Collaborative Research: Magnetotelluric Transect of a Modern Continent-Continent Collisional Orogen: The SouthernAlps, New Zealand

合作研究：现代大陆-大陆碰撞造山带的大地电磁断面：新西兰南阿尔卑斯山

• 批准号: 9725883
• 负责人: Philip Wannamaker
• 金额: $ 7.9万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-03-01 至 2000-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9725883&HistoricalAwards=false
• 关键词: Collaborative; Research; Magnetotelluric; Transect; Modern

9725883 Wannamaker On the South Island of New Zealand, convergence of the Pacific and Australian plates has given rise to a relatively narrow (~80 km wide) and less complex zone of active mountain building than in most other regions of the world. The dominant structural elements of the plate boundary are the Southern Alps where vertical movement and accompanying rates of erosion are among the highest in the world, and the Alpine Fault which has components of both strike- slip and dip-slip movement. The magnetotelluric work that willl be done under this project is part of a four year cooperative study of the South Island plate boundary involving U.S. and New Zealand scientists at USC, MIT, Woods Hole, UC Berkeley, Purdue, San Diego State, Utah, Institute for Geological and Nuclear Sciences (IGNS, NZ), Victoria University (NZ), and Otago (NZ). Support is being provided by both countries. The centerpiece of the project is a pair of multifaceted geophysical transects across the South Island including active source seismology, offshore multichannel and OBS data acquisition, passive seismology, petrophysics, magnetotellurics, gravity measurements, and surface geology. Experiments are aimed at delineating the crustal and upper mantle structure beneath the Southern Alps and adjacent regions. MT data collected so far has led to a high-quality magnetotelluric transect across the central South Island. The MT response of the interior of this orogen holds the exciting promise of understanding the thermal regime and rheology of the South Island at depth. The complete resistivity structure will provide essential bounds on crustal strain partitioning, metamorphism in the lower crust, relative deformation of the crust versus the mantle, compensation of the South Island uplift, and several other important processes. However, there presently exists a crucial gap in the MT coverage along the transect due to lack of land vehicle access across the principal region of u plift through the Main Divide of the South Island. The data collected in this project will close this gap in coverage with six-eight new MT soundings supported by helicopter transport. Personnel from the IGNS will participate in this effort and will provide manpower and logistical support. ***

9725883 Wannamaker 在新西兰南岛，太平洋板块和澳大利亚板块的交汇形成了相对狭窄（约 80 公里宽）且与世界上大多数其他地区相比不太复杂的活跃造山带。 板块边界的主要结构要素是南阿尔卑斯山，其垂直运动和伴随的侵蚀速率是世界上最高的，以及具有走滑和倾滑运动成分的阿尔卑斯断层。 该项目将进行的大地电磁工作是一项为期四年的南岛板块边界合作研究的一部分，该研究涉及美国和新西兰南加州大学、麻省理工学院、伍兹霍尔大学、加州大学伯克利分校、普渡大学、圣地亚哥州立大学、犹他州、地质与核科学研究所（IGNS，新西兰）、维多利亚大学（新西兰）和奥塔哥大学（新西兰）的美国和新西兰科学家。 两国正在提供支持。 该项目的核心是横跨南岛的一对多方面的地球物理横断面，包括主动源地震学、海上多通道和 OBS 数据采集、被动地震学、岩石物理学、大地电磁学、重力测量和地表地质学。 实验旨在描绘南阿尔卑斯山及邻近地区下方的地壳和上地幔结构。 迄今为止收集的大地电磁数据已经形成了横跨南岛中部的高质量大地电磁横断面。 该造山带内部的 MT 响应为深入了解南岛的热状况和流变学带来了令人兴奋的希望。 完整的电阻率结构将为地壳应变分配、下地壳变质作用、地壳与地幔的相对变形、南岛隆起的补偿以及其他几个重要过程提供必要的界限。 然而，由于缺乏穿过南岛主要分水岭的隆起主要区域的陆地车辆通道，目前横断面沿线的 MT 覆盖范围存在重大差距。 该项目收集的数据将通过直升机运输支持的 6-8 个新 MT 探测来缩小覆盖范围的差距。 IGNS 的人员将参与这项工作，并提供人力和后勤支持。 ***