Do ages of authigenic K-feldspar date the formation of Mississippi Valley-type Pb-Zn deposits, central and southeastern United States?: Pb isotopic evidence

Aleinikoff, John N.; Walter, Marianne; Kunk, Michael J.; Hearn, P.P.

doi:10.1130/0091-7613(1993)021<0073:daoakf>2.3.co;2

Cited by 23 publications

(6 citation statements)

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“…In addition to sulphides containing lead, zinc, copper and other metals, these basinal fluids precipitate large quantities of dolomite cement (Beales & Hardy, 1980) and are capable of dolomitizing lime-stones (Gregg, 1985;Machel & Mountjoy, 1987). Basinal fluids have affected carbonate rocks throughout much of North America, including major petroleum producing regions such as west Texas (Mazzullo, 1986;Kupecz & Land, 1991;Amthor & Friedman, 1992), the Appalachian Basin (Montafiez & Read, 1992), the Anadarko Basin (Gao & Land, 1991), the US Gulf Coast (Land & Prezbindowski, 1981;Woronick & Land, 1985), western Canada (Beales & Jackson, 1966;Mattes & Mountjoy, 1980;Walls & Burrowes, 1985;Qing & Mountjoy, 1989 and the Michigan Basin (Haefner et af., 1988). Petroleum commonly is associated with MVT deposits, sometimes creating problems during mining (e.g.…”

Section: Introductionmentioning

confidence: 99%

Porosity evolution of the Cambrian Bonneterre Dolomite, south‐eastern Missouri, USA

Gregg¹,

Laudon

Woody³

et al. 1993

Sedimentology

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The Cambrian Bonneterre Dolomite of south‐eastern Missouri, USA, hosts the large Mississippi Valley type (MVT) lead‐zinc‐copper ore deposits of the region. The Bonneterre Dolomite consists of dolomitized algal bioherms, oolitic grainstone and associated lithologies that were deposited on a carbonate platform surrounding the Precambrian age St Francois Mountains. Porosity was determined by point counting thin sections from cores and mines in the Bonneterre Dolomite and by gas porosimetry. Volumes of epigenetic cements were estimated by point counting cement filling micro‐ and mesoporosity using cathodoluminescence. Cement volumes were added to present porosity to estimate porosities during various stages of mineralization. Prior to the onset of mineralization, micro‐ and mesoporosity in the Bonneterre Dolomite averaged approximately 19%. Precipitation of early dolomite cement (roughly concurrent with the main period of sulphide deposition) reduced average porosity to approximately 7% and closed off much of the intercrystalline pore space. Later cementation by dolomite (prior to late stage sulphides) reduced porosity to approximately 5%, and late cementation by quartz further reduced porosity to the present average value of <4%. Periods of carbonate dissolution during MVT mineralization enhanced large scale megaporosity associated with fractures and breccias but did not significantly increase smaller scale porosity. Dolomite cementation associated with MVT mineralization, porosity and permeability were facies controlled. Today, as a result of mineralization, large scale fractures and breccias control porosity and permeability. This study indicates that dolomite porosity may undergo significant change during basinal brine migrations associated with MVT mineralization.

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Section: Introductionmentioning

confidence: 99%

Porosity evolution of the Cambrian Bonneterre Dolomite, south‐eastern Missouri, USA

Gregg¹,

Laudon

Woody³

et al. 1993

Sedimentology

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“…Recycled Pb in the United States is a major contributor (67%) to Pb used in manufacturing, and the United States only imports a small percentage of Pb; therefore, it is safe to assume that Pb used for bullet manufacture would be largely composed of recycled Pb, of predominantly U.S. origin . Despite the fact that Pb mined in the United States exhibits varying uranogenic and thorogenic character, one cannot conclusively localize the source of U.S. Pb. ,− Data collected from Pb extracted from ammunition manufactured in the United States were well separated, with Pb samples from American Eagle manufactured projectiles exhibiting relatively high levels of radiogenic Pb, specifically 206 Pb, compared to both published data of U.S. Pb samples and projectile samples within the current study. When compared to previous data collected from the largest ore-producing mines in the United States, these data correlate most closely with Pb mined in the Western region of the United States; however, as previously mentioned, no conclusion can be drawn from this similarity. ,,, Both Lake City arsenal-produced ammunition and Winchester ammunition display much less unique Pb isotope ratios.…”

Section: Resultsmentioning

confidence: 61%

Lead Isotope Ratio Determination for the Forensic Analysis of Military Small Arms Projectiles

et al. 2003

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A study focusing on the ability to utilize isotopic analysis of Pb used in small arms projectiles from varying geographic origin was undertaken using the GV Instruments Isoprobe multicollector inductively coupled plasma mass spectrometer. With the exception of two classes of ammunition, these samples were able to be distinguished from one another. Also, following rigorous normalization and mass bias correction, these data were compared to data collected by geochemists in localities corresponding to projectile manufacture. This comparison was successful when projectiles in certain economically isolated countries were analyzed. Pb isotopic analysis with MC-ICPMS is shown to be useful as a tool for distinguishing between ammunition of various manufacturing origins.

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“…K‐feldspars associated with hydrothermal mineralization of ore deposits were formed at temperatures higher than 200 °C (e.g. Hearn et al ., 1987; Aleinikoff et al ., 1993; Groff et al ., 1997).…”

Section: Introductionmentioning

confidence: 99%

Early formation of K‐feldspar in shallow‐marine sediments at near‐surface temperatures (southern Israel): evidence from K‐Ar dating

Sandler¹,

Harlavan²,

Steinitz³

2004

Sedimentology

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Authigenic K-feldspar was investigated in two Albian to Turonian sections in Israel using K-Ar and Ar-Ar dating, X-ray diffraction, scanning electron microscopy and chemical analysis. Both sections comprise a similar succession of shallow-marine limestones, dolomites and marls, with some sandstone and shale beds of continental origin. The HCl-insoluble residue fraction of the studied samples consists of clays, quartz, feldspars, goethite and trace amounts of heavy minerals. Most of the insoluble residues have a relatively high K-feldspar content that has an adularia habit and is concentrated in the 4-7 lm size fraction. The authigenic origin of the K-feldspar in the fine silt fraction is indicated by its high content relative to quartz, the uniform and idiomorphic shape of the crystals and its limited size range. Of the fine silt (4-7 or 4-10 lm) separates, 40% have ages that are similar to stratigraphic ages within the analytical and biostratigraphic errors. Ar-Ar dating of a fine silt fraction with 94% K-feldspar (4-10 lm, sample GYP 7) yields a plateau age identical to the total gas age and similar to the stratigraphic age. These results indicate that the K-Ar age is not a mixture between detrital and late diagenetic K-feldspar ages, but is rather an age of formation within a few million years after deposition. It is suggested that the early formation of the K-feldspar was associated with dolomitization and was induced by residual brines as part of a reflux process.

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Do ages of authigenic K-feldspar date the formation of Mississippi Valley-type Pb-Zn deposits, central and southeastern United States?: Pb isotopic evidence

Cited by 23 publications

References 0 publications

Porosity evolution of the Cambrian Bonneterre Dolomite, south‐eastern Missouri, USA

Porosity evolution of the Cambrian Bonneterre Dolomite, south‐eastern Missouri, USA

Lead Isotope Ratio Determination for the Forensic Analysis of Military Small Arms Projectiles

Early formation of K‐feldspar in shallow‐marine sediments at near‐surface temperatures (southern Israel): evidence from K‐Ar dating

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