asal usul pembentukkan granit, granitoid di daerah penelitian termasuk granitoid tipe-I, yaitu granitoid yang terbentuk dari diferensiasi batuan beku. Hal ini dibuktikan dengan adanya mineral penciri seperti kehadiran hornblenda dan biotit. Batuan granit yang berada pada daerah penelitian dapat diinterpretasikan terbentuk pada lingkungan tektonik zona konvergen yakni pada zona tepian benua aktif (Active Continental Margin).
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Dempsey, C. S., A. N. Halliday, and I. G. Meighan. "Combined Sm-Nd and Rb-Sr isotope systematics in the Donegal granitoids and their petrogenetic implications." Geological Magazine 127, no. 1 (1990): 75–80. http://dx.doi.org/10.1017/s0016756800014175.
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AbstractThe metaluminous to peraluminous granitoids of the Donegal batholith, northwest Ireland, were emplaced at c. 400 Ma into greenschist-amphibolite facies metasediments of the Dalradian Supergroup. Sm-Nd and Rb-Sr isotopic data are provided for eleven granitoid samples from six of the plutons and one specimen from the northeast granodiorite pluton of the Newry complex, Co. Down; the Donegal results reveal essentially similar initial Sr isotope ratios (0.7051–0.7068) but highly variable initial eNd values, −1.2 to −8.3 (and −0.5 for Newry). Certain granitoids have distinctive Nd isotopic compositions characteristic of the involvement of old, LREE-enriched continental crust in some cases or young crust and/or mantle-derived magmas in others. The Nd and Sr isotopic variations can be explained by a variety of mixing hypotheses.
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Karimpour, Mohammad Hassan, Nargess Shirdashtzadeh, and Martiya Sadeghi. "Tectonomagmatic settings of Jurassic granitoids in the Sanandaj-Sirjan Zone, Iran: A review." Geologos 28, no. 1 (2022): 19–37. http://dx.doi.org/10.2478/logos-2022-0002.
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Abstract The present paper discusses the geochemical affinities, origin and ages of Jurassic granitoids of the Sanandaj-Sirjan Zone (SaSZ) in the eastern part of the Zagros Thrust Zone. A multidisciplinary, integrated approach was carried out using existing granitoid geochemical data (major, trace, rare earth element and isotopes) and knowledge of the regional geology (geodynamic and metamorphic setting), coupled with geophysical data (magnetic susceptibility) from granitoids in the SaSZ. We re-interpret and re-classify the Jurassic granitoids of this zone into three main genetic groups: S-type, I-type and A-type subduction-related ones. In the central to southern part of the Sanandaj-Sirjan zone (between Hamadan and Sirjan), S-type magmatism appeared between 178 and 160 Ma during the Cimmerian orogeny, due to continental collision. To the north of the Sanandaj-Sirjan zone (between Sanandaj and Ghorveh), I-type and A-type magmatism occurred between 158 and 145 Ma. This heterogenic tectonomagmatic system along the SaSZ suggests a heterogenic subcontinental lithospheric mantle, resulting in two Jurassic tectonomagmatic zones of (1) the Sanandaj-Ghorveh Zone and (2) the Hamadan-Sirjan Zone.
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Kruk, Nikolay N., Olga A. Gavryushkina, Sergey Z. Smirnov, Elena A. Kruk, Sergey N. Rudnev, and Dina V. Semenova. "Formation of High-Silica Leucocratic Granitoids on the Late Devonian Peraluminous Series of the Russian Altai: Mineralogical, Geochemical, and Isotope Reconstructions." Minerals 13, no. 4 (2023): 496. http://dx.doi.org/10.3390/min13040496.
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This paper presents data on the geological position, geochemical features, main mineral composition (micas, feldspars), and melt and fluid inclusions in quartz from Aba high-silica leucocratic granitoids in the western part of the Talitsa batholith, Russian Altai. According to these new geochemical data, the granitoids are classified as S-type, meaning they are formed via the partial melting of metasedimentary source rocks. Geological data and oxygen isotope composition analysis indicate that major-phase granitoid magma evolution took place at the level of intrusion formation, whereas the parent melt of late-phase leucogranite evolved in a deeper chamber. The geochemical features (HFSE and REE, and REE spectra) of the granitoids indicate significantly higher differentiation in the late leucocratic phase. The presence of coexisting syngenetic melt and fluid inclusions shows that leucogranite magma was already saturated with volatiles in the early crystallization stages. Based on the new data presented in this work, the Aba rock formation is associated with the volatile saturation of magmatic melts, the exsolution of a fluid phase, and magma degassing.
