Early Oligocene glaciation and productivity in the eastern equatorial Pacific: Insights into global carbon cycling
Early Oligocene glaciation and productivity in the eastern equatorial Pacific: Insights into global carbon cycling
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DOI：
10.1029/2010pa002021
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发表时间：
2011-06-11
期刊：
影响因子：
--
通讯作者：
Wilson, Paul A.
中科院分区：
文献类型：
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作者：
Coxall, Helen K.;Wilson, Paul A.
在始新世-渐新世过渡期（EOT）持续的南极冰川作用的开始标志着地球气候的关键变化，但我们对这一事件的理解，特别是碳循环的作用，是有限的。为了弥补这一空白，我们提供了赤道东太平洋大洋钻探计划1218站（EEP）的以下古海洋代用记录：（1）表层底栖有孔虫（Cibicidoides spp.）改进（分辨率加倍）以前公布的记录;（2）在Oridorsalis umbonatus（一种浅水底栖物种）上测量的δ O-18和δ C-13记录;（3）底栖有孔虫积累率记录。我们新的同位素数据集证实了1218号站点存在两步δ O-18增加。他们还提供支持的假设存在一个晚始新世短暂三角洲O-18增加和早渐新世Oi-1a和Oi-1b冰川最大。我们的BFAR记录表明，一个短暂的（类似500 kyr）的两倍到三倍的峰值相对于基线渐新世的值与南极冰川的开始，我们归因于增强生物出口生产的EEP。这与南大洋蛋白石积累的历史具有相同的一般形式，表明高纬度与低纬度的海洋耦合很强。这些发现似乎支持EOT delta C-13漂移可追溯到有机碳（C-org）埋藏增加的想法。巧合的是，早渐新世沉积物中的EEP是非常C-org-穷人，和大气pCO（2）的代用品记录表明一个短暂的增加与EOT。
The onset of sustained Antarctic glaciation across the Eocene-Oligocene transition (EOT) marks a pivotal change in Earth's climate, but our understanding of this event, particularly the role of the carbon cycle, is limited. To help address this gap we present the following paleoceanographic proxy records from Ocean Drilling Program Site 1218 in the eastern equatorial Pacific (EEP): (1) stable isotope (delta O-18 and delta C-13) records generated in epifaunal benthic foraminifera (Cibicidoides spp.) to improve (double the resolution) the previously published records; (2) delta O-18 and delta C-13 records measured on Oridorsalis umbonatus, a shallow infaunal species; and (3) a record of benthic foraminifera accumulation rate (BFAR). Our new isotope data sets confirm the existence at Site 1218 of a two-step delta O-18 increase. They also lend support to the hypothesized existence of a late Eocene transient delta O-18 increase and early Oligocene Oi-1a and Oi-1b glacial maxima. Our record of BFAR indicates a transient (similar to 500 kyr) twofold to threefold peak relative to baseline Oligocene values associated with the onset of Antarctic glaciation that we attribute to enhanced biological export production in the EEP. This takes the same general form as the history of opal accumulation in the Southern Ocean, suggesting strong high-to-low-latitude oceanic coupling. These findings appear to lend support to the idea that the EOT delta C-13 excursion is traceable to increased organic carbon (C-org) burial. Paradoxically, early Oligocene sediments in the EEP are extremely C-org-poor, and proxy records of atmospheric pCO(2) indicate a transient increase associated with the EOT.