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OCTek Arctic: A New Ventures Exploration Tool for Mapping Ocean-Continent Transition Structure and Location

Abstract

The regional mapping of rifted continental margin crustal structure and continent-ocean boundary location is of critical importance to deep-water hydrocarbon exploration in frontier basins. In remote regions, (such as the Arctic) with little or no seismic coverage, such investigations may be carried out using gravity anomaly data which is freely available and has good global resolution. We have used OCTek gravity anomaly inversion, incorporating a lithosphere thermal gravity anomaly correction to determine Moho depth, crustal basement thickness and continental lithosphere thinning for the Arctic and North Atlantic oceans and their continental margins. Within the Arctic and North Atlantic region, these results are in turn used to map rifted continental margin structure, location of the continent-ocean boundary and the distribution of micro-continents. Maps of continental lithosphere thinning factor and crustal thickness for the Arctic, derived from OCTek gravity inversion, provide predictions of structure within the ocean-continent transition and the location of the continent-ocean boundary independent of magnetic isochrons. Sensitivity to, and corrections for, rifted margin breakup age, margin magmatic type (magma poor, normal or magma rich) and mantle dynamic topography have been carried out. A suite of 54 sets of grids, covering the range of numerous geodynamic scenarios within the Arctic region, have been combined to give a single set of maps and digital grids showing present-day Arctic crustal basement thickness, Moho depth, continental lithosphere thinning factor and residual continental crustal thickness. Using these crustal thickness and continental lithosphere thinning factor maps, with superimposed shaded-relief free-air gravity anomaly, we have improved the determination of pre-breakup rifted margin conjugacy and sea-floor spreading trajectory. Crustal thickness & continental lithosphere thinning maps of the Eurasia Basin & North Atlantic, restored to early post-breakup times, show the geometry and segmentation of the rifted continental margins at breakup together with the location of failed breakup basins and micro-continents e.g. Morris Jessop Rise & Yermak Plateau.