Paleoceanographic Change During the Middle Miocene Climate Revolution: An Antarctic Stable Isotope Perspective
Paleoceanographic Change During the Middle Miocene Climate Revolution: An Antarctic Stable Isotope Perspective
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DOI：
10.1029/151gm14
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发表时间：
2004-01
期刊：
影响因子：
--
通讯作者：
A. Shevenell;J. Kennett
中科院分区：
文献类型：
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作者：
A. Shevenell;J. Kennett
海洋环流和大气pCO 2变化被认为是中中新世冷却和南极冰冻圈扩张的潜在机制。来自南塔斯曼海隆（STR; ODP站点1170和1171）的年代久远的高纬度（南纬55°S）底栖有孔虫稳定同位素记录显示出中中新世气候变化的长期和短期模式以及推断的碳循环动力学。STR记录显示，中中新世δ 18 O主要在14.01 ~ 13.77Ma之间增加（1.2‰）。STR δ 18 O和δ 13 C记录在16.5 ~ 13.5Ma之间变化一致。综合的STR和西南太平洋（0-55°S）稳定同位素时间序列和时间切片数据表明，区域海洋环流变化（>1500 m）与中中新世全球气候转变（16.8-12 Ma）相当。STR稳定同位素和西南太平洋δ 13 C梯度表明，在中新世气候适宜期（MCO）的高峰期（16.8 ~ 16.2 Ma），特提斯海的暖咸水主要影响区域性底层沃茨（>1500 m），并对STR（~ 55°S）产生间歇性影响，直至MCO结束（~ 13.8 Ma）。16.2 Ma时，中、深水沃茨来源由低纬向高纬转移。16.2 Ma时，南海水开始影响STR（>1500 m），14.9 ~ 14.2 Ma和13.8 ~ 12 Ma时，南海水控制西南太平洋（1500-2100 m; 0-55°S）。尽管δ 18 O和δ 13 C的相关性表明pCO 2在其中起一定作用，但这些发现支持了中中新世冷却和南极冰冻圈发展与海洋环流和赤道热通量重组有关的假说。
Ocean circulation and atmospheric pCO 2 variations have been cited as potential mechanisms driving middle Miocene cooling and Antarctic cryosphere expansion. Well-dated high latitude (∼55°S) benthic foraminifer stable isotope records from the South Tasman Rise (STR; ODP Sites 1170 and 1171) exhibit familiar patterns of long and short term middle Miocene climate change and inferred carbon cycle dynamics. STR records illustrate the major middle Miocene δ 18 O increase (1.2‰) between 14.01 and 13.77 Ma. STR δ 18 O and δ 13 C records covary between 16.5 and 13.5 Ma. Integrated STR and southwest Pacific (0-55°S) stable isotope time series and time slice data indicate regional ocean circulation changes (>1500 m) commensurate with the middle Miocene global climate transition (16.8-12 Ma). STR stable isotopes and southwest Pacific meridional δ 13 C gradients suggest that Warm Saline Deep Water from the Tethys Sea dominated regional bottom waters (>1500 m) between 16.8 and 16.2 Ma, during the peak of the Miocene Climatic Optimum (MCO), and exerted intermittent influence on the STR (∼55°S) until the end of the MCO (∼13.8 Ma). A shift from low to high latitude sourced intermediate and deep waters occurred at ∼16.2 Ma. Southern Ocean derived Southern Component Water influenced the STR (>1500 m) beginning at 16.2 Ma and dominated the southwest Pacific (1500-2100 m; 0-55°S) from 14.9 to 14.2 Ma and 13.8 to 12 Ma. Although δ 18 O and δ 13 C coherence suggests some role for pCO 2 , these findings support hypotheses relating middle Miocene cooling and Antarctic cryosphere development to reorganization of oceanic circulation and meridional heat flux.