Geochemistry and Geochronology of the First Submarine Intraplate Lavas Recovered from the Arctic Ocean -- Bearing on the Plate Tectonic Evolution of the Amerasian Basin.

亚细亚盆地(北冰洋西部)的构造发展在很大程度上是未知的，但对于理解环绕北冰洋的巨大大陆架停机坪的形成至关重要。这一地区正变得越来越重要，原因包括全球变暖导致的冰盖消退、我们展望北极新航道的未来时的国家安全考量，以及七个北极国家(包括美国)根据《联合国海洋法公约》第76条扩大其大陆架管辖权的行动。该项目将通过对从北极西部挖出的第一套火山岩进行地球化学分析，来检验阿尔法和门捷列夫海脊形成的相互竞争的假说。这个为期三年的研究项目将涉及几个关键的分析领域：1)选定的疏浚样品的同位素测年，以建立后续地球化学工作和构造解释的年代学框架；2)薄片的岩相学和显微探针分析，以确定最适合于主元素和微量元素模拟的样品，以确定熔融的程度和深度，同时考虑任何分离结晶效应；3)通过傅立叶变换红外光谱(FTIR)光谱和二次电离质谱仪(SIMS)确定要测量的样品子集，以确定橄榄石熔体包裹体中的初级熔体挥发浓度；4)用电子探针测量常量元素，用激光烧蚀电感耦合等离子体质谱(ICPMS)测量与挥发分特征相同的熔体包裹体上的微量元素，以确定海底熔岩中以任何形式保存的最原始岩浆的成分；5)测定40个样品的整套同位素组成。该项目将资助一名研究生和一名本科生。

The tectonic development of the Amerasian Basin (the western Arctic Ocean) is largely unknown, but is key to understanding formation of the vast apron of continental shelves that ring the Arctic Ocean. This region is increasingly becoming important because of the receding ice cover due to global warming, national security considerations as we look to the future of new Arctic shipping lanes, and the maneuvering by the seven Arctic nations (including the United States) to expand their continental-shelf jurisdiction in accordance with Article 76 of the United Nations Convention on the Law of the Sea. This project will test competing hypotheses for formation of the Alpha and Mendeleev Ridges through geochemical analysis of the first suite of volcanic rocks that have been dredged from the western Arctic. This three-year research project will involve several key analytical areas: 1) isotopic dating of selected dredged samples to establish a chronologic framework for follow-up geochemical work, and for tectonic interpretations; 2) petrographic and microprobe analysis of thin sections to identify samples best suited for major and trace element modeling to determine the degrees and depth of melting while also being mindful of any fractional crystallization effects; 3) identify a subset of samples for measurements by Fourier transform infrared (FTIR) spectroscopy, and secondary ionization mass spectrometry (SIMS) of the primary melt volatile concentrations in olivine-hosted melt inclusions; 4) measurement of major elements by electron microprobe and trace elements by laser ablation ICP-MS on the same melt inclusions as those characterized for volatiles to identify the compositions of the most primitive magmas preserved in any form within the submarine lavas, and 5) measurement of a complete set of isotopic compositions for 40 samples. The project will support one graduate student and one undergraduate.