Enhanced paleoproductivity across the Oligocene/Miocene boundary as evidenced by benthic foraminiferal accumulation rates
Enhanced paleoproductivity across the Oligocene/Miocene boundary as evidenced by benthic foraminiferal accumulation rates
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DOI：
10.1016/j.palaeo.2011.02.006
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发表时间：
2011-03
期刊：
影响因子：
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通讯作者：
L. Diester-Haass;K. Billups;K. Emeis
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文献类型：
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作者：
L. Diester-Haass;K. Billups;K. Emeis
渐新世至中新世界线（23 Ma）标志着新生代主要的冷却步骤之一。在全球分布的沉积物岩芯中，底栖有孔虫方解石中相应但稍滞后的δ 13 C最大值被归因于陆地或海洋中有机物埋藏的增加。为了验证这一想法，我们重建的有机碳通量的海底在三个大西洋钻探计划（ODP）网站使用底栖有孔虫积累率（BFAR），并将其与稳定同位素记录。我们的数据表明，δ 18 O和δ 13 C最大值的特征渐新世/中新世边界伴随着一个明显的最大值在BFAR推导的古生产力在两个网站。在热带大西洋926站，渐新世/中新世界线的古生产力增长小于高纬度站，但22- 24 Ma的高分辨率采样表明，在偏心率时间尺度上，生产力和稳定同位素记录显著相关。在短期（~ 125 ky）偏心率分量上，产能记录与δ 18 O和δ 13 C记录同相。在长期偏心率时期（~ 400 ky），生产力与δ 18 O同相，但领先δ 13 C记录一定量，该量与已发表的δ 18 O和δ 13 C记录之间的相位滞后一致。这些结果意味着，有增强的有机物通量的洋底在O/M气候过渡和支持，海洋初级生产力可能发挥了作用，在这个时候的碳循环和大气CO2下降。
The Oligocene to Miocene boundary (23Ma) marks one of the major Cenozoic cooling steps. A corresponding but slightly lagging δ13C maximum in benthic foraminifer calcite of globally distributed sediment cores has been attributed to increased organic matter burial, either on land or in the oceans. To test this idea we reconstruct the organic carbon flux to the sea floor at three Atlantic Ocean Drilling Program (ODP) Sites using benthic foraminiferal accumulation rates (BFAR) and compare them with the stable isotope records. Our data show that the δ18O and δ13C maximum that characterizes the Oligocene/Miocene boundary is accompanied by a pronounced maximum in BFAR derived paleoproductivity at two of the sites. At tropical Atlantic Site 926 the paleoproductivity increase at the Oligocene/Miocene boundary is smaller than at the higher latitude sites, but high resolution sampling of a 2million year interval (22–24Ma) reveals that on eccentricity time scales productivity and stable isotope records are significantly correlated. The productivity records are in phase with the δ18O and δ13C records at the short-term (~125ky) component of eccentricity. At the long-term eccentricity period (~400ky) productivity is in phase with δ18O but leads the δ13C record by an amount that is consistent with published phase lags between the δ18O and δ13C records. These results imply that there was enhanced flux of organic matter to the ocean floor during the O/M climate transition and support that marine primary productivity may have played a role in the carbon cycle and atmospheric CO2draw-down at this time.