Abstract The Singhbhum Craton in eastern India preserves the records of Paleoarchean - Mesoarchean oceanic crust dominated by ultramafic-mafic extrusive rocks (greenstones), and sialic rafts composed of tonalite-trondhjemite-granodiorite, together with younger granitoids constituting the composite Singhbhum granite batholith. The greenstone sequences, intruded by younger granitoids are entrained as synformal keels in the batholith. The lower greenstone sequence of eastern Iron Ore Group (IOG) is composed of peridotitic komatiite, and komatiitic basalt with minor chert and BIF, whereas the upper sequence has tholeiite to tholeiitic andesite. Here we report results from first direct dating of the Karanjharan spinifex-textured komatiite from the lower part of Badampahar greenstone sequence of IOG. LA-ICPMS U-Pb analysis of zircon grains in the komatiites yielded consistent weighted mean 207Pb/206Pb age of 3340 Ma, with closely similar Hf depleted mantle age (TDM) between 3357 Ma and 3432 Ma. The high MgO (25–35%), and low Al2O3/TiO2 (

中文翻译：

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印度 Singhbhum 克拉通的地幔非均质性和壳幔相互作用：来自 3340 马科马提岩的新证据

摘要 印度东部的辛格布姆克拉通保存了以超基性-基性喷出岩（绿岩）为主的古太古代-中太古代洋壳，以及由闪长岩-长闪长岩-花岗闪长岩组成的唾液筏，以及组成复合Singhbhum花岗石的年轻花岗岩类的记录。年轻花岗岩侵入的绿岩层序被夹带为基岩中的同形龙骨。东部铁矿群（IOG）下部绿岩层序由橄榄岩科马提岩和科马提质玄武岩与少量燧石和 BIF 组成，而上部层序为拉斑岩至拉斑安山岩。在这里，我们报告了来自 IOG 巴丹帕哈尔绿岩序列下部的 Karanjharan spinifex 纹理的科马提岩的首次直接测年结果。对科马提岩中锆石颗粒的 LA-ICPMS U-Pb 分析得出一致的加权平均 207Pb/206Pb 年龄为 3340 Ma，与 3357 Ma 和 3432 Ma 之间的 Hf 耗尽地幔年龄 (TDM) 非常相似。高 MgO (25–35%) 和低 Al2O3/TiO2 (