The OCTek gravity inversion project combines gravity inversion and plate reconstructions to support new ventures exploration at deepwater rifted continental margins together with associated petroleum systems modelling.
OCTek Gravity Inversion uses free-air gravity, bathymetry and sediment thickness data to produce maps and grids of:
1 Depth to Moho
2 Total crustal thickness
3 Residual continental-crustal thickness
4 Crust and lithosphere thinning/beta factor
5 The lithosphere thermal-gravity-anomaly resulting from rifting and breakup
OCTek Gravity Inversion applies the 3D technique of Greenhalgh & Kusznir (2007, Geophysical Research Letters), Chappell & Kusznir (2008, Geophysical Journal International) and Alvey et al (2008, Earth and Planetary Science Letters), complemented by new plate reconstructions which progressively restore the OCTek maps of crustal thickness back through their sea-floor spreading history to the time of breakup. Key to this technique is the incorporation of:
1 The lithosphere thermal gravity anomaly resulting from breakup
2 A prediction of new volcanic crustal addition during breakup
Published results have shown the importance of incorporating both of these parameters in the inversion when investigating deepwater margins.
We believe that the output from OCTek Gravity Inversion will be of particular assistance to:
• New Ventures exploration strategy in deepwater areas, helping to determine ocean-continent transition location and discriminate crustal type prior to any specific data acquisition. The results can also assist the planning of regional seismic surveys.
• Petroleum Systems modelling, as input to which we have produced maps of beta/thinning factor and residual continental crustal-basement across rifted margins and their ocean-continent transitions.
Each OCTek Gravity Inversion report also provides a software tool to convert maps of beta/thinning factor into predictive maps of top basement heat-flow.
The OCTek project (tectonics of the Ocean-Continent Transition) is a collaboration between Badley Geoscience and Prof. Nick Kusznir, leader of the Geodynamics Research Group at Liverpool University, UK.