Forebulge Migration: A Three-dimensional Flexural Numerical Modeling and Subsurface Study of Southwestern Wyoming
Hongjun Luo, Dag Nummedal, 2013. "Forebulge Migration: A Three-dimensional Flexural Numerical Modeling and Subsurface Study of Southwestern Wyoming", Tectonics and Sedimentation: Implications for Petroleum Systems, Dengliang Gao
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The recognition of a forebulge in the subsurface is difficult because of its low amplitude and wide extent. It is further complicated by the subsequent tectonic modification (by the Laramide orogeny in this case) that may have overprinted the forebulge with complex younger structural patterns. Three-dimensional (3-D) flexural numerical modeling provides a strong supportive tool to help predict forebulge locations and focus subsurface search on their subtle isopach expression. Based on detailed well-log correlations and good outcrop control, three regional cross sections were established to identify Late Cretaceous forebulges in southwestern Wyoming. Along these sections in the Greater Green River Basin (two east-west and one northwest-southeast), the existence of forebulges was only recognized in the southern section. In response to the progressive eastward movement of the Crawford, early Absaroka, and late Absaroka thrusts, the forebulge migrated eastward to the Moxa Arch, the Rock Springs Uplift, and the Washakie Basin, respectively. The 3-D flexural modeling indicates that the forebulge was limited in its extent only to the southern part of the basin because of the distribution of thrust loads. The forebulge shifted southeastward over time because of the migration of these loads. The 3-D flexural modeling is critical to understanding Late Cretaceous forebulge migration across southwestern Wyoming.
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The influence of tectonics on sedimentation and hydrocarbon accumulation is different among extensional, strike-slip, and contractional structural styles. Addressing the role of different structural styles and syntectonic sedimentation in petroleum systems is essential to assess the hydrocarbon potential of sedimentary basins. This 18-chapter volume is small enough to focus on the interplay among tectonics, sedimentation, and petroleum systems. Yet it is big enough to cover the diversity of structural styles in important petroliferous sedimentary basins around the globe, including those in west Africa, east Africa, east Brazil, east United States of America, Gulf of Mexico, South China Sea, the Russian Arctic, and the Mediterranean Sea.