Bottom current control on sediment deposition between the Iselin Bank and the Hillary Canyon (Antarctica) since the late Miocene: An integrated seismic-oceanographic approach
Bottom current control on sediment deposition between the Iselin Bank and the Hillary Canyon (Antarctica) since the late Miocene: An integrated seismic-oceanographic approach
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DOI：
10.1016/j.dsr.2021.103606
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发表时间：
2021-09-22
影响因子：
2.4
通讯作者：
Lucchi, R. G.
中科院分区：
文献类型：
--
作者：
Conte, R.;Rebesco, M.;Lucchi, R. G.
在本文中，我们分析了海洋环流如何影响艾斯林浅滩和希拉里峡谷之间的罗斯海大陆边缘部分的沉积物沉积，以及这些过程自晚中新世以来如何演变。希拉里峡谷是南极大陆边缘周围少数几个在大陆架上产生的浓水的地方之一，这些浓水主要通过与海冰产生相关的盐水排斥，沿着大陆坡流下并到达深海洋底层。同时，希拉里峡谷代表了相对温暖的海水的通道，通常沿着南极坡流内的大陆坡流动，到达大陆架。温暖的海水侵入大陆架会导致冰架底部融化，降低其支撑作用并引发冰盖的不稳定，这是未来海平面预测的主要不确定因素之一。在本研究中，我们使用 R/V OGS Explora 于 2017 年获取的地震、形态测深和海洋学数据。地震剖面和多波束测深与来自国际海洋发现计划 (IODP) 第 374 次探险的两个钻探地点（U1523 和 U1524）的年龄模型一起进行解释。海洋学数据与区域海洋学模型一起用于通过显示当前海洋学对沉积物沉积的影响来支持我们的重建。主要地震不整合面的区域相关性使我们能够识别八个地震序列。地震剖面和多波束测深显示，自中新世早期以来，海底流活动对沉积物沉积产生了强烈影响，而在上新世中期温暖期，其强度有所减弱。海洋学数据和模型提供的证据表明，底部水流与罗斯海大陆架上产生并通过希拉里峡谷流出的稠密水域有关。大量物质运输沉积物和滑脱陡坡的存在表明，物质浪费也参与了沉积物运输。通过这种综合方法，我们将艾斯林浅滩和希拉里峡谷之间的区域视为等深线沉积系统 (ODYSSEA CDS)，该系统提供了独特环境中的海洋学和沉积条件的记录。这项工作中提出的假设旨在作为基于岩性、古生物学、地球化学和岩石物理数据的详细整合的未来重建的框架。
In this paper we analyze how oceanic circulation affects sediment deposition along a sector of the Ross Sea continental margin, between the Iselin Bank and the Hillary Canyon, and how these processes evolved since the Late Miocene. The Hillary Canyon is one of the few places around the Antarctic continental margin where the dense waters produced onto the continental shelf, mainly through brine rejection related to sea ice production, flow down the continental slope and reach the deep oceanic bottom layer. At the same time the Hillary Canyon represents a pathway for relatively warm waters, normally flowing along the continental slope within the Antarctic Slope Current, to reach the continental shelf. The intrusion of warm waters onto the continental shelf produces basal melting of the ice shelves, reduces their buttressing effect and triggers instabilities of the ice sheet that represent one of the main uncertainties in future sea level projections. For this study we use seismic, morpho-bathymetric and oceanographic data acquired in 2017 by the R/V OGS Explora. Seismic profiles and multibeam bathymetry are interpreted together with age models from two drilling sites (U1523 and U1524) of the International Ocean Discovery Program (IODP) Expedition 374. Oceanographic data, together with a regional oceanographic model, are used to support our reconstruction by showing the present-day oceanographic influence on sediment deposition. Regional correlation of the main seismic unconformities allows us to identify eight seismic sequences. Seismic profiles and multibeam bathymetry show a strong influence of bottom current activity on sediment deposition since the Early Miocene and a reduction in their intensity during the mid-Pliocene Warm Period. Oceanographic data and modelling provide evidence that the bottom currents are related to the dense waters produced on the Ross Sea continental shelf and flowing out through the Hillary Canyon. The presence of extensive mass transport deposits and detachment scarps indicate that also mass wasting participates in sediment transport. Through this integrated approach we regard the area between the Iselin Bank and the Hillary Canyon as a Contourite Depositional System (ODYSSEA CDS) that offers a record of oceanographic and sedimentary conditions in a unique setting. The hypotheses presented in this work are intended to serve as a framework for future reconstructions based on detailed integration of lithological, paleontological, geochemical and petrophysical data.