Publication Date:
2017-05-19
Description:
Regional erosion of the Rock Garden ridge top, a
bathymetric high within New Zealand’s Hikurangi Subduction
Margin, is likely associated with its gas hydrate
system. Seismic data reveal gas pockets that appear
partially trapped beneath the shallow base of gas hydrate
stability. Steady-state fluid flow simulations, conducted on
detailed two-dimensional geological models, reveal that
anomalous fluid pressure can develop close to the sea floor
in response to lower-permeability hydrate-bearing sediments
and underlying gas pockets. Transient simulations
indicate that large-scale cycling of fluid overpressure may
occur on time scales of a few to tens of years. We predict
intense regions of hydro-fracturing to preferentially develop
beneath the ridge top rather than beneath the flanks, due to
more pronounced overpressure generation and gas migration
through hydrate-bearing sediments. Results suggest
that sediment weakening and erosion of the ridge top by
hydro-fracturing could be owed to fluid dynamics of the
shallow gas hydrate system.
Type:
Article
,
PeerReviewed
Format:
text
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