Onset and role of the Antarctic Circumpolar Current
Onset and role of the Antarctic Circumpolar Current
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DOI：
10.1016/j.dsr2.2007.07.028
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发表时间：
2007-01-01
影响因子：
3
通讯作者：
Scher, Howard D.
中科院分区：
文献类型：
--
作者：
Barker, Peter F.;Filippelli, Gabriel M.;Scher, Howard D.
有一段时间，南极绕极流（ACC）的出现被认为是导致或稳定了南极冰川的形成。然而，最近行政协调会在这方面的重要性受到质疑。为了了解ACC和南极冰川之间的关系，从而了解海洋环流对古气候的重要性，我们需要确定这两个过程的发展历史。为此，我们总结了所有已发表的估计ACC发作。无论是根据构造研究，还是根据对沉积物记录变化的解释，都无法确定爆发的时间，无论是浅层环流还是深层环流。已经确定了环极气流的两个潜在的最终障碍;塔斯马尼亚南部和南美洲南部。前者受构造和海洋地质条件的制约，在32 Ma前形成深空区，最晚在35.5Ma前形成浅空区。这些年龄与33-34 Ma的南极冰川完全开始吻合，尽管一些工作者质疑因果关系。无论是根据构造学还是沉积地质学，对后者开启时间的估计范围很广，从最近的6 Ma到最早的41 Ma，差距深度也不确定。通过额外的调查解决基于构造的不确定性很可能既耗时又不确定，并且地质估计对其他解释开放，我们定义了额外的采样和测量的最佳策略，旨在更确定地解决发病时间，也可能解决深和浅开口之间的问题，从而限制ACC的作用。取样点必须靠近可能的最后屏障，以避免外来影响，并在ACC影响的现代区域内，理想的情况是形成一个深度样带，并具有连续的陆源和生源混合剖面。每一次都将测量一系列精心挑选的参数。(C)2007爱思唯尔有限公司保留所有权利。
For some time, onset of the Antarctic Circumpolar Current (ACC) was considered to have caused or stabilised full Antarctic glaciation. Recently, however, the importance of the ACC in this role has been questioned. In order to understand the relationship between the ACC and Antarctic glaciation, and thence the importance of ocean circulation to palaeoclimate, we need to determine the development history of both processes. To this end, we summarise all published estimates of ACC onset. The time of onset, of shallow circulation or deep, is uncertain, whether based on tectonic studies or the interpretation of changes in the sediment record. Two potential final barriers to circumpolar flow have been identified; south of Tasmania and south of South America. The former is well constrained by tectonics and marine geology to before 32 Ma for a deep gap, with a shallow gap in place by 35.5 Ma at the latest. These ages fit nicely with the onset of full Antarctic glaciation at 33-34 Ma, although some workers question the causality. Estimates of the time of opening of the latter range widely, whether based on tectonics or sedimentary geology, from as recently as 6 Ma to as early as 41 Ma, with the gap depth uncertain also. Resolution of the tectonics-based uncertainties by additional survey being most probably both time-consuming and inconclusive, and the geological estimates being open to alternative interpretations, we define an optimal strategy for additional sampling and measurement, designed to resolve the time of onset more certainly, possibly also resolving between deep and shallow opening, and thereby constraining the ACC role. Sample sites would have to be close to likely final barriers, to avoid extraneous influence, and within modern zones of ACC influence, ideally would form a depth transect, and would have continuous, mixed terrigenous and biogenic sections. A wide range of carefully selected parameters would be measured at each. (C) 2007 Elsevier Ltd. All rights reserved.