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J.S. Leventhal

Publications and source records attributed to J.S. Leventhal.

13 recordsLinked to original sources
USGS1992

Relationship between inferred redox potential of the depositional environment and geochemistry of the Upper Pennsylvanian (Missourian) Stark Shale Member of the Dennis Limestone, Wabaunsee County, Kansas, U.S.A.

Analyses of 21 samples collected from a core of the 52.8-cm-thick Stark Shale Member of the Dennis Limestone in Wabaunsee County, Kansas, demonstrate four cycles with two-orders-of-magnitude variations in contents of Cd, Mo, P, V and Zn, and order-of-magnitude variations in contents of organic carbon, Cr, Ni, Se and U. The observed variability in amounts and/or ratios of many metals and amounts and compositions of the organic matter appear related to the cause and degree of water-column stratification and the resulting absence/presence of dissolved O2 or H2S. High Cd, Mo, U, V, Zn and S contents, a high degree of pyritization (DOP) (0.75-0.88), and high high V (V + Ni) (0.84-0.89) indicate the presence of H2S in a strongly stratified water column. Intermediate contents of metals and S, intermediate DOP (0.67-0.75) and intermediate V (V + Ni) (054-0.82) indicate a less strongly stratified anoxic water column. Whereas, low metal contents and low V (V + Ni) (0.46-0.60) indicate a weakly stratified, dysoxic water column. High P contents at the top of the organic-matter-rich intervals within the Stark Shale Member indicate that phosphate precipitation was enhanced near the boundary between anoxic and dysoxic water compositions. Relatively abundant terrestrial organic matter in intervals deposited from the more strongly stratified H2S-bearing water column indicates a combined halocline-thermocline with the fresher near-surface water the transport mode for the terrestrial organic matter. The predominance of algal organic matter in intervals deposited from a less strongly stratified water column indicates the absence of the halocline and the presence of the more generally established thermocline. Relatively low amounts of degraded, hydrogen-poor organic matter characterize intervals deposited in a weakly stratified, dysoxic water column. The inferred variability in chemistry of the depositional environments may be related to climate variations and/or minor changes in sea level during the general phase of deeper water deposition responsible for this widespread shale member. ?? 1992.

Chemical Geology↗
USGS1991

Comparison of organic geochemistry and metal enrichment in two black shales: Cambrian Alum Shale of Sweden and Devonian Chattanooga Shale of United States

In most black shales, such as the Chattanooga Shale and related shales of the eastern interior United States, increased metal and metalloid contents are generally related to increased organic carbon content, decreased sedimentation rate, organic matter type, or position in the basin. In areas where the stratigraphic equivalents of the Chattanooga Shale are deeply buried and and the organic material is thermally mature, metal contents are essentially the same as in unheated areas and correlate with organic C or S contents. This paradigm does not hold for the Cambrian Alum Shale Formation of Sweden where increased metal content does not necessarily correlate with organic matter content nor is metal enrichment necessarily related to land derived humic material because this organic matter is all of marine source. In southcentral Sweden the elements U, Mo, V, Ni, Zn, Cd and Pb are all enriched relative to average black shales but only U and Mo correlate to organic matter content. Tectonically disturbed and metamorphosed allochthonous samples of Alum Shale on the Caledonian front in western Sweden have even higher amounts for some metals (V, Ni, Zn and Ba) relative to the autochthonous shales in this area and those in southern Sweden. ?? 1991 Springer-Verlag.

Mineralium Deposita↗
USGS1991

Organic matter and containment of uranium and fissiogenic isotopes at the Oklo natural reactors

Some of the Precambrian natural fission reactors at Oklo in Gabon contain abundant organic matter 1,2 , part of which was liquefied at the time of criticality and subsequently converted to a graphitic solid 3,4 . The liquid organic matter helps to reduce U(VI) to U(IV) from aqueous solutions, resulting in the precipitation of uraninite 5 . It is known that in the prevailing reactor environments, precipitated uraninite grains incorporated fission products. We report here observations which show that these uraninite crystals were held immobile within the resolidified, graphitic bitumen. Unlike water-soluble (humic) organic matter, the graphitic bituminous organics at Oklo thus enhanced radionuclide containment. Uraninite encased in solid graphitic matter in the organic-rich reactor zones lost virtually no fissiogenic lanthanide isotopes. The first major episode of uranium and lead migration was caused by the intrusion of a swarm of adjacent dolerite dykes about 1,100 Myr after the reactors went critical. Our results from Oklo imply that the use of organic, hydrophobic solids such as graphitic bitumen as a means of immobilizing radionuclides in pretreated nuclear waste warrants further investigation.

