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首页> 外文期刊>Paleoceanography >Paleogene biomarker records from the central Arctic Ocean (Integrated Ocean Drilling Program Expedition 302): Organic carbon sources, anoxia, and sea surface temperature
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Paleogene biomarker records from the central Arctic Ocean (Integrated Ocean Drilling Program Expedition 302): Organic carbon sources, anoxia, and sea surface temperature

机译：来自北冰洋中部的古生物标志物记录（综合海洋钻探计划探险队302）：有机碳源，缺氧和海面温度

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摘要

During Integrated Ocean Drilling Program Expedition 302 (Arctic Coring Expedition (ACEX)) a more than 200 m thick sequence of Paleogene organic carbon (OC)-rich (black shale type) sediments was drilled. Here we present new biomarker data determined in ACEX sediment samples to decipher processes controlling OC accumulation and their paleoenvironmental significance during periods of Paleogene global warmth and proposed increased freshwater discharge in the early Cenozoic. Specific source-related biomarkers including n-alkanes, fatty acids, isoprenoids, carotenoids, hopanes/hopenes, hopanoic acids, aromatic terpenoids, and long-chain alkenones show a high variability of components, derived from marine and terrestrial origin. The distribution of hopanoic acid isomers is dominated by compounds with the biological 17 beta(H), 21 beta(H) configuration indicating a low level of maturity. On the basis of the biomarker data the terrestrial OC supply was significantly enriched during the late Paleocene and part of the earliest Eocene, whereas increased aquatic contributions and euxinic conditions of variable intensity were determined for the Paleocene-Eocene thermal maximum and Eocene thermal maximum 2 events as well as the middle Eocene time interval. Furthermore, samples from the middle Eocene are characterized by the occurrence of long-chain alkenones, high proportions of lycopane, and high ratios (> 0.6) of (n-C-35 + lycopane)-C-31. The occurrence of C-37-alkenenones, which were first determined toward the end of the Azolla freshwater event, indicates that the OC becomes more marine in origin during the middle Eocene. Preliminary U(37)(K'-)based sea surface temperature (SST) values display a longterm temperature decrease of about 15 degrees C during the time interval 49-44.5 Ma (25 degrees to 10 degrees C), coinciding with the global benthic delta O-18 cooling trend after the early Eocene climatic optimum. At about 46 Ma, parallel with onset of ice-rafted debris, SST (interpreted as summer temperatures) decreased to values < 15 degrees C. For the late early Miocene a SST of 11 degrees-15 degrees C was determined. Most of the middle Eocene ACEX sediments are characterized by a smooth short-chain n-alkane distribution, which may point to natural oil-type hydrocarbons from leakage of petroleum reservoirs or erosion of related source rocks and redeposition.
机译：在302号综合海洋钻探计划探险队（北极取心探险队（ACEX））期间，钻了200 m厚的富含古有机碳（OC）（黑色页岩型）沉积物序列。在这里，我们介绍了在ACEX沉积物样品中确定的新生物标记数据，以解释在古近纪全球温暖期间控制OC积累及其古环境意义的过程，并提出在新生代早期增加淡水排放量。与源相关的特定生物标志物，包括正构烷烃，脂肪酸，类异戊二烯，类胡萝卜素，hop烷/戊糖、,烷酸，芳香族萜烯和长链烯酮，显示出源自海洋和陆地的成分差异很大。蛇麻酸异构体的分布主要由具有17β（H），21β（H）生物学构型的化合物所主导，表明其成熟度较低。根据生物标记数据，在古新世晚期和部分始新世期间，陆地OC的供应明显丰富，而对于古新世-始新世热最大值和始新世热最大值2事件，确定了水生贡献的增加和强度可变的好氧条件。以及始新世中期间隔。此外，来自始新世中期的样品的特征是长链烯酮的出现，高比例的番茄红素和高比例（> 0.6）的（n-C-35 +番茄红素）/ n-C-31。首先在Azolla淡水事件即将结束时确定的C-37链烯酮的出现表明，在始新世中期，OC起源于海洋。初步的基于U（37）（K'-）的海面温度（SST）值在49-44.5 Ma（25到10摄氏度）的时间间隔内显示约15摄氏度的长期温度下降，这与全球底栖生物相符始新世早期气候最佳之后，δO-18冷却趋势。在约46 Ma时，与冰激凌碎片的爆发平行，SST（被解释为夏季温度）降低至<15摄氏度。对于中新世晚期晚期，确定的SST为11摄氏度至15摄氏度。大部分中新世始新世ACEX沉积物的特征是光滑的短链正构烷烃分布，这可能是由于油气藏泄漏或相关烃源岩的侵蚀和再沉积所导致的天然石油型烃。

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