Evolution of the Philippine Sea Plate: Geochemical and Geochronological Studies of Pre-Oligocene Igneous Rocks

菲律宾海板块的演化：前渐新世火成岩的地球化学和年代学研究

• 批准号: 0928144
• 负责人: Rosemary Hickey-Vargas
• 金额: $ 7.46万
• 依托单位: Florida International University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2012-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0928144&HistoricalAwards=false
• 关键词: Evolution; Philippine; Sea; Plate; Geochemical

This research addresses the origin of the unusual felsic and intermediate intrusive rocks collected from the slope of the southern Mariana Trench. These unusual rocks appear to represent the middle part of the ocean crust under the Izu-Bonin/Mariana (IBM) volcanic arc. Unexpectedly, these early rocks have an island arc geochemical signature with Pb isotope ages indicating they are Cretaceous in age. If verified, this would indicate that older arc or crustal fragments comprise some of the IBM arc basement. which has significant ramifications for the evolution of the seafloor in the IBM arc area and possibly for volcanic arcs in general. Research goals are to determine at what time during arc evolution these rocks formed and/or whether they are parts of older or arcs and if these intrusive units enhanced intracrustal magmatic differentiation and middle crust development. Geochemical and isotopic data will be collected to examine possibly inhereted features and the development of the intrusive middle crustal section. Understanding the formation of how intra-oceanic arc crust forms is critical for development of continental crust and its modeling. Broader impacts of the work include support of an investigator and graduate student from a gender under-represented in the sciences, international collaboration, and support of faculty at minority-serving institution. The work enhances work being carried out by the NSF-funded MARGINS program.

这项研究解决了不寻常的长英质和中间侵入岩收集的南部马里亚纳海沟的斜坡的起源。 这些不寻常的岩石似乎代表伊豆-小笠原/马里亚纳（IBM）火山弧下的洋壳中部。 出乎意料的是，这些早期岩石具有岛弧地球化学特征，Pb同位素年龄表明它们是白垩纪的。如果得到证实，这将表明更古老的弧或地壳碎片构成了IBM弧基底的一部分。这对IBM弧区海底的演变以及可能对一般的火山弧有重大影响。 研究目标是确定在什么时候在弧演化这些岩石形成和/或他们是否是老弧或弧的一部分，如果这些侵入单位增强壳内岩浆分异和中地壳的发展。 将收集地球化学和同位素数据，以研究可能的内在特征和侵入中地壳部分的发展。 了解洋内弧壳的形成机制，对于大陆地壳的发育及其模拟具有重要意义。 这项工作的更广泛影响包括支持一名来自科学界代表性不足的性别的研究员和研究生，国际合作以及支持少数民族服务机构的教师。 这项工作加强了NSF资助的MARGINS计划正在进行的工作。