Southern ocean warming, sea level and hydrological change during the Paleocene-Eocene thermal maximum
Southern ocean warming, sea level and hydrological change during the Paleocene-Eocene thermal maximum
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DOI：
10.5194/cp-7-47-2011
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发表时间：
2010-09
影响因子：
4.3
通讯作者：
A. Sluijs;P. Bijl;Stefan Schouten;U. Röhl;G. Reichart;H. Brinkhuis
中科院分区：
文献类型：
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作者：
A. Sluijs;P. Bijl;Stefan Schouten;U. Röhl;G. Reichart;H. Brinkhuis
摘要。一个短暂的全球平均地表变暖期（约150 kyr）标志着约5600万年前的古新世和始新世之间的过渡。这个所谓的“古新世-始新世热极大值”（PETM）与13c -贫碳的大量注入有关，反映在负碳同位素偏移（CIE）上。生物响应包括亚热带鞭毛藻Apectodinium的全球丰度峰值（acme）。本文在ODP (Ocean Drilling Program) Site 1172对东塔斯曼高原的海相沉积序列进行了始新世纪（PETM）识别，并根据TEX86有机古温计显示，在始新世纪（PETM）期间，西南太平洋海面温度从~26°C上升至~33°C。在始新世纪之前、期间和之后的这些温度比古气候模式模拟在该纬度预测的温度高10°C左右。在某种程度上，这种差异可以用极地海洋中TEX86代用物潜在的季节偏差来解释。此外，数据表明，在当前一代完全耦合的气候模式对古代温室气候的模拟中，不仅北极，南极的温度也可能被低估。大量Apectodinium的早期涌入证实了全球范围内的环境变化先于CIE。有机鞭毛藻包囊组合表明，在PETM期间到达岩心地点的河流径流量局部减少，可能与海平面上升相一致。此外，这些组合表明了区域水文系统和风暴活动的季节性变化。最后，PETM期间鞭毛藻囊组合的显著变化表明西南太平洋气候在103 - 104年的时间尺度上发生了显著变化，这一发现与新泽西大陆架PETM演替的类似研究结果相当。
Abstract. A brief (~150 kyr) period of widespread global average surface warming marks the transition between the Paleocene and Eocene epochs, ~56 million years ago. This so-called "Paleocene-Eocene thermal maximum" (PETM) is associated with the massive injection of 13C-depleted carbon, reflected in a negative carbon isotope excursion (CIE). Biotic responses include a global abundance peak (acme) of the subtropical dinoflagellate Apectodinium. Here we identify the PETM in a marine sedimentary sequence deposited on the East Tasman Plateau at Ocean Drilling Program (ODP) Site 1172 and show, based on the organic paleothermometer TEX86, that southwest Pacific sea surface temperatures increased from ~26 °C to ~33°C during the PETM. Such temperatures before, during and after the PETM are >10 °C warmer than predicted by paleoclimate model simulations for this latitude. In part, this discrepancy may be explained by potential seasonal biases in the TEX86 proxy in polar oceans. Additionally, the data suggest that not only Arctic, but also Antarctic temperatures may be underestimated in simulations of ancient greenhouse climates by current generation fully coupled climate models. An early influx of abundant Apectodinium confirms that environmental change preceded the CIE on a global scale. Organic dinoflagellate cyst assemblages suggest a local decrease in the amount of river run off reaching the core site during the PETM, possibly in concert with eustatic rise. Moreover, the assemblages suggest changes in seasonality of the regional hydrological system and storm activity. Finally, significant variation in dinoflagellate cyst assemblages during the PETM indicates that southwest Pacific climates varied significantly over time scales of 103 – 104 years during this event, a finding comparable to similar studies of PETM successions from the New Jersey Shelf.