Hydrocarbon-seep deposits in the lower Permian Angie Formation, Central Lhasa Block, Tibet
Liu C, An X, Algeo TJ, Munnecke A, Zhang Y, Zhu T (2021)
Publication Type: Journal article
Publication year: 2021
Journal
Book Volume: 90
Pages Range: 258-272
Abstract
Methane seepage along continental margins has been linked to climatic warming, yet it is uncertain whether such seepage took place during the Permian, a period that witnessed a transition from an icehouse to a greenhouse world. To address this issue, we investigated calcareous concretions and layers within mudstones/shales of the Kungurian Angie Formation in the Xainza area, central Tibet. A combination of petrographic, mineralogical, elemental, and carbon‑sulfur isotopic analyses provide strong evidence for a hydrocarbon-seep origin of these carbonates, with thermogenic methane and crude oil being the most likely carbon sources. Our dataset also indicates that, although fueled by a common deep-buried hydrocarbon reservoir, these layers and concretions experienced different biogeochemical processes due to variable rates of cold-seep fluid flux combined with persistently low sulfate concentrations in bottom waters of the Bangong-Nujiang Tethyan Ocean. A biogeochemical switch from sulfate-dependent to iron oxide-coupled anaerobic oxidation of methane in the sulfate-methane transition zone, likely triggered by sulfate exhaustion, was inferred to affect carbonate layer formation near the sediment-water interface. If true, this switch, together with common vent structures, would have resulted in escape of large amounts of methane directly to the ocean-atmosphere system. The hydrocarbon seeps in the central Lhasa Block was approximately coeval with rapid climate warming in the peri-Gondwanan region during the early Kungurian. Although further investigations are required in the future, this study demonstrates a possible causal relationship between regional tectonic evolution, hydrocarbon seepage, and global climate change.
Authors with CRIS profile
Involved external institutions
China University of Geosciences / 中国地质大学
China (CN)
China Geological Survey (CGS) / 中国地质调查局
China (CN)
China (CN)
China Geological Survey (CGS) / 中国地质调查局
China (CN)
How to cite
APA:
Liu, C., An, X., Algeo, T.J., Munnecke, A., Zhang, Y., & Zhu, T. (2021). Hydrocarbon-seep deposits in the lower Permian Angie Formation, Central Lhasa Block, Tibet. Gondwana Research, 90, 258-272. https://dx.doi.org/10.1016/j.gr.2020.10.017
MLA:
Liu, Chao, et al. "Hydrocarbon-seep deposits in the lower Permian Angie Formation, Central Lhasa Block, Tibet." Gondwana Research 90 (2021): 258-272.
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