Evidence for a “Little Ice Age” glacial advance within the Antarctic Peninsula – Examples from glacially-overrun raised beaches
Evidence for a “Little Ice Age” glacial advance within the Antarctic Peninsula – Examples from glacially-overrun raised beaches
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DOI：
10.1016/j.quascirev.2021.107195
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发表时间：
2021-11
影响因子：
4
通讯作者：
Alexander R. Simms;M. J. Bentley;L. Simkins;J. Zurbuchen;L. Reynolds;R. DeWitt;E. Thomas
中科院分区：
文献类型：
--
作者：
Alexander R. Simms;M. J. Bentley;L. Simkins;J. Zurbuchen;L. Reynolds;R. DeWitt;E. Thomas
近年来，人们越来越认识到南极冰盖和冰川在全新世晚期的动态。代用资料表明存在新冰川的进步，但很少有冰碛或冰川的功能，从这个时候已经过时相比，北方半球的冰川景观。关于南极洲部分地区是否在“小冰期”（LIA）的同时经历了冰川前进的争论仍在继续，这在北方半球有很好的记录。我们提供了新的证据晚全新世冰川波动在三个地点沿着南极半岛。一个冰碛或冰碛层从一个冰川十字架削减了一系列的日期提出的海滩在泰头，乔因维尔岛沿着西北威德尔海。在格林威治岛的火花点，一条冰川已经淹没了全新世的海滩，一个含贝壳的海洋存款被改造成一个冰川杂岩。在较大的玛格丽特湾内的卡尔梅特湾的第三个地点也包含一个最近的冰碛，它穿过一系列过时的凸起的海滩山脊。新的年龄限制这些冰川的进步是在广泛的协议与少数其他现有的年龄冰碛和代理记录暗示南极半岛内的冷却条件。将现有的时间限制结合到贝叶斯模型中，得出横跨南极半岛的LIA的年龄为400至90 cal BP（1550-1860 CE; 95%）。在我们的贝叶斯框架内考虑两个阶段的冰川推进确实适合更多的南极半岛的数据，并建议从575到330 cal BP（1375-1620 CE）和400到50 cal BP（1550-1900 CE）的进步。然而，需要做更多的工作来确定这种两阶段的进展是否发生。无论如何，它在南极半岛与北方半球的相似时间支持了最近关于LIA的火山或太阳强迫的断言。这些最近的reavances也提供了一个可能的机制，在整个南极半岛记录的全新世相对海平面变化率的变化，这表明南极冰盖可能比以前认为的更响应过去的气候变化和冰川均衡调整从LIA和其他可能的全新世冰川振荡叠加在较长的松弛从末次冰期最大。
Recognition of how dynamic the Antarctic ice sheets and glaciers were during the late Holocene has grown in recent years. Proxy data suggests the presence of Neoglacial advances but few moraines or glacial features from this time have been dated compared to glaciated landscapes of the Northern Hemisphere. Debate continues on whether parts of Antarctica experienced glacial advance at the same time as the “Little Ice Age” (LIA), which is well-documented in the Northern Hemisphere. We provide new evidence for late Holocene glacial fluctuations at three locations along the Antarctic Peninsula. A moraine or till sheet from a tidewater glacier cross cuts a series of dated raised beaches at Tay Head, Joinville Island along the northwestern Weddell Sea. At Spark Point, on Greenwich Island, a glacier has overrun Holocene raised beaches and a shell-bearing marine deposit is reworked into a glacial diamicton. A third site in Calmette Bay within the larger Marguerite Bay also contains a recent moraine that cuts across a series of dated raised beach ridges. The new ages constraining these glacial advances are in broad agreement with the handful of other existing ages on moraines and proxy records suggestive of cooler conditions within the Antarctic Peninsula. Combining available timing constraints into a Bayesian model yields an age of 400 to 90 cal BP (1550–1860 CE; 95%) for the LIA across the Antarctica Peninsula. Consideration of a two-phase glacial advance within our Bayesian framework does fit more of the data from across the Antarctic Peninsula and suggests advances from 575 to 330 cal BP (1375–1620 CE) and 400 to 50 cal BP (1550–1900 CE). However, more work is needed to determine if such a two-phase advance occurred. Regardless, its similar timing within the Antarctic Peninsula to that of the Northern Hemisphere supports recent assertions of a volcanic or solar forcing for the LIA. These recent readvances also provide a possible mechanism for changes in the rates of Holocene relative sea-level change recorded across the Antarctic Peninsula suggesting that the Antarctic ice sheets may have been more responsive to past climate changes than previously thought and glacial isostatic adjustment from the LIA and possibly other Holocene glacial oscillations is superimposed upon the longer relaxation from the Last Glacial Maximum.