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Evolution of deep-sea sediments across the Paleocene-Eocene and Eocene-Oligocene boundaries
Earth-Science Reviews ( IF 10.8 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.earscirev.2020.103403
Bridget S. Wade , James F. O'Neill , Chawisa Phujareanchaiwon , Imran Ali , Mitchell Lyle , Jakub Witkowski

Abstract The composition and distribution of deep-sea sediments is the result of a multitude of climatic, biotic and oceanic conditions relating to biogeochemical cycles and environmental change. Here we utilize the extensive sediment archives of the International Ocean Discovery Program (IODP) and its predecessors to construct maps of deep-sea sediment type across two critical but contrasting boundaries in the Paleogene, one characterised by an interval of extreme warmth (Paleocene/Eocene) and the other by global cooling (Eocene/Oligocene). Ocean sediment distribution shows significant divergence both between the latest Paleocene and Paleocene Eocene Thermal Maximum (PETM), across the Eocene-Oligocene Transition (EOT), and in comparison to modern sediment distributions. Carbonate sedimentation in the latest Paleocene extends to high southern latitudes. Disappearance of carbonate sediments at the PETM is well documented and can be attributed to dissolution caused by significant ocean acidification as a result of carbon-cycle perturbation. Biosiliceous sediments are rare and it is posited that the reduced biogenic silica deposition at the equator is commensurate with an overall lack of equatorial upwelling in the early Paleogene ocean. In the Southern Ocean, we attribute the low in biosiliceous burial, to the warm deep water temperatures which would have impacted biogenic silica preservation. In the late Eocene, our sediment depositional maps record a tongue of radiolarian ooze in the eastern equatorial Pacific. Enhanced biosiliceous deposits in the late Eocene equatorial Pacific and South Atlantic are due to increased productivity and the spin-up of the oceans. Our compilation documents the enhanced global carbonate sedimentation in the early Oligocene, confirming that the drop in the carbonate compensation depth was global.

中文翻译:

跨越古新世-始新世和始新世-渐新世边界的深海沉积物演化

摘要 深海沉积物的组成和分布是与生物地球化学循环和环境变化相关的多种气候、生物和海洋条件的结果。在这里,我们利用国际海洋发现计划 (IODP) 及其前身的大量沉积物档案,构建了古近纪两个关键但对比鲜明的边界的深海沉积物类型图,其中一个以极端温暖的间隔(古新世/始新世)为特征)和另一个通过全球冷却(始新世/渐新世)。海洋沉积物分布显示了最新的古新世和古新世始新世热最大值 (PETM)、始新世-渐新世过渡 (EOT) 之间以及与现代沉积物分布相比的显着差异。最新古新世的碳酸盐沉积延伸到南高纬度地区。PETM 碳酸盐沉积物的消失有充分的记录,可归因于碳循环扰动导致海洋显着酸化引起的溶解。生物硅质沉积物很少见,据推测,赤道生物硅沉积物的减少与古近纪早期海洋中赤道上升流的总体缺乏相称。在南大洋,我们将生物硅质埋藏量低归因于温暖的深水温度,这会影响生物硅质的保存。在始新世晚期,我们的沉积物沉积图记录了赤道东太平洋的放射虫软泥舌。始新世晚期赤道太平洋和南大西洋的生物硅质沉积物增加是由于生产力的提高和海洋的旋转。我们的汇编记录了渐新世早期全球碳酸盐沉积的增强,证实碳酸盐补偿深度的下降是全球性的。
更新日期:2020-12-01
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