An integrated approach involving Sr–Nd isotope, trace and rare earth element analyses tracks multiple sources of the Mesozoic sediments of the Kutch Basin at the western continental margin of India. High (87Sr/86Sr)t (ratio at time of deposition), negative εNd and high concentrations of large-ion lithophile elements (LILEs) indicate the upper continental source. Ratios of Nb/Ta and Zr/Hf suggest sedimentary and felsic igneous sources of sediments. The moderate to high concentration of La, Th and Sc, light rare earth elements (LREE-) enrichment, weak negative Eu anomalies and the relationship between εNd(0) and Th/Sc indicate the dominantly felsic composition of source rocks. However, low contents of Th, low values of (87Sr/86Sr)t and depleted mantle model age TDM < 1600 Ma indicate input from a younger mafic source. Increasing concentrations of Zr, Hf and Nd isotopes and a gradual increase in mean TDM from the older to the younger formations indicate erosional unroofing at the source terrain. The increasing (87Sr/86Sr)t through time relates to increased weathering of the source rock. The overwhelmingly southwesterly palaeocurrent direction of current-generated sedimentary structures, and the mean TDM ages trace suggest source areas of the Kutch Basin to Precambrian rocks in the north and NE of this basin. The TDM ages highlight the dominance of late Palaeoproterozoic source rocks. Nd isotope composition indicates that Proterozoic rocks of Marwar Supergroup and Erinpura Granite, in particular, served as main sediment contributors for the Mesozoic sediments in Kutch. We therefore conclude that the Mesozoic sediments in the Kutch Basin are predominantly of late Palaeoproterozoic age with lesser inputs from rocks of early Mesoproterozoic and early Palaeoproterozoic age.

中文翻译：

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使用微量元素和 Nd 同位素地球化学追踪沉积物的多个来源：印度西部 Kutch 盆地中生代序列的物源

一种涉及 Sr-Nd 同位素、痕量和稀土元素分析的综合方法可追踪印度西部大陆边缘库奇盆地中生代沉积物的多个来源。高的 （87锶/86锶）吨（沉积时的比率），负 ε钕和高浓度的大离子亲石元素（LILEs）表明上陆源。Nb/Ta 和 Zr/Hf 的比率表明沉积物的沉积物和长英质火成岩来源。中高浓度La、Th和Sc，轻稀土元素（LREE-）富集，弱负Eu异常与ε之间的关系钕(0) 和 Th/Sc 表明烃源岩以长英质成分为主。但是，Th 含量低， (87锶/86锶）吨和耗尽的地幔模型年龄吨DM< 1600 Ma 表明输入来自较年轻的镁铁质来源。Zr、Hf 和 Nd 同位素浓度增加，平均浓度逐渐增加吨DM从较老的地层到较年轻的地层表明源地地形的侵蚀性剥落。增加（87锶/86锶）吨随着时间的推移，烃源岩的风化作用增强。水流生成的沉积构造的压倒性西南古洋流方向，以及平均吨DM年龄痕迹表明库奇盆地的源区到该盆地北部和东北部的前寒武纪岩石。这吨DM年龄突出了晚古元古代烃源岩的优势。Nd同位素组成表明Marwar超群和Erinpura花岗岩的元古代岩石是Kutch中生代沉积物的主要沉积物贡献者。因此，我们得出结论，卡奇盆地的中生代沉积物主要是晚古元古代，较少来自早中元古代和早古元古代岩石的输入。