罗斯海大陆边缘沉积环境自更新世中期以来的剧烈变化:南极西部冰原崩溃的更多证据

IF 3.8 2区 地球科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY
Chinmay Dash, Yeong Bae Seong, Ajay Kumar Singh, Min Kyung Lee, Jae Il Lee, Kyu-Cheul Yoo, Hyun Hee Rhee, Byung Yong Yu
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引用次数: 0

摘要

摘要本研究调查了罗斯海大陆隆起的沉积岩芯(RS15-LC47),以阐明过去 800 ka 年间海冰相互作用及其导致的古沉积变化。通过整合整个岩芯的磁感应强度(MS)、沉积物生物成份(TOC、CaCO3 和生物硅)、沉积学特征以及自生铍同位素比值(10Be/9Be)reac,我们揭示了古环境变化及其对沉积过程的影响。调查区间的下段(750-550 ka)表现出明显的岩性特征,包括平行层理和交叉层理,以及毫米尺度的断层,表明了等高线沉积过程。由于沉积物分选较差,该区段的 MS 值也呈现出不规则的趋势,这是沉积物坍塌的特征。该区间的最低(10Be/9Be)reac 比率表明,由于南极坡流(ASC)增强,环极深水(CDW)流入量减少。虽然总有机碳(TOC)在这一区间最高,但高碳氮比(C/N)和低钡过量(Baex)表明,由于陆地输入的增加,海洋生产力降低了,而陆地输入可能来自不断推进的冰盖。在中更新世过渡(MPT)之后,MS 值一直保持在较低水平,直到 MIS 8(约 250 ka),(10Be/9Be)reac 相对增加,表明温热状态持续存在。我们假设这一时间段有利于冰架解体和南极西部冰原(WAIS)的可能崩溃。在 550 ka 到 250 ka 之间,TOC/TN 水平类似于在罗斯海的透光层中观测到的水平,Baex 和 TOC 相对较高,表明在较长时间的温热条件下生产力较高。在晚更新世(250 ka)期间,粒度较粗且富含 IRD 的海层表明底层海流增强。在晚更新世,CDW 的上涌促进了(10Be/9Be)reac 比率的急剧上升。在晚更新世间冰期,乳白层厚度(OpalMAR)和总有机碳(TOC)%与(10Be/9Be)reac呈正相关趋势,表明在温暖时期生产力提高。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Drastic changes in Depositional Environments at the Ross Sea Continental Margin since the Mid-Pleistocene: More evidence for West Antarctic Ice Sheet collapse
Abstract. This study investigates a sediment core (RS15-LC47) from the Ross Sea continental rise to elucidate the sea-ice interaction and resulting paleodepositional changes over the past 800 ka. By integrating whole-core Magnetic Susceptibility (MS), sediment biogenic components (TOC, CaCO3, and biogenic silica), sedimentological features, and the isotopic ratio of authigenic beryllium (10Be/9Be)reac, we unravel the paleoenvironmental changes and their influence on the sedimentary processes. The lower segment of the investigated interval (750–550 ka) exhibits distinct lithological characteristics, including parallel and cross laminations, along with millimeter-scale faults, suggestive of contourite depositional processes. This section also displays irregular trends in MS values due to poorly sorted sediments, characteristics feature of sediment slumping. The lowest (10Be/9Be)reac ratio in this interval suggests reduced Circumpolar Deep Water (CDW) inflow due to strengthened Antarctic Slope Current (ASC). Although the Total Organic Carbon (TOC) is highest in this interval, high Carbon-to-Nitrogen (C/N) ratio and low Barium excess (Baex) suggests reduced marine productivity due to increased terrestrial input likely from advancing ice sheets. Following the Mid-Pleistocene Transition (MPT), MS values remain consistently low until MIS 8 (~250 ka) and (10Be/9Be)reac relatively increases, indicating persistent lukewarm condition. We hypothesize this timeframe favorable for ice-shelf disintegration and possible collapse of the West Antarctic Ice Sheet (WAIS). Between 550 and 250 ka, TOC/TN levels resemble those observed in the euphotic layer of the Ross Sea, with relatively higher Baex and TOC, indicating higher productivity during an extended lukewarm condition. During the late Pleistocene (> 250 ka), coarser grain size and IRD-rich layers suggest strengthening of bottom currents. The upwelling of CDW facilitated a drastic increase in the (10Be/9Be)reac ratio during the late Pleistocene. OpalMAR and TOC % exhibit positive trends with (10Be/9Be)reac during the late Pleistocene interglacials, suggesting increased productivity during warmer periods.
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来源期刊
Climate of The Past
Climate of The Past 地学-气象与大气科学
CiteScore
7.40
自引率
14.00%
发文量
120
审稿时长
4-8 weeks
期刊介绍: Climate of the Past (CP) is a not-for-profit international scientific journal dedicated to the publication and discussion of research articles, short communications, and review papers on the climate history of the Earth. CP covers all temporal scales of climate change and variability, from geological time through to multidecadal studies of the last century. Studies focusing mainly on present and future climate are not within scope. The main subject areas are the following: reconstructions of past climate based on instrumental and historical data as well as proxy data from marine and terrestrial (including ice) archives; development and validation of new proxies, improvements of the precision and accuracy of proxy data; theoretical and empirical studies of processes in and feedback mechanisms between all climate system components in relation to past climate change on all space scales and timescales; simulation of past climate and model-based interpretation of palaeoclimate data for a better understanding of present and future climate variability and climate change.
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