GS Joju, Anish Kumar Warrier, BS Mahesh, AS Yamuna Sali, Cheryl A Noronha-D’Mello, K Balakrishna, Rahul Mohan
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引用次数: 0
摘要
我们从南极洲东部施尔马赫绿洲(Schirmacher Oasis)的一个湖泊沉积物岩芯中获得了全新世中晚期环境变化的高分辨率记录,该记录涵盖了公元前 4.87 千年的时间。研究发现,L6 湖的磁信号主要受集水区铁磁矿物的控制。公元前 4.87 至公元前 3.35 千年期间出现了几次冷暖交替的情况。公元前 3.35 至公元前 2.43 年期间,该地区普遍温暖潮湿。磁感应强度值总体保持在较低水平,这表明细小磁性颗粒是由泥土形成的。化学风化指数值较高,反映了温暖潮湿的条件有利于化学风化。在大约 2.43 cal kyr BP 时,观察到向寒冷干燥条件的过渡,这代表了新冰期的冷却,磁浓度相关参数值较高。在新冰期之后,于公元前 1.63 千年恢复到温暖湿润的条件,与中世纪气候异常同时出现。我们的记录显示,晚全新世的降温以磁感应强度值的突然增加为标志,这可能代表了小冰河时期,随后在岩心顶部附近的条件转为温暖。
A high-resolution record of Mid- to Late-Holocene environmental changes from a land-locked lake in Schirmacher Oasis, East Antarctica
We present a high-resolution record of environmental changes during the Mid-Late Holocene obtained from a lake sediment core covering the past 4.87 cal kyr BP in the Schirmacher Oasis, East Antarctica. The magnetic signal of Lake L6 was found to be primarily controlled by catchment-derived ferrimagnetic minerals. The period between 4.87 and 3.35 cal kyr BP is marked by several episodes of cold and warm conditions. Warm and wet conditions prevailed in the region from 3.35 to 2.43 cal kyr BP. Magnetic susceptibility values remained generally low indicating the pedogenic formation of fine magnetic grains. The high values of the chemical weathering indices reflected the warm and wet conditions conducive to chemical weathering. A transition to cold and dry conditions was observed at around 2.43 cal kyr BP, representing the Neoglacial cooling, with high values of magnetic concentration-dependent parameters. Following the Neoglacial period, a return to warm and wet conditions was observed at 1.63 cal kyr BP, coeval with the Medieval Climate Anomaly. Our record shows a Late-Holocene cooling marked by a sudden increase in magnetic susceptibility values, which could represent the Little Ice Age, followed by a shift to warmer conditions near the core top.