Статті в журналах: "Southern granulite terrane"

1

Santosh, M. "The Southern Granulite Terrane: A synopsis." Episodes 43, no. 1 (March 1, 2020): 109–23. http://dx.doi.org/10.18814/epiiugs/2020/020006.

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Li, Shan-Shan, Richard M. Palin, M. Santosh, E. Shaji, and T. Tsunogae. "Extreme thermal metamorphism associated with Gondwana assembly: Evidence from sapphirine-bearing granulites of Rajapalayam, southern India." GSA Bulletin 132, no. 5-6 (October 10, 2019): 1013–30. http://dx.doi.org/10.1130/b35378.1.

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Abstract The Madurai block is the largest composite crustal block in the Southern Granulite terrane of India, where granulite-facies rocks metamorphosed at ultrahigh-temperature (UHT) conditions occur in several localities. Here, we investigated UHT rocks from Rajapalayam, in the southern domain of the Southern Granulite terrane, using integrated thermobarometry and in situ monazite geochronology to precisely constrain the nature and timing of this extreme metamorphism and its implications for regional tectonics. Conventional thermobarometry and petrological phase equilibrium modeling reveal prograde pressure-temperature (P-T) conditions at 0.75–1.2 GPa and <900 °C, followed by peak/postpeak UHT metamorphism at 0.72–0.82 GPa and 1025–1050 °C, and retrograde reequilibration at 0.72–0.80 GPa and 875–895 °C. The granulites thus record a clockwise P-T path defining geothermal gradients of 1200–1500 °C/GPa at peak metamorphism, indicating the presence of an extreme thermal perturbation in the middle to lower continental crust. In situ monazite dating indicates prograde metamorphism at 607–585 Ma, peak metamorphism at 546–543 Ma, and retrograde cooling and exhumation at 539–483 Ma. As such, the entire tectonothermal cycle was complete within ∼120 m.y., although temperatures exceeding 900 °C were likely sustained for at least 30 m.y. Such extreme thermal events preserved in geological terranes worldwide are commonly associated with lithospheric extension, although our data show that prolonged heating can occur during continental convergence instead, supporting inferences made by thermomechanical models. Thus, supercontinent formation may act as a driver for spatially distributed UHT tectonometamorphism, as shown by the episodic records in geological history. The age of peak metamorphism constrained here was synchronous with UHT metamorphism in other localities in the Southern Granulite terrane, Sri Lanka, Madagascar, and Antarctica, indicating their correlation with the final amalgamation of eastern Gondwana at ca. 550 Ma.

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3

KIHLE, J., and K. BUCHER-NURMINEN. "Orthopyroxene?sillimanite?sapphirine granulites from the Bamble granulite terrane, southern Norway." Journal of Metamorphic Geology 10, no. 5 (September 1992): 671–93. http://dx.doi.org/10.1111/j.1525-1314.1992.tb00114.x.

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4

Sajeev, K. "The Tectonic and Metamorphic Perspective of Southern Granulite Terrane, India." Journal of the Geological Society of India 97, no. 9 (September 2021): 1112. http://dx.doi.org/10.1007/s12594-021-1830-z.

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5

George, P. M., M. Santosh, Nengsong Chen, V. Nandakumar, T. Itaya, M. K. Sonali, R. P. Smruti, and K. Sajeev. "Cryogenian magmatism and crustal reworking in the Southern Granulite Terrane, India." International Geology Review 57, no. 2 (January 23, 2015): 112–33. http://dx.doi.org/10.1080/00206814.2014.999260.

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6

Wang, Runsan, Dingwu Zhou, Juli Wang, Yan Wang, and Yangjie Liu. "Variscan terrane of deep-crustal granulite facies in Yushugou area, southern Tianshan." Science in China Series D: Earth Sciences 42, no. 5 (October 1999): 482–90. http://dx.doi.org/10.1007/bf02875242.

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7

Gilotti, Jane A., and Synnøve Elvevold. "Extensional exhumation of a high-pressure granulite terrane in Payer Land, Greenland Caledonides: structural, petrologic, and geochronologic evidence from metapelites." Canadian Journal of Earth Sciences 39, no. 8 (August 1, 2002): 1169–87. http://dx.doi.org/10.1139/e02-019.

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The Payer Land gneiss complex is unique among the mostly amphibolite-facies, mid-crustal gneiss complexes in the East Greenland Caledonides due to its well-preserved, regional high-pressure (HP) granulite-facies metamorphism. High-pressure high-temperature (HPHT) assemblages are recognized in mafic, ultramafic, granitic, and metasedimentary lithologies. Anatectic metapelites contain the assemblage garnet + kyanite + K-feldspar + antiperthite (exsolved ternary feldspar) + quartz ± biotite ± rutile and record approximately the same peak metamorphic conditions (pressure (P) = 1.41.5 GPa, temperature (T) = 800850°C) as those of the neighboring mafic HP granulites. The HP granulite-facies metamorphism is Caledonian based on in situ UThPb electron microprobe dating of monazite from two samples of the aluminous paragneiss. The monazites are found along garnetkyanite phase boundaries, as inclusions in garnet and kyanite, and within small leucocratic melt pods (K-feldspar + plagioclase + kyanite ± garnet) within the HPHT paragneisses. Mylonitic equivalents of the metapelites contain a detrital monazite age signature that suggests the Payer Land paragneisses correlate with other Mesoproterozoic metasedimentary sequences in the area. The gneisses form a metamorphic core complex that is separated from the overlying low-grade sedimentary rocks of the Neoproterozoic Eleonore Bay Supergroup by an extensional detachment. This newly recognized Payer Land detachment is part of a system of prominent extensional faults located in the southern half of the Greenland Caledonides (i.e., south of 76°N). The HP granulites preserve the deepest level of crust exposed in this southern segment of the orogen and attest to significant crustal thickening.

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8

Karmakar, Shreya, Subham Mukherjee, and Upama Dutta. "Origin of corundum within anorthite megacrysts from anorthositic amphibolites, Granulite Terrane, Southern India." American Mineralogist 105, no. 8 (August 1, 2020): 1161–74. http://dx.doi.org/10.2138/am-2020-7108.

