Collaborative Research: Subduction below extreme sedimentation - A multidisciplinary transect from the Ganges-Brahmaputra Delta to the IndoBurma Backarc

该项目涉及对一种鲜为人知的独特地质环境的研究：一种拥有异常大量沉积物的俯冲带--恒河-雅鲁藏布江三角洲(GBD)。GBD是世界上最极端的沉积物吸积例子，孟加拉盆地的沉积物厚达19公里。与其他俯冲带相比，该地区的火山活动很少，地震风险很大；最近的GPS结果表明，这一高度倾斜的板块边界锁定了发生8.2级地震的可能性，这场地震可能会影响1.4亿多人。该项目的动机是极端沉积如何影响俯冲现象的问题。该项目将涉及来自孟加拉国、印度和缅甸、新加坡、挪威和美国的科学家的多机构、多国合作。PIS将专注于三个主要问题：1)新近纪增量棱柱的增长和地震危险；2)印缅山脉和缅甸盆地的地壳缩短和变形；以及3)传入的流体含量和火山作用。为了解决这些问题，他们将在孟加拉国-印度-缅甸阵列(BIMA)从变形前沿到弧后的横断面上部署地震、全球定位系统、大地电磁和重力传感器。构造地质学、地球化学和热年代学将提供额外的限制。他们将使用一个广泛的数值和实验室建模程序来整合和解释来自多个数据集的结果。这一极端沉积物俯冲的端员案例对理解所有俯冲带的这些问题具有广泛的影响。

This project involves a study of a poorly understood and unique geologic setting: a subduction zone that has an exceptionally large amount of sediment, the Ganges-Brahmaputra Delta (GBD). The GBD is the world's most extreme example of sediment accretion, with sediments up to 19 km thick in the Bengal Basin. The region has little volcanism compared to other subduction zones and a large seismic risk; recent GPS results indicate that this highly oblique plate boundary is locked with the potential for a M8.2 earthquake that could affect more than 140 million people. The project is motivated by the question of how the extreme sedimentation affects subduction phenomena. The project will involve a multi-institution, multi-nation collaboration involving scientists from Bangladesh, India and Myanmar, Singapore, Norway, and the U.S.The PIs will focus on three major issues: 1) Neogene growth of the accretionary prism and earthquake hazard; 2) Crustal shortening and deformation across the IndoBurma Ranges and Burma Basin; and 3) Incoming fluid content and volcanism. To address these issues, they will deploy seismic, GPS, magnetotellurics and gravity sensors in a transect from the deformation front to the backarc in the Bangladesh-India-Myanmar Array (BIMA). Structural geology, geochemistry and thermochronology will provide additional constraints. They will use a broad program of numerical and laboratory modeling to integrate and interpret the results from the multiple data sets. This end-member case of extreme sediment subduction has broad implications for understanding these issues at all subduction zones.