45 Tectonics, Volcanology, Petrology (Posters)

Tuesday, 13 April 2010
8:30 AM - 12:00 PM
Taneycomo A

POSSIBLE NORTHERN EXTENSION OF THE REUNION HOTSPOT TRACK; BASED ON SAMPLES FROM THE BELA OPHIOLITE, PAKISTAN

Paper number: 45-4
Program: Technical Sessions
Time: 8:30 AM – 12:00 PM

Authors

Abstract

This study deals with a selection of rock samples thought to be related to the Reunion Hotspot. These samples were collected from igneous intrusions which intrude into the Bela Ophiolite in Pakistan; making these samples part of the Pre-Deccan extension of the Reunion Hotspot track. Petrographic, geochemical, and isotope data has been collected in order to provide information regarding the formation of these rocks. Information that will help to further the understanding of the tectonics involved in the collision of the Eurasian and Indian plates.

Petrographic analyses were performed on all but one of the samples. XRF and ICPMS analysis were used to obtain major oxide data, and trace element data. This data shows that these samples represent low K tholeiites with continental signatures, as can be seen when plotted on Zr/Y-Zr and Al/Fe+Ti/Mg diagrams. This data was also used in determining which samples were sent for isotope study.

Out of the samples four had isotope data collected. The isotopes being analyzed in each sample were 143Nd/144Nd (values ranging from 0.51276 to 0.512855), and 87Sr/86Sr (values ranging from 0.704847 to 0.707242), while Pb isotope data is still pending. The data shows that these samples represent a mixture of primitive Pre-Deccan trap lavas, which are very similar to samples from Reunion, mixing with continental crust. Our samples compare well to those of the Deccan Traps, which tend to show more evidence of continental crustal contamination. This is supported in the geochemical data, having LIL element concentrations of 30-200×chondrite and HFS element concentrations of 10-30×chondrite, with trace element signatures that are similar to those of the Deccan traps and Reunion.

Based on these results it can be shown that the samples display an affinity to Reunion hotspot magma that has undergone crustal mixing.