Holocene glacier fluctuations and environmental changes in subantarctic South Georgia inferred from a sediment record from a coastal inlet
Holocene glacier fluctuations and environmental changes in subantarctic South Georgia inferred from a sediment record from a coastal inlet
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DOI：
10.1017/qua.2018.85
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发表时间：
2019-01-01
影响因子：
2.3
通讯作者：
Viehberg, Finn
中科院分区：
文献类型：
--
作者：
Berg, Sonja;White, Duanne A.;Viehberg, Finn
亚南极南乔治亚岛提供了气候变化的陆地和沿海海洋记录，这对于理解亚南极地区全新世气候变化的驱动因素至关重要。在这里，我们使用元素、脂肪生物标记物、硅藻和稳定同位素数据对南乔治亚州沿海海湾的沉积物岩芯(Co1305)进行调查，以推断环境条件的变化，并限制晚冰期和全新世冰川波动的时间。由于陆相大型化石的稀缺性以及沉积物中重新沉积和残留有机质的存在，记录的年龄控制是通过主要来自海洋的n-C-16脂肪酸的化合物特有的放射性碳测年获得的。在小贾森泻湖发现的一层基本耕作层很可能是在南极寒冷逆转期间当地冰川推进期间沉积的。冰川消退后，一个营养较少的湖泊占据了该地点，由于相对海平面的上升，该地点在8.0+/-0.9ka左右过渡到一个海口。从7.0+/-0.6 ka到4.0+/-0.4 ka，集水区植被覆盖率降低，以及高硅质碎屑输入和冰筏碎屑沉积，表明冰川在陆地集水区和可能在邻近的峡湾推进。第二个较小范围的冰川推进时期发生在全新世晚期，发生在1.8+/-0.3ka之后。
The subantarctic island of South Georgia provides terrestrial and coastal marine records of climate variability, which are crucial for the understanding of the drivers of Holocene climate changes in the subantarctic region. Here we investigate a sediment core (Co1305) from a coastal inlet on South Georgia using elemental, lipid biomarker, diatom, and stable isotope data to infer changes in environmental conditions and to constrain the timing of late-glacial and Holocene glacier fluctuations. Because of the scarcity of terrestrial macrofossils and the presence of redeposited and relict organic matter in the sediments, age control for the record was obtained by compound-specific radiocarbon dating of mostly marine-derived n-C-16 fatty acids. A basal till layer recovered in Little Jason Lagoon was likely deposited during an advance of local glaciers during the Antarctic cold reversal. After glacier retreat, an oligotrophic lake occupied the site, which transitioned to a marine inlet around 8.0 +/- 0.9 ka because of relative sea-level rise. From 7.0 +/- 0.6 to 4.0 +/- 0.4 ka, reduced vegetation coverage in the catchment, as well as high siliciclastic input and deposition of ice-rafted debris, indicates glacier advances in the terrestrial catchment and likely in the adjacent fjord. A second, less extensive period of glacier advances occurred in the late Holocene, after 1.8 +/- 0.3 ka.