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Hölttä, Pentti, Irmeli Mänttäri, Hannu Huhma, Matti Kurhila, Tapio Ruotoistenmäki, and Asko Kontinen. "Growth of the Archean sialic crust as revealed by zircon in the TTGs in eastern Finland." Bulletin of the Geological Society of Finland 93, no. 2 (2021): 77–104. http://dx.doi.org/10.17741/bgsf/93.2.001.
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U–Pb age determinations on zircon from granitoids in the Archean of eastern Finland were conducted using the SIMS, LA-ICP-MS and TIMS techniques, with an emphasis on low-HREE granitoids. The oldest rocks in the Fennoscandian Shield are 3.4–3.5 Ga. Several samples were collected close to these rocks, but none of the samples were as old, indicating that the oldest rocks are only small, possibly allochthonous fragments in the Neoarchean bedrock. Some tonalite–trondhjemite–granodiorite (TTG) samples yielded homogeneous 2.72–2.73 Ga zircon populations, and in these samples, the initial εNd was also close to the depleted mantle (DM) values. However, several granitoid samples with a main zircon population of 2.7–2.8 Ga had 2.9–3.2 Ga grains or inherited cores, and in some samples, all grains were of 2.9–3.0 Ga. In these samples, the εNd value was also close to zero or slightly negative. These features suggest that apart from the juvenile Neoarchean magmas, the abundance of reworked 2.9 Ga material is considerable in the Archean crust, which developed during successive juvenile magmatic inputs that melted and assimilated the older sialic crust. The low- HREE geochemical character of granitoids has no correlation with their age, with the low-HREE granitoids yielding an age span of 2.72–2.98 Ga.
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Hicks, N., and D. J. C. Gold. "A reinterpretation of the Archaean stratigraphy south of Nkandla, southern Kaapvaal Craton, South Africa: Geophysical and stratigraphic constraints on a sheared granitoid-greenstone remnant." South African Journal of Geology 124, no. 3 (2021): 685–98. http://dx.doi.org/10.25131/sajg.124.0025.
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Abstract A new lithostratigraphic framework based upon a review of historic data, field mapping and remote sensing, including aerial photography, high-resolution airborne aeromagnetic and radiometric data, is proposed for the Archaean geology along the southeastern margin of the Kaapvaal Craton, South Africa. A synthesis of new and existing data reveals that previously accepted lithostratigraphic schemes require complete revision, with reinterpretations identifying multiple major shear zones and previously unidentified granitoid successions along the margin of the craton. In this new lithostratigraphic framework, lithologies of the Southern Syncline previously correlated with the Nsuze Group of the Pongola Supergroup, are redefined as greenstone lithologies associated with the Ilangwe Greenstone Belt. The geology of the Nkandla region can be subdivided into five distinct geophysical domains including: (i) an extension of the Ilangwe Greenstone Belt, (Domain 1) which is subdivided into; a lower volcanic succession, the Thathe Formation, comprising pillow and amygdaloidal volcanics; the adjoining Sabiza Formation, comprising pillow volcanics exposed in the southeast of the study area; the volcano-sedimentary Mtshwili Formation, which overlies the Thathe and Sabiza formations, consisting of quartz (sericite) schist, phyllite, metavolcanics and iron formation; the Nomangci Formation, which occurs as a region of highly deformed quartz-kyanite-sericite schists, and the Simbagwezi Formation, which comprises maroon to green phyllites and schists in the north of the study area. (ii) granitoids of the Impisi Granitoid Suite (Domain 2) which border the greenstone succession to the north, intruding the Nomangci and Simbagwezi formations. (iii) a southern complex of sheared granitoids termed the Umgabhi Granitoid Suite (Domain 3), which intrudes the Thathe, Sabiza and Mtshwili formations. (iv) The two remaining domains, comprise the Mesoproterozoic Mfongosi and Ntingwe Groups (Domain 4) and Mesoarchaean volcano-sedimentary sequences of the Pongola Supergroup (Domain 5).
