Thesis (Ph. D.)--University of Michigan, 1938. / Caption title. Thesis note on label attached to p. 437. "Reprinted from Economic Geology, vol. XXXIV, no.4, June-July, 1939." eContent provider-neutral record in process. Description based on print version record.

Uppsala universitet, 1783, Thesis (doctoral). / Goldsmiths'-Kress no. 12400.1-3. - OCLC, 24367571. - Reproduction of original from Kress Library of Business and Economics, Harvard University.

Thesis (Ph. D.)--University of Michigan, 1938. / Caption title. Thesis note on label attached to p. 437. "Reprinted from Economic Geology, vol. XXXIV, no.4, June-July, 1939."

Thesis (doctoral)--Uppsala universitet, 1783. / Reproduction of original from Kress Library of Business and Economics, Harvard University. Goldsmiths'-Kress no. 12400.1-3.

Volcanogenic massive sulphide deposits are important sources of base metals throughout the world. The Canadian Cu-Zn-(Au, Ag) deposits of Archaean age occur in greenstone terrains within the Canadian Shield. These deposits are closely associated with volcanic vents developed along zones of rifting within mobile belts. The vents are manifested by coarse felsic pyroclastics and/or rhyolitic domes. The Japanese Pb-Zn-Cu-Ba(Ag) deposits, generally known as Kuroko deposits, are of Miocene age, and although also associated with volcanic vents, are developed above zones of subduction. Mineralization in volcanogenic deposits is a result of submarine exhalation of metalliferous hydrothermal solutions derived from fractionation of predominantly calc-alkaline magmas. The deposits are characterized by certain geological features that result from the interaction of specific physical and chemical conditions during deposition. Primary features include massive and stringer sulphide bodies, alteration zones, mineralogical and metal zoning, and certain depositional textures and structures. These features are commonly modified by subsequent metamorphism and deformation which impart secondary ore textures and affect metal distribution and shape. The disparity in age between Canadian and Japanese deposits allows the entire spectrum of geological features to be studied; from the completely unaltered to the high deformed and recrystallized. The characteristic geological features are the prime factors which control the metal distribution and concentration, and the size and shape of the deposits, thereby influencing the viability of the respective ore bodies. A knowledge of these factors and the physico-chemical parameters which control them are thus fundamental in the "understanding" of these deposits. They ultimately control the geological interpretations and predictions made during ore body delineation, ore reserve estimation, mining and ore beneficiation.

This thesis forms part of a larger effort which aims to establish the means of assessing the fluid mechanical behaviour of magma 1 as it cools inside a magma chamber surrounded by porous country rock. The reason for doing so is to advance the understanding of some types of mineral deposits; for example,the Platinum Group Elements (PGEs). The magma is modelled with the governing equations for a single-phase incompressible Newtonian fluid with variable viscosity and density. In this thesis, thermal conductivity and specific heat are approximated as constants and the country rock is treated as a conducting solid so as to save on computational time in the initial phases of the project. A basic review of the relevant literature is presented as background material and three basic models of magma chambers are discussed: crystal settling, compositional convection and double diffusive convection.The results presented in this thesis are from finite element calculations by a commercial computer code: ANSYS 5.4. This code has been employed in industry for over 26 years and has a long and successful benchmark history. In this context, finite element methods that are applicable to the code are discussed in chapter 5. In chapter 6, results that were obtained in the course of this research are presented. The thesis concludes with an indication of the possible geological significance of the results and various refinements that should be made to future models.

No description available.

No description available.

The intrusion-related Cerro Negro Norte Fe-oxide (Cu-Au) deposit is hosted in andesites and diorites of the early to middle Cretaceous Coastal Cordilleran arc of northern Chile. Tabular and irregularly shaped magnetite orebodies are localized on splays and fractures of the regional NINE striking Atacama Fault Zone. Production from this district was [approximately]100 MT @ [approximately] 65 wt. % Fe. Early Na-Ca alteration assemblages associated with magnetite �� apatite �� pyrite �� chalcopyrite ore include actinolite, marialitic scapolite, oligoclase, titanite, and epidote. Na-Ca alteration is extensive (>4 km�� in area), locally pervasive in the district, and is locally associated with granodiorite dike emplacement. The alkali-rich alteration and sulfide poor mineralization at CNN is characterized by metasomatic exchange of major, minor, and trace elements (added Fe, Na, Ca, Cl, P, Rare Earth Elements) between andesitic and diorite host rocks and halite-saturated saline hydrothermal fluids preserved as inclusions. Intrusion-heated fluids converge along the Atacama Fault Zone, and dikes, and may have been derived either from seawater or evaporitic water trapped in sedimentary rocks of the protoarc. Younger, cross-cutting hydrothermal assemblages such as tourmaline-quartzsericite (�� breccias), associated with granodiorite dikes, and chiorite-calcite-tourmalinequartz assemblages are related to pyrite �� chalcopyrite �� hematite and Cu-Au mineralization. Supergene minerals include goethite, Cu-carbonates and Cu-oxide. Later carbonate (dolomite) alteration is also localized along northeast-striking faults. Inferred Cu-Au estimates are [approximately] 1 MT @ [approximately] 1 g/T Au and 0.25 wt. % Cu. Late alteration assemblages may contain a component of magmatic saline fluids generated by observed monzodiorite-granodiorite dikes and pluton emplacement. Massive magnetite ore and associated Na-Ca alteration assemblages were deposited at high temperatures ( 500 to 6000 C), with igneous intrusions providing heat but not necessarily fluids and metals. Later moderate to low temperature Cu-Au mineralization (sulfide + oxide) replaces magnetite, and records the transition to more brittle faulting, with NW �� re-activated NNE structural control, and a greater proportion of magmatic fluids, sulfur ([delta]�����S[subscriptpy] = -1 0/00), and metals. / Graduation date: 2002

No description available.