Preliminary Precambrian basement map showing geologic-geophysical domains, Wyoming

Sims, P.K.; Finn, Carol A.; Rystrom, V.L.

doi:10.3133/ofr01199

Cited by 21 publications

(29 citation statements)

References 25 publications

(25 reference statements)

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“…The main body of these gabbros appears to be located south of Blackhall Mountain, with the northern outcrops apparently representing dikes. This body also corresponds to a prominent aeromagnetic high (see Sims et al, 2001, their plate 2). The relatively isolated nature of this body on the aeromagnetic map supports the idea that this body represents a discrete mafi c complex, as suggested by Houston et al (1975).…”

Section: Bimodal Metagabbro-granodiorite Suitementioning

confidence: 91%

New models for Paleoproterozoic orogenesis in the Cheyenne belt region: Evidence from the geology and U-Pb geochronology of the Big Creek Gneiss, southeastern Wyoming

Jones

Snoke

Premo

et al. 2010

Geological Society of America Bulletin

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The disputed age of the deep crust of the Colorado Province is central to hypotheses for Paleoproterozoic crustal growth in the region. We studied the high-grade Big Creek Gneiss, southeastern Wyoming, as a potential exposure of pre-1780 Ma basement rocks. New geologic mapping and U-Pb geochronological data indicate that the Big Creek Gneiss exposes a deeper, but coeval, level of the Green Mountain arc relative to the predominantly supracrustal section to the west. The Big Creek Gneiss is composed of: supracrustal rocks; a ca. 1780 Ma Green Mountain arc-correlative, bimodal intrusive suite; a ca. 1763 Ma extensional(?) bimodal intrusive suite; and widespread ca. 1630 Ma pegmatitic leucogranite. The mafi c member of the younger bimodal suite is documented here for the fi rst time. U-Pb zircon ages from migmatite leucosomes indicate penetrative deformation of the Big Creek Gneiss at ca. 1750 Ma.We fi nd that the postarc intrusive suite is mantle-involved, implying a second period of crustal growth. Shortening postdates arc magmatism by ~20 m.y., implying that termination of arc magmatism and accretion were separate events. Finally, criteria previously used to constrain the polarity of subduction for the Green Mountain arc are not reliable. We propose two competing models: (1) southward-dipping Green Mountain arc subduction (present coordinates), with slab breakoff-related magmatism following arc accretion; or (2) northward-dipping subduction, with extensional postarc magmatism. In both models, high-temperature deformation coincides with accretion along the Cheyenne belt, and extensional magmatism is an impor-tant component of crustal growth. We prefer the northward-dipping subduction model because it can be better integrated with regional tectonic events and published isotopic compositions of the igneous rocks.

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Section: Bimodal Metagabbro-granodiorite Suitementioning

confidence: 91%

New models for Paleoproterozoic orogenesis in the Cheyenne belt region: Evidence from the geology and U-Pb geochronology of the Big Creek Gneiss, southeastern Wyoming

Jones

Snoke

Premo

et al. 2010

Geological Society of America Bulletin

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“…Inherited Precambrian tectonic features can influence subsequent deformation patterns and continental evolution over hundreds of millions of years [e.g., Allmendinger et al ., ; Karlstrom and Humphreys , ]. The Precambrian tectonics of northern Wyoming have largely been reconstructed through outcrop studies of widely spaced basement exposures [e.g., Chamberlain et al ., ; Frost et al ., , ; Kilian et al ., ; Mueller and Frost , ] and potential field analysis [ Sims et al ., ]. Details of the deep crustal structure of the region away from the exposures are not well known due to a lack of geophysical imaging, limiting understanding not only of Precambrian tectonics but also of Laramide kinematics.…”

