Late Holocene relative sea levels near Palmer Station, northern Antarctic Peninsula, strongly controlled by late Holocene ice-mass changes
Late Holocene relative sea levels near Palmer Station, northern Antarctic Peninsula, strongly controlled by late Holocene ice-mass changes
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南极半岛北部帕尔默站附近的晚全新世相对海平面，受到晚全新世冰块变化的强烈控制
DOI：
10.1016/j.quascirev.2018.09.017
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发表时间：
2018
影响因子：
4
通讯作者：
Bentley, Michael J.
中科院分区：
文献类型：
--
作者：
Simms, Alexander R.;Whitehouse, Pippa L.;Simkins, Lauren M.;Nield, Grace;DeWitt, Regina;Bentley, Michael J.
许多关于整个南极洲全新世相对海平面（RSL）变化的研究假设，他们的重建记录了末次盛冰期（LGM）冰盖消亡引起的冰川均衡调整造成的抬升。然而，最近对 GPS 观测结果的分析表明，南极半岛下方的地幔粘度比之前认为的要弱，这意味着固体地球运动不是由末次盛冰期后冰盖退缩控制，而是由全新世晚期冰块变化控制。如果这一假设正确，人们可能会期望找到全新世 RSL 记录，这些记录并不反映 RSL 下降速率的单调下降，而是显示整个全新世 RSL 变化速率的变化。我们提出了南极半岛西部帕尔默站附近托格森岛全新世晚期 RSL 变化的新记录，该记录显示，全新世晚期相对海平面下降速度从 3.0±1.2 毫米/年增加到 5.1±1.8 毫米/年。对该地区冰川历史的独立研究提供了类似时间尺度内冰盖变化的证据，这些变化可能推动了这一变化。当我们的 RSL 记录针对与冰川均衡调整 (GIA) 相关的海面高度变化进行校正时，托格森岛 0.79 ka 后陆地抬升速率为 5.3±1.8 毫米/年，远高于 2002 年拉森 B 解体之前在帕尔默站附近 GPS 站点记录的抬升速率（公元 1998-2002 年；<0.1 毫米/年），但是与 2002 年之后观察到的速率相似（2002-2013 年；6-9 毫米/年）。抬升率的这种巨大变化进一步支持了这样的假设：全新世 RSL 变化率记录的是对全新世晚期和当地冰荷载近期变化的响应，而不是南极半岛部分地区末次盛冰期后的信号。因此，全新世中晚期RSL数据可能不是限制地幔较弱的南极半岛部分末次冰盖大小的有效工具。此外，当前的全球规模 GIA 模型无法预测我们观察到的全新世晚期 RSL 的变化。在用于校正现代卫星冰块损失观测的 GIA 模型中，需要考虑地球结构和新冰川历史的复杂性。
Many studies of Holocene relative sea-level (RSL) changes across Antarctica assume that their reconstructions record uplift from glacial isostatic adjustment caused by the demise of the Last Glacial Maximum (LGM) ice sheets. However, recent analysis of GPS observations suggests that mantle viscosity beneath the Antarctic Peninsula is weaker than previously thought, which would imply that solid Earth motion is not controlled by post-LGM ice-sheet retreat but instead by late Holocene ice-mass changes. If this hypothesis is correct, one might expect to find Holocene RSL records that do not reflect a monotonic decrease in the rate of RSL fall but show variations in the rate of RSL change through the Holocene. We present a new record of late Holocene RSL change from Torgersen Island near Palmer Station in the western Antarctic Peninsula that shows an increase in the rate of relative sea-level fall from 3.0 ± 1.2 mm/yr to 5.1 ± 1.8 mm/yr during the late Holocene. Independent studies of the glacial history of the region provide evidence of ice-sheet changes over similar time scales that may be driving this change. When our RSL records are corrected for sea-surface height changes associated with glacial isostatic adjustment (GIA), the rate of post-0.79 ka land uplift at Torgersen Island, 5.3 ± 1.8 mm/yr, is much higher than the rate of uplift recorded at a nearby GPS site at Palmer Station prior to the Larsen B breakup in 2002 AD (1998-2002 AD; <0.1 mm/yr), but similar to the rates observed after 2002 AD (2002-2013 AD; 6–9 mm/yr). This substantial variation in uplift rates further supports the hypothesis that Holocene RSL rates of change are recording responses to late Holocene and recent changes in local ice loading rather than a post-LGM signal across portions of the Antarctic Peninsula. Thus middle-to-late Holocene RSL data may not be an effective tool for constraining the size of the LGM ice sheet across portions of the Antarctic Peninsula underlain by weaker mantle. In addition, current global-scale GIA models are unable to predict our observed changes in late Holocene RSL. Complexities in Earth structure and neoglacial history need to be taken into consideration in GIA models used for correcting modern satellite-based observations of ice-mass loss.