Early Jurassic carbon-isotope excursion in the Qiangtang Basin (Tibet), the eastern Tethys: Implications for the Toarcian Oceanic anoxic event

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• 作者：Xiugen Fu^a ; ^b ; ^{fuxiugen@126.com" class="auth_mail" title="E-mail the corresponding author} ; Jian Wang^a ; ^b ; Xinglei Feng^a ; Dong Wang^a ; Wenbin Chen^a ; Chunyan Song^a ; ^b ; Shengqiang Zeng^a
• 关键词：Toarcian Oceanic anoxic event ; Carbonate and organic carbon isotopes ; Total organic carbon ; Qiangtang Basin ; Eastern Tethys
• 刊名：Chemical Geology
• 出版年：2016
• 出版时间：28 November 2016
• 年：2016
• 卷：442
• 期：Complete
• 页码：62-72
• 全文大小：2079 K

文摘

The Early Jurassic was characterized by a global disturbance of the carbon cycle known as the Toarcian oceanic anoxic event (T-OAE). This event is recorded by a large negative carbon-isotope excursion (CIE) in marine carbonates and marine organic matter, as well as fossil wood. Here, we present new high-resolution carbonate (δ¹³C_carb) and organic (δ¹³C_org) carbon-isotope records and total organic content from the Bilong Co section in the Qiangtang Basin, the eastern Tethys. This section is high in organic carbon, and black shale facies are also identified. The Bilong Co section shows heavy δ¹³C_org values compared to other reported marine organic carbon-isotope values for the T-OAE. This is explained by variable mixing of terrestrial and marine organic matter. Compared to European sections, the magnitude of the negative CIE in the Bilong Co section is slightly different, which could be explained by different local paleoenvironmental conditions and strata missing. Although these, the carbon-isotope profile from the Bilong Co area displays a similar trend to those in contemporaneous strata in the western Tethyan and Boreal realms of NW Europe, which is characterized by a distinct negative excursion in the Early Toarcian. Our new data from the Bilong Co section in N Tibet provide the first high-resolution record of the Early Toarcian Oceanic Anoxic Event in the eastern Tethys.