Dynamics and Evolution of Magma Systems: Mass Spectrometry of U and Th Isotopes in Young Volcanics

点击翻译按钮获取中文摘要

This project is for U-Th-Ra isotopic studies of young volcanic systems. Traditionally, these measurements have been made by alpha spectroscopy and the ability to see into the volcanic system has been limited by the precision and large sample requirements of the counting techniques. The new Isolab 54 mass spectrometer at Lamont enable the PIs to make direct measurement of 230Th/232dTh ratios in igneous rocks. They also plan to measure 226Ra abundances with the mass spectrometer made by counting techniques. RE/Os isotope measurements should also be possible with this new machine. Enhanced precision afforded by mass spectrometric methods yields finer time resolution for magmatic processes, including partial melting and fluid transfer in the mantle, evolution of crustal magma reservoirs, and dynamics of volcanic plumbing systems, as well as better understanding of the transport and fractionation of U/Th in the Earth. They plan specific work on four well-characterized young volcanic centers, covering a spectrum of magma type, tectonic setting, and volcanic style.