Ages and Nature of Volcanic Activity on the Southern High Plains, New Mexico and Colorado

Stormer, John C.

doi:10.1130/0016-7606(1972)83[2443:aanova]2.0.co;2

Cited by 37 publications

(33 citation statements)

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“…Previous studies of the Rio Grande Rift have established the broad geochronologic framework for rift volcanism (Stormer, 1972a(Stormer, , 1972bLipman and Mehnert, 1979;O'Neill and Mehnert, 1988a;Stroud, 1997;Appelt, 1998;Penn, 1994;Leat et al, 1988;Perry et al, 1987;Thompson et al, 1991;Gibson et al, 1992), a framework that can be used in conjunction with more detailed studies in aerially restricted segments of the rift to deµne both the timing of rift initiation and the uplift or exhumation history of rift ×anks.…”

Section: Introductionmentioning

confidence: 99%

Extension and uplift of the northern Rio Grande Rift: Evidence from 40Ar/39Ar geochronology from the Sangre de Cristo Mountains, south-central Colorado and northern New Mexico

Miggins¹,

Thompson²,

Pillmore³

et al. 2002

Volcanic Rifted Margins

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New 40 Ar/ 39 Ar dating and geologic mapping of middle to late Cenozoic volcanic rocks and basin-µll sedimentary rocks preserved in the San Luis Valley and adjacent Sangre de Cristo Mountains give new insights into the timing of rift volcanism and opening of the northern Rio Grande Rift. The age, orientation, and elevation of these preserved sections delimit the timing of early rift volcanism, establishment of protorift or paleorift basins, and the uplift rate of the Sangre De Cristo crustal block along the eastern rift margin. We use offset geomorphic surfaces along with newly dated volcanic rocks to determine the exhumation or uplift rate of the Culebra Range relative to the adjacent San Luis Valley. On a µrst-order scale, we determined an exhumation rate of 58 m/m.y. based on the preserved section of 25 Ma volcanic rocks in the Culebra Range and ageequivalent volcanic rocks preserved in the San Luis Hills. A second uplift rate based on a 400 m offset section of Servilleta basalt dated as 4.7 Ma yields an exhumation rate of 87 m/m.y. Previous age data, exhumation and uplift rates, and µeld observations from the San Luis Valley region indicate that a major period of uplift and subsequent block faulting occurred during the middle Miocene (15 Ma), ~10 m.y. after the initiation of rifting.

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Section: Introductionmentioning

confidence: 99%

Extension and uplift of the northern Rio Grande Rift: Evidence from 40Ar/39Ar geochronology from the Sangre de Cristo Mountains, south-central Colorado and northern New Mexico

Miggins¹,

Thompson²,

Pillmore³

et al. 2002

Volcanic Rifted Margins

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“…In the western Great Plains, timing is constrained by the age of volcanic flows and interbedded ash layers within the basin fill. These indicate that incision began after 5 Ma (Naeser, et al, 1980) in the northwestern Great Plains, and after 8 and before 3 Ma (Stroud, 1997;Stormer, 1972) in the southwestern Great Plains. Volcanic flows and ash-fall tuffs also constrain the timing in southern Wyoming and northern Colorado to be after 11 Ma and (Buffler, 2003;Segerstrom and Young, 1972;Snyder, 1980;Izett, 1975) and before 8 Ma (Buffler, 2003;Lange et al, 2000).…”

Section: Timing Of Incisionmentioning

confidence: 99%

History and causes of post-Laramide relief in the Rocky Mountain orogenic plateau

