Evolution of the Early Proterozoic Colorado province: Constraints from U-Pb geochronology

Reed, John C.; Bickford, M. E.; Premo, Wayne R.; Aleinikoff, John N.; Pallister, John S.

doi:10.1130/0091-7613(1987)15<861:eotepc>2.0.co;2

Cited by 91 publications

(61 citation statements)

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“…The Cheyenne Belt, a series of east to northeast trending, south dipping shear zones that are exposed in southern Wyoming, marks the current northern boundary of the Colorado province [Hills and Houston, 1979;Karlstrom and Houston, 1984;Duebendorfer and Houston, 1987;Houston et al, 1989;Chamberlain, 1998]. The southern boundary separating the Colorado/Yavapai province from the circa 1.65 Ga Mazatzal province [Karlstrom and Bowring, 1988] is a northeast trending diffuse zone that extends from southern Arizona to central Colorado [Bennett and DePaolo, 1987;Reed et al, 1987;Shaw and Karlstrom, 1999;Karlstrom et al, 2002]. Geochronologic, geochemical, xenolith, and structural data suggest that this boundary was initially a north dipping subduction zone [e.g., Reed et al, 1987;Knoper and Condie, 1988;Selverstone et al, 1999;Shaw and Karlstrom, 1999], but seismic data have been used to argue for a south dipping structure .…”

Section: Overviewmentioning

confidence: 99%

“…[13] A network of northeast trending Proterozoic shear zones [Tweto and Sims, 1963;Warner, 1978] divides the region into separate crustal blocks that record complex deformational histories [e.g., Reed et al, 1987;Selverstone et al, 2000]. From the Wyoming border to the Denver area, the shear zones are distributed approximately every 25 km.…”

Section: Shear Zones In the Northern Front Rangementioning

confidence: 99%

“…[7] The Colorado/Yavapai province is a $500-km-wide swath of northeast striking rocks that contains the first Proterozoic material accreted to the Archean Wyoming craton, beginning around 1.79 Ga [Condie and Shadel, 1984;Bickford et al, 1986;Reed et al, 1987] (Figure 1). Prior to that time (circa 2.1-1.8 Ga), the southern margin of the Wyoming province was characterized by rifting and development of a passive margin [Karlstrom et al, 1983;Karlstrom and Houston, 1984;Chamberlain, 1998].…”

Section: Overviewmentioning

confidence: 99%

“…Taken together, these data have been used to argue that southward growth of Laurentia occurred via successive accretion of island arc/backarc terranes onto the Archean craton along multiple subduction zones [e.g., Hills and Houston, 1979;Condie, 1982;Karlstrom and Houston, 1984;Reed et al, 1987;Knoper and Condie, 1988;Houston et al, 1989;Van Schmus et al, 1993].…”

Section: Introductionmentioning

confidence: 99%

“…[3] Geochemical data from metavolcanic and metasedimentary rocks within the Early Proterozoic terranes of the southwestern United States are generally interpreted to represent arc, backarc, and intra-arc deposits [Condie and Martel, 1983;Reed et al, 1987;Bickford and Boardman, 1984;Boardman and Condie, 1986;Knoper and Condie, 1988;Premo and Loucks, 2000]. Taken together, these data have been used to argue that southward growth of Laurentia occurred via successive accretion of island arc/backarc terranes onto the Archean craton along multiple subduction zones [e.g., Hills and Houston, 1979;Condie, 1982;Karlstrom and Houston, 1984;Reed et al, 1987;Knoper and Condie, 1988;Houston et al, 1989;Van Schmus et al, 1993].…”

Section: Introductionmentioning

confidence: 99%

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Early Proterozoic oceanic crust in the northern Colorado Front Range: Implications for crustal growth and initiation of basement faults