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Abstract Growth of corundum in metamorphosed anorthosites and related basic-ultra-basic rocks is an exceptional feature, and its origin remains elusive. We describe the occurrence of and offer an explanation for the genesis of corundum in anorthositic amphibolites from ~2.5 Ga old basement of the Granulite Terrane of Southern India (GTSI). The studied amphibolites from two localities, Manavadi (MvAm) and Ayyarmalai (AyAm), contain anorthite lenses (An90–99) with euhedral to elliptical outline set in a finer-grained matrix of calcic plagioclase (An85–90) and aluminous amphibole (pargasite-magnesiohastingsite). The lenses, interpreted as primary magmatic megacrysts, and the matrix are both recrystallized under static condition presumably during the regional high pressure (HP) metamorphism (~800 °C, 8–11 kbar) at ~2.45 Ga. Corundum occurs in the core of some of the recrystallized anorthite lenses (An95–99) in two modes: (1) Dominantly, it forms aggregates with magnetite (with rare inclusion of hercynite; in MvAm) or spinel (and occasionally hematite-ilmenite; in AyAm). The aggregates cut across the polygonal grain boundaries of the anorthite and contain inclusions of anorthite. (2) Corundum also occurs along the grain boundaries or at the triple junctions of the polygonal anorthite grains, where it forms euhedral tabular grains, sieved with inclusions of anorthite or forms skeletal rims around the recrystallized anorthite, such that it seems to be intergrown with anorthite. Combined petrological data and computed phase relations are consistent with growth of corundum in an open system during regional metamorphism in the presence of intergranular fluids. Two mechanisms are proposed to explain the formation of the corundum in the amphibolites: (1) corundum + magnetite/spinel aggregates formed dominantly by oxy-exsolution of pre-existing Al-Fe-Mg-(Ti)-spinel. This pre-existing spinel may be primary magmatic inclusions within the anorthite phenocrysts or could have formed due to reaction of primary magmatic inclusions of olivine with the host anorthite. Pseudosections of fO2-nH2O-T-P in the CaO–FeO–MgO–Al2O3–SiO2–H2O (CFMASH) system indicate that fO2 and H2O strongly influence the formation of corundum + amphibole from the initial magmatic assemblage of anorthite (phenocrysts) + spinel ± olivine (inclusions). (2) The corundum with anorthite presumably formed through desilification and decalcification of anorthite, as is indicated by computed phase relations in isobaric-isothermal chemical potential diagrams (µSiO2-µCaO) in parts of the CASH system. Growth of corundum in this mode is augmented by high activity of anorthite in plagioclase, high pressure, and low-to-medium temperature of metamorphism. This study thus presents a new viable mechanism for the origin of corundum in anorthositic amphibolites, and basic-ultra-basic rocks in general, which should provide new insight into lower crustal processes like high-pressure metamorphism.

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9

Rao, V. Vijaya, Kalachand Sain, P. R. Reddy, and Walter D. Mooney. "Crustal structure and tectonics of the northern part of the Southern Granulite Terrane, India." Earth and Planetary Science Letters 251, no. 1-2 (November 2006): 90–103. http://dx.doi.org/10.1016/j.epsl.2006.08.029.

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10

JingLi, WANG, and ZHANG HongFu. "Formation and evolution of lower crustal granulite terrane in the southern North China Craton." Acta Petrologica Sinica 38, no. 12 (2022): 3819–34. http://dx.doi.org/10.18654/1000-0569/2022.12.18.

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11

Scherstén, Anders, Henrik Stendal, and Tomas Næraa. "Geochemistry of greenstones in the Tasiusarsuaq terrane, southern West Greenland." Geological Survey of Denmark and Greenland (GEUS) Bulletin 15 (July 10, 2008): 69–72. http://dx.doi.org/10.34194/geusb.v15.5047.

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Tonalite-trondhjemite–granodiorite (TTG) gneisses and mela nocratic to ultramafic greenstones dominate the Arc haean basement of southern West Greenland. The greenstones are likely to represent different original environments, which is important as the mineral deposits they may host depend on this. For example, massive sulphide deposits associated with gold and base metals are commonly volcan og enic, while chrome, nickel and platinum group elements are more commonly associated with layered intrusions (Robb 2005). Cur rent investigations by the Geological Survey of Denmark and Greenland (GEUS) in southern West Greenl and are therefore focused on the origin of greenstones and their relationship to associated TTG gneisses. Here, we report on work in progress on greenstones within the Tasiusarsuaq terrane (Fig. 1; Friend et al. 1996). They differ from many other greenstone belts in southern West Green land in their spatial association with the TTG gneisses. Unlike the Isua, Ivisârtoq and Storø greenstone belts in the central and northern Nuuk region, the Tasiusarsuaq greenstones are not proximal to terrane boundaries but form dismembered blocks and slivers within the terrane (Fig. 1). Contact relationships to the gneisses are almost exclusively tectonic, and primary textures are, with rare exceptions, ob literated by amphibolite to granulite facies metamorphism.

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12

Garde, A. A., C. R. L. Friend, A. P. Nutman, and M. Marker. "Rapid maturation and stabilisation of middle Archaean continental crust: the Akia terrane, southern West Greenland." Bulletin of the Geological Society of Denmark 47 (December 31, 2000): 1–27. http://dx.doi.org/10.37570/bgsd-2000-47-01.

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from the Akia terrane, southern West Greenland, supported by Sm-Nd isotope geochemistry, document its middle Archaean accretional history and provide new evidence about the location of its northern boundary. Zircon populations in grey gneiss and inherited zircons in granite show that magmatic accretion of new continental crust, dominated by intrusion of tonalite sheets in a convergent island arc setting, occurred between c. 3050 and 3000 Ma, around and within a c. 3220 Ma continental core. In the central part of the terrane, tonalite sheets were intercalated with older supracrustal rocks of oceanic affinity by intrusion, thrusting and folding during the Midterhøj and Smalledal deformation phases of Berthelsen (1960). Continued tonalite injection led to a thermal maximum with granulite facies conditions at c. 2980 Ma, dated by metamorphic zircons in grey gneiss. The metamorphic maximum was contemporaneous with upright, angular folds of the Pâkitsoq deformation phase. Within a few million years followed high-grade retrogression and intrusion of two large dome-shaped tonalite-granodiorite complexes, granites s.l. derived from remobilisation of grey gneiss, and post-kinematic diorite plugs. Whereas the relative chronology of these events is firmly established from field observations, zircons from the post-granulite facies intrusions all yielded statistically indistinguishable emplacement ages of c. 2975 Ma. These results show that crustal growth occurred in several short-lived events starting at c. 3220 Ma, and that final maturation and stabilisation of new, thick continental crust took place rapidly (within c. 20 Ma) at c. 2975 Ma.

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13

Chetty, T. R. K. "Multiple thrust systems from the Southern Granulite Terrane, India: Insights on Precambrian convergent margin tectonics." Journal of Asian Earth Sciences 208 (April 2021): 104674. http://dx.doi.org/10.1016/j.jseaes.2021.104674.

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14

ACQUAFREDDA, PASQUALE, ANNAMARIA FORNELLI, ANTONIO PAGLIONICO, and GIUSEPPE PICCARRETA. "Petrological evidence for crustal thickening and extension in the Serre granulite terrane (Calabria, southern Italy)." Geological Magazine 143, no. 2 (March 2006): 145–63. http://dx.doi.org/10.1017/s0016756805001482.

