An Isotopic and Elemental Study of Deccan Traps Dikes

在羽头模型中，预测岩石圈的大规模扩张是在大陆洪水火山作用之后发生的，而在其他模型中，大规模扩张是洪水火山作用的先决条件。在印度德干圈闭中，一大群没有优先取向的岩脉被解释为主要的给养系统，优先取向的缺乏被认为是峰值喷发活动不伴随显著伸展的有力证据；反过来，有人认为这为全球范围内的羽顶模型提供了一些最好的证据。然而，这个蜂群是一个喂食系统的关键结论仅仅是基于对少数堤防的初步、未发表的研究。此外，还有另外两个主要的堤防系统；两处岩脉均具有较强的择优取向，形成于岩石圈持续伸展的作用下。目前还没有对这三个群落中的任何一个进行系统的地球化学研究。幸运的是，最近对这三个地区的许多定位良好的样本进行了主要元素和几种微量元素的分析。我们建议对这三个群落的岩脉进行详细的微量元素（~100个样本）和Nd-Pb-Sr同位素（~65个样本）分析。组合的Nd-Pb-Sr同位素、微量元素和主元素数据将用于评估岩脉与熔岩地层的亲和力，并确定德干主要补给系统的位置。更广泛的影响：培养博士生是该项目的重要组成部分，它还需要美国、印度和意大利科学家的合作。

EAR-0229824MahoneyIn the plume-head model, major lithospheric extension is predicted to follow continental flood volcanism, whereas significant extension is a prerequisite for flood volcanism in other models. In the Deccan Traps of India, a large swarm of dikes with no preferred orientations has been interpreted to be the main feeder system, and the lack of preferred orientations has been taken as strong evidence that peak eruptive activity was not accompanied by significant extension; in turn, this has been argued to provide some of the best evidence available worldwide for the plume-head model. However, the key conclusion that this swarm is a feeder system is based only on a preliminary, unpublished study of a small number of dikes. Furthermore, two other major dike systems are present; the dikes in both have strong preferred orientations and were emplaced under persistent lithospheric extension. No systematic geochemical study of any of the three swarms has been done. Fortunately, many well-located samples from all three have been analyzed recently for major elements and several trace elements. We propose to carry out detailed trace element (~100 samples) and Nd-Pb-Sr isotopic (~65 samples) analysis of dikes from all three swarms. The combined Nd-Pb-Sr isotopic, trace element, and major element data will be used to evaluate the affinities of the dikes with the lava formations and determine the location of the major Deccan feeder system(s).Broader Impacts: Training of a doctoral student is an important part of the project, which also entails collaborative work involving US, Indian, and Italian scientists.