High-resolution carbon isotope records of the Toarcian Oceanic Anoxic Event (Early Jurassic) from North America and implications for the global drivers of the Toarcian carbon cycle
High-resolution carbon isotope records of the Toarcian Oceanic Anoxic Event (Early Jurassic) from North America and implications for the global drivers of the Toarcian carbon cycle
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DOI：
10.1016/j.epsl.2016.11.021
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发表时间：
2017-02
影响因子：
5.3
通讯作者：
T. Them;Benjamin C Gill;A. Caruthers;D. Gröcke;E. T. Tulsky;R. Martindale;T. Poulton;Paul L. Smith-Paul-L.
中科院分区：
文献类型：
--
作者：
T. Them;Benjamin C Gill;A. Caruthers;D. Gröcke;E. T. Tulsky;R. Martindale;T. Poulton;Paul L. Smith-Paul-L.
中生代经历了几次环境突变，与气候的不稳定，全球碳循环的重组和物种灭绝率的升高有关。通常在这些扰动期间，海洋中出现缺氧条件，导致富含有机物的沉积物广泛沉积-这些事件被称为海洋缺氧事件或OAE。这些事件与大规模火山活动的短暂发作和海洋环境中甲烷笼形物的不稳定导致温室气体大量注入海洋-大气系统有关。然而，不确定性围绕着特定的环境驱动因素和反馈，发生在OAE，造成扰动的碳循环，这是特别真实的早侏罗世Toarcian OAE（183.1 Ma）。在这里，我们提出了生物地层约束的碳同位素数据从北美西部（阿尔伯塔和不列颠哥伦比亚省，加拿大），以更好地评估全球范围内的碳循环扰动。我们确定了大的负碳同位素偏移与OAE沿着高频振荡和步骤内的发病，这偏移。我们认为，这些高频碳同位素漂移反映了全球碳循环的变化，也与天文时间尺度上陆地环境中温室气体的产生和释放有关。此外，在海洋缺氧事件和地球历史上的其他类似事件中，陆地甲烷生成的增加应被视为一个重要的气候反馈后，陆地植物的增殖。
The Mesozoic Era experienced several instances of abrupt environmental change that are associated with instabilities in the climate, reorganizations of the global carbon cycle, and elevated extinction rates. Often during these perturbations, oxygen-deficient conditions developed in the oceans resulting in the widespread deposition of organic-rich sediments — these events are referred to as Oceanic Anoxic Events or OAEs. Such events have been linked to massive injections of greenhouse gases into the ocean–atmosphere system by transient episodes of voluminous volcanism and the destabilization of methane clathrates within marine environments. Nevertheless, uncertainty surrounds the specific environmental drivers and feedbacks that occurred during the OAEs that caused perturbations in the carbon cycle; this is particularly true of the Early Jurassic Toarcian OAE (∼183.1 Ma). Here, we present biostratigraphically constrained carbon isotope data from western North America (Alberta and British Columbia, Canada) to better assess the global extent of the carbon cycle perturbations. We identify the large negative carbon isotope excursion associated with the OAE along with high-frequency oscillations and steps within the onset of this excursion. We propose that these high-frequency carbon isotope excursions reflect changes to the global carbon cycle and also that they are related to the production and release of greenhouse gases from terrestrial environments on astronomical timescales. Furthermore, increased terrestrial methanogenesis should be considered an important climatic feedback during Ocean Anoxic Events and other similar events in Earth history after the proliferation of land plants.