Oil and gas plays of the Las Animas Arch, southeastern Colorado

Merewether, E.A.

doi:10.3133/ofr87450d

Cited by 5 publications

(10 citation statements)

References 3 publications

(1 reference statement)

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“…Paleozoic compression reactivated faults in each suture zone, impounding the Denver basin and the NW end of the Anadarko basin 12 13 . The Cenozoic Laramide orogeny created 3 km of structural relief in the CB 14 (exhuming Archean rocks) and reactivated the YMS 15 , where units as old as Permian are now locally exposed.…”

mentioning

confidence: 99%

Gravitational body forces focus North American intraplate earthquakes

2017

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Earthquakes far from tectonic plate boundaries generally exploit ancient faults, but not all intraplate faults are equally active. The North American Great Plains exemplify such intraplate earthquake localization, with both natural and induced seismicity generally clustered in discrete zones. Here we use seismic velocity, gravity and topography to generate a 3D lithospheric density model of the region; subsequent finite-element modelling shows that seismicity focuses in regions of high-gravity-derived deviatoric stress. Furthermore, predicted principal stress directions generally align with those observed independently in earthquake moment tensors and borehole breakouts. Body forces therefore appear to control the state of stress and thus the location and style of intraplate earthquakes in the central United States with no influence from mantle convection or crustal weakness necessary. These results show that mapping where gravitational body forces encourage seismicity is crucial to understanding and appraising intraplate seismic hazard.

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confidence: 99%

Gravitational body forces focus North American intraplate earthquakes

2017

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“…The contrast between unusually low pressures (and heads) in Mississippian reservoirs and higher pressures (and heads) in Pennsylvanian reservoirs on the Las Animas arch was noted by Clair and Volk (1968) and Merewether (1987). In south-central Kansas, the presence of high-porosity Mississippian chert reservoirs (called "chat") resulted from diagenesis due to subaerial exposure and structural features.…”

Section: Hydraulic Head In Paleozoic Stratamentioning

confidence: 95%

Underpressure in Mesozoic and Paleozoic rock units in the Midcontinent of the United States

2015

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A B S T R A C TPotentiometric surfaces for Paleozoic strata, based on water well levels and selected drill-stem tests, reveal the control on hydraulic head exerted by outcrops in eastern Kansas and Oklahoma. From outcrop in the east, the westward climb of hydraulic head is much less than that of the land surface, with heads falling so far below land surface that the pressure:depth ratio in eastern Colorado is less than 5.7 kPa/m (0.25 psi/ft). Permian evaporites separate the Paleozoic hydrogeologic units from a Lower Cretaceous (Dakota Group) aquifer, and a highly saline brine plume pervading Paleozoic units in central Kansas and Oklahoma is attributed to dissolution of Permian halite. Underpressure also exists in the Lower Cretaceous hydrogeologic unit in the Denver Basin, which is hydrologically separate from the Paleozoic units. The data used to construct the seven potentiometric surfaces were also used to construct seven maps of pressure:depth ratio. These latter maps are a function of the differences among hydraulic head, landsurface elevation, and formation elevation. As a consequence, maps of pressure:depth ratio reflect the interplay of three topologies that evolved independently with time. As underpressure developed, gas migrated in response to the changing pressure regime, most notably filling the Hugoton gas field in southwestern Kansas. The timing of underpressure development was determined by the timing of outcrop exposure and tilting of the Great Plains. Explorationists in western Kansas and eastern Colorado should not be surprised if a reservoir is underpressured; rather, they should be surprised if it is not.

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“…These are presented as Figs. DR1-DR2 1 and are grounded in earlier revisions of the region's Permian-Triassic nomenclature (Hill, 1899;Lee and Knowlton, 1917;Clifton, 1925;Sanders, 1934;Maher and Collins, 1952;Shaw, 1956;Broin, 1957;Maughan, 1980;Wiggs, 1986;Merewether, 1987). Our methodology for fi eld and laboratory analyses is described in the GSA Data Repository (Appendix DR1; see footnote 1).…”

Section: Nomenclature and Methodsmentioning

confidence: 99%

The Permian-Triassic transition in Colorado

Hagadorn

Whiteley

Lahey

et al. 2016

Unfolding the Geology of the West

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The Lykins Formation and its equivalents in Colorado are a stratigraphically poorly constrained suite of redbeds and intercalated stromatolitic carbonates, which is hypothesized to span the Permian-Triassic boundary. Herein we present a preliminary detrital zircon geochronology, new fossil occurrences, and δ 13 C chemostratigraphy for exposures along the Front Range and in southeastern Colorado, to refi ne understanding of the unit's age and depositional history. Detrital zircons from the uppermost Lykins Formation and an overlying eolianite consist of a complex and highly diverse primary and multi-cycle grain population transported from Laurentian and Gondwanan terranes, potentially both by wind and water. Youngest concordant zircons do not rule out deposition of the uppermost Lykins Formation during a portion of Early Triassic time. Conodonts from the lower Lykins Formation require Middle Permian (Guadalupian) deposition. Conodont alteration indices of 1 indicate the unit has a shallow burial history and is amenable to paleomagnetic inquiry. Conodonts, together with other vertebrate, invertebrate, microfossil, and trace fossils, suggest a very shallow to emergent marine origin for the unit's most substantial carbonates, and hint at a marine origin for the unit's intercalated gypsum-anhydrite members. Chemostratigraphy corroborates fi eld evidence of emergence and karst development capping certain units, like the Forelle Limestone Member of the Lykins Formation, where potential sequence boundaries appear to be punctuated by a short-lived meteoric signature. Results presented here are a progress report of ongoing work in these successions. This fi eld trip consists of a brief tour through exposures of the Lykins Formation, in which we will examine well-known localities as well as view new ones for which we seek insights.

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Oil and gas plays of the Las Animas Arch, southeastern Colorado

Cited by 5 publications

References 3 publications

Gravitational body forces focus North American intraplate earthquakes

Gravitational body forces focus North American intraplate earthquakes

Underpressure in Mesozoic and Paleozoic rock units in the Midcontinent of the United States

The Permian-Triassic transition in Colorado

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