Seismic stratigraphy of the Plio-Pleistocene Ross Island flexural moat-fill: a prognosis for ANDRILL Program drilling beneath McMurdo-Ross Ice Shelf
Seismic stratigraphy of the Plio-Pleistocene Ross Island flexural moat-fill: a prognosis for ANDRILL Program drilling beneath McMurdo-Ross Ice Shelf
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上里奥-更新世罗斯岛弯曲护城河填充物的地震地层学：麦克默多-罗斯冰架下 ANDRILL 计划钻探的预测
DOI：
10.1016/j.gloplacha.2004.09.014
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发表时间：
2005
影响因子：
3.9
通讯作者：
G. Wilson
中科院分区：
文献类型：
--
作者：
H. Horgan;T. Naish;Stephen Bannister;N. Balfour;G. Wilson
罗斯岛火山群随着伯德山和恐怖山玄武岩盾状火山的就位而开始形成。 4.6 和 1.3 Ma，尽管它在过去 1 Ma 的喷发阶段发展最为显着，导致了埃里伯斯山 3794 米高的复合喷口。在此期间，罗斯岛火山堆对恐怖裂谷南端岩石圈的负荷逐渐压低了地壳，导致岛屿周边出现了一条亚圆形弯曲护城河。从麦克默多-罗斯冰架 (MRIS) 收集的多道地震反射数据揭示了罗斯岛东南侧护城河填充物的地层结构。护城河地区在凹陷最深处海底以下至少 1.2 公里处存在分层良好、区域广泛的沉积序列。确定了三个地震地层单元，这些单元通常向罗斯岛增厚和倾斜，并以角度（重叠）不整合面为界。我们推断，这三个单元沉积在火山载荷引起的沉降的离散阶段中形成的居住空间中：这些载荷引起的沉降阶段可能周期性地使护城河过度加深，使得沉积填充物可能相对连续，并且在过去的南极西部冰盖（WAIS）和磁共振成像系统（MRIS）冰川扩张期间很大程度上逃脱了冰接地的侵蚀。各种火山负荷的放射性测年提供的年龄关系表明，这里的沉积物有可能为 WAIS-MRIS 的过去行为和罗斯海西部地区早至 5 Ma 的气候历史提供相对连续和高分辨率的冰川记录。该地层记录计划由 ANDRILL 计划于 2006 年夏季进行钻探。根据地震相的解释，我们对拟钻探地点提出了地层预测。
Ross Island volcanic complex began forming with the emplacement of the basaltic shield volcanoes of Mt. Bird and Mt. Terror between ca. 4.6 and 1.3 Ma, though it has developed most significantly over the last 1 Ma during an eruptive phase resulting in the 3794-m-high composite vent of Mt. Erebus. Throughout this time, loading of the lithosphere at the southern end of the Terror Rift by the Ross Island volcanic pile has progressively depressed the crust, resulting in a subcircular flexural moat around the periphery of the island. Multichannel seismic reflection data collected from the McMurdo-Ross Ice Shelf (MRIS) reveal the stratigraphic architecture of the moat-fill on the southeastern side of Ross Island. The moat region has accommodated a well-stratified, regionally extensive sedimentary succession of at least 1.2 km below the seafloor in the deepest part of the depression. Three seismic stratigraphic units are identified that generally thicken and dip towards Ross Island and are bounded by angular (onlap) unconformities. We infer that the three units were deposited in accommodation space created during discrete phases of volcanic load-induced subsidence: These phases of load-induced subsidence may have periodically overdeepened the moat, making it likely that the sedimentary fill is relatively continuous and has largely escaped erosion by ice grounding during past glacial expansions of the West Antarctic Ice Sheet (WAIS) and the MRIS. The age relationships provided by radiometric dating of the various volcanic loads imply that the sediments here have the potential to provide a relatively continuous and high-resolution glacimarine record of the past behavior of the WAIS–MRIS and the climate history of the western Ross Sea region back to ∼5 Ma. This stratigraphic record is scheduled to be drilled by the ANDRILL Program in the austral summer of 2006. From the interpretation of seismic facies, we present a stratigraphic prognosis for the proposed drill site.