EGU21-8529, updated on 04 Mar 2021
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Gas hydrate destabilization and sea-level changes: insights from Miocene seep carbonate deposits of the northern Apennines (Italy)

Daniela Fontana1, Stefano Conti1, Chiara Fioroni1, and Claudio Argentino2
Daniela Fontana et al.
  • 1( Dept od Chemical and Geological Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy,
  • 2Centre for Arctic Gas Hydrate, Environment and Climate UiT – The Arctic University of Norway Department of Geosciences N-9037, Tromsø, Norway

The effects of global warming on marine gas hydrate stability along continental margins is still unclear and discussed within the scientific community. Long-term datasets can be obtained from the geological record and might help us better understand how gas-hydrate reservoirs responds to climate changes. Present-day gas hydrates are frequently associated or interlayered with authigenic carbonates, called clathrites, which have been sampled from many continental margins worldwide. These carbonates show peculiar structures, such as vacuolar or vuggy-like fabrics, and are marked by light δ13C and heavy δ18O isotopic values. Evidences of paleo-gas hydrate occurrence are recorded in paleo-clathrites hosted in Miocene deposits of the Apennine chain, Italy, and formed in different positions of the paleo foreland system: in wedge-top basins, along the outer slope of the accretionary prism, and at the leading edge of the deformational front. The accurate nannofossil biostratigraphy of sediment hosting paleo-clathrites in the northern Apennines allowed us to ascribe them to different Miocene nannofossil zones, concentrated in three main intervals: in the Langhian (MNN5a), in the upper Serravallian-lower Tortonian (MNN6b-MNN7) and the upper Tortonian-lowermost Messinian (MNN10-MNN11). By comparing paleo-clathrite distributions with 3rd order eustatic curves, they seem to match phases of sea-level lowering associated with cold periods. Therefore, we suggest that the drop in the hydraulic pressure on the plumbing system during sea-level lowering shifted the bottom of the gas hydrate stability zone to shallower depths, inducing paleo gas-hydrate destabilization. The uplift of the different sectors of the wedge-top foredeep system during tectonic migration might have amplified the effect of the concomitant eustatic sea-level drop, reducing the hydrostatic load on the seafloor and triggering gas-hydrate decomposition. We suggest that Miocene climate-induced sea-level changes played a role in controlling gas hydrate stability and methane emissions along the northern Apennine paleo-wedge, with hydrate destabilization roughly matching with sea-level drops and cooling events.


How to cite: Fontana, D., Conti, S., Fioroni, C., and Argentino, C.: Gas hydrate destabilization and sea-level changes: insights from Miocene seep carbonate deposits of the northern Apennines (Italy), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8529,, 2021.

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