Macerals analyses of sediment cores from the Laptev Sea@en

In order to reconstruct the depositional environment from the Laptev Sea continental slope and shelf during the past ~15,000 years BP maceral analysis was carried out on two sediment cores (PS2458-4, PS2725-5) and compared with organic-geochemical parameters. During the transition from the Last Glacial to the Holocene the environment of the Laptev Sea shelf was controlled by the post-glacial sea level rise, variations in river discharge, surface-water productivity, and Atlantic-water inflow along the Eurasian continental margin. Based on our results, we identify the following significant changes of the environment: (a) at approximately 13,500 years BP the first step of deglaciation (Termination 1a) is documented by the deposition of marine and fresh-water organic matter; (b) at approximately 10,400 years BP the first post-glacial influence of Atlantic-water inflow along the Eastern Laptev Sea continental margin is indicated by an increase in marine organic matter; (c) at the beginning of the Holocene an increased fluvial supply is documented by an increase in fresh-water alginite; and (d) since ~9500-8000 years BP modern marine conditions are established at the Laptev Sea continental margin as documented in increased amounts of marine macerals, biomarkers (dinosterol, brassicasterol, short-chain fatty acids), and dinoflagellate cysts.为重建过去约15000年前（BP）拉普捷夫海（Laptev Sea）大陆坡与陆架的沉积环境，研究人员对两个沉积岩芯（PS2458-4、PS2725-5）开展了显微组分分析（maceral analysis），并将分析结果与有机地球化学参数进行对比。末次冰期向全新世过渡期间，拉普捷夫海陆架环境受冰后海平面上升、河流径流量变化、表层水生产力以及欧亚大陆边缘大西洋水入侵的共同调控。基于本研究结果，本研究识别出该区域环境的四项显著变化：(a) 约13500年前（BP），末次冰消作用第一阶段（Termination 1a）以海相与淡水有机质的沉积为记录；(b) 约10400年前（BP），拉普捷夫海东部大陆边缘首次出现大西洋水入侵的冰后影响，该信号以海相有机质含量升高为指示；(c) 全新世初期，淡水藻角质体（alginite）含量升高，指示河流输入量显著增加；(d) 约9500~8000年前（BP）以来，拉普捷夫海大陆边缘已形成现代海洋环境，该环境可通过海相显微组分、生物标志物（biomarkers）：甲藻甾醇（dinosterol）、菜籽甾醇（brassicasterol）、短链脂肪酸（short-chain fatty acids）以及鞭毛藻囊孢（dinoflagellate cysts）含量升高得到佐证。