Airborne geophysical investigation targets basal boundary conditions for the Institute and Moller ice streams, West Antarctica

机载地球物理调查的目标是南极洲西部研究所和莫勒冰流的基础边界条件

• 批准号: NE/G013071/2
• 负责人: Martin Siegert
• 金额: $ 20.72万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FG013071%2F2
• 关键词: Airborne; geophysical; investigation; targets; basal

The Institute and Möller ice streams (IIS/MIS) drain about 20% of the West Antarctic Ice Sheet (WAIS) to the Ronne Ice Shelf, yet our knowledge of their current form and flow history is severely restricted compared with other fast flowing regions in West Antarctica. Data relating to the ice thickness and the ice-sheet bed is limited to reconnaissance transects acquired in the 1970s. Bingham and Siegert (2007) inspected these data, and showed the remarkably smooth and flat bed was similar to the Siple Coast ice streams that drain to the Ross Ice Shelf. As the Siple Coast region is thought to be underlain by marine sediments, deposited when the ice sheet size was smaller than today, Bingham and Siegert (2007) concluded a similar, probably simultaneous, history for the Institute/Möller region. The implications of this finding are significant for future changes in West Antarctica. Bingham and Siegert's (2007) analysis allows us to hypothesise substantial former ice-shelf loss and grounding line retreat in two of the three major drainage outlets of West Antarctica. An extensive airborne geophysical survey of the Institute and Möller ice streams is therefore clearly warranted, to test this hypothesis and better understand the risk of future change. The survey will also allow a better depiction of bed topography and geological boundary conditions in West Antarctica, which will allow us to better quantify the flow and form of the entire WAIS through numerical modelling. The project's objectives are as follows. 1. To undertake an airborne geophysical survey of the Institute and Möller ice streams of West Antarctica. 2. To quantify bed topography and measure bed roughness from radar data. 3. To map englacial structures (layering and crevasses). 4. To determine power reflection coefficients, forming an appreciation of basal water distribution. 5. To analyse magnetic and gravity anomalies to derive geological boundary conditions for ice flow. 6. To employ numerical modelling to quantify modern and ancient ice flow processes. 7. To use numerical modelling to predict the risk of former changes reoccurring. This project will result in the following deliverables: 1. The quantification of subglacial topography (and bed roughness) in a hitherto poorly known region of West Antarctica. This information will be made available to the BEDMAP II database, and will make a fundamental contribution as an ice sheet modelling boundary condition. We will analyse these data to determine landscape evolution and ice sheet history. 2. The classification of subglacial thermal conditions and locations of subglacial lakes. This will allow us to comprehend how ice stream flow and subglacial lake/hydrology evolution is both interrelated and affected by subglacial geology and thermal conditions. 3. The measurement of the englacial structure in the WAIS. We will analyse this information to calculate the flow history of the ice sheet and to delineate the margins of the IIS and MIS both now and in the recent past. 4. The definition of crustal structure and subglacial geology of the IIS and MIS catchments of the WAIS. The glacial history of the WAIS is of direct relevance to assessments of the present day risk of collapse and sea level rise. We aim to report our results directly to the international scientific community by linking to the Scientific Committee on Antarctic Research's (SCAR) scientific research programme entitled Antarctic Climate Evolution (ACE), which integrates geology and geophy sical datasets, forming hypotheses concerning past changes, which can be tested through modelling. The ACE link also allows us to disseminate results to the IPCC through SCAR's observer status in that organisation. We will also make results available to the SCAR programme named Subglacial Antarctic Lake Environments (SALE) and will contribute the new magnetic dataset to the international Antarctic Digital Magnetic Anomaly Project.

