--> Abstract: 3-D Flexural Numerical Modeling of the Late Cretaceous Forebulge Migration Across the Southwestern Wyoming, by Hongjun Luo and Dag Nummedal; #90078 (2008)

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3-D Flexural Numerical Modeling of the Late Cretaceous Forebulge Migration Across the Southwestern Wyoming

Hongjun Luo1 and Dag Nummedal2
1EPT Geological Services, BP America Inc., Houston, TX
2Energy Research Institute, Colorado School of Mines, Golden, CO

The recognition of a forebulge in the subsurface is difficult due to its low amplitude and wide extent. It is further complicated by the fact that subsequent tectonic modification (such as the Laramide orogeny in this case) may have decoupled the locations of the forebulge from the more obvious regional isopach patterns. 3-D flexural numerical modeling provides a strong supportive tool to identify forebulges and their migration with time. Three regional cross sections are established to define the late Cretaceous forebulges in southwestern Wyoming based on detailed well log correlations and good outcrop control. Along these three sections (south, north, and NW-SE sections), forebulge migration is only recognized in the southern section by detailed regional correlation. In response to the eastward progressive movement of the Crawford, Early Absaroka, and Late Absaroka thrusts, the forebulges migrated eastward to the Moxa arch, the Rock Springs uplift, and the Washakie basin, respectively. 3-D flexural modeling indicates that the forebulges were located only in the southern part of the basin due to the 3-D geometry of the thrust load. The forebulge shifted southeastward over time due to migration of this 3-D load. The southern section is the only section across the 3-D forebulge migration pathway. 3-D flexural modeling is critical to the understanding of the late Cretaceous forebulge migration across southwestern Wyoming.

 

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas