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The western margin of the Rio Grande Rift in northern New Mexico: An aborted boundary?

1994; Geological Society of America; Volume: 106; Issue: 12 Linguagem: Inglês

10.1130/0016-7606(1994)106 2.3.co;2

1943-2674

W. Scott Baldridge, John Ferguson, L. W. Braile, Bin Wang, KRISTINE ECKHARDT, David H. Evans, Craig A. Schultz, Bernard E. Gilpin, George R. Jiracek, Shawn Biehler,

Geological Studies and Exploration

Research Article| December 01, 1994 The western margin of the Rio Grande Rift in northern New Mexico: An aborted boundary? W. SCOTT BALDRIDGE; W. SCOTT BALDRIDGE 1Earth and Environmental Sciences Division, M.S. D462, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 Search for other works by this author on: GSW Google Scholar JOHN F. FERGUSON; JOHN F. FERGUSON 2Program in Geosciences, University of Texas at Dallas, Box 830688, Richardson, Texas 75080 Search for other works by this author on: GSW Google Scholar LAWRENCE W. BRAILE; LAWRENCE W. BRAILE 3Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907 Search for other works by this author on: GSW Google Scholar BIN WANG; BIN WANG 3Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907 Search for other works by this author on: GSW Google Scholar KRISTINE ECKHARDT; KRISTINE ECKHARDT 4Earth Sciences Board of Studies, University of California at Santa Cruz, Santa Cruz, California 95064 Search for other works by this author on: GSW Google Scholar DAVID EVANS; DAVID EVANS 5Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125 Search for other works by this author on: GSW Google Scholar CRAIG SCHULTZ; CRAIG SCHULTZ 6Earth Resources Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142 Search for other works by this author on: GSW Google Scholar BERNARD GILPIN; BERNARD GILPIN 7Department of Physics, Golden West College, Huntington Beach, California 92647 Search for other works by this author on: GSW Google Scholar GEORGE R. JIRACEK; GEORGE R. JIRACEK 8Department of Geological Sciences, San Diego State University, San Diego, California 92182 Search for other works by this author on: GSW Google Scholar SHAWN BIEHLER SHAWN BIEHLER 9Department of Earth Sciences, University of California, Riverside, California 92521 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1994) 106 (12): 1538–1551. https://doi.org/10.1130/0016-7606(1994)106 2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation W. SCOTT BALDRIDGE, JOHN F. FERGUSON, LAWRENCE W. BRAILE, BIN WANG, KRISTINE ECKHARDT, DAVID EVANS, CRAIG SCHULTZ, BERNARD GILPIN, GEORGE R. JIRACEK, SHAWN BIEHLER; The western margin of the Rio Grande Rift in northern New Mexico: An aborted boundary?. GSA Bulletin 1994;; 106 (12): 1538–1551. doi: https://doi.org/10.1130/0016-7606(1994)106 2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The northwestern margin of the Española basin, part of the Rio Grande rift in northern New Mexico, is characterized by a zone >17 km wide of oblique-slip faults that offset upper Paleozoic and Mesozoic strata of the eastern Colorado Plateau from Eocene and younger sedimentary rocks of the rift. Along this margin, a reasonably complete section of pre- and synrift Tertiary sediments is exposed. Combined interpretations of seismic reflection, seismic refraction, gravity, and geologic data acquired along a profile perpendicular to this boundary define the geometry of faulting, possible rotation of sedimentary units, and stratigraphy of rift fill. Vertical separation on the westernmost major fault, assumed to be the bounding fault between the rift and the Colorado Plateau, is <500 m; separation on other faults in the zone is <200 m. Thus the northwestern part of the Española basin ("Abiquiu embayment") is a shallow platform rather than a deep rift basin. The embayment is separated from the main Española basin by the east-northeast-striking Embudo transfer fault, which appears to act as the northern bounding fault of the main basin.Although Tertiary units are progressively faulted downward toward the axis of the rift, depth to inferred Precambrian crystalline rocks becomes shallower and the stratigraphic thickness of the intervening Paleozoic and Mesozoic units decreases toward the axis. We interpret pinching out of these units toward the east as erosional thinning on the western flanks of the Laramide-age Sangre de Cristo/Brazos geanticline, which underlay much of the present rift basin.Imprecise age constraints suggest that faulting of the rift margin began 10-7 Ma, but was not active after 7 Ma. Extension was apparently transferred to the Embudo fault zone, which remained active until at least 2.5 Ma and possibly into Quaternary time. The Embudo transfer zone effectively decoupled the Abiquiu embayment from the main Española basin. Thus the boundary at Abiquiu preserves an early stage in the formation of the rift boundary. The shift in activity may have resulted from a change in regional stress field, or from increasing magnitude of strain, or both. The change in locus of extension reflects a narrowing of rift basins through time and an integration of main bounding structures between adjacent basins.Although we are uncertain whether the Abiquiu region, which uniquely preserves an early stage of deformation, is representative of other areas of continental extension, our results indicate that the initial formation of rift basins may occur as high-angle, planar normal faults distributed over a broad zone. No evidence from seismic data or from rotation of beds exists to indicate that faults become listric with depth, which is compatible with the small amount of extension (3.5%) inferred at this boundary. This content is PDF only. Please click on the PDF icon to access. 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