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

点击翻译按钮获取中文摘要

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.