Regional
Crustal
Structure
of the Gulf of Mexico From Gravity Inversion
Abstract
An understanding of crustal
thickness, ocean-continent-transition
structure
, continent-ocean-boundary location and
crustal
type (continental, oceanic or exhumed mantle) is a critical component of petroleum systems evaluation in the Gulf of Mexico (GoM) and elsewhere. Using public-domain data and OCTek 3D gravity inversion, we have produced regional grids and maps of Moho depth,
crustal
-basement thickness, continental-lithosphere thinning-factor and residual continental-
crustal
-thickness for the GoM.
Crustal
-basement thickness and lithosphere thinning from the 3D gravity inversion show the distribution of oceanic crust within the GoM and constrain continent-ocean-boundary location.
Crustal
cross-sections using Moho depths from the 3D gravity inversion show the form of the ocean-continent transition. Superposition of shaded-relief satellite free-air gravity onto maps of
crustal
-basement thickness and lithosphere thinning from gravity inversion show clearly the pattern and location of ocean-ridge and transform segments within the western and central GoM. These in turn reveal sea-floor spreading trajectory along with pre-breakup rifted-margin conjugacy. Maps of
crustal
thickness with superimposed shaded-relief free-air gravity may be used to test and refine plate-reconstruction models for the development of the GoM and its relationship to the formation of the early Central Atlantic. 2D and 3D flexural-backstripping and subsidence modelling, driven by lithosphere thinning/beta-factors from gravity inversion, have been used to predict the evolution of palaeobathymetry through the post-breakup history of the GoM. We also use lithosphere thinning determined from gravity inversion, together with
crustal
type, to predict the residual continental radiogenic heat-flow contribution and the post-rift transient heat-flow component, which together permit predictions of heat-flow history. Outputs from 3D gravity inversion for the GoM include grids of lithosphere thinning, β-factor and heat-flow history for input to petroleum systems modelling.
AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015