The evolutionary nature of the Neoarchean basement, concealed below 66 Ma Deccan Large Igneous Province, remains largely unknown. We present here detailed results of integrated geoscientific investigations, carried out on 43 basement cores that cover an entire 270 m thick column, penetrated by the KLR-1 deep scientific borehole, drilled in the epicentral zone of 1993 Killari earthquake (Maharashtra, India). They dominantly contain high velocity-high density, halogen-rich, retrogressed and metasomatized amphibolite to granulite facies mid-crustal rocks, with intercalations of TTG, which were subjected to temperatures between 540 and 860 °C and pressure 5–7 kb, equating to 15–21 km emplacement depth. The granitic-gneissic layer, typical of the upper crust, appears absent. Geochemically, these iron_-rich rocks are characterized by wide variation in which SiO₂, MgO and FeO_T contents vary from 45.12 to 69.96 wt% (avg. 58.11 wt%), 0.18–11.95 wt% (avg. 4.22 wt%), and 0.34–22.92 wt% (avg. 9.01 wt%) respectively. Measured FeO_T contents are even higher than the normal lower crust. The granulite rocks exhibit tholeiite affinity, while amphibolite (which dominate the lithology) and TTG rocks show calc-alkaline character. Further, chondrite and primitive mantle normalized plots, show consistent and complimentary REE patterns (except in HREE), with negative Eu anomalies and LILE enrichment, indicating source rock fractionation. Well-marked depletion in Nb–Ta, Zr–Hf, subordinate depletion in Sr and Ba, and their distinct calc-alkaline to tholeiite character, indicate their subduction zone/arc-related affinity. In addition, large-scale crust-mantle interaction and pervasive metasomatism, have led to considerable alteration to the basic fabric of the rock thereby making it weak and characterized by reduced velocities due to biotitization and substantial Fe-enrichment. Quite likely, earthquake nucleation in intraplate stable regions may have a close link with mantle metasomatism.

隐藏在 66 Ma 德干大火成岩省以下的新太古代基底的演化性质在很大程度上仍然未知。我们在此展示了综合地球科学调查的详细结果，该调查对覆盖整个 270 m 厚柱的 43 个地下室岩心进行，这些岩心被 KLR-1 深科学钻孔穿透，在 1993 年 Killari 地震（印度马哈拉施特拉邦）的震中区钻探。它们主要包含高速高密度、富卤、后退和交代角闪岩到麻粒岩相中地壳岩石，夹层 TTG，温度在 540 至 860 °C 之间，压力为 5-7 kb，相当于15-21 公里的安置深度。上地壳典型的花岗岩-片麻岩层似乎不存在。从地球化学上讲，这些铁_-富岩的特点是变化很大，其中 SiO ₂、MgO 和 FeO _T含量从 45.12 到 69.96 wt%（平均 58.11 wt%）、0.18-11.95 wt%（平均 4.22 wt%）和 0.34-22.92 wt% %（平均 9.01 wt%）。测量的 FeO _T含量甚至高于正常的下地壳。麻粒岩表现出拉斑岩亲和性，而角闪岩（在岩性中占主导地位）和 TTG 岩表现出钙碱性特征。此外，球粒陨石和原始地幔归一化图显示出一致和互补的 REE 模式（HREE 除外），具有负 Eu 异常和 LILE 富集，表明烃源岩分馏。Nb-Ta、Zr-Hf 的明显消耗，Sr 和 Ba 的次要消耗，以及它们独特的钙碱性到拉斑沸石特征，表明它们的俯冲带/弧相关亲和力。此外，大规模的壳幔相互作用和普遍的交代作用已导致岩石基本结构发生相当大的改变，从而使其变弱，并且由于黑云母化和大量铁富集导致速度降低。