An Isotopic and Elemental Study of Deccan Traps Dikes

University Of Hawaii, Honolulu

Investigators

Abstract

EAR-0229824 Mahoney In 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 However, the key conclusion that this swarm is a feeder system is based only on a preliminary, unpublished study of a small number of dikes.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.