Sedimentary Signatures of Persistent Subglacial Meltwater Drainage From Thwaites Glacier, Antarctica
Sedimentary Signatures of Persistent Subglacial Meltwater Drainage From Thwaites Glacier, Antarctica
复制标题
DOI：
10.3389/feart.2022.863200
复制
发表时间：
2022-05-31
影响因子：
2.9
通讯作者：
Wacker, L.
中科院分区：
文献类型：
--
作者：
Lepp, A. P.;Simkins, L. M.;Wacker, L.
冰下融水的排泄可以增强沿着接地区和海洋终止冰川的冰架下的局部融化。限制冰下水文的演变及其对空间和十年至千年时间尺度上冰稳定性的影响的努力是缺乏的。在这里，我们应用沉积学、地球化学和统计方法分析南极洲西部思韦茨冰川近海回收的沉积物芯，以重建卫星出现前时代的融水排泄活动。我们发现的证据，一个长寿的冰下水文系统Thwaites冰川和迹象表明，融水羽流是今天的冰川向海沉积的主要机制。通过计算机断层扫描揭示的详细岩心地层学捕捉到了排水方式的变化，并表明与过去几千年相比，近几个世纪以来已向海洋输送了更大数量的沉积物融水。Thwaites冰川近海的融水羽沉积物与其他南极冰川系统中描述的融水羽沉积物之间的基本相似性意味着独立于冰下地质发生的广泛和相似的冰下水文过程。在全新世变化的思韦茨冰川边缘的背景下，很可能是冰下排水增强海底融化沿着接地区和放大冰架融化驱动的海洋过程，与其他西南极冰川的观测今天。这项研究强调了在预测南极大陆周围的斯韦茨冰川冰缘和海洋冰川的未来行为时，考虑冰下水文对地面区和冰架融化的影响的必要性。
Subglacial meltwater drainage can enhance localized melting along grounding zones and beneath the ice shelves of marine-terminating glaciers. Efforts to constrain the evolution of subglacial hydrology and the resulting influence on ice stability in space and on decadal to millennial timescales are lacking. Here, we apply sedimentological, geochemical, and statistical methods to analyze sediment cores recovered offshore Thwaites Glacier, West Antarctica to reconstruct meltwater drainage activity through the pre-satellite era. We find evidence for a long-lived subglacial hydrologic system beneath Thwaites Glacier and indications that meltwater plumes are the primary mechanism of sedimentation seaward of the glacier today. Detailed core stratigraphy revealed through computed tomography scanning captures variability in drainage styles and suggests greater magnitudes of sediment-laden meltwater have been delivered to the ocean in recent centuries compared to the past several thousand years. Fundamental similarities between meltwater plume deposits offshore Thwaites Glacier and those described in association with other Antarctic glacial systems imply widespread and similar subglacial hydrologic processes that occur independently of subglacial geology. In the context of Holocene changes to the Thwaites Glacier margin, it is likely that subglacial drainage enhanced submarine melt along the grounding zone and amplified ice-shelf melt driven by oceanic processes, consistent with observations of other West Antarctic glaciers today. This study highlights the necessity of accounting for the influence of subglacial hydrology on grounding-zone and ice-shelf melt in projections of future behavior of the Thwaites Glacier ice margin and marine-based glaciers around the Antarctic continent.