Upper crustal structure of the southern Rio Grande Rift

Alfredo Ruiz, University of Texas at El Paso


The Rio Grande Rift consists of a series of asymmetric grabens extending from Leadville, Colorado to Presidio, Texas and Chihuahua, Mexico. Rifting has been active for about the last 30 Ma and has resulted in the production of the basins that define the rift. The study area is centered on the Franklin Mountains along the New Mexico-Texas State line in between the Mesilla and Hueco Basins. This study focused on the kinematic and geometric development of faults and basins in the southern Rio Grande Rift near El Paso, Texas. A seismic reflection profile, wells and geological ground truth were used to constrain a crustal scale gravity model across the rift from the Potrillo Mountains on the west to the Hueco Mountains on the east. The combined data set shows that both the Hueco and Mesilla basins are bound by listric normal faults. Stratigrahic relationships in the Franklin Mountains require that some of the low angle normal faults are reactivated thrust faults formed during Laramide deformation. Seismic reflection data show that the western side of the Hueco Basin coincides with the western edge of the Pennsylvanian Orogrande basin which filled during the Ancestral Rocky Mountains orogeny. Inversion of fault slip data and the geometry of map scale structures show that Laramide structures formed in response to NE-SW shortening. Rift related structures formed during two stages of strain. The first was north-northeast directed extension. The second event is ongoing and is in response to east-west directed extension. These relationships indicate that the geometry of the rift was controlled in large part by preexisting structural and stratigraphic relationships. ^

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Recommended Citation

Ruiz, Alfredo, "Upper crustal structure of the southern Rio Grande Rift" (2004). ETD Collection for University of Texas, El Paso. AAIEP10805.