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Heat flow from the depth of the base of gas hydrate stability

Heatflow from the depth of the base of gas hydrate stability

BSRs occur at the base of gas hydrate stability controlled by the pressure-temperaure conditions of the methane hydrate phase boundary. Pressure as a function of depth in marine sediments is usually well constrained and hence, the BSR marks a temperature point in the sediment column. By using estimates for water temperature and thermal conductivity (both parameters that are reasonably well known), it is possible to calculate heat flow from the depth of BSRs (Yamano et all., 1982).

Knowledge of temperatures deep in the earth is important to understand plate dynamics, in particular along subduction zones like the Hikurangi margin, offshore New Zealand 's East Coast, where the maximum size of earthquakes is linked to temperatures on the interface between the subducting Pacific plate and the overriding New Zealand continent.

Heatflow from the depth of BSRs across the Hikurangi margin (Henrys et all., 2003).

We have investigated heatflow from the depth of BSRs on the Hikurangi margin (Henrys et all.. 2003, Townend. 1997). A thickening of accretionary wedge sediments is probably the cause of the observed regional decrease of heatflow from the trench landwards. We also performed numerical modelling to explain local variations in heatflow, which we found to be caused by a combination of seabed bathymetry and sedimentation.

References

  1. Yamano, M., S. Uyeda, Y. Aoki, and T.H. Shipley (1982), Estimates of heat flow derived from gas hydrates, Geology , 10 , 339-343.
  2. Henrys, S.A., S. Ellis, and C. Uruski (2003), Conductive heat flow variations from bottom-simulating reflectors on the Hikurangi margin, New Zealand , Geophys. Res. Lett. , 30 , 1065-1068, doi:10.1029/2002GL015772.
  3. Townend, J. (1997), Estimates of conductive heat flow through bottom-simulating reflectors on the Hikurangi margin and southwest Fiordland , New Zealand , Mar. Geol. , 141 , 209-220.
Heatflow from the depth of BSRs across the Hikurangi margin (Henrys et all., 2003).

Heatflow from the depth of BSRs across the Hikurangi margin (Henrys et all., 2003).