Miocene deepwater oceanography
Miocene deepwater oceanography
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DOI：
10.1029/pa004i001p00087
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发表时间：
1989-02
期刊：
影响因子：
--
通讯作者：
F. Woodruff;S. Savin
中科院分区：
文献类型：
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作者：
F. Woodruff;S. Savin
中新世底栖有孔虫碳氧同位素和动物丰度数据的全球综合表明，中新世温盐环流演化经历了大约对应于中新世早期、中期和晚期的三个阶段。有证据表明，现代海洋的环流与 11 Ma 之前的中新世海洋之间存在重大的质的差异。底栖有孔虫 Cibicidoides 的 13C/12C 比率可以根据水团老化来解释，即随着水从海洋表面的源头进一步流动，由于有机物氧化，溶解的 O2 逐渐耗尽，δ13C 值降低。同位素和动物群数据都表明，中新世早期（22 至 15 Ma）与今天的情况最大不同。在此期间，大西洋和太平洋的中层和深层水域都向北老化，而印度洋、南大西洋和南太平洋的中层水域始终是全球海洋中最年轻的。我们推测，中新世早期的全球温盐环流可能受到温暖咸水（特提斯印度咸水）从特提斯流入北印度洋的强烈影响。同位素和动物群数据表明，从特提斯地区流入印度洋的水流在大约 14 Ma 时减少或终止。同位素和动物群数据没有提供北大西洋深水 (NADW) 在大约 14.5 Ma 之前形成的证据（除了中新世早期的短暂事件）。从 14.5 Ma 到 11 Ma，NADW 形成很弱，随着南极冰盖的增长，环极地和南极海水淹没了南大西洋和南太平洋深处。从大约 10Ma 到中新世末期，温盐环流在很多方面与现代环流相似。在中新世晚期（6 到 5 Ma），环流模式与今天非常相似，只是 NADW 的形成大大减少。中新世沉积物中硅质软泥的分布模式与我们提出的温盐环流重建一致。中中新世期间发生的环流的重大变化可能与特提斯洋的关闭有关，并可能导致南极冰盖中中新世的快速增长。附录 1、4、6 和 7 可与整篇文章的缩微胶片一起获取。美国地球物理联盟订购，2000 Florida Avenue, N.W., Washington, DC 20009。文件 88P-002； 5.00 美元。付款必须伴随订单。
A global synthesis of Miocene benthic foraminiferal carbon and oxygen isotopic and faunal abundance data indicates that Miocene thermohaline circulation evolved through three regimes corresponding approximately to early, middle, and late Miocene times. There is evidence for major qualitative differences between the circulation of the modern ocean and the Miocene ocean prior to 11 Ma. The 13C/12C ratios of the benthic foraminifera Cibicidoides are interpreted in terms of water mass aging, i.e., the progressive depletion of dissolved O2 and lowering of δ13C values as the result of oxidation of organic matter as water flows further from its sources at the surface of the oceans. Both isotopic and faunal data indicate that the early Miocene regime, from 22 to 15 Ma, was the most different from today's. During that interval intermediate and deep waters of both the Atlantic and the Pacific oceans aged in a northward direction, and the intermediate waters of the Indian, the South Atlantic and the South Pacific oceans were consistently the youngest in the global ocean. We speculate that early Miocene global thermohaline circulation may have been strongly influenced by the influx of warm saline water, Tethyan Indian Saline Water, from the Tethys into the northern Indian Ocean. The isotopic and faunal data suggest that flow from the Tethyan region into the Indian Ocean diminished or terminated at about 14 Ma. Isotopic and faunal data give no evidence for North Atlantic Deep Water (NADW) formation prior to about 14.5 Ma (with the exception of a brief episode in the early Miocene). From 14.5 to 11 Ma NADW formation was weak, and circumpolar and Antarctic water flooded the deep South Atlantic and South Pacific as the Antarctic ice cap grew. From about 10 Ma to the end of the Miocene, thermohaline circulation resembled the modern circulation in many ways. In latest Miocene time (6 to 5 Ma) circulation patterns were very similar to today's except that NADW formation was greatly diminished. The distribution pattern of siliceous oozes in Miocene sediments is consistent with our proposed reconstruction of thermohaline circulation. Major changes which occurred in circulation during the middle Miocene were probably related to the closing of the Tethys and may have contributed to rapid middle Miocene growth of the Antarctic ice cap. Appendices 1, 4, 6, and 7 are available withentire article on microfiche. Order fromAmerican Geophysical Union, 2000 FloridaAvenue, N.W., Washington, DC 20009.Document 88P-002; $5.00. Payment mustaccompany order.