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The paper presents the metamorphic trajectory recorded by metapelitic migmatites of the upper part of the Hercynian lower continental crust of the Serre (southern Calabria, Italy). The relict minerals, reaction textures and phase equilibria define a clockwise P–T path. The prograde metamorphism from temperature of about 500°C and pressure of 4–5 kbar to T<700°C and P∼8 kbar stabilized the assemblage Grt+Ky+Bt+Ms(Si/11ox=3.26–3.29) in the uppermost metapelites of the profile. Progressive heating led to H2O-fluxed and dehydration melting first of Ms, then of Bt at T<700°C in the stability field of sillimanite. This process was followed by nearly isothermal decompression producing additional melt with a transition from Grt to a Grt+Crd stability field. Further decompression caused the formation of Crd-corona around garnet. Nearly isobaric cooling led to rehydration and retrogression across the stability field of andalusite up to the stability field of kyanite. The lowermost metapelites of the studied profile have lost most of the memory of the prograde P–T path; they record decompression and cooling. High-temperature mylonites occur in which boudinage, elongation and pull-aparts characterize the porphyroclasts. The pull-aparts in the high-T mylonites are filled with low-P minerals (Crd+Spl). The Hercynian metamorphic trajectory and the microtextures are consistent with crustal thickening and subsequent extensional regime. During extension, an important tectonic denudation probably caused the isothermal decompression. Extension also occurred in post-Hercynian times as documented by pull-aparts in sillimanite porphyroclasts filled with chloritoid within a low-grade mylonite.

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15

Manickavasagam, R. M., A. K. Jain, J. Devaraju, J. Sahoo, and Sandeep Singh. "Tectonometamorphic Evolution of Moyar, Bhavani and Palghat-Cauvery Shear Zones of Southern Granulite Terrane, India." Gondwana Research 4, no. 4 (October 2001): 697. http://dx.doi.org/10.1016/s1342-937x(05)70495-0.

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Indares, A., and J. Martignole. "Metamorphic constraints on the evolution of the gneisses from the parautochthonous and allochthonous polycyclic belts, Grenville Province, western Quebec." Canadian Journal of Earth Sciences 27, no. 3 (March 1, 1990): 357–70. http://dx.doi.org/10.1139/e90-033.

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The tectono-metamorphic history of polycyclic "grey gneisses" located in the central Grenville Province of western Quebec has been constrained along a transect perpendicular to the length of the Grenville Orogen. Two terranes, the Réservoir Dozois terrane (RDT) and the Réservoir Baskatong terrane (RBT), were recognized from their structural, lithological, and geochronological characteristics. This subdivision has been confirmed by application of geothermobarometric techniques to appropriate mineral assemblages.The RDT is the southern extension of the parautochthonous belt of the Grenville Province, which in this area is composed of Archean rocks of upper-amphibolite grade. During the Grenvillian Orogeny, northwest-directed thrusting resulted in the tectonic burial of this terrane as a single tectonic unit, in contrast with the northern part of the parautochthonous belt, where several slices were imbricated against the Grenville Front. Maximum P–T conditions in the RDT (850 MPa, 720 °C) were likely Grenvillian and were followed by pervasive retrogression down to the hornblende–epidote subfacies. Locally, the RDT is overlain by remnants of thrust slices composed of monocyclic metasedimentary rocks that were deformed and metamorphosed in the granulite facies during the Grenvillian Orogeny.To the southeast, the RBT is an allochthonous or exotic terrane probably of Proterozoic age. It also experienced tectonic burial by thrusting (1030 MPa, 710 °C) during the Grenvillian Orogeny, whose thermal climax (790 °C) coincided with charnockite emplacement during decompression to 850 MPa.These two terranes are separated by a narrow strip of sheared rocks, the Renzy shear belt (RSB), which comprises mafic and ultramafic rocks subjected to high P and T (975 MPa, 745 °C). In view of the significant discrepancy between the metamorphic histories of the two terranes separated by the RSB, major tectonic transport has to be envisaged along this zone.

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17

Gibbons, Wes, and J. Brendan Murphy. "Mylonitic mafic granulite in fault megabreccia at Clarke Head, Nova Scotia: a sample of Avalonian lower crust?" Geological Magazine 132, no. 1 (January 1995): 81–90. http://dx.doi.org/10.1017/s0016756800011444.

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AbstractThe Clarke Head fault megabreccia was produced within a major Late Palaeozoic transcurrent structure (the Minas fault system) which separates the displaced Meguma terrane of southern Nova Scotia from rocks more typical of the Avalon Superterrane. A large clast of anomalously high grade metabasite embedded in the clay matrix of the fault megabreccia displays a fresh granulite facies mineralogy (2-pyroxene + garnet + plagioclase) and mylonitic to ultramylonitic textures induced by anhydrous shearing deep in the roots of the fault zone. Whole rock geochemistry reveals the granulite protolith to have been a continental, within-plate mafic magma transitional between theoleiitic and alkaline. The original geochemical signature has survived strong dynamic recrystallization at granulite grade. Well-preserved REE abundances testify to a lack of metasomatic fractionation during high grade shearing under water-absent conditions. Sm—Nd data indicate that the basic granulite has a TDM age of c. 1 Ga. Isotopic comparisons with adjacent areas reveal similar TDM ages both north and south of the Minas fault system. The high grade clast may be typical of the lower crust in Nova Scotia and is thought to offer a rare window into the deep crust of the Avalon Superterrane in North America.

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18

Vasanthi, A., and M. Santosh. "A Gondwanan micro-fragment adjacent to southern granulite terrane of India: Evidence from satellite gravity studies." Physics of the Earth and Planetary Interiors 322 (January 2022): 106832. http://dx.doi.org/10.1016/j.pepi.2021.106832.

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Mukhopadhyay, Sarmistha, Jyotisankar Ray, V. Balaram, A. Keshav Krishna, Biswajit Ghosh, and Subrata Mukhopadhyay. "Geochemistry and petrogenesis of syenites and associated rocks of the Elagiri complex, Southern Granulite Terrane, India." Journal of Asian Earth Sciences 42, no. 6 (November 2011): 1256–70. http://dx.doi.org/10.1016/j.jseaes.2011.07.011.

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Sundaralingam, K., T. K. Biswal, and V. Thirukumaran. "Strain analysis of the Salem-Attur shear zone of Southern Granulite Terrane around Salem, Tamil Nadu." Journal of the Geological Society of India 89, no. 1 (January 2017): 5–11. http://dx.doi.org/10.1007/s12594-017-0552-8.

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Sundaralingam, K., Sam Uthup, Toshiaki Tsunogae, M. L. Renjith, and Munesh K. Sahu. "Neoarchean ultrahigh-temperature sapphirine granulites from the Karimnagar Granulite Terrane, Southern India: Implications for hot orogen along the Eastern Dharwar Craton margin." Lithos 406-407 (December 2021): 106537. http://dx.doi.org/10.1016/j.lithos.2021.106537.