该研究所和穆勒冰流（IIS/MIS）的排水约20%的西南极冰盖（WAIS）的伦讷冰架，但我们的知识，其目前的形式和流动的历史是严重限制相比，其他快速流动的地区在西南极洲。有关冰厚和冰盖床的数据仅限于1970年代获得的勘测断面。Bingham和Siegert（2007）检查了这些数据，并表明非常光滑和平坦的床类似于流入罗斯冰架的Siple海岸冰流。由于西普尔海岸地区被认为是由海洋沉积物所覆盖，这些沉积物是在冰盖规模小于今天的时候沉积的，宾厄姆和西格特（2007年）得出了一个类似的结论，可能是同时的，研究所/穆勒地区的历史。这一发现对南极洲西部未来的变化具有重要意义。Bingham和Siegert（2007）的分析使我们能够假设在南极洲西部三个主要排水口中的两个，以前的冰架损失和接地线退缩。因此，显然有必要对该研究所和穆勒冰流进行广泛的航空地球物理调查，以检验这一假设并更好地了解未来变化的风险。该调查还将更好地描述南极洲西部的河床地形和地质边界条件，这将使我们能够通过数值模拟更好地量化整个WAIS的流量和形式。该项目的目标如下。1.对研究所和南极洲西部Möller冰流进行航空地球物理调查。2.利用雷达资料量化河床地形及量度河床粗糙度。3.绘制冰内构造（分层和裂隙）。4.确定功率反射系数，形成对基底水分布的评价。5.分析磁力和重力异常，导出冰流的地质边界条件。6.采用数值模拟来量化现代和古代的冰流过程。7.使用数值模型预测以前变化再次发生的风险。本项目将产生以下交付成果：1.南极洲西部一个迄今为止知之甚少的地区冰下地形（和河床粗糙度）的量化。这些信息将提供给BEDMAP II数据库，并将作为冰盖模拟边界条件作出重要贡献。我们将分析这些数据，以确定景观演变和冰盖的历史。2.冰下热条件的分类和冰下湖泊的位置。这将使我们能够理解冰流流动和冰下湖泊/水文演变是如何相互关联的，并受到冰下地质和热条件的影响。3. WAIS中冰内结构的测量。我们将分析这些信息来计算冰盖的流动历史，并描绘IIS和MIS的边缘，现在和最近的过去。4. WAIS的IIS和MIS流域的地壳结构和冰下地质的定义。WAIS的冰川历史与当今崩塌和海平面上升风险的评估直接相关。我们的目标是通过与南极研究科学委员会题为“南极气候演变"的科学研究方案建立联系，直接向国际科学界报告我们的研究结果，该方案综合了地质学和地球物理学数据集，形成了关于过去变化的假设，可以通过建模加以检验。ACE链接还使我们能够通过SCAR在该组织的观察员地位向IPCC传播结果。我们还将把结果提供给名为冰下南极湖环境（销售）的SCAR计划，并将为国际南极数字磁异常项目提供新的磁数据集。

项目成果

A temperate former West Antarctic ice sheet suggested by an extensive zone of subglacial meltwater channels

广阔的冰下融水通道表明前南极洲西部是温带冰盖

• DOI: 10.1130/g35980.1
• 发表时间: 2014
• 期刊: Geology
• 影响因子: 5.8
• 作者: Rose K

Inland extent of the Weddell Sea Rift imaged by new aerogeophysical data

通过新的航空地球物理数据成像的威德尔裂谷的内陆范围

• DOI: 10.1016/j.tecto.2012.09.010
• 发表时间: 2013
• 期刊: Tectonophysics
• 影响因子: 2.9
• 作者: Jordan T

Ice-flow structure and ice dynamic changes in the Weddell Sea sector of West Antarctica from radar-imaged internal layering

• DOI: 10.1002/2014jf003291
• 发表时间: 2015-04-01
• 期刊: JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
• 影响因子: 3.9
• 作者: Bingham, Robert G.;Rippin, David M.;Siegert, Martin J.
• 通讯作者: Siegert, Martin J.

Evidence from ice shelves for channelized meltwater flow beneath the Antarctic Ice Sheet

• DOI: 10.1038/ngeo1977
• 发表时间: 2013-11-01
• 期刊: NATURE GEOSCIENCE
• 影响因子: 18.3
• 作者: Le Brocq, Anne M.;Ross, Neil;Siegert, Martin J.
• 通讯作者: Siegert, Martin J.

The Ellsworth Subglacial Highlands: Inception and retreat of the West Antarctic Ice Sheet

埃尔斯沃思冰下高地：南极西部冰盖的形成和消退

• DOI: 10.1130/b30794.1
• 发表时间: 2013
• 期刊: Geological Society of America Bulletin
• 影响因子: 4.9
• 作者: Ross N