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James M. Schopf

Publications and source records attributed to James M. Schopf.

9 recordsLinked to original sources
USGS1975

Paleotectonic investigations of the Pennsylvanian system in the United States, Part II: Interpretive summary and special features of the Pennsylvanian system

Interpretation of the paleotectonic history of the Pennsylvanian System is represented on two sets of maps, one referred to as interpretive isopach maps and the other as interpretive paleotectonic maps (pi. 15A-C). Each set includes five maps, one for each interval of the Pennsylvanian. All maps of both sets were prepared at the same scale (1:5,000,000) and are published at a scale of 1:10,000,000. Therefore direct comparisons can readily be made.

Professional Paper↗
USGS1971

Comment about the origin of micrinite

The granular micrinite in coal may result from the same process that acts during the peat stage to form fusain but dispersed humic matter, rather than organized plant tissue, seems to be involved in micrinite formation. The closely sized micrinite granules that occur in cell lumens of fragments of woody tissue in a few Paleozoic coals are exceptional and may be the result of selective infiltration. The morphologic distinction between micrinite and fusinite should not obscure the fundamental genetic relationship of these macerals.

Economic Geology↗
USGS1954

Germanium and uranium in coalified wood from Upper Devonian black shale

Microscopic study of black, vitreous, carbonaceous material occurring in the Chattanooga shale in Tennessee and in the Cleveland member of the Ohio shale in Ohio has revealed coalified woody plant tissue. Some samples have shown sufficient detail to be identified with the genus Callixylon. Similar material has been reported in the literature as "bituminous" or "asphaltic" stringers. Spectrographic analyses of the ash from the coalified wood have shown unusually high percentages of germanium, uranium, vanadium, and nickel. The inverse relationship between uranium and germanium in the ash and the ash content of various samples shows an association of these elements with the organic constituents of the coal. On the basis of geochemical considerations, it seems most probable that the wood or coalified wood was germanium-bearing at the time logs or woody fragments were floated into the basins of deposition of the Chattanooga shale and the Cleveland member of the Ohio shale. Once within the marine environment, the material probably absorbed uranium with the formation of organo-uranium compounds such as have been found to exist in coals. It is suggested that a more systematic search for germaniferous coals in the vicinity of the Chattanooga shale and the Cleveland member of the Ohio shale might be rewarding.

Trace Elements Investigations↗
USGS1949

Research in coal paleobotany since 1943

The varied applications of paleobotany to coal resource studies, coal technology, and to fundamental physical and chemical research on coal are briefly indicated. The usual conception of paleobotany is not as broad as this, and many of the studies of fossil plants have been conducted without reference to the part the plant materials assume in composing coal. The interrelationship of paleobotany with the physical constitution and petrography of coal is an intimate one. which is too involved for treatment in the present paper. Chief emphasis is devoted to review of plant microfossil investigations during the past several years.The consistent abundance of plant microfossils in coal and its associated rocks is now generally recognized. One of the greatest difficulties in using this material for correlation and for extending our knowledge of the plant composition of coal has been in systematic (taxonomic) treatment of the materials. The reviews of recent literature are presented chiefly with reference to the diverse systematic approaches of various authors. The contrast between essentially nonbotanical or morphologic classification schemes, which are simpler to apply and which may serve adequately for local correlational studies, and those studies conceived on a more fundamental basis of plant taxonomy, for paleogeographic and ecologic interpretation of botanically related groups, is presented. Both viewpoints should be kept clearly in mind, since differing circumstances of study and differing objectives may suggest the advisability of using one rather than the other method of systematic treatment of these fossils. No other fossils are so conveniently available from the coal deposits of primary interest.

Economic Geology↗