Submillennial resolution carbon isotope stratigraphy across the Oceanic Anoxic Event 2 horizon in the Tappu section
Submillennial resolution carbon isotope stratigraphy across the Oceanic Anoxic Event 2 horizon in the Tappu section
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Tappu 部分海洋缺氧事件 2 地平线的亚千禧年分辨率碳同位素地层学
DOI：
10.1016/j.palaeo.2011.06.009
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
T.
中科院分区：
文献类型：
--
作者：
Nemoto;T. and Hasegawa;T.
建立了日本北海道上诺曼期陆相有机碳的最高分辨率碳同位素地层学。白垩纪海洋缺氧事件2 （OAE2）主期段的碳同位素曲线与英国伊斯特本参考剖面的剖面基本一致，但未显示出底部环境缺氧的特征。在“第二次堆积阶段”中观察到在任何碳酸盐岩剖面中都无法识别的负偏移2.6‰。伊斯特本和普韦布洛部分的这个地平线最近的研究表明，这是与加勒比海-哥伦比亚大火成岩省有关的强烈火山喷发的证据。这里观察到的负碳同位素偏移似乎可以用陆地植物群落13c /12C比值的变化来解释，这是对更温暖和更潮湿气候的反应，直接由火山升高的大气pco2引起，最终由大型火成岩省位进引起。接受这种情况，负偏移使我们能够估计火山脉冲的最大持续时间（12.6kyr）。由于负偏移恢复的持续时间受整个海洋-大气co2库ΣCO2concentration平衡的影响，估计OAE2期间热盐环流的平均时间尺度为5.3-6.3kyr。
Highest resolution carbon isotope stratigraphy was established for terrestrial organic carbon through the uppermost Cenomanian in Hokkaido, Japan. The interval of the main phase of Cretaceous oceanic anoxic event 2 (OAE2) has a carbon isotope curve that almost mirrors the profile of the reference section in Eastbourne, United Kingdom, but does not show any signature of oxygen depletion in the bottom environment. A negative excursion of 2.6‰, which cannot be recognized in any carbonate sections, is observed within the “second build-up phase”. This horizon in the Eastbourne and Pueblo sections is known from recent studies to be evidence of an intensive volcanic eruption associated with the Caribbean–Colombian large igneous province. The negative carbon isotope excursion observed here is plausibly explained by a change in the13C/12C ratio of the terrestrial plant community as a reaction to a warmer and more humid climate induced directly by volcanically elevated atmospheric pCO2and ultimately by the large igneous province emplacement. Accepting this scenario, the negative excursion allows us to estimate the maximum duration of the volcanic pulse (12.6kyr). As the duration of the recovery from the negative excursion is expected to be subject to equilibration of the ΣCO2concentration in the whole ocean–atmospheric CO2reservoir, the mean time scale of thermohaline circulation during OAE2 is estimated as 5.3–6.3kyr.