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Galán, Gumer, Gloria Gallastegui, Andrés Cuesta, Guillermo Corretgé, Ofelia Suárez, and Luis González-Menéndez. "Contrasting appinites, vaugnerites and related granitoids from the NW Iberian Massif: insight into mantle and crustal sources." European Journal of Mineralogy 35, no. 5 (2023): 845–71. http://dx.doi.org/10.5194/ejm-35-845-2023.
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Abstract. Post-collisional Mg–K-rich mafic rocks with associated granitoids appear regularly in most orogens. They are relevant to evaluate the mantle role in the genesis of granitoids and thereby of the continental crust itself. The most characteristic Mg–K mafic rocks in the Variscan Iberian Massif are appinites and vaugnerites. Two examples with associated granitoids from NW Iberia have been compared to assess their mantle and crustal sources and the magmatic processes involved in their formation. Related granitoids are tonalites, granodiorites and monzonitic granites. Available whole-rock major and trace element compositions, as well as Sr and Nd isotopes, were used for this comparison, along with new Sr–Nd isotopic data. The appinite–granitoid association is calc–alkalic, whereas the vaugneritic one is calc–alkalic transitional to alkali–calcic. Vaugnerites are more enriched in Mg and K, compatible and incompatible trace elements and display more fractionated rare-earth element (REE) patterns than appinites. Associated granitoids provide similar differences. Appinites and vaugnerites have Sr and Nd crustal isotopic signatures resulting from partial melting of a different subduction-type metasomatised mantle: amphibole spinel lherzolites for appinites and more refractory and deeper amphibole phlogopite ± garnet peridotites for vaugnerites. Further interaction of these basic melts with coeval granitoids occurred during their ascent and emplacement. The monzonitic granites derived from partial melting of metaigneous acid granulites, without discarding contribution of metasediments and/or an increasing role of biotite incongruent melting in those related to vaugnerites. An assimilation with fractional crystallisation process between appinite magmas and granulites could explain tonalites and granodiorites. This process was not confirmed for granodiorites related to vaugnerites.
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Mondal, M. E. A., M. Faruque Hussain, and Talat Ahmad. "Archean granitoids of the Bastar Craton, Central India." Geological Society, London, Special Publications 489, no. 1 (2019): 135–55. http://dx.doi.org/10.1144/sp489-2019-311.
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AbstractArchean granitoids of the Bastar Craton mainly occur as gneisses (3.56, 3.50 Ga) and undeformed granitoids (c. 2.5–2.48 Ga). Based on detailed geochemical characteristics two compositional types of gneisses: tonalite–trondhjemite–granodiorite (TTG) and transitional TTG (t-TTG) have been identified. The TTG rocks are further classified into low-HREE (heavy rare earth element) type and high-HREE type. It is proposed that melting of a thick enriched oceanic plateau basalt at deeper level may have generated the low-HREE TTG, whereas melting at shallower depth of the thick plateau can explain the geochemical signatures of the high-HREE TTG. The t-TTG was formed as a result of reworking of the older TTG crust. These two gneisses were probably formed at different time at 3.56 and 3.50 Ga as manifested from the age of the gneisses. The granitoids were formed at a later stage (c. 2.5–2.48 Ga) by reworking of the pre-existing gneissic crust consisting of TTG and t-TTG. Presence of a small 3.58 Ga undeformed K-rich granitoid from the northern part of the craton might indicate yet another earlier crustal reworking event.
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USTAÖMER, P. AYDA, and GRAEME ROGERS. "The Bolu Massif: remnant of a pre-Early Ordovician active margin in the west Pontides, northern Turkey." Geological Magazine 136, no. 5 (1999): 579–92. http://dx.doi.org/10.1017/s0016756899003015.
