A shifting rift—Geophysical insights into the evolution of Rio Grande rift margins and the Embudo transfer zone near Taos, New Mexico

Grauch, V.J.S.; Bauer, Paul W.; Drenth, Benjamin J.; Kelson, Keith I.

doi:10.1130/ges01425.1

Cited by 10 publications

(29 citation statements)

References 74 publications

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“…Both wells in the San Luis Basin lie within the structurally deepest area of the basin (Grauch et al, 2017) and show similar subsidence histories (Fig. 4).…”

Section: Results: Tectonic Subsidence Curves Of the Rio Grande Riftmentioning

confidence: 83%

“…It is not known if the Miocene-Pliocene unconformity is present in these wells. The Airport well (Taos Airport well of Grauch et al, 2017) is located in the Los Cordovas fault zone on the west side of the structural low, and the K3 well lies within the western (inner) side of a 6-km-wide fault system bounding the southeastern side of this structural low ( Fig. 3; Grauch et al, 2017).…”

Section: Results: Tectonic Subsidence Curves Of the Rio Grande Riftmentioning

confidence: 99%

“…In the Albuquerque Basin, the unconformity has been described on both western and eastern margins of the basin (Maldonado et al, 2007; Unconformity extent unknown because of cover by Servilleta Basalt. Drawn around southwest margins of Timber Mountain horst and the structural high under the San Luis Hills, the boundaries of which were interpreted using geophysical interpretations (Grauch et al, 2004(Grauch et al, , 2017Drenth et al, 2013) and geologic mapping (Thompson et al, 2015).…”

Section: Lateral Extent and Charactermentioning

confidence: 99%

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Tectonic subsidence, geoid analysis, and the Miocene-Pliocene unconformity in the Rio Grande rift, southwestern United States: Implications for mantle upwelling as a driving force for rift opening

et al. 2018

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We use tectonic subsidence patterns from wells and stratigraphic sections to describe the mid-Miocene to present tectonic subsidence history of the Rio Grande rift. Tectonic subsidence and therefore rift opening were quite fast until ca. 8 Ma, with net subsidence rates (~25-65 mm/k.y.) comparable to those of the prerupture phase of rifted continental margins. The rapid subsidence was followed by a late Miocene-early Pliocene unconformity that developed mainly along the flanks of most rift basins. The age of its associated lacuna is spatially variable but falls within 8-3 Ma (mostly 7-5 Ma) and thus is synchronous with eastward tilting of the western Great Plains (ca. 6-4 Ma). Tectonic subsidence rates either remained similar or decreased after the Miocene-Pliocene unconformity. North of 35°N, our analysis of geoid-to-elevation ratios suggests that, at present, topography of the Rio Grande rift region is compensated by a component of mantle-driven dynamic uplift. Previous work has indicated that this dynamic uplift is caused by focused vertical flow in the upper mantle resulting from slab descent and fragmentation of the Farallon slab, and Rio Grande rift opening, which affected the Rio Grande rift area beginning in the late Miocene. The spatial distribution and timing of the unconformity, as well as eastward tilting of the western Great Plains, can be explained by this dynamic mantle uplift, with contributions from variations in rift opening tectonics and climate. The focused mantle upwelling is not associated with increased rift opening rates.

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“…Both wells in the San Luis Basin lie within the structurally deepest area of the basin (Grauch et al, 2017) and show similar subsidence histories (Fig. 4).…”

Section: Results: Tectonic Subsidence Curves Of the Rio Grande Riftmentioning

confidence: 83%

Section: Results: Tectonic Subsidence Curves Of the Rio Grande Riftmentioning

confidence: 99%

Section: Lateral Extent and Charactermentioning

confidence: 99%

See 1 more Smart Citation

Tectonic subsidence, geoid analysis, and the Miocene-Pliocene unconformity in the Rio Grande rift, southwestern United States: Implications for mantle upwelling as a driving force for rift opening

et al. 2018

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“…The deviations between our inverse model and the Bouguer gravity profile are unsurprising given our schematic approach. In particular, amphibolite‐facies metavolcanics have measured density as high as 2,900 kg/m 3 in the region (Grauch et al, ). Thus, larger bodies of amphibolite would cause Δρ to deviate from 100 kg/m 3 .…”

Section: Discussionmentioning

confidence: 99%

Geochronology of a Bouguer Gravity Low

et al. 2019

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Dense drill core and subsurface mapping at the Questa molybdenum mine, combined with regional structural tilt, permit detailed 3‐D documentation of plutonic rocks in the Latir magmatic center, New Mexico. Integration of mapping with new and existing U‐Pb zircon geochronology (a total of 136 analyses from 15 intrusions) allows for examination of the space‐time evolution of the Bouguer gravity low associated with the magmatic center. The Questa batholith at Latir was assembled by discrete pulses of magma over a 5.5‐Ma interval (approximately 25.3–19.8 Ma) of generally downward stacking intrusions following the volcanic peak at 25.52 Ma. This contradicts interpretations that the Bouguer gravity lows here and elsewhere are the plutonic crystal cumulate residues left after extraction of large‐volume silicic magmas. Estimates of magma flux based on the volume of plutonic rocks inferred from gravity data combined with the extrapolation of geochronology of exposed surface rocks are questionable because the assumption that unexposed plutonic rocks are the same age as dated surface rocks directly above them likely underestimates the true range of ages.

