Bibliography of Minor-Element Content of Marine Black Shales and Related Sedimentary Rocks, 1930-65
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Selected Annotated Bibliography of Minor-Element Content of Marine Black Shales and Related Sedimentary Rocks, 1930-65 By ELIZABETH B. TOURTELOT GEOLOGICAL SURVEY BULLETIN 1293 Includes abstracts of about 375 selected articles published during 1 f) 30-65 pertaining to worldwide occurrences of black shale UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1970 UNITED STATES DEPARTMENT OF THE INTERIOR WALTER ]. HICKEL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director Library of Congress catalog-card No. 75-604512 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402- Price 60 cents CONTENTS Page Introduction ... v Analyses included . VIII Indexing ..... IX Acknowledgments. X Abbreviations of serials X Abstracts . Index ........ 95 Ill SELECTED ANNOTATED BIBLIOGRAPHY OF MINOR-ELEMENT CONTENT OF MARINE BLACK SHALES AND RELATED SEDIMENTARY ROCKS, 1930-65 By ELIZABETH B. TOURTELOT INTRODUCTION This bibliography presents minor-element data from analyses of black shales and related organic-rich sedimentary rocks plus selected dis cussions on the source of the minor elements. Shales generally contain greater quantities of minor elements than do sandstones or limestones (Turekian and Wedepohl, 1961, table 2). However, many fine-grained sedimentary rocks and unconsolidated sediments that are rich in car bonaceous matter, such as black shales and euxinic muds of modern seas, contain unusually high concentrations of minor elements (Krauskopf, 1955). In the Mansfeld district of Germany, the Kupferschiefer, a bed of black shale about 1 meter thick, has been mined for copper for centuries. Locally, the same bed or its equivalent contains economic concentrations of lead, zinc, silver, and other metals. Copper is also produced from a black shale of Precambrian age in northern Michigan. Black shales have been studied as possible low-grade re sources of other metals, including uranium and vanadium, especially in the lower Paleozoic rocks of northern Europe. In some parts of the world, black shales are parent materials of soils associated with selenium poisoning of livestock. Thus, minor-element concentrations in black shales can have many economic implications. How common are metal-rich black shales? Are they limited to met allogenic provinces, to certain time periods, or to specific environments of deposition? If not otherwise of economic value, do they represent a potential source of metals that may be redistributed and enriched by granitization, metamorphism, or hydrothermal activity? What is the origin of the metals in black shales? Are they concentrated by means of biological activity, by sorption from sea water by decaying organisms, by sulfide precipitation in a reducing environment, or by epigenetic mineralization? Can analogues be identified in modern sediments from inland seas, restricted shallow marine basins, or deep-se.a troughs? In the search for answers to these and similar questions, perhaps another Kupferschiefer or other deposit of economic value may be discovered. v VI BIBLIOGRAPHY OF MINOR ELEMENTS IN BLACK SHALES This bibliography is intended as an aid in this search. It may also serve as a guide to suggest what quantities of minor elements in black shales are anomalous. By indicating the types and amounts of published data available, the limits of our knowledge of black shales are roughly out lined and perhaps new directions for investigation are suggested. Interest in the geochemistry of rocks rich in organic matter arose with the development of the emission spectrographic technique in the 1920's. By use of this technique, a large number of minor elements in very small amounts can be identified in many different materials. During the 1930's, V. M. Goldschmidt and his students in Gottingen reported many examples of unusual concentrations of minor elements in organic-rich rocks and their ashes, including black shales, coals, bitumen, and kolm (a jet-black organic substance that occurs in some lower Paleozoic shales). In an effort to determine the distribution and crustal abundance of various elements, Goldschmidt and his students made many different analyses of a composite sample of 36 European Paleozoic shales. The reported results of these analyses are of interest not only because some black shales are included in the composite, but also because these analyses provided the first indications of the amount of each element that could be reasonably expected in a fine-grained sedimentary rock. Many later papers, such as that by Vinogradov and Ronov (1956) on the abundance of elements in rocks of the Russian platform (summarized by Green, 1959), serve also to suggest the normal range in abundance