Date of Award

1996

Degree Type

Thesis

Degree Name

M.Sc.

Department

Geology

First Advisor

Blackburn, W. H.

Keywords

Geology.

Rights

CC BY-NC-ND 4.0

Abstract

Detailed petrographic and chemical studies reveal that deformation along the Parry Sound shear zone has greatly modified the Whitestone gabbroic anorthosite in texture, mineralogy and chemistry under amphibolite facies conditions. The strained Whitestone rocks are classified into two distinct series, designated as Series I and Series II. In both series, a strain index is established using average grain sizes of the rocks and Sibson's (1977) textural classification of mylonite series. With increasing deformation, the grain sizes of the rocks are progressively reduced and a penetrative fabric is coevally developed, accompanied by the development of abundant deformational features in minerals. The penetrative fabrics developed in the sheared rocks acted as conduits of fluid flows during and following deformation, which have catalyzed metamorphic transformations and late-stage alterations. The mineralogic alteration of such fluids are observed in the deformed Whitestone rocks and distinct zones of alteration can be observed in outcrop, hand-specimen and thin section. The differences of mineralogic variations in Series I and II attest that the compositions of fluids moving through them were dissimilar, an earlier alkali-poor, CO$\sb2$-rich fluid altering Series I rocks, and a fluid rich in alkalis and SiO$\sb2$ affecting Series II rocks. Mineralogic modifications are reflected by significant changes in rock chemistry. The volume-loss plus partitioning model is most reasonable to interpret those chemical variations in the strained rocks of the Whitestone gabbroic anorthosite. The volume-loss of rocks is accommodated by the significant losses of CaO, Fe$\sb2$O$\sb3$ and MgO, and minor losses of Al$\sb2$O$\sb3$ and SiO$\sb2.$ Accordingly, Y, Zr, Nb and the rare earth elements are progressively enriched due to this volume loss. Because of selective mobility of these elements, their enrichments are variable.Dept. of Earth Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1996 .L58. Source: Masters Abstracts International, Volume: 37-01, page: 0211. Adviser: William H. Blackburn. Thesis (M.Sc.)--University of Windsor (Canada), 1996.

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