AbstractThe low Re abundance in arc-type volcanic rocks characterized by high 187Os/188Os ratios is an unsolved puzzle of the 187Re-187Os isotope system, leaving a significant gap in our understanding of the evolution of the upper mantle–continental crust system. Here we report new observations of high Re concentrations in fresh, submarine-erupted—i.e., relatively undegassed—island arc–like volcanic glasses dredged from the eastern Manus Basin, offshore Papua New Guinea. These observations, together with previously published reports of high Re concentrations in arc-type melt inclusions, indicate that undegassed arc-type volcanic rocks and the mantle wedge are enriched in Re. Consequently, the Re concentration in the continental crust is likely to be as high as ∼2 ppb, much higher than previously estimated. The low Re concentrations in subaerial arc-type volcanic rocks are probably due to Re loss during magma degassing.
Weidong Sun*1, Richard J. Arculus*2, Vickie C. Bennett*3, Stephen M. Eggins*3 and Raymond A. Binns*4
+ Author Affiliations
1Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia
2Department of Geology, Australian National University, Canberra, ACT 0200, Australia
3Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia
4Commonwealth Scientific and Industrial Research Organisation, Exploration and Mining, North Ryde, NSW 1670, Australia