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Heaman, L. M., Ch O. Böhm, N. Machado, T. E. Krogh, W. Weber, and M. T. Corkery. "The Pikwitonei Granulite Domain, Manitoba: a giant Neoarchean high-grade terrane in the northwest Superior ProvinceThis article is one of a series of papers published in this Special Issue on the theme of Geochronology in honour of Tom Krogh.N. Machado, T.E. Krogh, and W. Weber are deceased." Canadian Journal of Earth Sciences 48, no. 2 (February 2011): 205–45. http://dx.doi.org/10.1139/e10-058.

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The Pikwitonei Granulite Domain located at the northwestern margin of the Superior Province is one of the largest Neoarchean high-grade terranes in the world, with well-preserved granulite metamorphic assemblages preserved in a variety of lithologies, including enderbite, opdalite, charnockite, and mafic granulite. U–Pb geochronology has been attempted to unravel the protolith ages and metamorphic history of numerous lithologies at three main localities; Natawahunan Lake, Sipiwesk Lake, and Cauchon Lake. The U–Pb age results indicate that some of the layered enderbite gneisses are Mesoarchean (3.4–3.0 Ga) and the more massive enderbites are Neoarchean. The high-grade metamorphic history of the Pikwitonei Granulite Domain is complex and multistage with at least four episodes of metamorphic zircon growth identified: (1) 2716.1 ± 3.8 Ma, (2) 2694.6 ± 0.6 Ma, (3) 2679.6 ± 0.9 Ma, and (4) 2642.5 ± 0.9 Ma. Metamorphic zircon growth during episodes 2 and 3 are interpreted to be regional in extent, corresponding to M1 amphibolite- and M2 granulite-facies events, respectively, consistent with previous field observations. The youngest metamorphic episode at 2642.5 Ma is only recognized at southern Cauchon Lake, where it coincides with granite melt production and possible development of a major northeast-trending deformation zone. The timing and multistage metamorphic history recorded in the Pikwitonei Granulite Domain is similar to most Superior Province high-grade terranes and marks a fundamental break in Archean crustal evolution worldwide at the termination of prolific global Neoarchean greenstone belt formation.

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Catlos, E. J., C. S. Dubey, and P. Sivasubramanian. "Monazite ages from carbonatites and high-grade assemblages along the Kambam Fault (Southern Granulite Terrane, South India)." American Mineralogist 93, no. 8-9 (August 1, 2008): 1230–44. http://dx.doi.org/10.2138/am.2008.2712.

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Pivarunas, Anthony F., Joseph G. Meert, Manoj K. Pandit, and Anup Sinha. "Paleomagnetism and geochronology of mafic dykes from the Southern Granulite Terrane, India: Expanding the Dharwar craton southward." Tectonophysics 760 (June 2019): 4–22. http://dx.doi.org/10.1016/j.tecto.2018.01.024.

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Sengupta, Pulak, Michael M. Raith, Ellen Kooijman, Moumita Talukdar, Priyadarshi Chowdhury, Sanjoy Sanyal, Klaus Mezger, and Dhruba Mukhopadhyay. "Chapter 20 Provenance, timing of sedimentation and metamorphism of metasedimentary rock suites from the Southern Granulite Terrane, India." Geological Society, London, Memoirs 43, no. 1 (2015): 297–308. http://dx.doi.org/10.1144/m43.20.

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Owen, J. V., and K. L. Currie. "The Disappointment Hill complex: Proterozoic granulites in southwestern Newfoundland." Transactions of the Royal Society of Edinburgh: Earth Sciences 82, no. 1 (1991): 55–63. http://dx.doi.org/10.1017/s0263593300007513.

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ABSTRACTThe Steel Mountain terrane of the southern Long Range Mountains forms a fault-bounded massif of (meta)plutonic rocks including the Disappointment Hill complex (DHC), a sequence of granulite-facies lithologies containing charnockite emplaced at 1498 Ma (U-Pb, zircon). Quartzofeldspathic gneiss of the DHC contains garnet + biotite + orthopyroxene ± cordierite assemblages indicative of metamorphic P–T conditions of ca 750°C and 400 MPa. The relatively high thermal gradient (ca 70°C km−1) inferred for the DHC is attributed to a magmatic heat source.On grounds of lithology, age and metamorphic grade, the DHC correlates to granulites of the Long Range Inlier (LRI) exposed farther north. Both complexes occur in blocks thrust westward over Taconic allochthons capped by ophiolite nappes. The block containing the DHC, however, preserves younger cover rocks, suggesting that it originated at a higher structural level than the LRI. This model is supported by lower pressure estimates for the DHC relative to the LRI (400 MPa vs 500–800 MPa). The DHC forms a link between Grenvillian rocks of the northern Long Range of Newfoundland and those of Cape Breton Island. The structural position of these massifs suggests that their emplacement was a post-Taconic event.

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Omer, M. A. Y. A., and A. P. Pradeepkumar. "Magnetic fabric analysis of meta-ultramafic rocks and associated gneisses from the Moyar Shear Zone, Southern Granulite Terrane, India." Results in Geophysical Sciences 6 (June 2021): 100017. http://dx.doi.org/10.1016/j.ringps.2021.100017.

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Brandt, Sönke, Michael M. Raith, Volker Schenk, Pulak Sengupta, C. Srikantappa, and Axel Gerdes. "Crustal evolution of the Southern Granulite Terrane, south India: New geochronological and geochemical data for felsic orthogneisses and granites." Precambrian Research 246 (June 2014): 91–122. http://dx.doi.org/10.1016/j.precamres.2014.01.007.

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Santosh, M., Qiong-Yan Yang, M. Ram Mohan, T. Tsunogae, E. Shaji, and M. Satyanarayanan. "Cryogenian alkaline magmatism in the Southern Granulite Terrane, India: Petrology, geochemistry, zircon U–Pb ages and Lu–Hf isotopes." Lithos 208-209 (November 2014): 430–45. http://dx.doi.org/10.1016/j.lithos.2014.09.016.

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30

Mukhopadhyay, Sarmistha, Jyotisankar Ray, Basab Chattopadhyay, Shyamal Sengupta, Biswajit Ghosh, and Subrata Mukhopadhyay. "Significance of mineral chemistry of syenites and associated rocks of Elagiri complex, Southern Granulite Terrane of the Indian shield." Journal of the Geological Society of India 77, no. 2 (February 2011): 113–29. http://dx.doi.org/10.1007/s12594-011-0015-6.

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31

Plavsa, Diana, Alan S. Collins, John D. Foden, and Chris Clark. "The evolution of a Gondwanan collisional orogen: A structural and geochronological appraisal from the Southern Granulite Terrane, South India." Tectonics 34, no. 5 (May 2015): 820–57. http://dx.doi.org/10.1002/2014tc003706.

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32

HARTMANN, LÉO A., WILLIAM R. LOPES, and JAIRO F. SAVIAN. "Integrated evaluation of the geology, aerogammaspectrometry and aeromagnetometry of the Sul-Riograndense Shield, southernmost Brazil." Anais da Academia Brasileira de Ciências 88, no. 1 (February 2, 2016): 75–92. http://dx.doi.org/10.1590/0001-3765201520140495.

