--> Abstract: OCTek Arctic Gravity Inversion Mapping of Crustal Thickness & Continental Lithosphere Thinning: A Regional Tool for New Ventures Exploration, by Andy Alvey; #90177 (2013)

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OCTek Arctic Gravity Inversion Mapping of Crustal Thickness & Continental Lithosphere Thinning: A Regional Tool for New Ventures Exploration

Andy Alvey

The investigation and mapping of rifted continental margins and ocean basins is the focus of much current attention motivated by hydrocarbon exploration, territorial claims and geo-dynamic research. In regions that have poor seismic coverage, this investigation may be carried out using gravity anomaly data which has good global resolution. We use OCTek gravity anomaly inversion incorporating a lithosphere thermal gravity anomaly correction to determine Moho depth, crustal basement thickness and continental lithosphere thinning for oceans and continental margins worldwide. These parameters are used to map rifted continental margin structure, continent-ocean boundary location and the distribution of micro-continents within ocean basins. The newly developed gravity anomaly inversion method, which also includes a correction for magmatic crustal addition during margin rifting and breakup, has been used to produce a global suite of maps showing crustal thickness and oceanic lithosphere distribution for all of the world's oceans and continental margins. Here we focus on results from the Arctic & North Atlantic region. Maps of OCTek Arctic continental lithosphere thinning factor and crustal thickness from gravity inversion provide predictions of ocean-continent structure and continent ocean boundary location independent of magnetic isochrons. Mapping sensitivity to 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 numerous range of 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 improve 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 the time of breakup together with the location of failed breakup basins and micro-continents.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013