Biomarker records from lacustrine sediments, Larsemann Hills, East Antarctica

Abstract

东南极拉斯曼丘陵地区莫愁湖（69°22.3’ S，76°22.0’ E）沉积柱中的有机生物标志物记录了全新世中晚期该地区气候演变过程。不饱和长链烯酮在沉积柱111-76 cm （6450-5100 cal. yr. BP）和36-30 cm（3700-3500 cal. yr. BP）深度有检出，76 cm深度以上基本消失，表明该地区在5100 cal. yr. BP前后气候开始由冷转暖，冰川消融，陆壳抬升，相对海平面下降，同时大量的冰融水使湖泊逐渐淡化。沉积柱底部长链烯酮的检出阶段与东南极相对海平面较高时期相一致，而沉积柱36-30 cm（3700-3500 cal. yr. BP）深度不饱和长链烯酮的痕量检出则揭示了一个短暂的气候干冷，湖泊盐度升高的时期。沉积物中正构烷烃反映的当地气候变化所控制的湖生植物群落演变过程与上述过程基本一致。 Biomarker records from Mochou lake sediments, Larsemann Hills (69°22.3′S, 76°22.0′E), East Antarctica, reveals mid-late Holocene climate history in the region. . As biomarkers for a limited number of certain haptophytes, the long chain alkenones (LCAs) were found from bottom to 76 cm of the sediment core (6500-5100 cal. yr. BP), a period with high relative sea level. Trace amounts of LCAs were also found at 36-30 cm (3700-3500 cal. yr. BP), which reflected change of lake salinity caused by cold climate with fewer ice melt water and higher evaporation. The absence of LCAs above 76cm (about 5100 cal. yr. BP) was consistent with the climate switching from cold to warm and gradually dropping of relative sea level, resulting in more glacial melting water and less intrusion of sea water. The evolution of n-alkanes (C19-C33) reflected the same history of hygrophyte population.