Air-Ground Study of Tectonics at the Boundary Between the Eastern Ross Embayment and Western Marie Byrd Land, Antarctica: Basement Geology and Structure

南极洲东罗斯湾和西玛丽伯德地边界的空地构造研究：基底地质和结构

• 批准号: 9615282
• 负责人: Christine Siddoway
• 金额: $ 11.5万
• 依托单位: Colorado College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-15 至 2003-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9615282&HistoricalAwards=false
• 关键词: Air; Ground; Study; Tectonics; Boundary

OPP 9615281 Luyendyk OPP 9615282 Siddoway Abstract This award supports a collaborative project that combines air and ground geological-geophysical investigations to understand the tectonic and geological development of the boundary between the Ross Sea Rift and the Marie Byrd Land (MBL) volcanic province. The project will determine the Cenozoic tectonic history of the region and whether Neogene structures that localized outlet glacier flow developed within the context of Cenozoic rifting on the eastern Ross Embayment margin, or within the volcanic province in MBL. The geological structure at the boundary between the Ross Embayment and western MBL may be a result of: 1) Cenozoic extension on the eastern shoulder of the Ross Sea rift; 2) uplift and crustal extension related to Neogene mantle plume activity in western MBL; or a combination of the two. Faulting and volcanism, mountain uplift, and glacier downcutting appear to now be active in western MBL, where generally East-to-West-flowing outlet glaciers incise Paleozoic and Mesozoic bedrock, and deglaciated summits indicate a previous North-South glacial flow direction. This study requires data collection using SOAR (Support Office for Aerogeophysical Research, a facility supported by Office of Polar Programs which utilizes high precision differential GPS to support a laser altimeter, ice-penetrating radar, a towed proton magnetometer, and a Bell BGM-3 gravimeter). This survey requires data for 37,000 square kilometers using 5.3 kilometer line spacing with 15.6 kilometer tie lines, and 86,000 square kilometers using a grid of 10.6 by 10.6 kilometer spacing. Data will be acquired over several key features in the region including, among other, the eastern edge of the Ross Sea rift, over ice stream OEO, the transition from the Edward VII Peninsula plateau to the Ford Ranges, the continuation to the east of a gravity high known from previous reconnaissance mapping over the Fosdick Metamorphic Complex, an d the extent of the high-amplitude magnetic anomalies (volcanic centers?) detected southeast of the northern Ford Ranges by other investigators. SOAR products will include glaciology data useful for studying driving stresses, glacial flow and mass balance in the West Antarctic Ice Sheet (WAIS). The ground program is centered on the southern Ford Ranges. Geologic field mapping will focus on small scale brittle structures for regional kinematic interpretation, on glaciated surfaces and deposits, and on datable volcanic rocks for geochronologic control. The relative significance of fault and joint sets, the timing relationships between them, and the probable context of their formation will also be determined. Exposure ages will be determined for erosion surfaces and moraines. Interpretation of potential field data will be aided by on ground sampling for magnetic properties and density as well as ground based gravity measurements. Oriented samples will be taken for paleomagnetic studies. Combined airborne and ground investigations will obtain basic data for describing the geology and structure at the eastern boundary of the Ross Embayment both in outcrop and ice covered areas, and may be used to distinguish between Ross Sea rift- related structural activity from uplift and faulting on the perimeter of the MBL dome and volcanic province. Outcrop geology and structure will be extrapolated with the aerogeophysical data to infer the geology that resides beneath the WAIS. The new knowledge of Neogene tectonics in western MBL will contribute to a comprehensive model for the Cenozoic Ross rift and to understanding of the extent of plume activity in MBL. Both are important for determining the influence of Neogene tectonics on the ice streams and WAIS.

电话9615282 该奖项支持一个合作项目，该项目结合了空中和地面地质地球物理调查，以了解罗斯海裂谷和玛丽伯德地（MBL）火山省之间边界的构造和地质发展。 该项目将确定该地区的新生代构造历史，以及确定出口冰川流局部化的新近纪结构是在罗斯湾东部边缘的新生代裂谷背景下发展起来的，还是在MBL的火山区内发展起来的。 罗斯湾和西MBL之间的边界处的地质结构可能是：1）罗斯海裂谷东肩的新生代伸展; 2）与西MBL的新近纪地幔柱活动有关的隆起和地壳伸展;或两者的组合。 断层和火山活动，山脉隆起，冰川下切现在似乎是活跃的西MBL，一般由东向西流动的出口冰川切割古生代和中生代基岩，冰川消退的高峰表明以前的南北冰川流动方向。 这项研究需要使用SOAR（航空地球物理研究支持办公室，由极地计划办公室支持的设施，利用高精度差分GPS来支持激光高度计，冰穿透雷达，拖曳式质子磁力计和Bell BGM-3重力仪）进行数据收集。 该调查需要37，000平方公里的数据，使用5.3公里的线间距和15.6公里的连接线，以及86，000平方公里的数据，使用10.6 × 10.6公里的网格间距。 将在该地区的几个关键特征上采集数据，其中包括罗斯海裂谷的东部边缘，冰流OEO，从爱德华七世半岛高原到福特山脉的过渡，从以前在福斯迪克变质杂岩上的勘测测绘中已知的重力高向东的延续，以及高幅磁异常（火山中心？）其他调查人员在北方福特山脉东南部发现了这一点。 SOAR产品将包括对研究西南极冰盖驱动应力、冰川流动和物质平衡有用的冰川学数据。 地面计划集中在南部的福特山脉。 地质野外绘图将侧重于小规模脆性结构，以便进行区域运动学解释，侧重于冰川表面和沉积物，侧重于可确定年代的火山岩，以便进行地质年代学控制。 还将确定断层和节理组的相对重要性、它们之间的时序关系以及它们形成的可能背景。 将确定侵蚀面和冰碛的暴露年龄。 位场数据的解释将通过对磁性和密度的地面采样以及地面重力测量来辅助。 定向取样将用于古地磁研究。 结合空中和地面调查将获得描述罗斯湾东部边界露头和冰覆盖区地质和结构的基本数据，并可用于区分罗斯海裂谷相关的构造活动与MBL圆顶和火山区周边的隆起和断层。 将利用航空地球物理数据推断露头地质和结构，以推断WAIS下方的地质。 MBL西部新近纪构造的新知识将有助于建立新生代罗斯裂谷的综合模型，并有助于了解MBL中地幔柱活动的程度。 这两个都是重要的，以确定新第三纪构造对冰流和WAIS的影响。