Neotectonic Evolution of Antarctic Peninsula/Scotia Sea Region: Multi-Beam, Sidescan Sonar, Seismic, Magnetics and Gravity Studies

该奖项支持对布兰斯菲尔德海峡和沙克尔顿断裂带及其周围地区进行海洋地球物理调查，以努力了解该地区的新构造演化。多波束条带测绘和侧扫声纳测绘将与多通道地震成像一起使用。这项提议的主要目标是收集多波束和侧扫声纳数据，以绘制出西南斯科舍海、沙克尔顿断裂带和布兰斯菲尔德海峡不断演变的板块边界的结构特征和构造组构。将在西南斯科舍海进行后续多道地震调查。第二个目标是使用侧扫声纳反射率图像来生成这些区域海底的详细结构图，并将新数据与现有的地震反射、地球观测卫星重力、水波扫描和海束测深数据结合起来。一旦底图制作完成，其他研究人员就可以使用它们来帮助解释多道和单道地震反射记录。南极半岛和斯科舍海的新构造演化极其复杂。了解德雷克-斯科舍-南极-南美板块交汇处最近的演化，将为主要板块边界在长期扩张中心消亡后如何重组以及由此导致的板块数量减少提供重要信息。板块重组可能导致了沙克尔顿海脊的抬升，这可能影响了斯科舍海的沉积模式，也可能影响了韦德尔海的沉积模式。如果沙克尔顿变换断层与南美洲南端相交时，多波束和侧扫声纳可以追踪到它的断裂，那么变换断层与南美大陆相交时断层、裂缝和形变的方向和几何形状将有助于解释该复杂区域的构造。布兰斯菲尔德海峡目前正在进行扩张，这是基于高热流、活火山和地震反射工作的推断。地震折射表明地壳很厚，类似于东非裂谷或大陆的被动火山边缘。相比之下，对最近火山岩的同位素和稀土元素的分析表明，似乎没有大陆污染。布兰斯菲尔德海峡的活动伸展肯定与板块重组有关，但目前还不清楚到底发生了什么构造过程。除了阐明布兰斯菲尔德海峡的构造结构外，多波束和侧扫声纳测量还将确定潜在的疏浚目标和DSRV Alvin潜水地点。

This award supports a marine geophysical investigation of the Bransfield Strait and the Shackleton Fracture Zone and environs in the Scotia Sea in an effort to understand the neotectonic evolution of the region. Multibeam swath mapping and sidescan sonar mapping will be used along with multichannel seismic imaging. The main goal of this proposal is to collect multibeam and sidescan sonar data to map the structural character and tectonic fabric of the evolving plate boundary in Southwest Scotia Sea, Shackleton Fracture Zone, and Bransfield Strait. Follow up multichannel seismic surveys will be done in the Southwest Scotia Sea. The secondary goal is to use sidescan sonar reflectivity images to generate detailed structural maps of the seafloor of these regions and to integrate the new data with existing seismic reflection, Geosat gravity, Hydrosweep and Seabeam bathymetric data. Once the base maps are produced they can be used by other researchers to help interpret multichannel and single channel seismic reflection records. The neotectonic evolution of the Antarctic Peninsula and Scotia Sea is extremely complex. Understanding the recent evolution of the Drake-Scotia-Antarctic-South America plate intersections will provide important information as to how major plate boundaries reorganize after demise of a long-lived spreading center and the consequential reduction in the number of plates. The plate reorganization probably resulted in the uplift of the Shackleton Ridge which may have effected the sedimentary patterns in both the Scotia Sea and possibly the Weddell Sea. If the break of the Shackleton transform fault can be traced with multibeam and sidescan sonar as it intersects the southern end of South America then the orientation and geometry of the faults, fractures and deformation as the transform fault intersects the South American continent will help to interpret the structures in that complex region. Bransfield Strait is presently undergoing extensi on based on high heat flow, active volcanoes and inferences from seismic reflection work. Seismic refraction indicates thick crust similar to the East African Rift or passive volcanic margins of continents. In contrast, analysis of isotopes and rare earth elements of the recent volcanics shows seemingly no continental contamination. The active extension in Bransfield Strait must be related to the plate reorganization but it is unclear exactly what tectonic processes are occurring. Besides elucidating the tectonic fabric of Bransfield Strait, the multibeam and sidescan sonar survey will identify potential dredge targets and DSRV Alvin dive sites.