Modeling the crust and upper mantle structure of the southern U.S. continental margin using seismic and gravity data.

Abstract

The southern U.S. continental margin is economically and scientifically significant as its crustal structure is home to abundant hydrocarbon reserves and records a rich geologic history. The latter spans ~1.35 Ga and includes two complete Wilson cycles, resulting in a passive margin lithosphere comprised of a mosaic of tectonic terranes. This study, which is split into three phases aims at imaging these different terranes and other geologic features by resolving the velocity and density structure of the crust and upper mantle of this passive margin. In phase 1, recently published S-wave tomography and crustal thickness models are compared and analyzed. Large-scale patterns of crustal velocity anomalies consistent between the different models are observed. These patterns also correspond to regional geologic features. Additionally, we observe an inverse relationship between crustal thickness and Bouguer gravity across the study region. In phase 2, relative teleseismic arrival times are inverted to constrain the P- and S-wave velocity structure of the upper mantle beneath the southern U.S. In the final phase, a constrained inversion of gravity anomaly data is conducted to resolve the average crustal density across the region. This helps spatially segregate the different tectonic terranes. There is a consistency in results produced in the different phases of the project. Finally, future research in this area should include denser deployments of seismic stations along with joint inversions of multiple, complementary geophysical datasets to provide more comprehensive constraints of the lithospheric structure.

Description

Keywords

Southern U.S. Geophysical inversion.

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