M. Sc. / The Pering Pb-Zn deposit is hosted in the stromatolitic dolomites of the Campbellrand Subgroup of the Ghaap Group, Transvaal Supergroup. The deposit is situated 20 km northeast of the town Reivilo in the semi-arid region of the Northwest Province, South Africa. It has been classified as a Mississippi Valley type deposit and is, together with the Bushy Park Pb-Zn deposit and F-Pb-Zn deposits near Zeerust, the only known MVT deposit of Paleoproterozoic age. The Pering open cast mine has been operational since 1986, yielding 18 Mt at an average ore grade of 3.6 wt.% Zn and 0.6 wt.% Pb. The aim of this study is to devise a metallogenetic model by integrating core logging, petrography, fluid inclusion and stable C-0-S isotope studies. The mineralogy includes sphalerite, galena and minor chalcopyrite as ore minerals, with diagenetic pyrite, hydrothermal dolomite, quartz and calcite as gangue minerals. Sphalerite predominates over galena. Mineralisation occurs as (a) disseminated stratabound replacements sheets restricted mainly to stromatolitic zones of the Steekdorings Member of the Reivilo Formation, and as (b) open space infill in breccia bodies that cross-cut the stratigraphy. Three events of hydrothermal brecciation, resultant of prolonged pulses of fluid infiltration, and mineralisation are recognised. The first brecciation event is marked by the cementation of the dolomite host rock by sparry dolomite, closely associated with finegrained disseminated sphalerite and galena. The second brecciation event is of minor importance, and is marked by the formation of small amounts of the second sphalerite generation, while the third, and final, brecciation event is marked by the formation of euhedral sphalerite, galena, quartz, sparry dolomite, and calcite as open space fill.

The interpretation of leached outcrops as guides to the specific minerals from which they were formed has been developed to a rather high degree by earlier workers, among whom Boswell and Blanchard deserve particular mention. In the present work, a gossan that led to the discovery of a lead deposit is described. Since many hand specimens of the limonite from this gossan lack the characteristic boxwork structures described by the authors above, microscopic investigations of thin and polished sections were carried out. However, the gossan is classified into six types mainly on the basis of its physical properties. At least three of these are correlated with types described by Boswell and Blanchard, one of pyrite derivation and the others from galena. The relative solubility of different limonite types in dilute HC1 was not found to be of as much value as some writers have indicated. The mineral deposits to which the limonite pointed the way have not been sufficiently exposed to allow detailed study, but the presence of tremolite and phlogopite in an area of disseminated mineralization indicates that this portion at least may be of contact metamorphic origin. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

A total of 34 lead ore samples from selected hydrothermal deposits in Wyoming, Montana, and Idaho have been isotopically analyzed and geochronological interpretations made from the results. Leads from along the southeastern flank of the Idaho Batholith appear to have a primary component 2500 my old. Leads from Butte and Cassia counties, Idaho, may be interpreted as having this same primary component with an added component that is estimated to be 1400 to 1600 my old. The radiogenic component of leads along the southeastern flank of the Idaho Batholith commenced development in a closed system 2500 my ago. Radiogenic components of the leads from Butte and Cassia counties commenced development 1900 and 2700 my ago respectively. Preliminary results of analyses from the south end of the Wind River Mtns, Wyoming, and the Little Belt Mtns, Montana, show primary lead ages of about 3200 and 2200 my respectively. Common lead geochronology indicates that the basement rocks of Southern Idaho may be assigned to the Superior Province of North America as defined by Kanasewich (1965). A second Precambrian event was recorded by a change in the lead isotope abundances during the Penokian era. Thus, Southern Idaho had been subjected to several uplifts during parts of Early and Middle Precambrian time. The ages of the anomalous leads from Butte and Cassia counties could represent the times of formation of sedimentary layers which remained closed systems until the time of formation of the ore bodies. A model for continental accretion and growth is discussed. The contribution of the present report to tectonic development models is in the suggestion of a geological sequence which may give rise to anomalous lead suites. This geological sequence is concerned with regional tectonic events which take place in the lower crust and are manifested by igneous activity. Examples of leads with apparent enrichment in the 208 isotope were found during this study and other instances are mentioned. The enrichment is tentatively considered to occur as a result of concentration of the thorium decay product in sedimentary basins. This could occur if the thorium is in more easily weathered minerals than are the uranium isotopes. Evidence supporting naturally occurring lead isotope enrichment phenomena is cited. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1930. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed October 30, 2009) Includes bibliographical references (p. 27) and index (p. 28).

Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1929. / Figures 2-5 and Tables 1-5 are missing from text document. The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed October 1, 2009)

Thesis (Ph. D.)--University of Wisconsin--Madison, 1960. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 67-68).

Thesis (M.S.)--University of Wisconsin--Madison, 1983. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 100-107).

From Introduction: For at least two centuries and a corresponding number of generations of geologists and miners there has been active argument concerning the origin of certain types of carbonate hosted mineral deposit. The characterization of the type itself was and still is debatable. Objections have been raised to grouping several examples under one heading because each has its individually distinctive features. ·This is especially applicable to the carbonate hosted lead-zinc "sedimentary" deposits. The type that will be discussed in the text to follow is composed chiefly of galena, sphalerite, barite and fluorite, with pyrite , marcasite and chalcopyrite as conspicuous accessory ore minerals. Exceptions to this general copper deficient characteristic displayed by the sedimentary carbonate-hosted lead-zinc deposits are the deposits at Tsumeb and Kombat, Namibia. These deposits are hosted by the carbonate sequence of the Otavi Shelf sediments, and copper, in the form of tennantite, chalcopyrite and bornite, is the major ore constituent. Calcite, aragonite, dolomite and quartz are the commonest nonmetallic gangue minerals but siderite and silica may also be present. In contrast with other lead and zinc sulphide (volcanogenic) deposits, those to be considered here seldom carry noteworthy amounts of silver or any other precious metals. Commonly the country rock is a carbonate; limestone or dolomite, but deposits in. sandstone, shale and conglomerate are not unknown. Characteristic features are ore bodies that extend parallel or nearly so with the bedding although many such deposits are partly, or completely developed along crosscutting fissures and breccias. Some observers regard these fissure fillings as evidence for a magmatic source of the metals, whereas others regard them as an indication of remobilization of ions, metals or minerals orginally present in low-grade stratiform deposits elsewhere in the stratigraphic succession.

Economically important Mississippi Valley type zinc-lead deposits exist in a late Proterozoic dolomite, the Society Cliffs Formation, at north Baffin Island, District of Franklin, N.W.T., Canada. The Society Cliffs Formation ranges from 1,000 to 2,000 feet in thickness and is underlain by up to 2,000 feet of black, organic-rich shale, the Arctic Bay Formation, and overlain by either black shale and limestone of the Victor Bay Formation or by red, fine- to coarse-grained clastic rocks of the Strathcona Sound Formation. Disconformities exist between each of the formations. Society Cliffs Formation has undergone at least four temporally distinct episodes of karstification since its deposition. The most important karst episode, with respect to the formation of the zinc-lead deposits, occurred during the hiatal interval between the deposition of the Victor Bay Formation and the deposition of the Strathcona Sound Formation. During this hiatal interval a holokarst developed in Society Cliffs Formation and a large integrated cave system of the Mammoth Cave-Flint Ridge Cave System type was formed; i.e. long, nearly horizontal, tubular passages were formed during initial periods of base-level stabilization, followed by the development of sub-vertical canyons beneath the tubes when the base-level dropped. After this karst episode the Society Cliffs Formation was deeply buried and the cave system was partially or completely filled with sulphide and carbonate minerals. The zinc-lead deposits are characterized by banded structure which comprises pyrite, relict marcasite, sphalerite and galena interlayered with sparry dolomite. The zinc-lead deposits contain several sedimentary structures that were formed by a chemical deposition-chemical corrosion process. These include cross-stratification, cut-and-fill and onlap. Onlap indicates the paleocaves were filled from the floor up. The meteoric waters which formed the caves did not form the zinc-lead deposits because the temperature of ore deposition was between 200°C and 150°C, the calculated oxygen isotope composition of the ore fluid is +12.8 per mil, and mineral stability and isotopic data indicate the oxygen fugacity decreased during ore deposition. The sulphide sulphur isotope composition of the zinc-lead deposits has a relatively narrow range about +26 per mil, similar to that of sulphate evaporite (+23.7 per mil) which exists locally within the Society Cliffs Formation. Lead isotope data indicate the lead in the deposits was derived by at least a two-stage process from a source with a uniform uranium-thorium ratio. The ore fluid and contained metals are postulated to have been derived from the Arctic Bay Formation during a late-stage dewatering of the shale. Sulphide deposition may have been caused by the chemical reduction of sulphate which existed in the ore fluid when the ore fluid entered hydrocarbon-filled caves. The hydrocarbons were probably expelled from the Arctic Bay Formation shale during an earlier stage of thermal metamorphism and dewatering. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1931. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed February 9, 2010) Includes bibliographical references (p. 38-39).