This project is to undertake a geochronologic, petrologic and geochemical study of the Bering Sea Volcanic Province to evaluate the hypothesis that magmatism in the area was triggered by rift-related decompression, but also that it was facilitated by presence of volatiles introduced by subduction during the lithospheric assembly of Alaska, Bering Sea, and the Chukchi Peninsula (Russia) in the Cretaceous. A comprehensive 40Ar/39Ar isotopic dating program is proposed to clarify the eruption history of the province, and also to provide a chronologic framework for follow-up isotopic determinations. Major oxide and trace element concentrations will be measured to model degree of melting and geochemical character of the source. Data will be evaluated using the more commonly utilized standard element partition models, employing modal batch melting formulations but also equations for the dynamic melting model, which are likely to be more representative of mantle melting scenarios. Primary melt water concentrations will be estimated from olivine melt inclusions by FTIR spectroscopy. The isotopic compositions of Nd, Sr, Pb and Hf will be measured for a detailed assessment of source characteristics and modeling mixing relationships. Some U-series isotopes (U, Th, and Ra) will be measured to further constrain the melting processes and to estimate the depth of melting.
The study will comprise the Ph.D. dissertation research for Christopher Stefano, a new graduate student in our program. It will also provide some undergraduate research experience for Tanya Shavalia, a female minority student with a promising academic career. This is a collaborative study with Dr. Vyacheslav (Slava) Akinin of the North East Interdisciplinary Scientific Research Institute (NEISRI), Far East Branch of the Russian Academy of Sciences in Magadan. This work will contribute to our understanding the plate tectonic development of the Arctic region, recognized to be an important boundary condition for other studies including climate change, environmental change and life/lithosphere interactions.
