In the Chhotanagpur Gneissic Complex (CGC) of Eastern India a suite of mafic and ultramafic rocks occurs as sills, dykes and enclaves within porphyritic granitoid pluton. These mafic and ultramafic rocks and host porphyritic granitoids were emplaced in a post-collisional setting around 998 ± 10 Ma ago. Field occurrence, petrology and mineral chemistry of the mafic–ultramafic rocks have been studied. Both the mafic (Pl + Hyp + Di + Hbl + Bt + Mag + Spn ± Ol ± Spl) and ultramafic rocks (Di + Hyp + Bt ± Hbl ± Ol ± Pl ± Spl ± Ep ± Spn) are composed of same minerals but in different modal proportions. Plagioclase, clinopyroxene, orthopyroxene, amphibole, biotite and rarely olivine and spinel are important primary minerals of mafic–ultramafic suite. Primary amphiboles, biotites and pyroxenes show their affinity with shoshonitic lamprophyres. Chemically these rocks are similar to the kentallenite (of appinite suite) and are enriched in both compatible (Fe, Mg, Ni, and Cr) and incompatible (K, Ba, Rb, and LREE) elements and show crust-like trace element patterns. Crystallization of clinopyroxene before labradorite and presence of primary hornblende and biotite suggest high water content while biotite–magnetite–sphene assemblage suggests high fO₂ of the magma. Liquidus temperature (975–1088°C) of the parental magma of the mafic–ultramafic rocks was obtained by two-pyroxene thermometer. The pressure (2.9–5.7 kbar) and near-solidus temperature (782–819°C) of crystallization were determined using the amphibole–plagioclase geothermobarometry. Similar range of values of pressure, temperature and fO₂ values were obtained using other thermobarometers. High H₂O and fO₂ (>NNO buffer) of the magma are characteristics of convergent setting. The mafic–ultramafic rocks of the suite probably crystallized from a magma which had high SiO₂ (48.16–67.64 wt%), high CaO (3.01–11.73 wt%), high K₂O (1.34–4.49 wt%) and low TiO₂ (0.04–2.71 wt%) contents and intermediate Mg# (46.73 and 59.78).

在印度东部的乔塔纳格普尔片麻岩复合体（CGC）中，斑岩质花岗岩体中的基岩，堤坝和飞地中出现了一组镁铁质和超镁铁质岩石。这些镁铁质和超镁铁质岩石以及斑岩质花岗岩被安置在约998±10 Ma的碰撞后环境中。研究了镁铁质-超镁铁质岩石的场发生，岩石学和矿物化学。镁铁质岩石（Pl + Hyp + Di + Hbl + Bt + Mag + Spn±Ol±Spl）和超镁铁质岩石（Di + Hyp + Bt±Hbl±Ol±Pl±Spl±Ep±Spn）都由相同的矿物组成以不同的模式比例 斜长石，斜生辉石，邻位辉石，角闪石，黑云母以及很少的橄榄石和尖晶石是镁铁矿-超音波组的重要主要矿物。初级闪石，黑云母和辉石显示出它们与shoshonitic煌斑岩的亲和力。从化学角度讲，这些岩石类似于硅钙石（牙膏石套件），并且富含相容性元素（Fe，Mg，Ni和Cr）和不相容性元素（K，Ba，Rb和LREE），并显示出类似壳的微量元素模式。拉长长石前的斜辉石结晶以及原生角闪石和黑云母的存在表明含水量高，而黑云母-磁铁矿-蝶斑的组合表明水含量高。f O ₂的岩浆。镁铁质-超镁铁质岩体母岩浆的液相线温度（975-1088°C）通过二two温度计获得。结晶的压力（2.9–5.7 kbar）和接近固相线的温度（782–819°C）使用闪石－斜长石地质热压法测定。使用其他热压计可获得相似的压力，温度和f O ₂值范围。岩浆的高H ₂ O和f O ₂（> NNO缓冲区）是收敛设置的特征。该组的镁铁质-超镁铁质岩石可能是由具有高SiO ₂（48.16-67.64 wt％），高CaO（3.01-11.73 wt％），高K的岩浆结晶而成的。₂ O（1.34-4.49 wt％）和低TiO ₂（0.04-2.71 wt％）含量和中间Mg＃（46.73和59.78）。