Improved Satellite Gravity Data: Enhanced Tool for Structural Interpretation

Abstract

Satellite gravity is a valuable tool for structural interpretation – providing roughly uniform coverage in ice-free marine areas. Early maps showed the tectonic fabric of the world's oceans and more recent gravity data sets continue to be used to fine-tune plate tectonic models. Along continental shelves and margins, satellite gravity is now a basic data set for imaging and modelling of crustal architecture, basin structure and sediment thickness distribution. Satellite gravity is derived from altimeters measuring the height of the sea surface and since 2010, there have been two new satellite altimeter missions collecting data along closely spaced tracks. Thus the available data coverage has been doubled, which has allowed us to improve accuracy, resolution and reliability in new gravity grids covering the continental margins and adjacent ocean areas of the world. The new data sets are now being used to interpret structures on continental shelves and margins. When integrated with land gravity data, the continuity of features across coastlines can be assessed and mapped. The enhanced gravity grids based on a wider range of track orientations are more isotropic in character and lack the track-oriented features seen in some previous satellite gravity grids. This leads to improved confidence that the structures we are now mapping are real geological features rather than data artefacts. These improvements also enhance modelling and inversion of gravity profiles and grids to further constrain sedimentary basin geometries, depth-to-basement as well as passive margin structure. Gravity-constrained extension estimates are a pre-requisite for full-fit plate reconstructions of conjugate continental margins. We use a range of gravity derivatives (total horizontal derivative, tilt derivative etc.) to enhance the delineation of structures and mapping of textures in offshore areas. New techniques to analytically compare automatically generated lineaments are used to select only the most robust features for mapping into structural interpretations. In this presentation, examples from Africa and South East Asia are used to illustrate delineation and discrimination of features based on the new satellite gravity data and integration of these data into the interpretation workflow.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016