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ABSTRACT An integrated evaluation of geology, aerogammaspectrometry and aeromagnetometry of the Sul-Riograndense Shield is permitted by the advanced stage of understanding of the geology and geochronology of the southern Brazilian Shield and a 2010 airborne geophysical survey. Gamma rays are registered from the rocks near the surface and thus describe the distribution of major units in the shield, such as the Pelotas batholith, the juvenile São Gabriel terrane, the granulite-amphibolite facies Taquarembó terrane and the numerous granite intrusions in the foreland. Major structures are also observed, e.g., the Dorsal de Canguçu shear. Magnetic signals register near surface crustal compositions (analytic signal) and total crust composition (total magnetic signal), so their variation as measured indicates either shallow or whole crustal structures. The Caçapava shear is outstanding on the images as is the magnetic low along the N-S central portion of the shield. These integrated observations lead to the deepening of the understanding of the largest and even detailed structures of the Sul-Riograndense Shield, some to be correlated to field geology in future studies. Most significant is the presence of different provinces and their limits depending on the method used for data acquisition - geology, aerogammaspectrometry or aeromagnetometry.

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33

Hudon, Pierre, Richard M. Friedman, Gilles Gauthier, and Jacques Martignole. "Age of the Cabonga nepheline syenite, Grenville Province, western Quebec." Canadian Journal of Earth Sciences 43, no. 9 (September 1, 2006): 1237–49. http://dx.doi.org/10.1139/e06-022.

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This study presents isotope dilution – thermal ionization mass spectrometry (ID–TIMS) U–Pb data for megacrystic zircon from the Cabonga Nepheline Syenite Complex of the Réservoir Cabonga terrane (Grenville Province). This terrane is an allochthonous slab metamorphosed under granulite-grade conditions ~1.18–1.14 Ga and transported onto migmatites of the Grenvillian Parautochthon at about 1.02 Ga. The very low uranium and lead concentrations of zircon from the Cabonga nepheline syenite (CNS) did not permit determination of a statistically significant crystallization age using laser ablation microbeam techniques. Consequently, extensive microsampling (15 zircon chips), guided by X-ray and electronic imaging, followed by ID–TIMS analyses were carried out on a single megacrystic zircon. A regression of 13 out of 15 U–Pb isotopic analyses results in a crystallization age of 1171 ± 3 Ma for the CNS. Criteria based on zircon morphologies, zoning patterns, varying Th/U ratios (0.3–0.9), and a highly fractionated Zr/Hf ratio (68) suggest an igneous derivation for the CNS. The Cabonga alkaline rocks, intruded under high-grade metamorphic conditions, preceded the onset of the widespread and ubiquitous (1.15 ± 0.01 Ga) anorthosite–mangerite–charnockite–granite magmatism in the southern part of the Grenville Province.

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34

ZHOU, Dingwu. "Zircon U-Pb SHRIMP ages of high-pressure granulite in Yushugou ophiolitic terrane in southern Tianshan and their tectonic implications." Chinese Science Bulletin 49, no. 13 (2004): 1415. http://dx.doi.org/10.1360/03wd0598.

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35

Tsunogae, Toshiaki, and M. Santosh. "Sapphirine + quartz assemblage from the Southern Granulite Terrane, India: diagnostic evidence for ultrahigh-temperature metamorphism within the Gondwana collisional orogen." Geological Journal 46, no. 2-3 (July 8, 2010): 183–97. http://dx.doi.org/10.1002/gj.1244.

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36

Garde, A. A. "Post-kinematic diorite intrusions in Archaean basement rocks around outer Fiskefjord, southern West Greenland." Bulletin of the Geological Society of Denmark 39 (December 20, 1991): 167–77. http://dx.doi.org/10.37570/bgsd-1991-39-07.

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About twenty small dioritic intrusions around outer Fiskefjord, southern West Greenland, which are undeformed and unmigmatised, mark the final stage in middle Archaean accretion of continental crust, deformation and high-grade metamorphism in the Akia terrane. The diorites were emplaced into hot tonalitic gneisses, some of which were thoroughly retrograded from granulite facies prior to diorite intrusion. The diorites are themselves sporadically retrograded. A conventional zircon U-Pb age of 3017 + 12/-10 Ma has been obtained from one of the diorites. The diorites have SiO2 contents between ea. 52 and 58 wt. % and up to ea. 15% MgO, and some of them border on leuconorite or anorthosite, with normative plagioclase contents up to ea. 85 wt. % . Trace element compositions are characterised by elevated amounts of Zn, Co, Ni, and especially Cr, but low contents of several LIL elements, and they were probably contaminated with sialic crust. The diorite intrusions may be related to a group of a more mafic intrusions with anomalous contents of precious metals, forming the "norite belt" some 50 km north of Fiskefjord.

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37

Bridgwater, D., and L. Schiøtte. "The Archaean gneiss complex of northern Labrador A review of current results, ideas and problems." Bulletin of the Geological Society of Denmark 39 (December 20, 1991): 153–66. http://dx.doi.org/10.37570/bgsd-1991-39-06.

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1. The early Archaean rocks in northern Labrador can be subdivided into the ea. 3.78 Ga Nulliak supracrustal association, the migmatitic Uivak I gneisses, the dominant phase of which was emplaced at ea. 3.73 Ga, and the Uivak II augen gneiss. Inherited low-U rounded inclusions within igneous zircons in the Uivak I gneisses have ages between 3.73 and 3.86 Ga and are more likely to have been derived from a pre-existing high-grade metamorphic gneiss complex than from the Nulliak association. In the early Archaean there were probably several rapid cycles of sedimentary deposition and volcanism followed by emplacement of major plutons. Mid Archaean gneisses are more abundant in northern Labrador than previously realised. The late Archaean metamorphic history of these gneisses is different from the history of the early Archaean gneisses. Whereas an important part of the mid Archaean suite was emplaced in granulite facies and retrogressed at the time of granitoid veining at ea. 2.99 Ga, the major part of the early Archaean rocks were reworked under granulite facies conditions in a sequence of closely spaced events between 2. 7 and 2.8 Ga. The two groups of gneisses had different metamorphic histories until ea. 2.7 Ga, but late and post-tectonic granites of 2.5- 2. 7 Ga age cut across both. It is suggested that the terrane model in southern West Greenland can be extended to Labrador and that tectonic intercalation of early and mid Archaean gneisses took place around 2.7 Ga. Correlation between the Maggo gneisses around Hopedale, mid Archaean gneisses in northernmost Labrador and gneisses from the Akia terrane in West Greenland is suggested. Like the Malene supracrustals in West Greenland the Upernavik supracrustals in Labrador are composite associations, the youngest of which are thought to have been deposited around 2. 7 Ga.

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38

Dutta, Dripta, Santanu Misra, and Shreya Karmakar. "Deformation mechanisms and characteristics of the meta-BIFs from an early Proterozoic shear system of the Southern Granulite Terrane (SGT), India." Journal of Structural Geology 156 (March 2022): 104534. http://dx.doi.org/10.1016/j.jsg.2022.104534.