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The scope of this study is to understand better the pre-Early Ordovician history of the west Pontides of northern Turkey by focusing on the best-exposed part of the Bolu Massif, which is located between Bolu and Yedigöller (Seven Lakes). The Palaeozoic rocks of the west Pontides tectonic belt of northern Turkey comprise a transgressive sedimentary sequence known as ‘Palaeozoic of İstanbul.’ In a few areas, the basement of the Palaeozoic sequence is exposed, the largest part of which is the Bolu Massif, which is located in the middle of the west Pontides. The lowermost unit of the Palaeozoic of İstanbul in the Bolu area is the Işığandere Formation, which is made up of fluvial red conglomerates and sandstones of Lower Ordovician age. Three different units are exposed unconformably beneath these continental clastics, forming the Bolu Massif. From the structural base to the top, these are as follows: (1) a high-grade metamorphic unit, known as the Sünnice Group); (2) granitoid intrusions, known as the Bolu Granitoid Complex; and (3) a greenschist meta-volcanic sequence (the Çaşurtepe Formation).The Sünnice Group is the lowest, structurally speaking. It is a southwest–northeast-trending belt of migmatitic basement, consisting of amphibolites and paragneisses cut by small (< 10 m) metagranitic intrusions. The Sünnice Group is tectonically overlain by the Bolu Granitoid Complex and the Çaşurtepe Formation along the Karadere Fault. In the study area the Bolu Granitoid Complex is represented by two distinct, north-northeast–south-southwest-trending intrusions, the Tüllükiriş and Kapikaya plutons. The granitoids are mainly tonalitic and granodioritic in composition, cut by lam-prophyre and aplite dykes and intruded into the Çaşurtepe Formation. The Çaşurtepe Formation is composed mainly of andesitic and minor rhyolitic lavas, along with a meta-ignimbrite sequence.The lavas have geochemical characteristics indicative of eruption in a subduction-related tectonic setting. The geochemistry of the intrusions also suggests emplacement in an arc-type setting. Initial Nd isotope data for the Çaşurtepe Formation indicate derivation from a depleted mantle source, whereas those for the granitoids are consistent with greater degrees of crustal contamination.
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Reis, Rafael Souza dos, Marcus Vinicius Dornelles Remus, Norberto Dani, and Henrique De Maman Anzolin. "Alteração clorítica no flanco leste do Granito Caçapava, Rio Grande do Sul: evolução do metassomatismo e sulfetos de Cu-Fe associados." Geologia USP. Série Científica 17, no. 4 (2018): 61. http://dx.doi.org/10.11606/issn.2316-9095.v17-121013.
Full textAbstract:
Este trabalho investigou a origem e a evolução de clorititos — rochas portadoras de clorita e/ou sulfetos de Cu-Fe —, associados a sills e apófises do Granito Caçapava que intrudem nos mármores dolomíticos da Formação Passo Feio, Terreno São Gabriel do Escudo Sul-Riograndense (ESRG). A interação dos fluidos graníticos com os mármores gera associações minerais de alta e baixa temperatura. Os halos de alteração de baixa temperatura nos granitoides são constituídos dominantemente por clorita seguida de albita, titanita, sulfetos e raro rutilo. Clorita, calcita e, eventualmente, serpentina, talco e sulfetos constituem a alteração de baixa temperatura nos mármores encaixantes. Os halos de alteração distribuem-se em domínios ao longo da matriz dos granitoides, bem como em stockworks ou em brechas hidrotermais e fraturas contendo calcopirita e pirita. Identificam-se processos importantes de alteração hidrotermal-metassomática, notadamente cloritização e albitização no protólito granitoide. A alteração é progressiva nas apófises granitoides com modificações desde incipiente até rochas compostas majoritariamente por cloritas, culminando com a geração de clorititos. A nucleação e o crescimento da clorita ocorre a partir da substituição da biotita e do plagioclásio ou deposita em espaços vazios na rocha carbonática encaixante. O balanço de massa pelo método da isócona indica que o processo de cloritização evoluiu por meio do enriquecimento de MgO e FeO e do empobrecimento em SiO2, K2O e Na2O dos protólitos granitoides. Os padrões de abundância e distribuição de elementos terras raras (ETR) indicam correlação direta das rochas portadoras de clorita e dos clorititos com fácies pertencentes ao Complexo Granítico de Caçapava do Sul. Geotermometria a partir da composição da clorita indica temperatura média entre 280 e 300ºC para formação das cloritas.