气候和海平面变化导致亚南极马里恩岛脱冰期和泥炭形成之间的两万年差距

IF 1.9 3区 地球科学 Q3 GEOGRAPHY, PHYSICAL
Werner Nel, DOMINIC A. Hodgson, DAVID W. Hedding, Alex Whittle, ELIZABETH M. Rudolph
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引用次数: 0

摘要

基底泥炭的放射性碳测年是确定亚南极岛屿退化最低年龄的关键因素。在马里恩岛上,泥炭沼泽在海拔 300 米以下的地形中占主导地位,泥炭岩心的古生物学评估被用来评估植被历史和演替率,以及本地植物区系对气候变化的敏感性。亚南极岛屿泥炭的形成标志着一次重大的地貌变化,而这一变化以前被认为与冰川退缩有关。在这里,我们通过比较马里恩岛以前公布的和新的基底泥炭年龄、脱冰期的宇宙成因同位素日期以及当地和区域古环境变化,对这一假设进行了验证。结果表明,与其他亚南极岛屿一样,泥炭的形成也发生在南极寒冷逆转(15-13 ka)之后和全新世早期最佳气候时期。这大大晚于玄武岩脱冰的宇宙同位素证据,该证据显示,泥炭地主要分布的地区从海洋同位素阶段(MIS)2(约 31 ka)开始就没有冰。这表明是环境条件控制了泥炭的形成,而不是泥炭的消融。区域气候代用指标显示,在 MIS 2 期间和之后,极低的气温、大面积的海冰、低迷的海面温度以及岛屿范围内较低的海平面,可能会使泥炭在其当前位置保持不利于泥炭形成的条件。在马里恩岛上,降冰期与泥炭形成时间之间存在约 2 万年的巨大差距,这表明使用泥炭基龄作为亚南极降冰期最小年龄的替代物应极为谨慎。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Twenty‐thousand‐year gap between deglaciation and peat formation on sub‐Antarctic Marion Island attributed to climate and sea level change
Radiocarbon dating of basal peats has been a key factor in determining minimum ages for deglaciation on sub‐Antarctic islands. On Marion Island, peat bogs dominate the landscape below 300 m a.s.l., and palynological assessments of peat cores have been used to assess the vegetation history and succession rates as well as the sensitivity of the indigenous flora to climatic change. Initiation of peat on the sub‐Antarctic islands signifies a major landscape change which has previously been linked to the retreat of glaciers. Here we test this hypothesis by comparing previously published and new basal peat ages from Marion Island with cosmogenic isotope dates for deglaciation, and local and regional palaeo‐environmental changes. Results show that, in common with other sub‐Antarctic islands, peat initiation occurred after the Antarctic Cold Reversal (15–13 ka) and through the early Holocene climate optimum. This substantially post‐dates cosmogenic isotope evidence for deglaciation from the basalts which shows that the areas where the peatlands dominate were ice‐free from the start of Marine Isotope Stage (MIS) 2 (~31 ka). This suggests that environmental conditions controlled peat initiation rather than deglaciation. Regional climatic proxies show that during and after MIS 2, extremely low temperatures, extensive sea ice conditions and depressed sea surface temperatures together with lower sea levels at an island scale could have maintained conditions unfavourable for peat initiation at their current locations. On Marion Island, the significant gap of ~20 000 years between the timing of deglaciation and peat formation indicates that the use of peat basal ages as a proxy for the minimum age of deglaciation in the sub‐Antarctic should be used with extreme caution.
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来源期刊
Journal of Quaternary Science
Journal of Quaternary Science 地学-地球科学综合
CiteScore
4.70
自引率
8.70%
发文量
82
审稿时长
6-12 weeks
期刊介绍: The Journal of Quaternary Science publishes original papers on any field of Quaternary research, and aims to promote a wider appreciation and deeper understanding of the earth''s history during the last 2.58 million years. Papers from a wide range of disciplines appear in JQS including, for example, Archaeology, Botany, Climatology, Geochemistry, Geochronology, Geology, Geomorphology, Geophysics, Glaciology, Limnology, Oceanography, Palaeoceanography, Palaeoclimatology, Palaeoecology, Palaeontology, Soil Science and Zoology. The journal particularly welcomes papers reporting the results of interdisciplinary or multidisciplinary research which are of wide international interest to Quaternary scientists. Short communications and correspondence relating to views and information contained in JQS may also be considered for publication.
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