Gas hydrates represent a huge reservoir of methane in marine sediments, prone to dissociation in response to environmental changes. There is consensus that past events of gas hydrate dissociation in the marine environment mainly occurred during periods of low sea level. Here, we report geochemical data for 2-m-thick layers of seep carbonate collected from a hydrate-bearing drill core from ~800-m water depth in the northern South China Sea. The aragonite-rich carbonates reveal positive δ18O values, confirming a genetic link with gas hydrate dissociation. Uranium-thorium dating of seep carbonates indicates that gas hydrates at the study site dissociated between 133,300 and 112,700 years BP, hence coinciding with the Last Interglacial (MIS 5e) sea-level highstand. We put forward the concept that a climate-driven increase in temperature was responsible for a period of pronounced gas hydrate dissociation.
Bibliographical noteFunding Information:
We thank the crew and scientists of the research vessel during the GMGS2 gas hydrate drilling expedition. Yuncheng Cao (Shanghai Ocean University) is acknowledged for assistance during preparation of the gas hydrate phase diagram. This research was supported by the NSF of China (Grants 41776066, 41773091, 41730528, and 41888101) and the Qingdao National Laboratory for Marine Science and Technology (Grant QNLM2016ORP0204). Xudong Wang acknowledges the China Scholarship Council for supporting a research visit to IFREMER. Data sets for this research are available in the following in‐text data citation references: supporting information , Mendeley Data, and V3 ( https://doi.org/10.17632/nkkd44zcyk.3 ). This article benefited from insightful comments of three anonymous reviewers.
- methane seep gas hydrate seep carbonate