Nature↗
USGS1990

Organic matter and thermochemical sulfate reduction in the Viburnum Trend, southeast Missouri

The role of organic matter in Mississippi Valley-type Pb-Zn deposits has been studied by systematically sampling and characterizing various types of organic matter in the Upper Cambrian Bonneterre formation in lead-zinc mines from the Viburnum Trend and from rocks as far as 20 km away from the Trend. Organic matter that is several kilometers from ore consists of insoluble disseminated kerogen in carbonates. Kerogen from brown dolostones yields mainly n-alkane pyrolysis products up to approximately n-C 20 H 42 , whereas gray and white carbonates that are poorer in organic carbon give much smaller quantities of pyrolysis products. Within meters to centimeters of ore in the Milliken mine, at the south end of the Viburnum Trend, organic matter occurs as solid, partly soluble tacky bitumen and insoluble hard blebs of millimeter to centimeter size. These hydrocarbon materials also yield n-alkane pyrolysis products up to C 20 . In contrast, the solid insoluble organic matter in intimate contact (intergrown) with ore (galena and chalcopyrite) is friable and brittle. Products from pyrolysis-gas chromatography-mass spectrometry of this material are quite different from the kerogen in rocks or the hydrocarbon blebs; they are substituted aromatic molecules such as toluene and methyl naphthalene, rather than n-alkanes.The sulfur content of solid organic matter from the Milliken mine varies and is lowest for tacky material away from ore, intermediate for blebs near ore, and highest for friable material in intimate contact with ore.Pyrolysis-gas chromatography of this sample suite documents the progression of kerogen (far from ore) through solid petroleumlike material (near ore) to degraded organic matter (in contact with ore). The change in the organic matter from n-alkane to a hydrogen poorer aromatic character with a higher sulfur content when associated with sulfide ores, suggests that chemical reactions such as nonbiological (thermochemical) sulfate reduction, which consume hydrogen and produce reactive sulfur, were responsible for organic degradation.

Economic Geology↗
USGS1986

Organic geochemical analysis of sedimentary organic matter associated with uranium

Samples of sedimentary organic matter from several geologic environments and ages which are enriched in uranium (56 ppm to 12%) have been characterized. The three analytical techniqyes used to study the samples were Rock-Eval pyrolysis, pyrolysis-gas chromatography-mass spectrometry, and solid-state C-13 nuclear magnetic resonance (NMR) spectroscopy. In samples with low uranium content, the pyrolysis-gas chromatography products contain oxygenated functional groups (as hydroxyl) and molecules with both aliphatic and aromatic carbon atoms. These samples with low uranium content give measurable Rock-Eval hydrocarbon and organic-CO 2 yields, and C-13 NMR values of > 30% aliphatic carbon. In contrast, uranium-rich samples have few hydrocarbon pyrolysis products, increased Rock-Eval organic-CO 2 contents and > 70% aromatic carbon contents from C-13 NMR. The increase in aromaticity and decrease in hydrocarbon pyrolysis yield are related to the amount of uranium and the age of the uranium minerals, which correspond to the degree of radiation damage. The three analytical techniques give complementary results. Increase in Rock-Eval organic-CO 2 yield correlates with uranium content for samples from the Grants uranium region. Calculations show that the amount of organic-CO 2 corresponds to the quantity of uranium chemically reduced by the organic matter for the Grants uranium region samples.

Applied Geochemistry↗
USGS1983

An interpretation of carbon and sulfur relationships in Black Sea sediments as indicators of environments of deposition

Syngenetic iron sulfides in sediments are formed from dissolved sulfide resulting from sulfate reduction and catabolism of organic matter by anaerobic bacteria. It has been shown that in recent marine sediments deposited below oxygenated waters there is a constant relationship between reduced sulfur and organic carbon which is generally independent of the environment of deposition. Reexamination of data from recent sediments from euxinic marine environments ( e.g. , the Black Sea) also shows a linear relationship between carbon and sulfur, but the slope is variable and the line intercepts the S axis at a value between 1 and 2 percent S. It is proposed that the positive S intercept is due to watercolumn microbial reduction of sulfate using metabolizable small organic molecules and the sulfide formed is precipitated and accumulates at the sediment-water interface. The variation in slope and intercept of the C to S plots for several cores and for different stratigraphic zones for the Black Sea can be interpreted in relation to thickness of the aqueous sulfide layer or thinness of the oxygen containing layer and to deposition rate, but also may be influenced by availability of iron, and perhaps the type of organic matter (Leventhal, 1979).

Geochimica et Cosmochimica Acta↗
USGS1983

Geochemistry of the Chattanooga shale, Dekalb County, central Tennessee.

