Holocene Indian Ocean sea level, Antarctic melting history and past Tsunami deposits inferred using sea level reconstructions from the Sri Lankan, Southeastern Indian and Maldivian coasts
Holocene Indian Ocean sea level, Antarctic melting history and past Tsunami deposits inferred using sea level reconstructions from the Sri Lankan, Southeastern Indian and Maldivian coasts
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利用斯里兰卡、印度东南部和马尔代夫海岸的海平面重建推断出全新世印度洋海平面、南极融化历史和过去的海啸沉积物
DOI：
10.1016/j.quascirev.2018.11.024
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发表时间：
2019
影响因子：
4
通讯作者：
Miyairi Yosuke
中科院分区：
文献类型：
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作者：
Yokoyama Yusuke;Hirabayashi Shoko;Goto Kazuhisa;Okuno Jun'ichi;Sproson Adam D.;Haraguchi Tsuyoshi;Ratnayake Nalin;Miyairi Yosuke
利用地球化学和地球物理方法研究了北方印度洋全新世海平面变化。从斯里兰卡南部沿海泻湖取回的沉积物岩心进行放射性碳测年，对软体动物进行了二次取样。然后将它们与先前发表的来自同一泻湖的沉积物岩心放射性碳年龄相结合。我们观察到在4 ka左右，沉积速率减少了20倍，这是由于海平面上升速率的降低。以前报道的放射性碳年龄的基础上总有机质在泻湖显示显着的协议与我们的新的日期表明稳定和均匀的沉积在过去的8万年。对比两个数据集的岩芯年龄趋势发现，除与古海啸层相邻的层位外，沉积物的年龄均大于同期软体动物的年龄，表明海啸事件期间提供了新鲜和较年轻的沉积物，这可能成为识别古海啸的新代理。对斯里兰卡、印度东南部和马尔代夫先前报告的海平面指标的汇编，以及从冰川-水文-均衡调整模型（GIA）获得的预测海平面，表明在全新世中期，由于南极和/或格陵兰冰盖的退缩，全球海平面相当于冰盖融化了3-4米。早期的研究表明，全新世晚期（约。4ka）低纬和高纬气候异常。我们认为，晚全新世低纬气候异常通过大气向高纬传递，可能引起了极地冰盖的变化。
Holocene sea level change in the northern Indian Ocean was studied using geochemical and geophysical approaches. Molluscs were sub-sampled for radiocarbon dating from sediment cores retrieved from a south Sri Lankan coastal lagoon. They were then combined with previously published sediment core radiocarbon ages from the same lagoon. We observe a ∼20-fold reduction in sedimentation rates at around 4 ka, attributed to a decrease in the rate of sea level rise. Previously reported radiocarbon ages based on total organic matter in the lagoon show remarkable agreement with our new dates suggesting stable and homogeneous sedimentation during the last 8 ka. Comparison of down core age trends of both data sets reveal that sediments are older than coeval molluscs, except for the horizons adjacent to the paleo Tsunami layers, indicating fresh and younger sediments are provided during Tsunami events, which could become a new proxy for identifying paleo Tsunamis. Compilation of previously reported sea level indicators from Sri Lanka, Southeastern India and the Maldives, together with predicted sea level obtained from a glacio-hydro-isostatic adjustment model (GIA), suggest that 3–4 m of global sea level equivalent ice sheet melting occurred during the Mid Holocene due to the retreat of the Antarctic and/or Greenland ice sheets. Previous works suggests late Holocene (ca. 4 ka) climate anomalies in both the low and high latitudes. We suggest the low latitude climate anomaly, transmitted via atmosphere to the high latitude during the late Holocene, seems to have induced changes in polar ice sheets.