Organic carbon content and carbon isotope variations across the Permo-Triassic boundary in the Gartnerkofel-1 borehole, Carnic Alps, Austria
Organic carbon content and carbon isotope variations across the Permo-Triassic boundary in the Gartnerkofel-1 borehole, Carnic Alps, Austria
复制标题
DOI：
10.1007/s11631-017-0249-0
复制
发表时间：
2018-06
期刊：
影响因子：
1.6
通讯作者：
M. Brookfield;W. Wolbach;A. Stebbins;I. Gilmour;D. R. Roegge
中科院分区：
文献类型：
--
作者：
M. Brookfield;W. Wolbach;A. Stebbins;I. Gilmour;D. R. Roegge
Gartnerkofel钻孔是世界上研究和描述最彻底的二叠纪-三叠纪剖面之一。详细的有机碳同位素研究表明，晚二叠世的负基移从− 24‰到− 28‰，后者的值持续到早三叠世，之后略有下降到− 26‰。晚二叠世有两个大于− 38‰的强烈负峰，早三叠世有一个小于− 31‰的负峰，这两个峰的负性太强，不可能是因为负性有机质的比例更大，而一定是由于非常负的甲烷效应。根据相变化，整个Bulla/Tesero边界向更负值的总体变化符合该过渡期海平面的相对上升。有机碳同位素值在晚二叠世事件层的一个积极的转变，可能是由于在这一水平的陆源有机碎屑的增加，所有特提斯二叠纪-三叠纪边界部分所示的功能，但这些其他部分没有相同的值。碳酸盐碳同位素趋势在所有剖面中相似，在二叠纪-三叠纪界线上下降2-3个单位。令人惊讶的是，考虑到普遍存在的石化作用，Gartnerkofel碳酸盐氧值与其他地方的值相一致，并表明最后二叠纪sabkhas的合理热带温度为60 °C，而上覆海洋过渡层的温度为20-40 °C。晚二叠世事件层的陆源输入增加可能是由于海啸的离岸运输，其沉积物在印度已被确认为这一水平。
The Gartnerkofel borehole is one of the most thoroughly studied and described Permo-Triassic sections in the world. Detailed bulk organic carbon isotope studies show a negative base shift from − 24‰ to − 28‰ in the Latest Permian which latter value persists into the Earliest Triassic after which it decreases slightly to − 26‰. Two strongly negative peaks of > − 38‰ in the Latest Permian and a lesser peak of − 31‰ in the Early Triassic are too negative to be due to a greater proportion of more negative organic matter and must be due to very negative methane effects. The overall change to more negative values across the Bulla/Tesero boundary fits the relative rise in sea level for this transition based on the facies changes. A positive shift in organic carbon isotope values at the Late Permian Event Horizon may be due to an increase in land-derived organic detritus at this level—a feature shown by all Tethyan Permo-Triassic boundary sections though these other sections do not have the same values. Carbonate carbon isotope trends are similar in all sections dropping by 2–3 units across the Permo-Triassic boundary. Gartnerkofel carbonate oxygen values are surprisingly, considering the ubiquitous dolomitization, compatible with values elsewhere and indicate reasonable tropical temperatures of 60 °C in the Latest Permian sabkhas to 20–40 °C in the overlying marine transition beds. Increased land-derived input at the Late Permian Event Horizon may be due to offshore transport by tsunamis whose deposits have been recognized in India at this level.