Collaborative Research: Australia Down Under: Quantification of Rates and Amount of Continental Subduction During Neogene Arc-continent Collision on Timor

合作研究：澳大利亚：帝汶新近纪弧大陆碰撞期间大陆俯冲速率和量的量化

• 批准号: 1158748
• 负责人: Nadine McQuarrie
• 金额: $ 27.86万
• 依托单位: University of Pittsburgh
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2015-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1158748&HistoricalAwards=false
• 关键词: Collaborative; Research; Australia; Down; Under

The objective of this project is to test whether arc-continent collision events modify overall convergence rates, with the island of Timor as test-case. The mountainous island of Timor exposes a tectono-stratigraphic section of a typical arc-continent collision, with elements from the overriding Asian oceanic/arc plate, a wedge of high pressure/low temperature metamorphic rocks and an underlying deformed Australian continental passive margin sedimentary sequence. An accurate geologic map of the Island, which describes the distribution of rock types and structures, will be produced that will form the basis for balanced structural cross-sections, which, in turn, will be used to quantify how much the sedimentary rocks once deposited on the margin have been telescoped during collision. The magnitude of shortening should correlate with the amount of continental crust that has been subducted. Paleomagnetic analysis is used to determine paleolatitude, rotation, and age of strata. High- to low-temperature thermochronologic data will document the magnitude, variability, and timing of exhumation.Shortly after the recognition of plate tectonics, the Wilson cycle was introduced in order to describe the creation and demise of ocean basins. The original four stages ? continental rifting, seafloor spreading and formation of ocean basins, closure of ocean basins by subduction of oceanic lithosphere, and continent-continent collision - still form a fundamental basis for our understanding of tectonic processes. Arc-continent collision marks the ultimate demise of an intra-oceanic subduction zone and is a common phenomenon during ocean closure. It is usually assumed that significant underthrusting of continental material under an oceanic island arc is inhibited by buoyancy but the magnitude of continental subduction remains unconstrained. This project will provide an estimate for the magnitude of continental crust that has been subducted, results that would have important implications for mantle chemistry and dynamics. The project involves a significant collaboration with researchers from Norway, Swiss, Australia, and Indonesia as well as training of U.S. and international students.

该项目的目标是测试弧大陆碰撞事件是否会改变整体收敛速度，以帝汶岛作为测试案例。帝汶岛多山的岛屿暴露了典型的弧-大陆碰撞的构造地层剖面，其中包含来自压倒性的亚洲洋/弧板块、高压/低温变质岩楔形物和下方变形的澳大利亚大陆被动边缘沉积序列的元素。将绘制一份准确的岛屿地质图，描述岩石类型和结构的分布，这将成为平衡结构横截面的基础，而平衡结构横截面又将用于量化沉积岩曾经沉积的数量边缘上的部分在碰撞过程中被收缩。缩短的幅度应该与俯冲的大陆地壳的数量相关。古地磁分析用于确定古纬度、旋转和地层年龄。高低温热年代学数据将记录折返的幅度、变化和时间。在认识板块构造之后不久，威尔逊循环被引入以描述海洋盆地的形成和消亡。原来的四个阶段？大陆裂谷、海底扩张和洋盆形成、海洋岩石圈俯冲导致洋盆闭合以及大陆与大陆碰撞——仍然是我们理解构造过程的基本基础。弧大陆碰撞标志着洋内俯冲带的最终消亡，是海洋闭合过程中的常见现象。 通常认为，浮力抑制了大洋岛弧下大陆物质的显着俯冲，但大陆俯冲的幅度仍然不受限制。该项目将对已俯冲的大陆地壳的大小进行估计，这些结果将对地幔化学和动力学产生重要影响。该项目涉及与挪威、瑞士、澳大利亚和印度尼西亚的研究人员的重大合作，以及对美国和国际学生的培训。