Fossil plant stomata indicate decreasing atmospheric CO 2 prior to the Eocene-Oligocene boundary
Fossil plant stomata indicate decreasing atmospheric CO 2 prior to the Eocene-Oligocene boundary
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DOI：
10.5194/cp-12-439-2016
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发表时间：
2015-10
影响因子：
4.3
通讯作者：
M. Steinthorsdottir;Amanda S. Porter;Aidan Holohan;L. Kunzmann;M. Collinson;J. McElwain
中科院分区：
文献类型：
--
作者：
M. Steinthorsdottir;Amanda S. Porter;Aidan Holohan;L. Kunzmann;M. Collinson;J. McElwain
摘要。利用德国中部一种已灭绝的山毛榉科植物Eotrigonobalanus furcinervis化石叶片的独特地层序列，获得了一个大气pCO2记录，该记录具有多个数据点，时间跨度为中晚期至晚始新世，两个采样水平可能是早渐新世，两个采样水平可能是晚渐新世。利用气孔密度与pCO2的反比关系，我们发现在始新世晚期至始新世晚期，pCO2持续下降，在始新世结束前达到一个相对稳定的低值。根据后来的记录，渐新世部分地区的二氧化碳分压与始新世的最新值相似。这些结果表明，在海洋氧同位素记录的始新世-渐新世转变之前，二氧化碳分压的降低就预示着海洋氧同位素记录的大转变，当二氧化碳分压的变化超过一定的阈值时，二氧化碳分压和其他因素的累积效应会导致温度的快速下降，南极冰面的积聚，从而导致气候模式的变化。
Abstract. A unique stratigraphic sequence of fossil leaves of Eotrigonobalanus furcinervis (extinct trees of the beech family, Fagaceae) from central Germany has been used to derive an atmospheric pCO2 record with multiple data points spanning the late middle to late Eocene, two sampling levels which may be earliest Oligocene, and two samples from later in the Oligocene. Using the inverse relationship between the density of stomata and pCO2, we show that pCO2 decreased continuously from the late middle to late Eocene, reaching a relatively stable low value before the end of the Eocene. Based on the subsequent records, pCO2 in parts of the Oligocene was similar to latest Eocene values. These results suggest that a decrease in pCO2 preceded the large shift in marine oxygen isotope records that characterizes the Eocene–Oligocene transition and that when a certain threshold of pCO2 change was crossed, the cumulative effects of this and other factors resulted in rapid temperature decline, ice build up on Antarctica and hence a change of climate mode.