Sediment waves on the Conrad Rise, Southern Indian Ocean : implications for the migration history of the Antarctic Circumpolar Current
Sediment waves on the Conrad Rise, Southern Indian Ocean : implications for the migration history of the Antarctic Circumpolar Current
复制标题
南印度洋康拉德隆起的沉积波：对南极绕极流迁移历史的影响
DOI：
10.1016/j.margeo.2013.10.008
复制
发表时间：
2013
期刊：
影响因子：
2.9
通讯作者：
Y
中科院分区：
文献类型：
--
作者：
Oiwane;H.;Ikehara;M.;Suganuma;Y.;Miura;H.;Nakamura;Y.;Sato,T.;Nogi;Y.;Yamane;M.;Yokoyama;Y
南极绕极流（ACC）是世界上最长、最大的洋流系统；因此，它在全球热量、养分和温室气体的分布中起着突出的作用。虽然一些研究利用南大洋的沉积记录重建了太平洋环流过去的变化，但对其时空变异性与地球气候系统变化之间关系的详细了解仍不清楚。在这项研究中，我们对位于ACC南印度洋区域的康拉德隆起进行了多波束测深、多通道地震反射和沉积物取心调查。这些资料揭示了地震剖面（A单元）上部具有低至中等反射振幅的连续和平行反射波的大尺度沉积波结构。这些现象很可能是由底部洋流与海底的相互作用和ACC下的沉积物输送形成的。根据浅层沉积岩心的沉积速率外推，估计A单元的基底年龄小于上新世/更新世边界。剖面下部（B单元）的特征是中等至高振幅的亚水平到水平反射，被解释为上层沉积，对单元上部的电流影响更强。根据与南大洋ODP位置的对比，我们估计B单元上部主要由钙质软泥组成。从B地震单元到A地震单元的沉积环境变化的年代尚未明确，但认为是由ACC向北移动引起的。
The Antarctic Circumpolar Current (ACC) is the worlds longest and largest current system; therefore, it plays a prominent role in the global distribution of heat, nutrients and greenhouse gasses. While past changes in the ACC have been reconstructed by a number of studies using sedimentary records in the Southern Ocean, a detailed understanding of the relationship between its temporal and spatial variability and the changes in the Earths climatic system remains unclear. In this study, we conducted multibeam bathymetry, multi-channel seismic reflection, and sediment coring surveys on the Conrad Rise, located in the southern Indian Ocean sector of the ACC. These data reveal large scale sediment wave structures with continuous and parallel reflectors that have low to moderate reflection amplitudes in the upper part of the seismic section (Unit A). These phenomena are most likely formed by bottom current interactions with the sea-floor and sediment transport under the ACC. The basal age of Unit A is estimated to be younger than Pliocene/Pleistocene boundary based on the extrapolation of sedimentation rates from a shallow sedimentary core. The lower part of the section (Unit B) is characterized by moderate to high amplitude sub-horizontal to horizontal reflectors that are interpreted as pelagic sedimentation with stronger current influence to the upper part of the unit. Based on the correlation with ODP sites in the Southern Ocean, we estimate that the upper part of Unit B mainly comprises calcareous ooze. Though the age of the change in the sedimentary environment from seismic Units B to A is not specified, it is thought to be caused by a northward shift of the ACC.