Contributions to Geology 15.2

The scope of coal geology

WALTER RIEGEL Geologisch-Palaeontologisches Institut der Georg-August-Universitat, 34 Gottingen, Goldschmidtstr. 3, West Germany

Pages
73-78

Keywords
coal, energy, petroleum, gas, fossil fuel

Abstract
With the new awareness of the energy problem and the rising specter of depletion of our petroleum and natural gas resources, coal has taken the central role in the ensuing scramble over alternative energy resources. With an estimated resource of a few trillion tons of coal the United States is blessed with the largest fossil fuel energy base of any country in the world, second perhaps only to the Soviet Union. But American industry, geared toward consumption of oil and natural gas during the oil rich years, now needs much new technology and geological expertise to readjust to the use of coal as a multipurpose energy source. With regard to geology, this sudden change has produced a considerable gap between the supply and demand of information, experience and manpower in coal geology. More and more geologists may find themselves answering questions relating to coal despite having been trained in fields as unrelated as, perhaps, igneous petrology and structural geology. Few schools of coal research at American universities have survived the "oil age" of American industry following World War II. The lag time for expansion of existing schools or development of new schools in this field may be anywhere between three to ten years, depending on existing facilities, objectives, funding and personal efforts. Thus, for some years to come, much of the manpower required will have to be recruited by on the job training, workshops, short courses and the like. Such training may be effective in the short term, but it is not well rounded and it is done at the expense of the employer. In this situation in which much of the training is closely directed toward immediate needs and to questions posed by the industry, it will take considerable time until coal geology can rise to its full potential and apply to the full benefit of the economy and society the vast amount of information and knowledge already accumulated.

It may therefore be justified at this stage to review briefly the broader scope of coal geology and to summarize the recent developments and applications of various segments of the field.

Wyoming coal and coal mining

GARY B. GLASS Staff Coal Geologist, Wyoming Geological Survey, Laramie, Wyoming 82071

Pages
79-92

Keywords
Cretaceous, coal, Wyoming, Tertiary

Abstract
Wyoming has nearly a trillion tons of coal underlying about 41 percent of its land area. This coal occurs in Cretaceous and Tertiary rocks that crop out in ten major basins, regions, or fields scattered across the State. While mountain building, folding, and subsequent erosion have restricted many Cretaceous outcrops to narrow bands around the margins of the coal-bearing areas, younger Tertiary rocks overlie them in the more central portions of the basins. Tertiary rocks are often nearly flat-lying while Cretaceous rocks exhibit steeper dips and more complex folding.

Coals within these rocks range from less than a foot thick to over 220 feet in thickness, and occur both at shallow and great depths. Cretaceous coals, which seldom exceed ten feet in thickness, range up to l lO feet in western Wyoming. The majority of the Cretaceous coals, especially the thinner ones, probably formed in various nearshore (paralic) environments associated with widespread Cretaceous seaways. Tertiary coals were developed in intermontane basins and are probably limnic in origin. Tertiary coals often exceed 10 feet in thickness, and 50-100 foot thick coals are common, especially in northeastern Wyoming.

While Cretaceous coals are bituminous to subbituminous in rank, Tertiary coals are either subbituminous or lignitic. These difference in rank alone account for significant variations in the quality of coals across the State.

The distribution of As, Be, Cd, Cu, Hg, Mo, Pb, and U associated with the Wyodak coal seam, Powder River Basin, Wyoming

JAMES I. DREVER, JACK W. MURPHY and RONALD C. SURDAM Department of Geology, The University of Wyoming, Laramie, Wyoming 82071

Pages
93-102

Keywords
trace element, Wyodak, coal, Powder River, Wyoming

Abstract
Analysis of core samples from the ARCO Black Thunder site indicates that the trace elements As, Be, Cd, Cu, Hg, Mo, Pb, and U are strongly enriched near the margins of the coal seam relative to the interior of the seam and to the overburden away from the seam. The enriched zones are approximately 6 ft (2m) wide and include both the margins of the coal and the adjacent detrital rocks. Within the enriched zones the correlations between pairs of individual trace elements, and between individual trace elements and sulfur or ash content are extremely poor.

The trace element contents of groundwaters from the coal and overburden are low (approximately 2 ppb for Cu, Mo, Pb, and U; 0.5 ppb for Cd, < 5 ppb for As, < 1 ppb for Be, < 0.5 ppb for Hg). The interface between the coal and overburden does not appear to correspond to a major change in pH, sulfide activity, or trace element concentration in the enclosed groundwaters.

Although the trace element enrichment at the margins of the seam is almost certainly a result of groundwater transport, the chemistry of the present-day groundwater does not provide any obvious explanation for the enrichment.

Development of Precambrian gneiss fabric in the southern Bighorn Mountains, Wyoming

ROBERT A. WELLS Amoco Production Company, Security Life Building, Denver, Colorado 80202

Pages
103-118

Keywords
tectonic, Precambrian, gneiss, Bighorn, Wyoming, fold, dikes

Abstract
Mesoscopic and macroscopic structural analysis reveal that two Precambrian fold events are preserved in the structures of a small area of Precambrian gneisses in the southern Bighorn Mountains, Wyoming.

The early fold event is preserved as isoclinal, intrafolial, flexural flow folds, linear structures parallel to these fold axes, and lenticular compositional layering. These structures are evidence of transposition of a pre-existing compositional layering by dismemberment and rotation on the mesoscopic scale. A macroscopically planar foliation parallel to the axial planes of the folds was the final product.

The later fold event was characterized by flexural slip and flexural flow folding about an east-southeast trending axis on both mesoscopic and macroscopic scales. Metadiabase dikes, intruded after the early fold event, were deformed by the later event.

The method of analysis used in this study requires close attention to tectonic style and field relations of the various structures as well as to their orientation. This study demonstrates that the fabric of the complex and often poorly expressed structures preserved in Precambrian gneiss terrain can be determined. This fabric determination can be applicable to the study of Precambrian tectonic history, to the prediction of structurally controlled mineral deposit distribution, and to the study of the relation of Precambrian fabrics to subsequent deformation.

Taphonomy of the dinosaur quarry, Dinosaur National Monument

REBECCA LAWTON Dinosaur National Monument, Jensen, Utah 84035

Pages
119-126

Keywords
dinosaur, Dinosaur National Monument, sedimentological, Utah

Abstract
Sedimentological study of the fluvial sandstones in the dinosaur quarry near Jensen, Utah revealed evidence of: (1) at least three major phases of bone deposition; (2) fairly high current velocity; (3) periodically shallow flow and abandonment of the streambed; (4) short time period of deposition; (5) short bone transportation distance. Application of "Voorhies Groups" of relative transport potential to the bone deposits showed a lack of early-transport items. Limb bones were well-represented. Considerations complicating the use of "Voorhies Groups" at the dinosaur quarry include the: (1) initial availability of all skeletal types; (2) shape and density differences between bones representing various orders and genera; (3) varying degrees of disarticulation of bones in the deposit; (4) poor representation of isolated bones.