Cavosie¹,

Selverstone

2003

Tectonics

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Early Proterozoic oceanic crust exposed in a shear zone in the northern Colorado Front Range provides insight into the tectonic evolution of the Colorado province. Tectonically intermingled mylonitic amphibolite (locally pillowed), metagabbro, clinopyroxenite, metachert, and mélange are preserved within the Buckhorn Creek shear zone west of Fort Collins. Whole rock geochemical data support formation of the igneous protoliths in an oceanic environment. Major and trace element data overlap samples from modern oceanic ridges, and are distinct from modern arc trends. Metagabbros and clinopyroxenites preserve a subhorizontal lineation defined by igneous pyroxenes; core and mantle microstructures indicate initial deformation at temperatures >900°C. Secondary amphiboles define both subhorizontal and subvertical lineations. Kinematic analysis indicates that the rocks experienced E‐W strike‐slip deformation prior to and during amphibolite‐facies metamorphism, followed by N‐S shortening. 40Ar/39Ar data from secondary hornblende yield age steps as old as 1.9 Ga. Based on the chemical data and kinematic evidence for strike‐slip deformation, we propose that the Buckhorn Creek rocks originated at an oceanic ridge‐transform intersection. The high‐T pyroxene fabrics formed during ocean floor deformation prior to 1.7 Ga regional deformation of the Colorado province. The Buckhorn Creek fragment likely represents original oceanic basement for 1.8–1.7 Ga arc magmatism and sedimentation that ultimately formed the Colorado province continental crust. Reactivation of original oceanic fracture zones may be responsible for the network of regularly spaced northeast trending shear zones in Colorado. Once formed, subvertical transform faults are likely to survive the transition from oceanic to continental crust and persist as long‐lived crustal discontinuities.

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Section: Overviewmentioning

confidence: 99%

Section: Shear Zones In the Northern Front Rangementioning

confidence: 99%

Section: Overviewmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Early Proterozoic oceanic crust in the northern Colorado Front Range: Implications for crustal growth and initiation of basement faults

Cavosie¹,

Selverstone

2003

Tectonics

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A rootless rockies—Support and lithospheric structure of the Colorado Rocky Mountains inferred from CREST and TA seismic data

Hansen

Dueker

Stachnik

et al. 2013

Geochem Geophys Geosyst

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[1] Support for the Colorado high topography is resolved using seismic data from the Colorado Rocky Mountain (CRM) Experiment and Seismic Transects. The average crustal thickness, derived from P wave receiver function imaging, is 48 km. However, a negative correlation between Moho depth and elevation is observed, which negates Airy-Heiskanen isostasy. Shallow Moho (<45 km depth) is found beneath some of the highest elevations, and therefore, the CRM are rootless. Deep Moho (45-51 km) regions indicate structure inherited from the Proterozoic assembly of the continent. Shear wave velocities from surface wave tomography are mapped to density employing empirical velocity-to-density relations in the crust and mantle temperature modeling. Predicted elastic plate flexure and gravity fields derived from the density model agree with observed long-wavelength topography and Bouguer gravity. Therefore, lowdensity crust and mantle are sufficient to support much of the CRM topography. Centers of Oligocene volcanism, e.g., the San Juan Mountains, display reduced crustal thicknesses and lowest average crustal velocities, suggesting that magmatic modification strongly influenced modern lithospheric structure and topography. Mantle velocities span 4.02-4.64 km/s at 73-123 km depth, and peak lateral temperature variations of 600 C are inferred. S wave receiver function imaging suggests that the lithosphereasthenosphere boundary is 100-150 km deep beneath the Colorado Plateau, and 150-200 km deep beneath the High Plains. A region of negative arrivals beneath the CRM above 100 km depth correlates with low mantle velocities and is interpreted as thermally modified/metasomatized lithosphere resulting from Cenozoic volcanism.

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Project Upper Crust: A Program to Sample the Precambrian Basement of the Midcontinent Region of North America Using Industrial Drill Holes

Schmus

Bickford

Latham

1988

Deep Drilling in Crystalline Bedrock

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Evolution of the Early Proterozoic Colorado province: Constraints from U-Pb geochronology

Cited by 91 publications

References 0 publications

Early Proterozoic oceanic crust in the northern Colorado Front Range: Implications for crustal growth and initiation of basement faults

Early Proterozoic oceanic crust in the northern Colorado Front Range: Implications for crustal growth and initiation of basement faults

A rootless rockies—Support and lithospheric structure of the Colorado Rocky Mountains inferred from CREST and TA seismic data

Project Upper Crust: A Program to Sample the Precambrian Basement of the Midcontinent Region of North America Using Industrial Drill Holes

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