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“…Furthermore, the temporal evolution of the structures bounding the basin and its subbasins has not been fully described. A previous model of the basin based on gravity modeling (Keller et al, 1984) is now obsolete in several areas due to (1) new information on basin-bounding structures; (2) a better understanding of rocks that constitute rift-related deposits; (3) better estimates of physical properties; (4) a better understanding of the geophysical signature of pre-rift and transitional rocks; and (5) more sophisticated approaches to geophysical modeling (Grauch and Keller, 2004;Drenth et al, 2011Drenth et al, , 2013Ruleman et al, 2013;Grauch et al, 2015Grauch et al, , 2017Thompson et al, in press;Turner et al, in press). These more recent concepts, developed locally within or at the edges of the present study area, await integration into a broader synthesis of the geometry and development of the southern San Luis Basin.…”

Section: Introductionmentioning

confidence: 99%

A shallow rift basin segmented in space and time: The southern San Luis Basin, Rio Grande rift, northern New Mexico, U.S.A.

Drenth

Grauch

Turner

et al. 2019

Rocky Mountain Geology

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Interpretation of gravity, magnetotelluric, and aeromagnetic data in conjunction with geologic constraints reveals details of basin geometry, thickness, and spatiotemporal evolution of the southern San Luis Basin, one of the major basins of the northern Rio Grande rift. Spatial variations of low-density basin-fill thickness are estimated primarily using a 3D gravity inversion method that improves on previous modeling efforts by separating the effects of the low-density basin fill from the effects of pre-rift rocks. The basin is found to be significantly narrower—and more complex in the subsurface—than indicated or implied by previous modeling efforts. The basin is also estimated to be significantly shallower than previously estimated. Five distinct subbasins are recognized within the broader southern San Luis Basin. The oldest and shallowest subbasin is the Las Mesitas graben along the northwestern basin margin, formed during the Oligocene transition from Southern Rocky Mountain volcanic field magmatism to rifting. In this subbasin, sediments are estimated to reach a maximum thickness of ~400 m within a north–south elongated structural depression. Other subbasins that likely initially developed during the Miocene are the dominant tectonic features in the southern San Luis Basin. This includes the Tres Orejas subbasin, which formed in the southwestern portion of the basin by the Embudo fault zone and a hypothesized fault zone along its western margin. This subbasin reaches a maximum thickness of ~2 km, as indicated by magnetotelluric and gravity modeling. The Sunshine Valley, Questa, and Taos subbasins occupy the eastern part of the southern San Luis Basin. The southern Sangre de Cristo fault zone is the dominant tectonic feature that controlled their development after ~20 Ma. The east-down Gorge fault zone controlled the western margins of significant parts of these eastern subbasins, although much of the Taos subbasin may be superimposed on the Tres Orejas subbasin. Maximum low-density basin-fill thicknesses are estimated to be 1.2 km for the Sunshine Valley subbasin, 800 m for the Questa subbasin, and 1.8 km for the Taos subbasin. Subbasin-forming tectonic activity along the Gorge fault zone and within the Tres Orejas subbasin ceased by the end of the development of the largely Pliocene Taos Plateau volcanic field. After that, rift-related subsidence became more narrowly centered on the eastern margin of the basin, controlled mainly by the linked Embudo and southern Sangre de Cristo fault zones.

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A shifting rift—Geophysical insights into the evolution of Rio Grande rift margins and the Embudo transfer zone near Taos, New Mexico

Cited by 10 publications

References 74 publications

Tectonic subsidence, geoid analysis, and the Miocene-Pliocene unconformity in the Rio Grande rift, southwestern United States: Implications for mantle upwelling as a driving force for rift opening

Tectonic subsidence, geoid analysis, and the Miocene-Pliocene unconformity in the Rio Grande rift, southwestern United States: Implications for mantle upwelling as a driving force for rift opening

Geochronology of a Bouguer Gravity Low

A shallow rift basin segmented in space and time: The southern San Luis Basin, Rio Grande rift, northern New Mexico, U.S.A.

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