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

北冰洋首次发现的海底板内熔岩的地球化学和年代学——与美亚盆地板块构造演化的关系。

• 批准号: 1025513
• 负责人: Samuel Mukasa
• 金额: $ 28.69万
• 依托单位: University of New Hampshire
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1025513&HistoricalAwards=false
• 关键词: Geochemistry; Geochronology; First; Submarine; Intraplate

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.

美亚海盆（北冰洋西部）的构造发展在很大程度上是未知的，但这是了解北冰洋大陆架巨大裙板形成的关键。由于全球变暖导致的冰盖消退、我们展望未来北极新航道时的国家安全考虑以及北极七国（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策略，该地区正变得越来越重要。该项目将通过对从北极西部挖掘的第一组火山岩进行地球化学分析，测试阿尔法海岭和门捷列夫海岭形成的相互竞争的假设。这项为期三年的研究计划将包括几个主要的分析领域：1）对选定的疏浚样品进行同位素测年，以建立一个年代学框架，为后续的地球化学工作和构造解释提供依据;（二）对薄片进行岩相学和微探针分析，以确定最适合主元素和微量元素建模的样品，从而确定熔融程度和深度，同时注意任何结晶分离影响; 3）确定一个样本子集，用于通过傅里叶变换红外（FTIR）光谱和二次电离质谱（西姆斯）测量橄榄石托管熔体包裹体中的初级熔体挥发物浓度; 4）电子探针法测定常量元素，激光烧蚀法测定微量元素。对与挥发分特征相同的熔融包裹体进行质谱分析，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）对40个样品进行了一套完整的同位素组成测定。该项目将支持一名研究生和一名本科生。