New Perspectives on Rio Grande Rift Basins: From Tectonics to Groundwater
New perspectives on the geometry of the Albuquerque Basin, Rio Grande rift, New Mexico: Insights from geophysical models of rift-fill thickness
-
Published:April 01, 2013
-
CiteCitation
V.J.S. Grauch, Sean D. Connell, 2013. "New perspectives on the geometry of the Albuquerque Basin, Rio Grande rift, New Mexico: Insights from geophysical models of rift-fill thickness", New Perspectives on Rio Grande Rift Basins: From Tectonics to Groundwater, Mark R. Hudson, V.J.S. (Tien) Grauch
Download citation file:
- Share
Discrepancies among previous models of the geometry of the Albuquerque Basin motivated us to develop a new model using a comprehensive approach. Capitalizing on a natural separation between the densities of mainly Neogene basin fill (Santa Fe Group) and those of older rocks, we developed a three-dimensional (3D) geophysical model of syn-rift basin-fill thickness that incorporates well data, seismic-reflection data, geologic cross sections, and other geophysical data in a constrained gravity inversion. Although the resulting model does not show structures directly, it elucidates important aspects of basin geometry. The main features are three, 3–5-km-deep, interconnected structural depressions, which increase in size, complexity, and segmentation from north to south: the Santo Domingo, Calabacillas, and Belen subbasins. The increase in segmentation and complexity may reflect a transition of the Rio Grande rift from well-defined structural depressions in the north to multiple, segmented basins within a broader region of crustal extension to the south. The modeled geometry of the subbasins and their connections differs from a widely accepted structural model based primarily on seismic-reflection interpretations. Key elements of the previous model are an east-tilted half-graben block on the north separated from a west-tilted half-graben block on the south by a southwest-trending, scissor-like transfer zone. Instead, we find multiple subbasins with predominantly easterly tilts for much of the Albuquerque Basin, a restricted region of westward tilting in the southwestern part of the basin, and a northwesterly trending antiform dividing subbasins in the center of the basin instead of a major scissor-like transfer zone. The overall eastward tilt indicated by the 3D geophysical model generally conforms to stratal tilts observed for the syn-rift succession, implying a prolonged eastward tilting of the basin during Miocene time. An extensive north-south synform in the central part of the Belen subbasin suggests a possible path for the ancestral Rio Grande during late Miocene or early Pliocene time. Variations in rift-fill thickness correspond to pre-rift structures in several places, suggesting that a better understanding of pre-rift history may shed light on debates about structural inheritance within the rift.
- accommodation zones
- Albuquerque Basin
- antiform folds
- basins
- boreholes
- Cenozoic
- density
- depressions
- dip
- faults
- folds
- geometry
- geophysical methods
- gravity anomalies
- gravity methods
- half grabens
- magnetotelluric methods
- Miocene
- models
- morphology
- Neogene
- New Mexico
- North America
- Pliocene
- rift zones
- Rio Grande
- Rio Grande Rift
- Santa Fe Group
- sedimentary basins
- sedimentary rocks
- sedimentation
- seismic methods
- subsidence
- tectonics
- Tertiary
- thickness
- three-dimensional models
- United States
- Calabacillas Subbasin
- Southern Belen Subbasin
- Northern Belen Subbasin
- Central Belen Subbasin