McMillan

Heller

Wing

2006

Geological Society of America Bulletin

152

153

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The Rocky Mountain orogenic plateau has the highest mean elevation and topographic relief in the contiguous United States. The mean altitude exceeds 2 km above sea level and relief increases from 30 m in the river valleys of the Great Plains to more than 1.6 km deep in the canyons and basins of the Rocky Mountains and Colorado Plateau. Despite over a century of study, the timing and causes of elevation gain and incision in the region are unclear. Post-Laramide development of relief is thought to either result from tectonic activity or climatic change. Interpretation of which of these causes dominated is based upon reconstruction of datums developed from, and supported by, paleoelevation proxies and interpretations of landscape incision. Here we reconstruct a datum surface against which regional incision can be measured in order to evaluate late Cenozoic tectonic and climatic influences. The distribution, magnitude, and timing of post-Laramide basin filling and subsequent erosion are constrained by depositional remnants, topographic markers, and other indicators across the region. We suggest that post-Laramide basin filling resulted from slow subsidence during Oligocene to Miocene time. Incision into this basin fill surface began in late Miocene time and continues today. The pattern of incision is consistent with control by localized extensional tectonism superimposed upon regional domal surface uplift. Localized extension r E-mail: memcmillan@ualr.edu. 'E-mail: heller@uwyo.edu. ^E-mail: wing.scott@nmnh.si.edu.is associated with the projection of the Rio Grande Rift into the central Rockies, and the domal uplift generally coincides with the position of buoyant mantle anomalies interpreted at depth. If the magnitudes of incision directly reflect magnitudes of surface elevation gain, they are less than can be resolved by existing paleoelevation proxy methods. In addition, the combination of post-Laramide subsidence followed by regional surface uplift reduces the net magnitude of surface elevation change since Laramide time.

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“…Previous geochronological studies (Armstrong, 1969;Stormer, 1972;Smith, 1975) indicate that the oldest igneous bodies in the Spanish Peaks region were emplaced 27-26 Ma, coincident with regional extensional deformation and the most active and widespread phase of magmatism in the Rio Grande rift (Baldridge et al, 1995). Intrusive activity related to the Spanish Peaks predates the ~17-Ma lull in rift volcanism that signaled a change from aerially extensive, bimodal andesitic and basaltic volcanism to concentrated, dominantly basaltic volcanism in north-central and northeastern New Mexico (Baldridge et al, 1995).…”

Section: Regional Geological Settingmentioning

confidence: 99%

“…Previous studies loosely constrain emplacement of the Spanish Peaks intrusive rocks from late Oligocene to ea rly Miocene (Armstrong, 1969;Stormer, 1972;Smith, 1975;Miggins, 2002), roughly synchronous with initiation and development of the surface manifestations of the Rio Grande rift in southern Colorado (Tweto, 1979). However, these data are somewhat ambiguous and do not clearly delineate an intrusive order.…”

Section: Introductionmentioning

confidence: 96%

40Ar/39Ar dates for the Spanish Peaks intrusions in south-central Colorado

Penn

Lindsey

2009

Rocky Mountain Geology

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A diverse suite of spatially and temporally juxtaposed igneous rocks ranging from alkaline lamprophyres to granites intruded south-central Colorado during late Oligocene and early Miocene time. In addition to the stocks of the East and West Spanish Peaks, there are three types of dikes exposed in the region, based on orientation: radial, subparallel (striking approximately east-west), and independent dikes. The most striking features of this area are the numerous dikes radiating out from West Spanish Peak, some rising several tens of meters above the surrounding terrain and discontinuously exposed for tens of kilometers. New results from 40 Ar/ 39 Ar dating indicate that magmatism in the Spanish Peaks region began about 26.6 Ma and continued until about 21.8 Ma. Field evidence suggests that the initial intrusions were subparallel alkaline lamprophyre dikes south of the Spanish Peaks. A subsequent period of sub-alkaline magmatism occurred, producing West Spanish Peak (24.6 ± 0.13 Ma), East Spanish Peak (23.9 ± 0.08 Ma), and the radial dikes focused on West Spanish Peak. The final phase of magmatism included subparallel sub-alkaline lamprophyre dikes northeast of the Spanish Peaks. The 40 Ar/ 39 Ar results of this study substantiate the intrusive history derived from field relationships and establish the order of intrusion as West Spanish Peak, East Spanish Peak, and radial dikes, respectively. This study has implications for both the timing and style of the initiation of the Rio Grande rift, as well as the petrogenetic relationship between alkaline and sub-alkaline rocks in relatively stable cratonic areas.

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Ages and Nature of Volcanic Activity on the Southern High Plains, New Mexico and Colorado

Cited by 37 publications

References 0 publications

Extension and uplift of the northern Rio Grande Rift: Evidence from <sup>40</sup>Ar/<sup>39</sup>Ar geochronology from the Sangre de Cristo Mountains, south-central Colorado and northern New Mexico

Extension and uplift of the northern Rio Grande Rift: Evidence from <sup>40</sup>Ar/<sup>39</sup>Ar geochronology from the Sangre de Cristo Mountains, south-central Colorado and northern New Mexico

History and causes of post-Laramide relief in the Rocky Mountain orogenic plateau

40Ar/39Ar dates for the Spanish Peaks intrusions in south-central Colorado

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