This Upper Devonian shale is of interest because of its unusual enrichment in trace elements, especially U; a new chemical analysis for major, minor and trace elements is presented. Stable isotopes of carbon (organic) show delta 13C approx -29per mille and for total sulphur show -21 to -27per mille delta 34S. The organic matter was found to range from dominantly marine (Dowelltown member) to dominantly terrestrial (Gassaway member) by extraction-column chromatography-GS and also by pyrolysis-GS of kerogen. Trace elements U, Mo, Co, Zn, Cu, Ni, V, As and Hg are enriched in the organic- and sulphide-rich units. This enrichment can be related to a euxinic depositional environment, to a very slow sedimentation rate (approx 2 mm/1000 years), to the type of organic matter that varied from mainly marine to terrestrial, and to the source of the metals, which shows abundance variations that originated, at least in part, from volcanic ash layers.-R.S.M.

Southeastern Geology↗
USGS1982

Chemical and mineralogical analysis of devonian black-shale samples from Martin County, Kentucky; Carroll and Washington counties, Ohio; Wise County, Virginia; and Overton County, Tennessee, U.S.A.

Core samples of Devonian shales from five localities in the Appalachian basin have been analyzed chemically and mineralogically. The amounts of major elements are similar; however, the minor constituents, organic C, S, phosphate and carbonate show ten-fold variations in amounts. Trace elements Mo, Ni, Cu, V, Co, U, Zn, Hg, As and Mn show variations in amounts that can be related to the minor constituents. All samples contain major amounts of quartz, illite, two types of mixed-layer clays, and chlorite in differing quantities. Pyrite, calcite, feldspar and kaolinite are also present in many samples in minor amounts. Dolomite, apatite, gypsum, barite, biotite and marcasite are present in a few samples in trace amounts. Trace elements listed above are strongly controlled by organic C with the exception of Mn which is associated with carbonate minerals. Amounts of organic C generally range from 3 to 6%, and S is in the range of 2-5%. Amounts of trace elements show the following general ranges in ppm (parts per million): Co, 20-40; Cu, 40-70; U, 10-40; As, 20-40; V, 150-300; Ni, 80-150; high values are as much as twice these values. The organic C was probably the concentrating agent, and the organic C and sulfide S together created an environment that immobilized and preserved these trace elements. Closely spaced samples showing an abrupt transition in color also show changes in organic C, S and trace-element contents. Several associations exist between mineral and chemical content. Pyrite and marcasite are the only minerals found to contain sulfide-S. In general, the illite-chlorite mixed-layer clay mineral shows covariation with organic C if calcite is not present. The enriched trace elements are not related to the clay types, although the clay and organic matter are intimately associated as the bulk fabric of the rock. ?? 1982.

Chemical Geology↗
USGS1981

Pyrolysis gas chromatography-mass spectrometry to characterize organic matter and its relationship to uranium content of Appalachian Devonian black shales

Gas Chromatographic analysis of volatile products formed by stepwise pyrolysis of black shales can be used to characterize the kerogen by relating it to separated, identified precursors such as land-derived vitrinite and marine-source Tasmanites . Analysis of a Tasmanites sample shows exclusively n- alkane "> n-alkane and -alkene pyrolysis products, whereas a vitrinite sample shows a predominance of one- and two-ring substituted aromatics. For core samples from northern Tennessee and for a suite of outcrop samples from eastern Kentucky, the organic matter type and the U content (<10−120ppm) show variations that are related to precursor organic materials. The samples that show a high vitrinite component in their pyrolysis products are also those samples with high contents of U.

Geochimica et Cosmochimica Acta↗
USGS1978

A literature review of interaction of oxidized uranium species and uranium complexes with soluble organic matter

Organic material is commonly found associated with uranium ores in sandstone-type deposits. This review of the literature summarizes the classes and separations of naturally occurring organic material but the emphasis is on soluble organic species. The main class of materials of interest is humic substances which are high-molecular-weight complex molecules that are soluble in alkaline solution. These humic substances are able to solubilize (make soluble) minerals and also to complex [by ion exchange and (or) chelation] many cations. The natural process of soil formation results in both mineral decomposition and element complexing by organic species. Uranium in solution, such as ground water, can form many species with other elements or complexes present depending on Eh and pH. In natural systems (oxidizing Eh, pH 5-9) the uranium is usually present as a complex with hydroxide or carbonate. Thermodynamic data for these species are presented. Interacting metals and organic materials have been observed in nature and studied in the laboratory by many workers in diverse scientific disciplines. The results are not easily compared. Measurements of the degree of complexation are reported as equilibrium stability constant determinations. This type of research has been done for Mn, Fe, Cu, Zn, Pb, Ni, Co, Mg, Ca, Al, and to a limited degree for U. The use of Conditional Stability Constants has given quantitative results in some cases. The methods utilized in experiments and calculations are reviewed.

Open-File Report↗