The significance of an Early Jurassic (Toarcian) carbon-isotope excursion in Haida Gwaii (Queen Charlotte Islands), British Columbia, Canada
The significance of an Early Jurassic (Toarcian) carbon-isotope excursion in Haida Gwaii (Queen Charlotte Islands), British Columbia, Canada
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DOI：
10.1016/j.epsl.2011.04.013
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发表时间：
2011-07-01
影响因子：
5.3
通讯作者：
Smith, Paul L.
中科院分区：
文献类型：
--
作者：
Caruthers, Andrew H.;Groecke, Darren R.;Smith, Paul L.
碳同位素记录显示，在早陶瓦世期间，短期活跃碳储层发生了重大破坏，这表明一个广泛的积极转变被5-7‰的大变化打断。负偏移（δ C-13(org)）。在许多地区，碳同位素偏移与富有机质页岩沉积同时发生。碳同位素的这种扰动被认为是严重气候变化和海洋缺氧的指示。关于这一事件原因的两种主要假设要么援引全球控制，要么援引区域控制。在这里，我们提出了来自加拿大不列颠哥伦比亚省海达瓜伊的碳同位素数据，显示了在沉积于古太平洋东北部的一个暂时受限制的早陶瓦世演替中存在显著的扰动。这些数据加强了短期活性碳储层受全球影响的概念，并有助于北美西部和欧洲之间的氨石地带性方案的对比。三角洲C-13（org）数据显示了一个广泛的正偏移，在早陶阿世卡南塞带被一个急剧而明显的负偏移打断，偏移量为千分之7（三角洲C-13（wood）为千分之8.5）。这种负偏移也与总有机碳（TOC）从0.4%增加到1.2%相一致。这些数据表明，早陶拉世的碳同位素扰动确实是全球性的，并在全球所有活跃的可交换碳循环储集层（深海、浅海、大气）上留下了印记。(c) 2011 Elsevier B.V.版权所有
During the Early Toarcian there was a significant disruption in the short-term active carbon reservoir as revealed by carbon-isotope records, which show a broad positive shift that is interrupted by a large 5-7 parts per thousand. negative excursion (delta C-13(org)). Carbon-isotope excursion co-occurs with the deposition of organic-rich shales in many areas. This perturbation in carbon isotopes is thought to be indicative of severe climate change and marine anoxia. The two leading hypotheses as to the cause of this event invoke either global or regional controls. Here we present carbon-isotope data from Haida Gwaii, British Columbia, Canada showing a significant perturbation within a temporally constrained Early Toarcian succession that was deposited in the northeastern paleo-Pacific Ocean. These data reinforce the concept that the short-term active carbon reservoir was affected globally, and assist with the correlation of ammonite zonal schemes between western North America and Europe. The delta C-13(org) data show a broad positive shift that is interrupted by a sharp and pronounced negative excursion of 7 parts per thousand (8.5 parts per thousand in delta C-13(wood)) in the Early Toarcian Kanense Zone. This negative excursion also coincides with increasing total organic carbon (TOC) from similar to 0.4% to similar to 1.2%. These data suggest that the Early Toarcian carbon-isotope perturbation was indeed global and imprinted itself on all active global reservoirs of the exchangeable carbon cycle (deep marine, shallow marine, atmospheric). (c) 2011 Elsevier B.V. All rights reserved.