Crustal Basement Structure of the Black Sea From Integrated Quantitative Analysis of Deep Seismic and Gravity Anomaly Data

Abstract

The composition and thickness of crustal basement are critical to frontier hydrocarbon exploration in deep-water rifted continental margin settings. For the Black Sea, we need to know the distribution of continental and oceanic crust, ocean-continent transition structure, continent-ocean boundary location and magmatic type (whether magma poor, normal or magma rich). We apply a set a quantitative analytical techniques based on ION's deep long-offset seismic reflection data. These quantitative analytical techniques consist of: (1) Gravity inversion, incorporating a lithosphere thermal gravity anomaly, to give Moho depth, crustal basement thickness & continental lithosphere thinning (2) RDA (residual depth anomaly) analysis to give departures from oceanic bathymetry (3) Subsidence analysis using 3D flexural backstripping to give lithosphere thinning (4) Joint inversion of deep seismic reflection and gravity data to give lateral variations in basement density and seismic velocity. The combined interpretation of these independent quantitative measurements are used together to determine OCT structure, COB location and crustal type. Superposition of the 3D Moho surface determined from gravity inversion onto PSDM and PSTM seismic sections provides assistance to, and validation of, deep seismic reflection interpretation. Integrated quantitative analysis maximises the use of the ION deep seismic data. Radiogenic heat-productivity within continental basement contributes significantly to hydrocarbon maturation; in contrast oceanic crust or exhumed mantle contributes very little. We use lithosphere thinning determined from gravity inversion together with crustal type determined from combined integrated quantitative analysis to predict the residual continental radioagenic heat flow contribution. Outputs from our 3D quantitative analysis of the Black Sea 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