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The content of chemical elements in four sets of Paleozoic black-shale samples was determined, and the data were analyzed statistically in search of element associations that may have geochemical significance. Silicon, aluminum, titanium, zirconium, and gallium generally are the principal elements in the detrital mineral fraction of these rocks. Locally, boron, beryllium, scandium, and vanadium are also in the detrital fraction. Calcium, magnesium, and manganese are associated chiefly with the carbonate-mineral fraction, where present. Different groups of elements are associated with the organic-matter fraction of these rocks in the different sets of samples. In the hypersaline carbonate-rich detrital rocks of the Pennsylvanian Paradox Member of the Hermosa Formation of Utah, copper and zinc are asso " Uc?d with the organic matter, but neither element is highly concentrated in the rocks. The geoehemical behavior of the minor elements in this evaporite basin is not known. Iron, cobalt, nickel, molybdenum, and uranium are associated with organic matter in the Devonian Chattanooga Shale of central Tennessee and northern Alabama, :md uranium and cobalt tend to be enriched in this epicontinental shallow-sea deposit. Copper, nickel, vanadium, chromium, molybdenum, lead, and calcium are associated with organic matter in the Pennsylvanian black shales of southeastern Kansas and northeastern Oklahoma. Of these, vanadium, chromium, nickel, and lead seem to have been locally enriched in this brackish or marine shallow-water shelf environment. In the silts-tones and phosphatic shales of the Permian Meade Peak Phosphatic Shale Member of the Phosphoria Formation, selenium, copper, molybdenum, chromium, nickel, and scandium are associated with organic matter in the detrital rocks; silver is more closely associated with the detrital mineral fraction; vanadium, zinc and lanthanum are associated with the organic matter in the more phosphatic shales; and yttrium is associated with phosphorite. All these elements except scandium are concentrated to an abnormally high degree in the Meade Peak Phosphatic Shale Member. The upwelling cold water that provided nutrients for an abundance of living organisms and that gave rise to the accumulation of phosphate along the margin of the Cordilleran miogeosyncline was probably also the source of the minor elements. INTRODUCTION The present report is the second in a series of reports describing the geoehemical distribution of elements in black-shale deposits of differGl G2 CONTRIBUTIONS TO GEOCHEMISTRY ent environments and of different ages. The first report (Vine, 1966a) compared the element distribution in some shelf and eugeosynclinal black-shale samples grouped into four sets, numbered 1^4. The present report continues with the summary of chemical data pertaining to four more sample sets, numbered 5-8. The latter four sets represent four diverse environments of black-shale deposition; they are different mineralogically and were collected by different techniques. The samples were analyzed by a routine six-step spectrographic method for major and minor elements, and chemically for organic carbon and mineral carbon. The range in content of each of the elements determined is described, and the relations of the elements to different major constituents of the rocks are discussed. Many fine-grained marine rocks are composed of various proportions of detrital minerals, chemically or biologically precipitated minerals, and organic matter. Refined laboratory techniques would be required to determine the proportions of each mineral species and to provide a means of interpreting the source of each. Therefore, the term "black shale" is used in a broad sense to include many dark-colored rocks that are not obviously classifiable as claystone, siltstone, limestone, dolomite, anhydrite, chert, phosphorite, or coal. These specific rock types commonly grade into black shale, and in some of the sets of samples, one or more end-member rock types are included. Where more than one end-member rock type was among the samples of black shale, the elements showed a much wider range in concentration. Furthermore, by including a few samples of the end-member rock types, the distribution of the minor elements with respect to the detrital mineral fraction, the chemically or biologically precipitated mineral fraction, and the organic-matter fraction can be more clearly defined. ACKNOWLEDGMENTS For their suggestions and encouragement in collecting the samples from southeastern Kansas, I thank F. C. Foley, State Geologist of Kansas, and various members of his staff. J. D. Love of the U.S. Geological Survey provided the necessary information to aid in collection of the Phosphoria Formation samples. J. I. Reese assisted in collecting these samples. The late Andrew Brown of the U.S. Geological Survey, at the time of his death in 1964, had an unpublished manuscript listing the locality and sample descriptions of the Chattanooga Shale cores. His locality and sample descriptions are included in the present report. 0. B. Raup and R. J. Hite of the U.S. Geological Survey, as part of their studies of potash and other mineral commodities in the Paradox Basin, Utah, helped to obtain samples of the Paradox Member. E. B. Tourtelot and J. R. Keith assisted in the compilation of data. ELEMENT DISTRIBUTION IN PALEOZOIC BLACK SHALES G3 Spectrographic analyses upon which this report is based were made by A. L. Sutton, Jr., and J. C. Hamilton, and most of the carbon analyses were made by I. C. Frost, all of the Denver laboratory of the U.S. Geological Survey. Other analyses were made in the Denver laboratory by E. J. Fennelly, G. T. Burrow, D. L. Skinner, Harriet Neiman, Wayne Mount joy, J. D. Mensik, and Lorraine Lee. Uranium analyses of the Chattanooga Shale samples were made in the Washington laboratory of the U.S. Geological Survey by Carmen Hoy, Joseph Budinsky, B. A. McCall, J. H. Goode, J. Smith, and J. J. Warr. M. S. Niles, P. A. Zimmerman, and Josephine Boerngen transcribed analytical data to punch cards. Computer programing and assistance was provided by R. N. Eicher, F. B. Sower, and G. I. Seiner. SAMPLE SETS Locality descriptions, listings of the individual stratigraphic intervals sampled, and analyses of individual samples for sets 5-8 are included in an open-file report (Vine, 1966b) available for consultation or reproduction at the libraries of the principal offices of the U.S. Geological Survey. Sample localities of sets 5-8 are shown in figure 1. Generalized descriptions of each sample set are given below. Set 5 consists of 40 samples collected from outcropping black-shale beds of Pennsylvanian age in southeastern Kansas and northeastern Oklahoma. At least 13 different shale beds are represented by the'40 samples. The beds are dark gray to black, are fissile where even slightly weathered, and commonly contain fish scales, conodonts, and brachiopods. Phosphate nodules 1-2 cm (centimeters) across are especially characteristic of the Excello Formation of Searight and others (1953), but they also occur in many of the other beds. Typically, these black-shale beds are 1-3 feet thick, and they overlie a bed of coal and are overlain by marine limestone. Exceptions to this generalization are the Pleasanton Group, which is as much as 15 feet thick, and the Eudora Shale Member, which separates two limestone beds in the Stanton Limestone. The stratigraphic sequence of black-shale units and the number of samples collected from each unit are given in table 1. Set 6 consists of samples from the entire sequence of black siltstone, phosphorite, dolomite, and limestone of the Meade Peak Phosphatic Shale Member of the Phosphoria Formation of Permian age. The member is exposed in a mine opening at Raymond Canyon in Sublette Ridge, Lincoln County, Wyo. The strata in this part of the western Wyoming fold belt are nearly vertical, strike approximately north, and dip to the east. The main adit extends along the strike of the beds. Open crosscuts perpendicular to the strike of the beds provide easy G4 CONTRIBUTIONS TO GEOCHEMISTRY X" 0) " 3 93 «2I & * . u at IS* &# a S&S d-ofl

Element distribution in some Paleozoic black shales and associated rocks