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76 / 2025-03-31 11:48:26
Episodic massive release of methane during the mid-Cretaceous greenhouse
carbon isotopes; clumped isotopes; trace elements; hydrothermal fluids; gas hydrates; Tibet
Theme 4: Microbial and Biogeochemical Evolution through Time > Session 4d: Biogeochemical Methane Cycle: Past, Present, and Future
摘要待审
Biao Chang / State Key Laboratory of Geological Processes and Mineral Resources； China； Wuhan 430074； China University of Geosciences； School of Earth Science
树成 谢 / 中国地质大学（武汉）
Methane-derived carbonates (MDCs) are common along modern and ancient continental margins, and the majority of such formations are associated with seafloor cold seeps. Here, we document petrographic, rare earth element + yttrium (REE+Y), carbonate clumped isotope temperature (TΔ47) and carbon-isotopic evidence from a shale succession in southern Tibet spanning a ~28-Myr interval (~113-85 Ma) that coincided with the mid-Cretaceous greenhouse. At least nine limestone nodule-bearing horizons exhibit seep-associated sedimentary structures, including carbonate fabrics (e.g., micritic crusts, crystal fans, and botryoidal textures) and 13C-depleted isotopic compositions (d13Ccarb < ‒32.3‰) indicative of methane-derived carbon sources. Along with sedimentary evidence, the patterns of TΔ47-d13Ccarb-d18Ocarb support precipitation of these MDCs over a large temperature range. The REE+Y compositions and europium (Eu) anomalies indicate that the release of methane was associated with hydrothermal fluids. Methane may have been derived from both thermogenic and biogenic sources based on the inorganic carbon isotopic signatures of the carbonate. These nodular carbonate horizons document multiple episodes of seafloor methane release during the mid-Cretaceous, representing exceptionally long-lived active methane seepage. Massive methane release events may have played a role in generating the greenhouse climate of the mid-Cretaceous.

 
重要日期

  • 会议日期

    06月10日

    2025

    至

    06月13日

    2025

  • 04月15日 2025

    初稿截稿日期

主办单位
National Natural Science Foundation of China
Geobiology Society
National Committee of Stratigraphy of China
Ministry of Science and Technology
Geological Society of China
Paleontological Society of China
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (CAS)
Institute of Vertebrate Paleontology and Paleoanthropology, CAS
International Commission on Stratigraphy
International Paleontological Association
承办单位
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (CUG, Wuhan)
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