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39

Schiøtte, L., A. P. Nutman, and D. Bridgwater. "U–Pb ages of single zircons within "Upernavik" metasedimentary rocks and regional implications for the tectonic evolution of the Archaean Nain Province, Labrador." Canadian Journal of Earth Sciences 29, no. 2 (February 1, 1992): 260–76. http://dx.doi.org/10.1139/e92-024.

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Detrital zircons and their postdepositional overgrowths from three units of the "Upernavik" supracrustal association in the northern (Saglek) block of the Archaean Nain Province have been dated with the ion microprobe SHRIMP. In one unit, from the granulite-facies area in inner Saglek Fiord, the zircon population is dominated by early Archaean grains thought to be derived from the Uivak gneisses. Recrystallization and growth of new zircon within this metasediment took place during granulite-facies metamorphism at 2761 ± 12 Ma (2σ), which is also a younger limit on the age of deposition.In a second unit, from the amphibolite-facies area in outer Saglek Fiord, detrital zircons have predominantly mid- and late Archaean ages. The mid-Archaean zircons are comparable in age to the 3235 Ma Lister gneisses. The ages of the late Archaean detrital zircons (2800–2960 Ma) do not correspond to any known rock complex in the Saglek block, but plutonic rocks associated or correlative with the ca. 2840 Ma Kanairiktok Plutonic Suite of the southern (Hopedale) block are a possible source for many of the grains. Overgrowths were dated at 2690–2730 Ma in this sample.A third metasedimentary unit from the Okak Bay area, 100 km south of Saglek Fiord, also contains detrital zircons with ages comparable to that of the Lister gneisses (3235 Ma). The age of recrystallization and zircon overgrowths was dated at ca. 2560 Ma in this sample. A single grain dated at ca. 2780 Ma is considered most likely to be detrital, which would imply an age of deposition between ca. 2780 and 2560 Ma for this unit.The results show that although late Archaean depositional ages are possible for all three units, the "Upernavik" supracrustal association is composite and sediments in different units have widely different sources and metamorphic histories. These conclusions support a new model for the Nain Province according to which separate terranes were tectonically juxtaposed in the late Archaean. In this model, the age of plutonic and supracrustal rocks and their metamorphic histories prior to juxtaposition differ from one terrane to another.

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40

Cubley, Joel F., and David R. M. Pattison. "Metamorphism and deformation of the Grand Forks complex: implications for the exhumation history of the Shuswap core complex, southern British Columbia." Canadian Journal of Earth Sciences 49, no. 11 (November 2012): 1329–63. http://dx.doi.org/10.1139/e2012-066.

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The Grand Forks complex (GFC) is an elongate, north–south-trending metamorphic core complex in the Shuswap domain of southeastern British Columbia. It comprises predominantly upper-amphibolite- to granulite-facies paragneisses, schists, orthogneisses, amphibolites, and calc-silicates of the Paleoproterozoic to Paleozoic Grand Forks Group. The GFC is juxtaposed against low-grade rocks of the Quesnel terrane across two bounding Eocene normal faults: the Kettle River fault (KRF) on the east flank and the Granby fault (GF) on the west flank. Peak metamorphic Sil + Kfs ± Grt ± Crd (Sil, sillimanite; Kfs, potassium feldspar; Grt, garnet; Crd, cordierite) assemblages in paragneiss and Hbl ± Opx ± Cpx (Hbl, hornblende; Opx, orthopyroxene; Cpx, clinopyroxene) assemblages in amphibolite in the GFC formed at 750 ± 25 °C, 5.6 ± 0.5 kbar (1 kbar = 100 MPa; 20 ± 2 km depth). Stratigraphically overlying Sil + St-bearing pelitic schists (St, staurolite) within the complex record peak conditions of 600 ± 15 °C, 5.5 ± 0.25 kbar. Crd + Ilm + Spl (Crd, cordierite; Ilm, ilmenite; Spl, spinel) and Crd + Qtz (Qtz, quartz) coronal textures in paragneiss, and Cpx + Opx + Pl + Mt (Pl, plagioclase; Mt, magnetite) symplectites in amphibolite, formed at 735 ± 20 °C, 3.3 ± 0.5 kbar, indicating high-temperature, near-isothermal decompression of the GFC of ∼2.3 ± 0.7 kbar (∼8.2 ± 2.5 km) from peak conditions. Transitional greenschist–amphibolite metamorphic assemblages in the hanging wall of the KRF indicate conditions of ∼425 ± 25 °C and 2.2 ± 0.6 kbar (∼8 ± 2 km depth), with local contact metamorphism around Jurassic intrusions as high as 630–650 °C at ∼2.5 ± 0.5 kbar. The pressure contrast across the Kettle River fault prior to greenschist facies displacement was ∼0.8 ± 0.7 kbar, for a vertical offset of ∼2.9 ± 2.5 km. This is similar to estimates for the Granby fault on the west flank of the GFC. The GFC therefore experienced a two-stage exhumation history: early high-temperature decompression at upper-amphibolite- to granulite-facies conditions, followed by low-temperature exhumation at greenschist-facies conditions owing to movement on the Eocene Granby and Kettle River faults.

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41

Fedo, Christopher M., Kenneth A. Eriksson, and Tom G. Blenkinsop. "Geologic history of the Archean Buhwa Greenstone Belt and surrounding granite–gneiss terrane, Zimbabwe, with implications for the evolution of the Limpopo Belt." Canadian Journal of Earth Sciences 32, no. 11 (November 1, 1995): 1977–90. http://dx.doi.org/10.1139/e95-151.

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The Buhwa Greenstone Belt (BGB) of southern Zimbabwe is the only major greenstone belt in the Archean Zimbabwe Craton directly adjacent to the granulite-facies rocks that constitute the Northern Marginal Zone of the Limpopo Belt. The deformational history and assembly of the BGB shed light on the evolution of the Northern Marginal Zone – Zimbabwe Craton transition. Assembly of the region began with deposition of the dominantly sedimentary cover succession at ~3.0 Ga on banded gneisses of the ~3.5 Ga Tokwe segment. At ~2.9 Ga the northern margin of the greenstone belt experienced kilometres of ductile, oblique-slip, dextral shearing. This shear zone was later intruded by the granitic to tonalitic ~2.9 Ga Chipinda batholith. The remaining events recognized in the region occurred during the time span 2.9–2.5 Ga. Northwest-directed thrusting of the Northern Marginal Zone over the Zimbabwe Craton took place along a collection of discrete, typically metre-wide shear zones, which collectively form the tectonic break between the Zimbabwe Craton and the Northern Marginal Zone. In response to thrusting, the cover succession and surrounding granitoids were folded and underwent regional greenschist-facies metamorphism. Two suites of potassic granites were emplaced north and south of the greenstone belt towards the end of thrusting. Plutonism was followed by conjugate faulting and later filling of the fractures by the Great Dyke of Zimbabwe. The youngest events may have occurred between ~2.5 and ~2.0 Ga, and include sinistral shearing along the southern margin of the belt, transecting cleavage formation, and open folding as a result of northeast-directed crustal shortening.

