Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1911. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed April 28, 2009) Includes bibliographical references (p. 3-6).

Proefschrift--Leiden. / Part of illustrative material folded. Summaries in Dutch and French. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1985. / Illustrative matter in pocket. Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 71-77).

Thesis (M.S.)--University of Wisconsin--Madison, 1982. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 118-131).

Thesis--Basel. / Errata slip inserted. Includes bibliographical references.

Carlin-type, fine-grained, "invisible" or Disseminated Replacement Type gold-silver deposits are all different names for a major new type of ore deposit that is currently being extensively developed in the Western United States. This type of deposit is now being found elsewhere. Thus a descriptive empirical model that emphasizes the geological and geochemical environment of formation is needed to assist the mining industry in the search for similar deposits. These deposits are typically formed in carbonaceous, silty dolomites and Iimestones or mineralization calcareous siltstones rocks and is exceedingly fine-grained is disseminated in the and claystones. host sedimentary Gold-silver , ore. Primary alteration usually less than one micron in size in unoxidized types include decalcification, argillitization, silicification resulting in the and pyritization. Silicification is commonly intense formation of jasperoid bodies which may be the host to higher grade ore. Supergene alteration is dominated by oxidation resulting in the formation of numerous oxides and sulphates and the release of gold from its association with sulphides and organic carbon. elements are As, Ba, Hg, Sb, and TI. Commonly associated trace Available geological, geochemical, fluid inclusion and stable-isotope studies lead to the conclusion that a circulating hydrothermal system is the important factor necessary for gold-silver concentration and deposition. A direct genetic or only casual relation between are deposition and discrete igneous formations remains unclear. However, it is considered that volcanism provided the source of heat necessary for the generation of a circulating hydrothermal system. High angle faults and fold structures facilitate transport and are of prime importance in directing are fluids to favourable host lithologies. The host rocks, overwhelmingly carbonate - rich, include those whose original and/or altered compositions and resulting permeability provide favourable sites for the precipitation of disseminated gold. The processes specialized. resulting Any th ick in the formation of these deposits are section of carbonate rocks has the potential not to produce Disseminated Replacement Type deposits wherever underlying igneous activity has developed a hydrothermal system

Agriculturists have long been interested in the minor element content of trees and lesser plants and of the soils in which they grow. This paper deals with the relation of plants to ore deposits. The investigations indicate that the zinc and copper content of some trees and lesser plants may reflect, to a striking extent, the presence of zinc and copper concentrations in the underlying soils or rock formations. / Science, Faculty of / Botany, Department of / Graduate

Besshi-type deposits range in age from early Proterozoic to early Tertiary, of which the largest number are late Proterozoic, early Palaeozoic or Mesozoic in age. No Archaean examples of Besshi-type deposits are known, probably due to insufficient availability of sialic crust for erosion and clastic marine sedimentation before the start of the Proterozoic. All Besshi-type deposits are contained within sequences of clastic sedimentary rock and intercalated basalts in a marine environment. The basalts and amphibolites are principally tholeiitic in composition. Besshi-type deposits characteristically form stratiform 1enses and sheet-like accumulations of semi-massive to massive sulphide. The main ore assemblage consists dominantly of pyrite and/or pyrrhotite with variable amounts of chalcopyrite, sphalerite and trace galena, arsenopyrite, gold and e1ectrum, barite being absent in general. The median Besshi-type deposit (n=75) contains 1.3 million tonnes (Mt) of massive sulphide with a Cu grade running at 1.43%. It is suggested that Besshi-type deposits form by both exhalative and synsedimentary replacement processes when considering geological features and comparisons with modern analogues in the Guaymas Basin, Middle Valley and Escanaba Trough. The currently forming metalliferous sediments in the Red Sea provide for a brine pool model explaining the lack of footwall feeder zones below sheet-like deposits. Where thick sulphide lenses are contained in some Besshi-type deposits, combinations of exhalative precipitation and sub-sea-floor replacement of permeable sediments and/or volcanic rocks, take place in the upper parts of submarine hydrothermal systems.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 89-98).

Thesis (M.S.)--Oregon State University, 2002. / Typescript (photocopy). Includes bibliographical references (leaves 187-194). Also available on the World Wide Web.