Pacing of the Toarcian Oceanic Anoxic Event (Early Jurassic) from astronomical correlation of marine sections
Pacing of the Toarcian Oceanic Anoxic Event (Early Jurassic) from astronomical correlation of marine sections
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DOI：
10.1016/j.gr.2013.06.023
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发表时间：
2014-05-01
影响因子：
6.1
通讯作者：
Hesselbo, Stephen P.
中科院分区：
文献类型：
--
作者：
Huang, Chunju;Hesselbo, Stephen P.
早侏罗世早托阿西期海洋缺氧事件（OAF）与碳同位素负漂移（CIE）、生物大灭绝、海侵和全球变暖有关。Toarcian OAF被认为是由洪水玄武岩岩浆作用造成的，可能是大规模灭绝的触发因素。然而，这些提出的Toarcian OAF和相关生物危机的原因并没有通过精确的年表得到充分解决。根据U-Pb测年，Toarcian OAF的持续时间估计为0.12到0.9百万年，最近的估计为0.74到3.26亿年。与Toarcian OAE相关的CIE在许多地方都有类似的模式，有证据表明海洋碳同位素变化记录了天文强迫信号。在这里，我们根据佩尼切（葡萄牙）海洋剖面405万年的天文偏心率调整，估计主要负CIE的持续时间类似于620万年，类似于polymorphum区的860万年，而levisoni区的持续时间>1.58万年。这405-kyr调谐系列提供了一个类似于2.5百万年的连续高分辨率年表，通过早期Toarcian。在佩尼切的CIE主周期中有6个或可能有7个短偏心周期。为了证实这一基于天文学的估计，我们分析了其他三个部分在约克郡（英国），Dotternhausen（德国）和Valdorbia（意大利）从海洋碳同位素系列。这四个来自早侏罗世西特提斯的地层剖面记录了Toarcian OAE，在CIE中具有类似于6个突出的碳同位素循环，持续时间为600 +/- 100 kyr。佩尼切405-kyr调谐系列表明，前和后CIE间隔经历了强烈的岁差偏心率强迫的气候变化，而CIE间隔的特点是占主导地位的旋度强迫。碳同位素天文响应的这些戏剧性和突然的变化表明，早期Toarcian古气候系统发生了根本性的变化，与全球碳循环直接相关。(C)2013年国际冈瓦纳研究协会。Elsevier B. V.出版，保留所有权利。
The Early Toarcian Oceanic Anoxic Event (OAF) in the Early Jurassic Period is associated with a major negative carbon isotope excursion (CIE), mass extinction, marine transgression and global warming. The Toarcian OAF is thought to have been caused by flood basalt magmatism, and may have been a trigger for mass extinction. However, these proposed causes of the Toarcian OAF and associated biotic crisis are not adequately resolved by a precise chronology. The duration of the Toarcian OAF has been estimated to be anywhere from similar to 0.12 to similar to 0.9 Myr, most recently 0.74 to 326 Myr from U-Pb dating. The CIE associated with the Toarcian OAE has a similar pattern at numerous localities, and there is evidence that the marine carbon isotope variations recorded astronomical forcing signals. Here we estimate a duration of similar to 620 kyr for the main negative CIE, similar to 860 kyr for the polymorphum zone and >1.58 Myr for the levisoni zone based on 405-kyr astronomical eccentricity tuning of the marine section at Peniche (Portugal). This 405-kyr tuned series provides a similar to 2.5 Myr continuous high-resolution chronology through the Early Toarcian. There are 6, or possibly 7 short eccentricity cycles in the main CIE interval at Peniche. To confirm this astronomically based estimate, we analyzed three other sections at Yorkshire (UK), Dotternhausen (Germany), and Valdorbia (Italy) from marine carbon isotopic series. These four stratigraphic sections from Early Jurassic western Tethys record the Toarcian OAE with similar to 6 prominent carbon isotope cycles in the CIE that span a 600 +/- 100 kyr duration. The Peniche 405-kyr tuned series indicates that the pre- and post-CIE intervals experienced strong precession-eccentricity-forced climate change, whereas the CIE interval is marked by dominant obliquity forcing. These dramatic and abrupt changes in astronomical response in the carbon isotopes point to fundamental shifting in the Early Toarcian paleoclimate system that was directly linked to the global carbon cycle. (C) 2013 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.