| Autor: |
Fabre, M., Riboulot, V., Loncke, L., Ker, S., Ballas, G., Thomas, Y., Ion, G., Sultan, N. |
| Předmět: |
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| Zdroj: |
Geophysical Research Letters; 5/28/2024, Vol. 51 Issue 10, p1-10, 10p |
| Abstrakt: |
Determining how gas hydrate distribution evolved along continental margins in the past is essential to understanding its evolution in the future. Moreover, hydrate decomposition has been linked to several catastrophic events, including some of the largest submarine landslides on Earth and the massive release of greenhouse gases into the ocean. Offshore Romania, the presence of a second bottom‐simulating reflector (BSR) provides an opportunity to gain valuable insights into hydrate dynamics since the Last Glacial Period (LGP). We conducted transient modeling of hydrate thermodynamic stability by merging in‐situ observations with indirect assessments of sea‐bottom temperature, thermal conductivity, salinity, sedimentation rate, and sea‐level variations. We reveal a strong correlation between the BSRs and the base of the Gas Hydrate Stability Zone (GHSZ) during both the present and LGP periods. The gradual evolution of the GHSZ over the past 34 ka presented here supports a conceptual model that excludes catastrophic environmental scenarios. Plain Language Summary: Methane hydrate is an ice‐like compound composed of a cage of water molecules enclosing a methane molecule. Hydrates can form in marine sediments along continental margins where water and methane are present under high pressure and low temperatures. As a result of climate change, hydrate melting has been linked to catastrophic events, including submarine landslides and the release of greenhouse gases into the ocean. Offshore Romania, the presence of a relic of the base of the hydrate layers formed in sediments during past glacial conditions, reveals the evolution of the hydrate stability zone since the last glacial period. The 2D modeling results have enabled us to define the area where hydrates alternately melt and reform in response to environmental changes such as rising temperatures and sea levels. Our results show that the evolution of gas‐hydrate accumulations generates multiple, slow chain reactions, preventing the system from disastrous destabilization, sequentially provoking catastrophic events. Key Points: A 2D modeling reveals the observed deeper secondary BSR is mostly consistent with a paleo‐BSR developed during the last glacial periodA paleo‐BSR can only be preserved in sediments if the period of stagnation of the base of hydrate layers is sufficient to trap enough gasAlthough rapid environmental changes, the hydrate‐free gas system reacts much more slowly preventing catastrophic submarine destabilization [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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