Organic geochemistry of ODP Leg 107 sediments@en

The Rock-Eval pyrolysis of rock samples and the elemental analysis of kerogens show clear differences between Messinian black shales and Pliocene-Pleistocene sapropels recovered during ODP Leg 107. The Messinian black shales are characterized by a large variety of compositions which probably reflects a great diversity of depositional and diagenetic paleoenvironments. In contrast, the Pliocene-Pleistocene sapropels, occurring as discrete layers in nannofossil oozes barren of organic carbon, constitute a rather homogeneous group in terms of organic content. A considerable contribution of terrestrial organic matter in the sapropels could mean that an identical phenomenon of terrestrial input has been periodically reproduced in the basin. The maturity and the nature of the organic matter are discussed with respect to anomalous values recorded for Tmax parameter.对岩样开展的Rock-Eval热解分析以及干酪根元素分析结果显示，大洋钻探计划（Ocean Drilling Program, ODP）第107航次所获取的墨西拿期黑色页岩与上新世-更新世腐泥岩之间存在显著差异。墨西拿期黑色页岩具有多样的组分特征，这大概率反映了沉积和成岩古环境的高度多样性。与之形成鲜明对比的是，赋存于不含有机碳的超微化石软泥中的离散层状上新世-更新世腐泥岩，在有机碳含量方面呈现出相当均一的特征。腐泥岩中陆生有机质占比可观，这或许意味着该盆地曾周期性重现了陆生有机质输入的同一地质过程。研究结合Tmax参数的异常记录，对有机质的成熟度与性质展开了讨论。