Contributions to Geology 14.1

Mapping of linear structural elements from remote sensing imagery

D. L. BLACKSTONE, JR. University of Wyoming, Laramie, Wyoming 82071

Pages
1-6

Keywords
remote sensing, linear, mapping, structural, Wyoming, Bighorn, Laramie

Abstract
Remote sensing imagery is utilized in analyzing linear elements in structural geology. Some cautions in the use of the imagery are outlined. In two cases, the Bighorn and Laramie Mountains, Wyoming-linear features have been counted, and analyzed as to orientation. The orientation of folds and faults in the area west of the Laramie Mountains is closely controlled by the linear elements in the Precambrian basement. Folds in the Bighorn basin show little relationship in orientation to the linear features mapped in the Bighorn Mountains.

Invertebrate burrows in an Oligocene fresh-water limestone

PAUL EDWARDS Division of Vertebrate Paleontology, University of Nebraska State Museum, Lincoln, Nebraska, 68588

Pages
7-8

Keywords
burrows, Oligocene, invertebrate, Brule, Nebraska, Miocene

Abstract
Fossilized invertebrate burrows, one horizontal and internally meniscate, and the other vertical, conical, and internally massive, are present in a "pond" limestone in the Brule Formation (Oligocene) of western Nebraska. The internally meniscate burrows, similar to internally meniscate burrows in the Lower Miocene of the same area, were probably formed by infaunal deposit feeding insects. The vertical internally massive burrows are assumed to be shelter burrows.

Distribution of meniscate burrows in non-marine Tertiary sediments of western U.S.

HEINRICH TOOTS Department of Geology and Geography, C. W. Post College, Greenvale, NY 11548

Pages
9-10

Keywords
meniscate burrows, lacustrine, fluvial, ichnofossils, Tertiary

Abstract
In the Tertiary of the Rocky Mountains and Great Plains cylindrical burrows with a meniscate structure characterize marginal lacustrine facies and the channel facies of fluvial sediments. The floodplain facies contains different ichnofossils. The sediments containing the burrows represent environments in which subaqueous conditions alternate with subaerial conditions within short intervals of time. It is not possible, for this reason, to decide whether the burrows represent subaqueous or subaerial conditions.

Technical feasibility of the proposed energy transportation systems incorporated well field, Niobrara County, Wyoming

PETER W. HUNTOON and TRAVIS WOMACK Department of Geology, University of Wyoming, Laramie, Wyoming 82071

Pages
11-26

Keywords
artesian, Niobrara, Wyoming, well field, Madison, Energy Transportation Systems

Abstract
Energy Transportation Systems Incorporated desires to pump 15,000 acre-feet of water per year from a well field consisting of up to 40 wells developed in the Madison aquifer in the vicinity of the Old Woman anticline in eastern Wyoming. The project life of the well field is 50 years from the first production of water, and the water is to be pumped from depths exceeding 2,500 feet. A simulation model based on the Theis well equation for an artesian aquifer was used to predict the response of the potentiometric surface during the first 20 years of the proposed development. The hydrologic character of a major fault in the immediate vicinity of the well field is presently unknown and was alternately modeled as a constant head boundary, impermeable boundary, and as if the aquifer were infinite. Results from these simulations for reasonable ranges of storage coefficients and transmissivities indicate that even under ideal conditions the well field will be only marginally feasible because the predicted water level changes after 20 years will cause dewatering of the Madison aquifer in the proposed well field.

Miocene sediment dispersal for western Nebraska and south-eastern Wyoming

H. A. BART Department of Geology, University of Nebraska, Lincoln 68508

Pages
27-40

Keywords
Miocene, Nebraska, Wyoming, Arikaree, volcanic, Laramie

Abstract
Miocene Arikaree deposits of the High Plains of western Nebraska and eastern Wyoming consist of volcaniclastic air-fall and epiclastic detritus. Multivariate analysis and paleocurrent data of detrital modes of sandstone indicate complete, statistically defined Miocene dispersal patterns for these deposits. Four principal factors have been extracted by the analysis and are identified (reified) as 1) plutonic, 2) volcanic, 3) amphibole and 4) plagioclase components.

Dispersal maps made by contouring scores of plutonic, amphibole and plagioclase factors and paleocurrent information define a broad drainage net system adjacent to the Laramie Range. Tributary streams in Wyoming were probably ephemeral and flowed in a direction ranging from north 70 degrees east to south 80 degrees east. Main streams of the drainage system flowed eastward into Nebraska and through the Wildcat Ridge of western Nebraska. The volcanic shard factor is not concentrated in areas when contoured but is instead more widely distributed. This is probably a consequence of aeolian distribution.

Pre-Wisconsin paleosols and related soils on the south French Creek-Middle Fork (Little Laramie River) interfluve, Medicine Bow Mountains, Wyoming

RICHARD G. REIDER and STEVE R. GURLEY: Department of Geography, University of Wyoming, Laramie, Wyoming 82071

Pages
41-50

Keywords
French Creek, Medicine Bow, Wyoming, paleosols, Pleistocene, Wisconsin

Abstract
Soil development at approximately 10,350 feet on late Pliocene?-early Pleistocene quartzite-rich gravels of the South French Creek-Middle Fork interfluve consists of moderately developed and very strongly developed profiles. The moderately developed type is considered to be no older than Wisconsin in age. The very strongly developed type is considered to be Pre-Wisconsin in age.

Pre-Wisconsin profiles are characterized by sola known to exceed eight feet in depth and may reach thicknesses of 15 feet or more. Relatively young A-horizons, which give indication of intermixing by frost action or by expansion-contraction of clays, are superposed on argillic paleo-B-horizons. These B-horizons have clay accumulations as great as 55 percent of fine earths. Clay mineralogy is dominated by montmorillonite, with secondary admixtures of chlorite-vermiculite, illite, and kaolinite.

Stone lines commonly occur in profiles at depths of approximately three feet and separate overlying B-horizons from lower, truncated B-horizons. It is thought that these stone lines represent a lag deposit formed at a time of truncation of the original profles, followed by burial by slope deposits and renewed pedogenesis and subsequent superposition of the existing A-horizons. The composite B-horizons probably represent periglacial and interglacial events on the interfluve in PreWisconsin time.

Clastic dikes in the Fountain and Casper Formations (Permo-Pennsylvanian) southeastern Wyoming

THOMAS S. AHLBRANDT and RAY E. HARRIS University of Wyoming, Laramie, Wyoming 82071

Pages
51-54

Keywords
dikes, Casper, Wyoming, dune, Fountain, clastic

Abstract
Clastic dikes are common in the Fountain and Casper Formations in the southern Laramie Basin, Wyoming. These dikes are roughly planar, though some are branching or ring-shaped in cross-section. The material within the dikes resembles the Fountain Formation both texturally and mineralogically where the host rock is the Fountain. Long axes of elongate particles are commonly oriented parallel to the long direction of the dike indicating movement of material within the dike. Upward movement of particles is indicated by concentrations of coarse grains in the dikes a few feet or less above coarse zones in the host rock and upturned laminae adjacent to some dikes. A hematite-rich zone characterizes the margins of the dikes, whereas a hematite-deficient zone in the host rock borders each dike. The dikes are better cemented than the host rock and stand in relief on weathered surfaces. Evidence suggests that the dikes are the result of the slow upward migration of fluids and particles along fractures, joint planes, bedding planes or zones of high permeability. Increasing lithostatic pressure during continued deposition of dune sand on the unconsolidated sequence may have caused this movement. Fluid migrating toward the dikes leached the host rock of iron and redeposited it as hematite at the margins of the dikes.