Section: Introductionmentioning

confidence: 99%

“…The Wyoming Province consists of 3.6–3.0 Ga gneisses added to and modified by multiple late Archean magmatic and tectonic events as well as Proterozoic extension and rifting [ Chamberlain et al ., ; Houston et al ., ]. Significant magmatism between 2.90 and 2.75 Ga contributed to the basement rocks of the mountains and surrounding basins, including both strongly foliated and unfoliated granitic rocks and calc‐alkalic gneisses [ Chamberlain et al ., ; Heimlich and Banks , ; Mogk et al ., ; Sims et al ., ; Wooden and Mueller , ]. The older Bighorn gneiss terrain is exposed in the southern Bighorn Arch and likely comprises the basement rocks in the southern portion of the Bighorn Basin (Figure ) [ Frost et al ., ; Sims et al ., ].…”

Section: Introductionmentioning

confidence: 99%

“…Significant magmatism between 2.90 and 2.75 Ga contributed to the basement rocks of the mountains and surrounding basins, including both strongly foliated and unfoliated granitic rocks and calc‐alkalic gneisses [ Chamberlain et al ., ; Heimlich and Banks , ; Mogk et al ., ; Sims et al ., ; Wooden and Mueller , ]. The older Bighorn gneiss terrain is exposed in the southern Bighorn Arch and likely comprises the basement rocks in the southern portion of the Bighorn Basin (Figure ) [ Frost et al ., ; Sims et al ., ]. The Bighorn batholith, intruded at 2.86–2.84 Ga, is exposed in the northern Bighorn Arch and likely underlies much of the northern Bighorn Basin (Figure ) [ Sims et al ., ].…”

Section: Introductionmentioning

confidence: 99%

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Crustal structure of the Bighorn Mountains region: Precambrian influence on Laramide shortening and uplift in north‐central Wyoming

et al. 2016

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The crustal structure of north-central Wyoming records a history of complex lithospheric evolution from Precambrian accretion to Cretaceous-Paleogene Laramide shortening. We present two active source P wave velocity model profiles collected as part of the Bighorn Arch Seismic Experiment in 2010. Analyses of these velocity models and single-fold reflection data, together with potential field modeling of regional gravity and magnetic signals, constrain crustal structure and thickness of the Bighorn region. We image a west dipping reflection boundary and model a sharp magnetic contact east of the Bighorn Arch that together may delineate a previously undetected Precambrian suture zone. Localized patches of a high-velocity, high-density lower crustal layer (the "7.× layer") occur across the study area but are largely absent beneath the Bighorn Arch culmination. Moho topography is relatively smooth with no large-scale offsets, with depths ranging from~50 to 37 km, and is largely decoupled from Laramide basement topography. These observations suggest that (1) the edge of the Archean Wyoming craton lies just east of the Bighorn Mountains, approximately 300 km west of previous interpretations, and (2) Laramide deformation localized in an area with thin or absent 7.× layer, due to its relatively weak lower crust, leading to detachment faulting. Our findings show that Precambrian tectonics in northern Wyoming may be more complicated than previously determined and subsequent Laramide deformation may have been critically dependent on laterally heterogeneous crustal structure that can be linked to Precambrian origins.The potential role of Archean (>2.5 Ga) and Proterozoic (0.541-2.5 Ga) structures in the development of the Laramide orogeny (~75 Ma to~40 Ma) has been suggested by numerous studies that note contrasting structural patterns in the southern and northern Rocky Mountain provinces [Brown, 1993;Erslev and Koenig, 2009;Stone, 1986]. Deformation, probably driven by flat-slab subduction [e.g., Bird, 1988;Coney and Reynolds, 1977;Dickinson and Snyder, 1978], led to basement-involved thick-skinned shortening during the Laramide orogeny (~75 Ma to~40 Ma) [Dickinson et al., 1988], forming basement-cored foreland arches. In the Proterozoic basement of Colorado, Laramide arches typically strike north-northwest, are separated by narrow basins, and form a well-defined, en echelon deformation front on their eastern margin. In the large Archean basement of Wyoming, Laramide structures exhibit a larger variety of strikes and are separated by wide basins, with no well-defined deformation front. These contrasting geometries of thick-skinned deformation have been attributed to the greater diversity of structural fabrics in the Archean Wyoming basement [Brown, 1993;Erslev and Koenig, 2009] and different crustal architectures. Most notably, the high-velocity, high-density lower crustal WORTHINGTON ET AL.CRUSTAL STRUCTURE OF THE BIGHORN ARCH 208

