@article{MukherjeeAdhikariNicolietal.2022,
  author    = {Mukherjee, Shreya and Adhikari, Avishek and Nicoli, Gautier and Vadlamani, Ravikant},
  title     = {Neoarchean (similar to 2.73-2.70 Ga) accretionary history of the eastern Dharwar Craton, India},
  series = {Precambrian research},
  volume    = {375},
  journal   = {Precambrian research},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0301-9268},
  doi       = {10.1016/j.precamres.2022.106657},
  pages     = {23},
  year      = {2022},
  abstract  = {Cratonic mid-crustal plutons may contain supracrustal enclaves that preserve evidence of an earlier growth history. The Eastern Dharwar craton records Neoarchean two-stage accretionary sequential growth (2.70 and 2.55 Ga) and a chronology of their enclaves could refine orogenic models. To test whether the metamorphic history of their enclaves was related to any of these stages, phase equilibria modelling and combined Lu-Hf and Sm-Nd geochronology on garnet were conducted on metapsammite, now preserved as garnet-orthopyroxene-cordierite gneiss. Phase equilibria modelling indicates peak metamorphic conditions, similar to 850 degrees C and similar to 8.5 kbar (M1a), were followed by near isothermal decompression to 5-6 kbar (M1b) and isobaric cooling to similar to 800 degrees C (M1c). The thermobaric gradient related to peak metamorphic conditions, similar to 30 degrees C kbar(-1), is typical of collisional orogens. Regression of the whole-rock and garnet, for sample S17b, yield Lu-Hf isochron ages of 2733 +/- 29 Ma, and for sample S18, 2724 +/- 13 Ma. A Lu-Hf weighted mean age for the porphyroblastic garnet suggests growth at 2725.5 +/- 11.9 Ma during the M1a-M1b stages. In contrast, the whole-rock sample S17b and the garnet fractions yield a Sm-Nd isochron age of 2696 +/- 10 Ma. From sample S18 the whole rock, garnet fractions, and orthopyroxene yield an isochron age of 2683 +/- 15 Ma. The garnet Sm-Nd weighted mean age at 2692.0 +/- 8.3 Ma constrains the M1b-M1c stages. We suggest that the protoliths to these supracrustal enclaves were deposited in an arc tectonic setting and underwent thickening followed by heating during peeled-back lithospheric convergence. Therefore, the earliest of the craton-forming accretionary stages is preserved as the similar to 2.73 Ga granulite-facies enclaves, marginally older than the 2.70-2.65 Ga cratonic greenstone volcanism. Tectonic exhumation of these mid-crustal granulite enclaves was in response to the late-Proterozoic (similar to 1.7 Ga) Bhopalpatnam orogeny.},
  language  = {en}
}
@article{SchmidtMezgerO'Brien2011,
  author    = {Schmidt, Alexander and Mezger, Klaus and O'Brien, Patrick J.},
  title     = {The time of eclogite formation in the ultrahigh pressure rocks of the Sulu terrane Constraints from Lu-Hf garnet geochronology},
  series = {Lithos : an international journal of mineralogy, petrology, and geochemistry},
  volume    = {125},
  journal   = {Lithos : an international journal of mineralogy, petrology, and geochemistry},
  number    = {1-2},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0024-4937},
  doi       = {10.1016/j.lithos.2011.04.004},
  pages     = {743 -- 756},
  year      = {2011},
  abstract  = {Eclogites from the main borehole of the Chinese Continental Scientific Drilling project yield highly precise Lu-Hf garnet-clinopyroxene ages of 216.9 +/- 1.2 Ma (four samples) and 220.5 +/- 2.7 Ma (one sample). The spatial distribution of the rare earth elements in garnet is consistent with the preservation of primary growth zoning, unmodified by diffusion, which supports the interpretation that the Lu-Hf ages date the time of formation of garnet, the major rock forming mineral in the eclogites. The preservation of primary REE-zoning, despite peak metamorphic temperatures around 800-850 degrees C. indicates that the Lu-Hf chronometer is perfectly suitable to date garnet-forming reactions in high grade rocks. The range of Lu-Hf ages for eclogites in the Dabie-Sulu UHP terrane point to episodic rather than continuous growth of garnets and thus punctuated metamorphism during the collision of the North China Block and the Yangtze Block. The U-Pb ages and Hf-isotope systematics of zircon grains from one eclogite sample imply a protracted geologic history of the eclogite precursors that started around 2 Ga and culminated in the UHP metamorphism around 220 Ma.},
  language  = {en}
}