印度阿里加尔穆斯林大学M. E. A. Mondal团队近日研究了古元古代海沟——印度中部构造带（CITZ）Mahakoshal盆地的远弧后设置起源。相关论文发表在2025年6月17日出版的《地球化学学报》杂志上。

研究组对变质玄武岩进行了研究，以了解印度中部构造带Mahakoshal群的地幔源和地球动力学背景。在这项研究中，课题组详细介绍了Mahakoshal变质玄武岩的野外、岩石学和全岩地球化学。Mahakoshal变质玄武岩本质上是亚碱性的，属于拉斑玄武岩系。变质玄武岩稀土元素模式的变化表明，浅层和深层的部分熔融程度不同。此外，Eu/Eu*在0.8至1.1之间变化（样品KP-144=0.3除外），Ce/Ce*在0.97至1.05之间变化，没有铈异常，Nb/Nb*在0.7至1.3之间变化（KP-144>0.1除外）。 

镁值（Mg#）在0.2到0.3之间变化，非常低，表明变质玄武岩的演化性质。所研究的变质玄武岩显示出E-MORB至OIB型亲缘关系，这些亲缘关系位于海沟远端弧后环境中。Mahakoshal盆地的开放是由于增生造山带环境中的造山带退缩造成的，与哥伦比亚超大陆的组装同时发生（~2.1-1.8 Ga）。因此，野外、岩相和地球化学特征表明，Mahakoshal盆地在Bundelkhand克拉通上是一个弧后裂谷盆地，变质玄武岩来自在不同深度经历了不同程度部分熔融的地幔。

附：英文原文

Title: Paleoproterozoic trench–distal back-arc setting origin of the Mahakoshal Basin, Central Indian Tectonic Zone (CITZ): Evidence from the geochemistry of the metabasalts

Author: Parvez, Kamaal, Mondal, M. E. A., Ahmad, Iftikhar, Khan, Wamiq Mohammed

Issue&Volume: 2025-06-17

Abstract: The present study of metabasalts was carried out to understand the mantle source and geodynamic setting of the Mahakoshal Group in the Central Indian Tectonic Zone. In this study, we present detailed field, petrography, and whole rock geochemistry of the Mahakoshal metabasalts. The Mahakoshal metabasalts are sub-alkaline in nature and belong to the tholeiitic series of rocks. The variation in rare-earth element patterns of metabasalts indicates the different degrees of partial melting at shallow as well as deeper depths. Further, Eu/Eu* varies from 0.8 to 1.1 (except sample KP-144=0.3), Ce/Ce* varies from 0.97 to 1.05, showing no cerium anomaly, and Nb/Nb* ranges from 0.7 to 1.3 (except KP-144=0.1). The magnesium number (Mg#) varies from 0.2 to 0.3, which is quite low, indicating the evolved nature of the metabasalts. The studied metabasalts show E-MORB to OIB-type affinities, which are placed in the trench-distal back-arc setting. The opening of the Mahakoshal Basin is due to retreating orogen in the accretionary orogen setting and is contemporaneous with the assembly of the Columbia Supercontinent (~2.1–1.8 Ga). Hence, field, petrographic, and geochemical signatures indicate that the Mahakoshal basin opened as a back-arc rift basin on the Bundelkhand Craton, and that metabasalts are derived from the mantle that underwent variable degrees of partial melting at different depths.

DOI: 10.1007/s11631-025-00788-5

Source: https://link.springer.com/article/10.1007/s11631-025-00788-5