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“…Р.П. Хартлауб с соавторами [Hartlaub et al, 2004] геологической картой южной половины провинции Вайоминг [Sims et al, 2001]. Дугообразно изогнутая выпуклостью на север северная граница провинции Вайоминг известна под названием Структура Вулкан (Vulcan structure).…”

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Deep Crustal Structure and Model of Neorchaean Evolution of the North American Craton

Mints¹,

Afonina²

2018

Geodin. tektonofiz.

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The structure of the Archaean crust of the North America has been studied based on the synthesis of geological and geophysical data, including seismic sections along LITHOPROBE Geotransects, magnetic and gravity anomaly maps, and seismic tomography data. The authors rely on the experience gained in the Russian Program of the deep geological and geophysical studies of the East European Craton. The juvenile Neoarchaean crust, containing the fragments of reworked Meso-and Paleoarchaean rocks, forms an asymmetric round-oval-shaped domain, wherein the geophysical, structural, and metamorphic parameters display a concentric zoning pattern. The Central zone occupies the Hudson Bay basin. The Internal zone (the northeastern and northern Superior Province) is mainly composed of the granulite facies of metaplutonic, metavolcanic and metasedimentary rocks. The External zone encompasses the southern Superior Province together with Hearne and Rae Provinces. This paper presents 3D crustal models of southern Superior Province. The crust development resulted from rifting and a partial disruption of the continental crust, short-term opening of the linear oceans, successive northward subduction and accretion of the ancient continental and juvenile Neoarchaean oceanic and island-arc terranes between ~2.78 and ~2.70 Ga. Subsequent events in the epicontinental environment, including formation of the metasedimentary belts, granulite facies metamorphism and intense ore formation processes, took place within the range from ~2.71 to ~2.63 Ga. The SCLM morphology within the limits of the Archaean North American Craton can be represented as a flattened overturned cone with a vertical axis (down to a depth of ~350 km). The Hudson Bay basin is located right above the lithospheric keel. A number of the main features of the structure and evolution of the Archaean crust of the North American Craton, primarily the ovalconcentric zoning, the important role of high-temperature magmatic and metamorphic processes and mainly intracontinental magmatism and sedimentation, indicates the leading role of the mantle-plume type processes. The Neoarchaean evolution of the North American craton represents the plate-tectonic processes initiated by a superplume. The Neoarchaean North American Craton is one of a series of similar phenomena that occurred ~2.75 Ga ago in a number of continental regions. The most important features, repeated to a certain degree in tectonic units of this type, are: (1) synchronous formation between 2.79 and 2.58 Ga; (2) mainly intracontinental development; (3) the prevalence of oval-shaped synformal tectonic structures of different ranks with some form of concentric zoning; (4) high-temperature magmatism (usually with the participation of enderbite-charnockites and gabbro-anorthosites) and metamorphism of the granulite facies; (5) a frequently repeated combination of high-grade (granulite and hightemperature amphibolites facies) and low-or moderate-grade (greenschist and epidote-amphibolite facies) metamorphic rocks; (6) the lower-c...

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Preliminary Precambrian basement map showing geologic-geophysical domains, Wyoming

Cited by 21 publications

References 25 publications

New models for Paleoproterozoic orogenesis in the Cheyenne belt region: Evidence from the geology and U-Pb geochronology of the Big Creek Gneiss, southeastern Wyoming

New models for Paleoproterozoic orogenesis in the Cheyenne belt region: Evidence from the geology and U-Pb geochronology of the Big Creek Gneiss, southeastern Wyoming

Crustal structure of the Bighorn Mountains region: Precambrian influence on Laramide shortening and uplift in north‐central Wyoming

Deep Crustal Structure and Model of Neorchaean Evolution of the North American Craton

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