Modeling Tectonic Uplift as a Mechanism for Destabilization of Gas Hydrate
Abstract
Gas hydrates form vast stores of greenhouse gas in deep-water marine sediment. Destabilization of gas hydrates has been suggested as a driver behind a greenhouse gas feedback effect, whereby methane released to the atmosphere leads to global warming. This warming could in turn lead to further destabilization of gas hydrates. Rising ocean temperatures and falling sea level are most commonly invoked as mechanisms behind methane hydrate destabilization, though recently tectonic uplift has also been suggested as a mechanism. However, the effect of uplift has not yet been modeled computationally. Here, we utilize an East Coast Basin, New Zealand model based on previous structural restorations of the 124-kilometer Hawke's Bay CM05-01 seismic line. We simulate gas hydrate stability zone presence at time steps of 24 Ma, when the East Coast Basin was at the end of a prolonged period of passive margin sedimentation, at 13.6 Ma, characterized by faulting and shortening, but not destabilization of gas hydrate, at 8.5 Ma, characterized by continued faulting and shortening, and the onset of gas hydrate destabilization, at 7 Ma, characterized by the most extreme faulting and shortening, and by extensive and widespread disruption of the gas hydrate stability zone, and at 0 Ma (Present Day), characterized by increased uplift and the persistence of just two isolated patches of gas hydrate stability zone in <10-kilometer-wide regions. Water depths >500 meters between 24 Ma and 13.6 Ma are inferred to be the primary driver for preservation of the gas hydrate stability zone, whereas shallower depths significantly lower hydrostatic pressures causing extensive destabilization of the gas hydrate stability zone from 8.5 Ma to present. Our model results support the mechanism of tectonic uplift as a driver for large-scale methane hydrate destabilization. We suggest that uplift in the marine realm should be considered as a potential driver behind global climate change.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMOS31F1858B
- Keywords:
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- 3004 Gas and hydrate systems;
- MARINE GEOLOGY AND GEOPHYSICS