Tag Archives: geology

Sandstone Dikes in the South Platte Area, Colorado.

Abstract (Geology) Sandstone dikes occur along the northeastern contact zone of the Pikes Peak batholith in the South Platte area, Colorado. The dikes range in width from a few inches to more than 10 feet and in length from a … Continue reading

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The Braided Stream Depositional Environment: Comparison of the Platte River with Some Silurian Calstic Rocks, North-Central Appalachians.

Abstract (Geology, Water Quality) Studies of the South Platte-Platte River in Colorado and Nebraska substantiate Ore’s (1964) conclusion that braided patterns in streams are created mainly by accretion of longitudinal bars and dissection of transverse bars. Distribution of bars in … Continue reading

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Geochemistry and Evolution of the South Platte Granite-Pegmatite System, Jefferson County, Colorado.

Abstract (Geology) The South Platte pegmatite district is well known for its significant enrichment in the rare earth elements (REE), Y, Nb, F, and for the exceptionally well-developed internal zonation of the complex pegmatites located within a reversely zoned portion … Continue reading

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Geoarchaeologic Analysis of South Platte River Terraces: Kersey, Colorado.

Abstract (Geology) Soil-sediment records and radiometric dating allow the development of environmental histories of three South Platte River alluvial terraces in the vicinity of Kersey, Colorado. These advocate a correlation with Holocene glacial records for the Colorado Front Range (Benedict, … Continue reading

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Stratigraphic Evidence of Desertification in the West-Central Great Plains within the past 1000 yr.

Abstract (Geology, Pollution – Sediment) Stratigraphic and geomorphic relations, archeological data, and eight radiocarbon ages at five widely scattered localities in northeastern Colorado indicate that eolian sand was mobilized over broad areas within the past 1000 yr. The mobilization began … Continue reading

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Gravel Deposits of the South Platte River Valley North of Denver, Colorado: Part C: Description, Composition, and Origin of Clay Lenses in Gravel.

Abstract (Geology, Pollution – Sedimentation) Clay lenses in the Western Mobile Howe and Mann Lake gravel pits were investigated to determine their distribution, form, composition, and depositional environment, with the ultimate goal of predicting their distribution beneath the surface.  Clay … Continue reading

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The Composition and Origin of Hydrothermal Fluids in a NYF-Type Granitic Pegmatite, South Platte District, Colorado: Evidence from LA-ICP-MS Analysis of Fluorite-and Quartz-Hosted Fluid Inclusions.

  Abstract (Geology) Hydrothermal fluorite–rare-earth-element REE mineralization occurs in the zoned Oregon No. 3 (niobium–yttrium–fluorine) granitic pegmatite (NYF-type) hosted by the Proterozoic Pikes Peak granite in north-central Colorado. The mineralization comprises secondary albite, fluorite and REE minerals (predominantly samarskite and … Continue reading

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Alteration as an End Phase of Igneous Intrusion in Sills on Loveland Mountain, Park County, Colorado

Abstract (Geology) Sills occurring in the sedimentary rocks on the lower slope of Loveland Mountain belong to two rock types of slightly different ages. Monzonitic-diorite porphyry is the older; quartz-monzonite porphyry, the younger. They are derived from the same magma … Continue reading

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Characterizing Fault Zone Permeability Through Integrated Geophysical and Hydrological Data, Elkhorn Fault, Park County, Colorado

Abstract (Geology,Wells) Fault zones are ubiquitous in ground-water aquifers and can play a significant role in fluid transport at local to regional scales. Fault-zone permeability structure controls whether the fault behaves as a barrier, conduit, or combined barrier-conduit for fluid … Continue reading

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Pleistocene Incision Rates in the Western United States Calibrated Using Lava Creek B Tephra.

Abstract The Lava Creek B ash bed, erupted from the Yellowstone caldera ca. 0.64 Ma, provides a datum for measuring long-term fluvial incision west of the Mississippi River. The ash is widely preserved due to its substantial volume, broad initial … Continue reading

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