Collaborative Research: Deep Structure of the Northeast Tibetan Collision Zone- INDEPTH IV

合作研究：青藏高原东北碰撞带的深层结构-INDEPTH IV

• 批准号: 0409870
• 负责人: James Ni
• 金额: $ 75.5万
• 依托单位: New Mexico State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-02-15 至 2017-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0409870&HistoricalAwards=false
• 关键词: Collaborative; Research; Deep; Structure; Northeast

This project (INDEPTH IV) is a continuation of previously funded projects (INDEPTH I, II, III). The overarching goal of the INDEPTH studies is to understand the basic processes that take place in a continent-continent collision. INDEPTH I, II, and III were joint Sino-U.S. studies to understand the formation of the Tibetan Plateau and Himalayan mountains, which together comprise Earth's type example of an active continent-continent collision zone. Results from these studies have profoundly influenced prevalent theories of mountain building in such tectonic settings. The focus of INDEPTH IV is the northeastern boundary of the Tibetan Plateau. This boundary plays a central role in a contemporary debate concerning continental plateau formation as an intracontinental response to collisional orogeny. Recent geological studies and limited geophysical measurements in this region have been cited to argue that a) uplift is due to internal imbricate "stacking" of Asian crust while b) Asian continental lithosphere is being detached and "subducted" into the Tibetan mantle. Such models contrast with a competing paradigm, derived primarily from observations in the southern and eastern portions of the Plateau, that attribute plateau formation to ductile flow in the deep crust. Critical to any model of surface tectonics is the mantle dynamics beneath the plateau and adjacent regions. Upper mantle geophysical properties beneath the northern plateau have been variously attributed to delamination triggered by instability of a thickened lithosphere, mantle lid detachment and/or asthenospheric counterflow associated with subduction of Indian continental lithosphere. INDEPTH IV will test key elements in these hypotheses with an integrated, focused program of geophysical surveys across three key segments of the NE Plateau boundary zone. Geophysical surveys will consist of integrated seismic reflection, refraction and densely spaced passive seismic profiles, a detailed magnetotelluric survey, and a regional broadband seismic array. Specific features to be investigated by the surveys include: a) the existence and nature of proposed Moho offsets; b) the deep geometry of major thrust faults at the plateau boundary; c) the relationship between major thrusts and strike slip faults; d) constraints on lower crustal flow from structural continuity of crustal markers; e) the existence and nature of subducting Asian lithosphere; and f) the mode of lithospheric thickening beneath the plateau foreland.

该项目 (INDEPTH IV) 是先前资助项目 (INDEPTH I、II、III) 的延续。 INDEPTH 研究的首要目标是了解大陆与大陆碰撞中发生的基本过程。 深度 I、II 和 III 是中美联合研究，旨在了解青藏高原和喜马拉雅山脉的形成，它们共同构成了地球上活跃的大陆-大陆碰撞带的典型例子。 这些研究的结果深刻地影响了此类构造环境中造山的流行理论。 INDEPTH IV 的重点是青藏高原的东北边界。 这一边界在当代关于大陆高原形成作为碰撞造山运动的陆内响应的争论中发挥着核心作用。 该地区最近的地质研究和有限的地球物理测量结果被认为：a) 隆升是由于亚洲地壳内部叠瓦状“堆积”造成的，而 b) 亚洲大陆岩石圈正在分离并“俯冲”到青藏高原地幔中。 这些模型与主要来自高原南部和东部部分的观测的竞争范式形成对比，该范式将高原的形成归因于地壳深处的延性流。 对于任何表面构造模型都至关重要的是高原和邻近区域下方的地幔动力学。 北部高原下方的上地幔地球物理特性可归因于由增厚的岩石圈不稳定、地幔盖脱离和/或与印度大陆岩石圈俯冲相关的软流圈逆流引发的分层。 INDEPTH IV 将通过横跨东北高原边界区三个关键部分的综合、集中的地球物理调查计划来测试这些假设中的关键要素。 地球物理勘探将包括综合地震反射、折射和密集的被动地震剖面、详细的大地电磁勘探和区域宽带地震阵列。 调查要调查的具体特征包括： a) 拟议的莫霍面偏移的存在和性质； b) 高原边界主要逆冲断层的深部几何形状； c) 主逆冲断层与走滑断层之间的关系； d) 地壳标志的结构连续性对下地壳流动的限制； e) 俯冲亚洲岩石圈的存在和性质； f) 高原前陆下方岩石圈增厚模式。