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42

Williams, Megan A., David E. Kelsey, Martin Hand, Tom Raimondo, Laura J. Morrissey, Naomi M. Tucker, and Rian A. Dutch. "Further evidence for two metamorphic events in the Mawson Continent." Antarctic Science 30, no. 1 (December 4, 2017): 44–65. http://dx.doi.org/10.1017/s0954102017000451.

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AbstractIn this study,in situand erratic samples from George V Coast (East Antarctica) and southern Eyre Peninsula (Australia) have been used to characterize the microstructural, pressure–temperature and geochronological record of upper amphibolite and granulite facies polymetamorphism in the Mawson Continent to provide insight into the spatial distribution of reworking and the subice geology of the Mawson Continent. Monazite U-Pb data shows thatin situsamples from the George V Coast record exclusively 2450–2400 Ma ages, whereas most erratic samples from glacial moraines at Cape Denison and the Red Banks Charnockite record only 1720–1690 Ma ages, consistent with known ages of the Sleaford and Kimban events, respectively. Phase equilibria forward modelling reveals considerable overlap of the thermal character of these two events. Samples with unimodal 1720–1690 Ma Kimban ages reflect either formation after the Sleaford event or complete metamorphic overprinting. Rocks recording only 2450–2400 Ma ages were unaffected by the younger Kimban event, perhaps as a result of unreactive rock compositions inherited from the Sleaford event. Our results suggest the subice geology of the Mawson Continent is a pre-Sleaford-aged terrane with a cover sequence reworked during the Kimban event.

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43

Tretyakov, A. A., A. V. Pilitsyna, K. E. Degtyarev, E. B. Salnikova, V. P. Kovach, H. Y. Lee, V. G. Batanova, K. L. Wang, N. A. Kanygina, and E. V. Kovalchuk. "Neoproterozoic granitoid magmatism and granulite metamorphism in the Chu-Kendyktas terrane (Southern Kazakhstan, Central Asian Orogenic Belt): Zircon dating, Nd isotopy and tectono-magmatic evolution." Precambrian Research 332 (September 2019): 105397. http://dx.doi.org/10.1016/j.precamres.2019.105397.

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44

Deeju, T. R., M. Santosh, Qiong-Yan Yang, A. P. Pradeepkumar, and E. Shaji. "Mid-Neoproterozoic intraplate magmatism in the northern margin of the Southern Granulite Terrane, India: Constraints from geochemistry, zircon U-Pb geochronology and Lu-Hf isotopes." Journal of Asian Earth Sciences 130 (November 2016): 88–115. http://dx.doi.org/10.1016/j.jseaes.2016.06.016.

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45

Behera, B. M., B. D. Waele, V. Thirukumaran, K. Sundaralingam, S. Narayanan, B. Sivalingam, and T. K. Biswal. "Kinematics, strain pattern and geochronology of the Salem-Attur shear zone: Tectonic implications for the multiple sheared Salem-Namakkal blocks of the Southern Granulite terrane, India." Precambrian Research 324 (May 2019): 32–61. http://dx.doi.org/10.1016/j.precamres.2019.01.022.

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46

Collins, Alan S. "A Report on the International Field Workshop to the Southern Granulite Terrane of India (February 18–25, 2004) organized by the National Geophysical Research Institute, Hyderabad." Gondwana Research 7, no. 4 (October 2004): 1248–49. http://dx.doi.org/10.1016/s1342-937x(05)71100-x.

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47

Xu, Wang-Chun, Hong-Fei Zhang, Li-Ran Chen, Bi-Ji Luo, Liang Guo, and Jing-Liang Guo. "Transition from the lithospheric to asthenospheric mantle-derived magmatism in the Early Jurassic along eastern Bangong–Nujiang Suture, Tibet: Evidence for continental arc extension induced by slab rollback." GSA Bulletin 133, no. 1-2 (June 2, 2020): 134–48. http://dx.doi.org/10.1130/b35554.1.

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Abstract The transition of the geochemical signature in mafic rocks along the eastern Bangong–Nujiang suture in Tibet contains important information about geodynamic processes in the upper mantle. This study recognized two episodes of Early Jurassic gabbros from the Kaqiong terrane, a microblock within the Bangong–Nujiang suture zone. Early gabbros (ca. 197–191 Ma) appear as lenses in the basement complex and were overprinted by amphibolite/granulite-facies metamorphism at ca. 180 Ma. Later undeformed hornblende gabbros (ca. 177–175 Ma) occur as dikes intruding into the basement complex. The early metagabbros are characterized by arc-like geochemical features and enriched Nd-Hf isotopic compositions (whole rock ∑Nd(t) = –0.7 to +0.3; zircon ∑Hf(t) = –5.7 to –2.2), which suggests formation by partial melting of an enriched lithospheric mantle source. In contrast, the later hornblende gabbros have depleted Nd-Hf isotopic compositions (whole rock ∑Nd(t) = +6.1 to +7.1; zircon ∑Hf(t) = +10.7 to +16.8) and normal mid–oceanic–ridge basalt (N–MORB)-type rare earth element (REE) features. They also show variable enrichments of fluid mobile elements (e.g., Rb, U, Pb), indicative of the input of slab-derived fluids in their mantle source. Thus, the hornblende gabbros were most likely originated from the asthenospheric mantle metasomatized by subducted oceanic slab-derived fluids. The transition in geochemical and isotopic compositions of these mantle-derived magmas reveals a long-lasting lithosphere extension and thinning along the southern margin of the Qiangtang terrane in the Early Jurassic. Combined with geological observations, we propose that this transition has resulted from the southward rollback of the subducting Bangong–Nujiang Tethyan oceanic slab. The slab rollback could have initiated the overriding plate extension and the asthenosphere upwelling. Wider implications of this study are that an onset of slab rollback could be an important trigger for the transition of magmatic geochemistry in subduction zones.

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48

Johnston, J. D., and W. E. A. Phillips. "Terrane amalgamation in the Clew Bay region, west of Ireland." Geological Magazine 132, no. 5 (September 1995): 485–501. http://dx.doi.org/10.1017/s0016756800021154.

