Significant Southern Ocean warming event in the late middle Eocene
Significant Southern Ocean warming event in the late middle Eocene
复制标题
DOI：
10.1130/g19800.1
复制
发表时间：
2003-11-01
期刊：
影响因子：
5.8
通讯作者：
Zachos, JC
中科院分区：
文献类型：
--
作者：
Bohaty, SM;Zachos, JC
在南大洋深海岩芯中发现了一个显著的始新世中期变暖事件，表明始新世中期和晚期的长期冷却不是单调的。在Maud Rise和Kerguelen Plateau的站点，观察到8180值的明显负移（类似于千分之1.0）。41.5 MA.这种偏移主要被解释为温度信号，在600 k. y以上瞬时升温4 ℃。影响到南大洋印度洋-大西洋区域的表层和中半深海沃茨。这个同位素事件被指定为中始新世气候最佳，并解释为代表一个显着的气候逆转中晚始新世深海冷却。缺乏一个显着的负碳同位素偏移，如在古新世始新世热最大值，高纬度变暖的逐渐速度表明，这一事件不是由甲烷水合物分解引发的。相反，PCO 2水平的短暂上升被怀疑，可能是由于喜马拉雅造山带的变质脱碳酸作用或中始新世晚期的山脊/弧火山作用的增加。
A prominent middle Eocene warming event is identified in Southern Ocean deep-sea cores, indicating that long-term cooling through the middle and late Eocene was not monotonic. At sites on Maud Rise and the Kerguelen Plateau, a distinct negative shift in 8180 values (similar to1.0parts per thousand) is observed ca. 41.5 Ma. This excursion is interpreted as primarily a temperature signal, with a transient warming of 4 degreesC over 600 k.y. affecting both surface and middle-bathyal deep waters in the Indian-Atlantic region of the Southern Ocean. This isotopic event is designated as the middle Eocene climatic optimum, and is interpreted to represent a significant climatic reversal in the midst of middle to late Eocene deep-sea cooling. The lack of a significant negative carbon isotope excursion, as observed during the Paleocene-Eocene thermal maximum, and the gradual rate of high-latitude warming suggest that this event was not triggered by methane hydrate dissociation. Rather, a transient rise in PCO2 levels is suspected, possibly as a result of metamorphic decarbonation in the Himalayan orogen or increased ridge/arc volcanism during the late middle Eocene.