The Deccan Traps in Space and Time: Geochemical Studies of the Eastern Deccan, Lower Western Ghats, and Madagascar

这是一个由三部分组成的分析程序， 德干火山作用的基本方面， 有据可查的样本;目标是向外扩展知识 从深入研究的西南地区，开始， 了解板块构造框架中巨大的德干事件了解板块构造框架中巨大的德干事件 以及其他大型大陆溢流玄武岩。 1)现有的化学证据表明， 不只是简单地重复了 五个后来，上层的阵法，现在已经很好了， 明白 其他岩石的Nd、Pb和Sr同位素研究 来自下层地层的熔岩特征十分明显， 提出了 将使用化学和同位素数据 评价其地幔源区的性质和演化， 德干早期污染的作用和机制 继承，以及与上覆地层的关系。 在 特别是，古代岩石圈地幔源被取代 由软流圈源; AFC过程是否占主导地位， 正如预测的那样，？ 2)更早的一套来自南部和 马达加斯加东部代表了一个火山作用阶段（70-80百万年）， 印度本土。 Nd、Sr和Pb同位素比值将在 一组马达加斯加熔岩，结合岩石学， 常量和微量元素，以及Festival的年代学工作 同事们，为了追踪火山的开始阶段， 活动 3)虽然一个巨大的背斜结构， 德干地层最近已被确定，地球化学 该省东西向的地层仍然是 完全未知 极端的观点认为， 德干中部和东北部只是 西部地层（最远1000公里或更远）;另一个 前者大部分或全部都是从堤坝上喷发出来的 沿着纳尔默达-儿子线，因此应该反映自己的 独特的岩石成因 同位素、化学和岩相学数据 在从Aurangabad Chikaldara和纳格布尔 区域将直接文本这两个冲突，但关键 假设

This is a thre-part analytical program to investigate fundammental aspects of Deccan-related volcanism using existing well-documented smaples; the goal is to expand knowledge outward from the intensively studied southwestern region, to begin to understand the huge Deccan episode ina plate-tectonic framework and with respect to other large continental flood basalts. 1) Existing chemical evidence shows that the lower six formations of the western Deccan do not simply repeat the geochemistry of the Five later, upper level formations, now quite well understood. A Nd, Pb, and Sr isotopic study of otherwise thoroughly characterized lavas from the lower formations is proposed. The combined chemical and isotopic data will be used to evaluate the nature and evolution of their mantle source(s), the roles and mechanisms of contamination early in the Deccan succession, and relationships to the overlying formations. In particular, were ancient lithospheric mantle sources supplanted by asthenospheric sources; and did AFC processes dominate early on, as has been predicted? 2) An even earlier suite of flood basalts from southern and eastern Madagascar represents a stage of volcanism (70-80 Myr) in India proper. Nd, Sr, and Pb isotopic ratios will be measured on a set of Madagascar lavas, in conjunction with petrographic, major and trace element, and geochronological work by Frency collegues, in order to trace the beginning phases of volcanic activity. 3) Though a huge anticlinal structure incorporating the western Deccan formations has been indentified recently, the geochemical stratigraphy of the province in a W-E direction remains completely unknown. On extreme view holds that lavas in the central and northeastern Deccan are simply distal fringes of the western formations (up to 1000 km or more away); another that most or all of the former were erupted more locally from dikes along the Narmada-Son Lineament and thus should reflect their own unique petrogenesis. Isotopic, chemical, and petrographic data on sections running W-I from Aurangabad, Chikaldara, and Nagpur areas will directly text these two conflicting but critical hypotheses.