Professional Paper 1720
The geologic, geophysical, and hydrogeologic properties of the La Bajada constriction and Santo Domingo Basin, northern New Mexico, result from tectonic and volcanic processes of the late Tertiary and Quaternary Rio Grande rift. An integrated geologic and geophysical assessment in the La Bajada constriction allows development of a geologic framework that can provide input for regional ground-water flow models. These models then can provide better estimates of future water supplies in a region that largely subsists on aquifers in Rio Grande rift basins. The combination of surface geologic investigations (stratigraphic and structural studies; chapters A, B, C, and E), airborne geophysics (aeromagnetic and time-domain electromagnetic surveys; chapters D and F), ground geophysical measurements (gravity and magnetotelluric surveys; chapters D and F), and data from the few wells in the area (chapter G) provides new constraints on the hydrogeologic framework of this area.
Summary results of our investigations are synthesized in chapter G. Through-going aquifers consisting of ancestral Rio Grande axial-river sand and gravel and of coarse western-piedmont gravel form the predominant ground-water pathways through the partly buried structural trough defining the La Bajada constriction between Española and Santo Domingo Basins. Thick, clay-rich Cretaceous marine shales of low hydraulic conductivity form a pervasive regional confining unit within the Cerrillos uplift on the southeast flank of the constriction. Numerous, dominantly north-northwest-striking, intrabasin faults that project part way across the La Bajada constriction create a matrix of laterally and vertically variable hydrogeologic compartments that locally partition and deflect ground-water flow parallel to faults.
Posted March 2007
Table of Contents: includes links to the chapters and plates.
Chapter A. Geologic Setting of the La Bajada Constriction and Cochiti Pueblo Area, New Mexico
Chapter B. Stratigraphy of Upper Cenozoic Fluvial Deposits of the La Bajada Constriction Area, New Mexico
Chapter C. Cenozoic Volcanism of the La Bajada Constriction Area, New Mexico
Chapter D. Gravity and Aeromagnetic Studies of the Santo Domingo Basin Area, New Mexico
Chapter E. Structure of the Santo Domingo Basin and La Bajada Constriction Area, New Mexico
Chapter F. Electromagnetic Studies and Subsurface Mapping of Electrical Resistivity in the La Bajada Constriction Area, New Mexico
Chapter G. Hydrogeologic Framework of the La Bajada Constriction Area, New Mexico—Integration of Subsurface and Surface Geology
Plate 1. Map Showing Physiographic and Cultural Features of the Santo Domingo Basin and Adjoining Areas, New Mexico
Plate 2. Geologic Map of the Cochiti Pueblo Area, New Mexico
Plate 2 with shaded relief
Plate 3. Isostatic Residual Gravity Map of the Santo Domingo Basin Area, New Mexico
Plate 4. Reduced-to-Pole Aeromagnetic Map of the Santo Domingo Basin Area, New Mexico
Plate 5. Map Showing Reduced-to-Pole Aeromagnetic Data, Geology, and Topography for the Cochiti Pueblo Area, New Mexico
Plate 6. Geologic Cross Sections Spanning the La Bajada Constriction and Northern Cerrillos Uplift, New Mexico