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AbstractThe Caledonides of the west of Ireland provide a well-exposed and well-mapped example of an oblique collision zone. The east-northeast trending Deer Park and Achill Beg Fault system is a crustal scale ductile sinistral strike-slip duplex of late Ordovician age, imbricating late Precambrian granulite facies lower crustal rocks, near eclogite facies supracrustal rocks, up to amphibolite facies Dalradian metasedimentary rocks and greenschist facies Cambro-Ordovician rocks. This fault system is correlated with a pre-Devonian component of the Highland Boundary Fault system in southern Scotland. In the Clew Bay area, the high pressure-low temperature facies metamorphic rocks, in tectonic contact with greenschist facies Cambro-Ordovician rocks, are together interpreted as an accretionary prism complex related to northwestward directed subduction. Both of these are allocthonous terrains with respect to the Dalradian terrane to the north (North West Mayo). To the south, the Cambro-Ordovician rocks docked with a probable Dalradian block containing ultramafic intrusives (Deer Park Complex) during the late Ordovician. The Deer Park Complex and South Mayo Trough linked earlier, during the Arenig.Silurian and Lower-Middle Devonian redbed successions sit unconformably on the metamorphic rocks. Deposition and deformation of these cover rocks was controlled by oblique strike-slip movements on the Leek Fault whose strike swings from west-northwest to north-northeast, following earlier basement trends, as it is traced eastwards from Clew Bay. The Leek Fault System may be correlated with the Leannan Fault of northwest Donegal, a splay of the Great Glen Fault system of central Scotland. East of Clew Bay, this sinistral shear generated local dilation on the more northerly trending bend of the Leek Fault. Lower and Middle Old Red Sandstone redbeds were developed here. The west-northwest trend of the Leek Fault in Clew Bay acted as a compressional bend during these sinistral movements and transpressional southwest directed thrusting developed in Silurian rocks. Post-Middle Old Red Sandstone pre-late Tournaisian dextral displacement on the Leek Fault reversed this pattern with transtension in Clew Bay allowing intrusion of small carbonated peridotite bodies into Silurian rocks and easterly directed thrusting of Middle Old Red Sandstone rocks east of the Bay on the transpressional north-south bend.A tectonic model for the region is presented here. This model involves a northwestward directed subduction system, 150 to 750 km of Arenig sinistral strike slip movement, and eastwards insertion of the Connemara block with formation of the Ordovician South Mayo Trough as a pull-apart basin. Subsequently, a further 130 to 650 km eastward displacement of rocks took place south of the Deer Park Fault in later Ordovician times. The magnitudes of these estimates are directly proportional to an assumed maximum wavelength of 1500 km for promontories on the original Laurentian margin, and using the current juxtaposition of terranes, a minimum wavelength of 300 km is inferred.

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49

Laberge, J. D., and D. RM Pattison. "Geology of the western margin of the Grand Forks complex, southern British Columbia: high-grade Cretaceous metamorphism followed by early Tertiary extension on the Granby fault." Canadian Journal of Earth Sciences 44, no. 2 (February 1, 2007): 199–228. http://dx.doi.org/10.1139/e06-101.

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The Grand Forks complex, in the southern Omineca belt of British Columbia, is a fault-bounded tectonic window exposing Proterozoic sediments and associated mafic rocks metamorphosed to upper amphibolite to granulite facies. Its western margin is marked by the Granby fault, an Eocene west-dipping, low-angle, normal fault characterized by brittle deformation. The metasediments of the Grand Forks complex consist of migmatitic paragneiss containing a peak metamorphic assemblage of garnet + cordierite + sillimanite + K-feldspar ± biotite + quartz. Pressure–temperature conditions for this assemblage are 800 ± 35 °C and 5.8 ± 0.6 kbar (1 kbar = 100 MPa). Resorption of garnet to cordierite ± spinel suggests nearly isothermal decompression of about 2 kbar from peak conditions, interpreted to have occurred prior to normal displacement on the Granby fault. Laser ablation U–Pb dating of monazite from the metasediments suggests a dominant episode of Late Cretaceous metamorphism at 84 ± 3 Ma, with evidence for earlier episodes of Cretaceous metamorphism at 119 ± 3 and 104 ± 3 Ma. Early Tertiary recrystallization at 51 ± 2 Ma is coeval with the emplacement of the nearby Coryell plutonic suite. In the hanging wall of the Granby fault, allochthonous sedimentary and volcanic rocks of Quesnel terrane contain mineral assemblages indicative of the upper greenschist to lower amphibolite facies. Pressure–temperature conditions are estimated at 425 ± 40 °C and 2.3 ± 0.7 kbar. The throw (vertical displacement) on the Eocene Granby fault is estimated to be on the order of 5 km. While significant, the fault cannot account for the entire amount of tectonic uplift of the core complex.

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50

Kozakov, I. K., E. B. Salnikova, I. V. Anisimova, P. Ya Azimov, V. P. Kovach, Yu V. Plotkina, M. V. Stifeeva, and A. M. Fedoseenko. "Tectonic position of the Early Neoproterozoic–Early Paleozoic metamorphic belts within the Tuva–Mongolian terrane of the Central Asian Orogenic Belt." Петрология 27, no. 1 (March 13, 2019): 47–64. http://dx.doi.org/10.31857/s0869-590327147-64.

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The Tuva–Mongolian terrane (TMT) of the Central Asian Orogenic Belt is a composite structure with a Vendian–Cambrian terrigenous-carbonate cover. The formation of the northern part of TMT is marked by the granitoids of the Sumsunur Complex with an age of 785 ± 11 Ma. The Sangilen and Khan-Khukhay blocks of its southern part also form a composite structure, which originated during Early Paleozoic(500–490 Ma) low-moderate pressure regional metamorphism reaching amphibolites-granulite facies. The earlier high-pressure metamorphism was established in the Moren Complex of both the blocks. In the Sangilen block, this metamorphism reached conditions of kyanite-garnet-biotite-orthoclase subfacies of amphibolites facies (temperature ~750oC, pressure 9–10 kbar). The upper age limit of this metamorphism is determined by granites with an age of 536 ± 6 Ma, which cut across migmatized biotite gneisses of the Moren Complex. The latter are intruded by the granitoids of the Ortoadir pluton, which were previously dated at 521 ± ± 12 Ma (U-Pb method, TIMS). Its emplacement predated the Early Paleozoic low-moderate pressure metamorphism, the timing of which is constrained by syn- and postmetamorphic granitoids with ages of 496 ± 4 and 489 ± 3 Ma. The age of 513 ± 4 Ma established for the granitoids of the Ortoadir Complex in the Khan-Khukhay Block more accurately constrains the lower age boundary of collision processes. This determined the amalgamation of the fragments of the high-pressure metamorphic belt with basement and carbonate-shelf cover units of the Tuva–Mongolian terrane, as well as the upper age boundary of early metamorphism. The timing of the main mappable structure of the Khan–Khukhay Block and low-moderate pressure regional metamorphism is marked by the synmetamorphic granitoids with an age of 505 ± ± 2 Ma. In general, the metamorphic rocks of the Sangilen, Khan–Khukhay, and Kaakhem blocks can be considered as fragments of the Late Ediacaran high-pressure metamorphic belt, which were amalgamated to the western margin of TMT within 515–505 Ma, after emplacement of the granitoids of the Ortoadir Complex, and were reworked by regional Early Paleozoic low-moderate pressure metamorphism.

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