Bering Sea Volcanic Province: Eruption History, Source Characteristics, Melting Processes and Plate Tectonic Context

本项目将对白令海火山省进行地质年代学、岩石学和地球化学研究，以评估该地区的岩浆活动是由裂谷相关的减压引发的假设，以及白垩纪阿拉斯加、白令海和楚科奇半岛岩石圈组合期间俯冲引入的挥发物的存在。提出了一种全面的40Ar/39Ar同位素定年方案，以澄清该省的喷发历史，并为后续的同位素确定提供了一个年代学框架。主要氧化物和微量元素的浓度将被测量，以模拟熔融程度和源的地球化学特征。数据将使用更常用的标准元素划分模型进行评估，该模型采用模态批量熔融公式，也采用可能更能代表地幔熔融情景的动态熔融模型方程。用傅里叶红外光谱法从橄榄石熔体包裹体中估计初级熔体水浓度。将测量Nd， Sr， Pb和Hf的同位素组成，以详细评估源特征和模拟混合关系。一些U系列同位素（U、Th和Ra）将被测量，以进一步限制熔化过程和估计熔化深度。该研究将包括我们项目的新研究生Christopher Stefano的博士论文研究。它还将为Tanya Shavalia提供一些本科研究经验，Tanya Shavalia是一名少数民族女学生，学术生涯很有前途。这是与马加丹俄罗斯科学院远东分院东北跨学科科学研究所（NEISRI）的Vyacheslav (Slava) Akinin博士合作进行的一项研究。这项工作将有助于我们了解北极地区的板块构造发展，这被认为是其他研究的重要边界条件，包括气候变化、环境变化和生命/岩石圈相互作用。

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.