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

这个项目的目的是测试是否弧大陆碰撞事件修改整体收敛率，与帝汶岛作为测试案例。多山的帝汶岛暴露了一个典型的弧-陆碰撞的构造-地层剖面，其元素来自覆盖的亚洲大洋/弧板块、高压/低温变质岩楔和下面变形的澳大利亚大陆被动边缘沉积序列。将绘制一份精确的该岛地质图，其中描述岩石类型和结构的分布情况，这将成为平衡结构剖面图的基础，而平衡结构剖面图又将用于量化曾经沉积在边缘的沉积岩在碰撞期间被压缩的程度。缩短的幅度应该与大陆地壳被俯冲的数量有关。古地磁分析用于确定地层的古纬度、自转和年代。高温到低温的热年代学数据将记录折返的规模、可变性和时间。在认识到板块构造后不久，威尔逊旋回被引入，以描述海洋盆地的产生和消亡。原来的四个阶段？大陆裂谷、海底扩张和洋盆的形成、大洋岩石圈俯冲导致洋盆闭合以及大陆-大陆碰撞--仍然是我们理解构造过程的基本依据。弧-陆碰撞标志着洋内俯冲带的最终消亡，是大洋闭合过程中的一种常见现象。 通常认为，大洋岛弧下大陆物质的显著俯冲受到浮力的抑制，但大陆俯冲的幅度仍然不受限制。该项目将对大陆地壳的俯冲程度作出估计，其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要合作，以及美国和国际学生的培训。

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.