The Jhalida porphyritic granitoid pluton is exposed in a regional shear zone belonging to the Chhotanagpur Gneissic Complex of the Satpura Orogen (c. 1.0 Ga), regarded as the collisional suture between the South and North Indian blocks. The pluton intruded the migmatitic gneisses, metapelites, calc-silicate rocks and amphibolites belonging to the amphibolite facies. The mineral assemblage indicates the calc-alkaline nature of the granitoids. Mafic (Pl–Qz–Bt±Hbl) schists occur as xenoliths within the pluton. The granitoids are classified as alkali-calcic to alkalic, dominantly magnesian grading to ferroan, metaluminous to slightly peraluminous, and shoshonitic to ultrapotassic. Geochemically, the granitoids are enriched in large-ion lithophile elements (LILE), particularly K, and light rare earth elements (LREE), but are comparatively depleted in Nb, Ta, and heavy rare earth elements (HREE). The strong negative correlation between SiO2 and P2O5, metaluminous to weakly peraluminous character, high liquidus temperature (798–891°C) and high fO2 (ΔQFM +0.8 to +1.6) of the melt suggest their I-type nature. Field relations and tectonic discrimination diagrams imply their post-collisional emplacement. Low Nb/U (average 8.5), Ce/Pb (average 9.0), and Al2O3/(Al2O3 + FeO(t) + MgO + TiO2) ratios and relatively low Mg number (average 0.15) of these granitoids indicate a crustal mafic source. Batch melting (at 825–950°C) of 10–20% of an old, incompatible elements-rich high-K high-alumina hornblende granulite can generate the porphyritic granite melt. The heat source for melting was an upwelling of the asthenospheric mantle in the post-collisional set-up. Textural and chemical characteristics of the mafic xenoliths show that invading porphyritic granitoid magma metasomatized the amphibolite protoliths.

中文翻译：

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印度东部 Chhotanagpur 片麻岩杂岩体 Jhalida 碰撞后斑状花岗岩的岩石成因

Jhalida 斑状花岗岩体暴露在属于 Satpura 造山带 Chhotanagpur 片麻岩杂岩的区域剪切带中。C。1.0 Ga），被认为是南印度块和北印度块之间的碰撞缝合线。岩体侵入了属于角闪岩相的混合片麻岩、变泥质岩、钙硅酸盐岩和角闪岩。矿物组合表明花岗岩的钙碱性。镁铁质 (Pl–Qz–Bt±Hbl) 片岩在岩体中以捕虏体的形式出现。花岗岩分为碱钙质至碱性、镁质至铁质、金属铝质至略过铝质、钾玄质至超钾质。地球化学上，花岗岩类富含大离子亲石元素（LILE），特别是K和轻稀土元素（LREE），但相对贫化Nb、Ta和重稀土元素（HREE）。SiO 之间的强负相关2和 P2○5, 金属铝至弱过铝特性, 高液相线温度 (798–891°C) 和高 fO2(ΔQFM +0.8 至 +1.6) 的熔体表明它们的 I 型性质。场关系和构造判别图暗示了它们的碰撞后就位。低 Nb/U（平均 8.5）、Ce/Pb（平均 9.0）和 Al2○3/(铝2○3+ FeO(t) + MgO + TiO2) 比率和相对较低的镁含量（平均 0.15）这些花岗岩表明地壳镁铁质来源。将 10-20% 的旧的、富含不相容元素的高 K 高铝角闪石麻粒岩批量熔化（在 825-950°C 下）可以生成斑状花岗岩熔体。融化的热源是软流圈地幔在碰撞后设置中的上升流。镁铁质捕虏体的结构和化学特征表明，侵入的斑状花岗岩浆交代了角闪岩原岩。