Paleogene biomarker records from the central Arctic Ocean (Integrated Ocean Drilling Program Expedition 302): Organic carbon sources, anoxia, and sea surface temperature
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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DOI：
10.1029/2007pa001472
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发表时间：
2008-03
期刊：
影响因子：
--
通讯作者：
P. Weller;R. Stein
中科院分区：
文献类型：
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作者：
P. Weller;R. Stein
[1]在综合大洋钻探计划第302次考察（北极取芯考察（ACEX））期间，钻探了一个200多米厚的富含有机碳（OC）的（黑色页岩型）沉积物序列。在这里，我们提出了新的生物标志物数据确定的ACEX沉积物样品破译控制过程中的OC积累和古环境的意义，在古近纪全球变暖的时期，并提出在新生代早期增加淡水排放。特定的源相关的生物标志物，包括正烷烃，脂肪酸，类异戊二烯，类胡萝卜素，藿烷/藿烯，藿烷酸，芳香萜类化合物，和长链烯酮显示出很高的变异性的组件，来自海洋和陆地起源。藿烷酸异构体的分布主要由具有生物学17β（H）、21β（H）构型的化合物控制，表明成熟度较低。的生物标志物数据的基础上，陆地有机碳供应显着丰富的古新世晚期和部分最早的始新世，而增加水生的贡献和不同强度的缺氧条件的古新世始新世热最大和始新世热最大2事件，以及始新世中期的时间间隔。此外，中始新世的样品的特征在于长链烯酮的存在，高比例的lycopane和高比例（>0.6）的（n-C35 + lycopane）/n-C31。C37-烯烯酮的出现，这是第一次确定接近年底的红萍淡水事件，表明OC成为更多的海洋起源在始新世中期。基于U37 K ′的初步海表温度（SST）值显示，在49-44.5 Ma（25°至10°C）的时间间隔内，温度长期下降约15°C，与早始新世气候最佳期后全球底栖δ 18 O冷却趋势一致。在大约46 Ma，与冰筏碎片的出现平行，SST（解释为夏季温度）下降到<15°C的值。早中新世晚期的SST为11°-15 ° C。中始新世ACEX沉积物中短链正构烷烃分布较平缓，可能是油气藏渗漏或相关烃源岩剥蚀再沉积形成的天然油型烃。
[1] 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 17β(H), 21β(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-C35 + lycopane)/n-C31. The occurrence of C37-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 U37K′-based sea surface temperature (SST) values display a long-term temperature decrease of about 15°C during the time interval 49–44.5 Ma (25° to 10°C), coinciding with the global benthic δ18O 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°C. For the late early Miocene a SST of 11°–15°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.