of various elements. Many of the articles from the Russian literature compare average abundance data for different lithologies and for rocks of different ages in an attempt to define possible changes in element content with grain size and possible trends through geologic time. Goldschmidt and Peters (1932c) suggested that boron content in sedi mentary rocks appeared to vary with the salinity of the depositional environment. In many subsequent articles, attempts have been made to distinguish different environments of deposition by the amounts or ratios of minor elements. Special emphasis has been placed on methods of distinguishing marine and nonmarine rocks by the use of indicator elements. (See, for example, Degens, Williams, and Keith, 1957 .) Many of these articles contain data on the abundance of other elements in addition to boron in a variety of sedimentary rocks, including black shales and related sediments. Many geochemists accept the theory that unusually high concentrations of minor elements in some black shales are of syngenetic origin-that is, the elements were emplaced at the same time that the mud was deposited without significant later additions. Mechanisms of emplacement, whether by fixation b~ living organisms, adsorption by decaying organic matter INTRODUCTION VII from sea water, or reduction and precipitation in an environment of negative Eh and low pH, are still subject to discussion. In these shales, no recognizable evidence exists for appreciable later additions of minor elements. The metals are usually found combined with the organic materials or clay minerals or are carried in pyrite. Black shales of this type include many rich in uranium and vanadium such as the Alum shales of Sweden and the Chattanooga Shale of Tennessee. In contrast to these, some black shales, such as the Kupferschiefer of Germany, the Mount Isa shale of Australia, and the Nonesuch Shale of :Michigan, contain identifiable sulfides of copper, lead, zinc, or other metals. Whether such deposits are syngenetic or epigenetic is subject to controversy. Many references to these shales are included in this bibliography (for example, W edepohl, 1964b; Love and Zimmerman, 1961) because they have direct bearing on the origin and distribution of minor elements in black shales. However, this bibliography is not intended to be comprehensive on the subject of strata-bound ore deposits. Thus, no references are included on the Northern Rhodesian Copper belt, for example, because the ores occur in a variety of rock types in addition to black shale. The study of minor-element distribution in black shale may provide additional evidence on the origin of some of these controversial deposits. Perhaps syngenetic deposits are characterized by a suite of elements significantly different from that of epigenetic deposits. More needs to be known about the effects of diagenesis on element suites also. Meta somatism at the trace-element level has been noted (Shaw, 1954a). Metal-rich black shale deposits with possible economic potential, equivalent to that of deposits that have been repeatedly described, may be readily overlooked. Several stratigraphic units in the western United States reported by Davidson and Lakin (1961, 1962b) may be worthy of more attention than they have received. More recently, beds of metal rich black shale on the north slope of the Brooks Range in Alaska have been reported (H. A. Tourtelot, written commun., 1965). Other metal rich black shale deposits have probably been overlooked because those who described the rocks had no reason to suspect they might contain unusual amounts of metals. Gold, for example, might be easily overlooked if its grain size is too small to be visible, because routine spectrographic analyses are not sufficiently sensitive to identify it in small amounts. Nevertheless, gold is reported in several black shale units in quantities that should encourage more thorough study of its distribution (Crouse, 1925; DeGrazia and Haskin, 1964; Leutwein, 195la, 195lb, 1952; Tischendorf, 1959). VIII BIBLIOGRAPHY OF MINOR ELEMENTS IN BLACK SHALES ANALYSES INCLUDED Elementsconsidered "minor elements" include all but silicon, aluminum, iron, calcium, sodium, potassium, oxygen, hydrogen, nitrogen, magnesium, sulfur, phosphorus, and the inert gases. Some complete rock analyses have been quoted, but generally, for the sake of brevity, only minor element data are included in the abstracts. In general, the limits of the term "black shale" as discussed by Swanson (1961) have been followed. Black shale, as the term is used here, is a fine grained sedimentary rock containing sufficient organic matter to color the rock dark gray to black; rocks composed largely of carbonate minerals are normally excluded, although some black shales are transitional with carbonate rocks. Terms