加州大学圣地亚哥分校Scripps海洋学院Emily J. Chin助理教授学术报告会

地球系统科学论坛第518期：Emily J. Chin助理教授学术报告会

应304am永利集团官网刘勇胜教授邀请，加州大学圣地亚哥分校Scripps海洋学院Emily J. Chin助理教授来我校访问并做学术交流。

报告时间：2017年4月7日（周五）下午3:30

报告地点：地质斋（主楼308）

报告题目：A deep crustal perspective on the origin of continental crust: the message from cumulates

报告人简介：Emily J. Chin目前任职于加州大学圣地亚哥分校Scripps海洋学院，助理教授。她曾于2013年在Rice university获得博士学位，并于2014-2016年在Brown University进行博士后研究工作。她的主要研究兴趣包括大陆演化，地幔岩石学、地球化学，美国西部构造演化等。目前，她已在JP，EPSL，G3等高影响地学期刊上发表文章达11篇。

报告内容简介：The calc-alkaline and tholeiitic magmatic series are the two most important igneous differentiation trends on Earth and are expressed by Earth’s crustal dichotomy of andesitic continental crust and basaltic oceanic crust, respectively. There is still debate over whether Fe depletion in arc magmas is caused by early fractionation of iron oxides due to convergent margin magmas being more oxidized or by crustal contamination with evolved end members rich in silica and poor in iron. To see through crustal processes, we examine deep crustal cumulates – the complementary crystalline solids fractionated from evolving magmas. We find that mid-ocean ridge cumulates are Fe-poor and complementary to Fe-enriched MORBs that evolve along the tholeiitic trend. In contrast, arc cumulates are Fe-rich and complementary to Fe-depleted arc magmas evolving along the calc-alkaline trend. The Fe-rich nature of arc cumulates is apparent in early-formed cumulates (Mg# > 80), suggesting that several factors unique to arcs (e.g., higher fO2, higher water, and/or thicker crust) probably play a role in the early evolution of arc magmas and that crustal assimilation is not likely the dominant control on iron depletion. Both continental and island arc cumulates are substantially Fe- and Ti-enriched relative to mid-ocean ridge cumulates suggesting the primary role of Fe-Ti oxide (magnetite, ilmenite) fractionation on the Fe-depletion of arc magmas and ultimately the Fe-depleted nature of the upper continental crust.

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