The petrogenesis of the Koperberg suite in the jubilee mine, Namaqualand.

Simple item page
dc.contributor.authorVan Zwieten, Adrianus Josephus Maria
dc.date.accessioned2019-03-27T09:17:09Z
dc.date.available2019-03-27T09:17:09Z
dc.date.issued1996
dc.descriptionThesis submitted for the degree MAGISTER SCIENTIAE to the Faculty of Science, Department of Geology, University of the Witwatersrand, Johannesburgen_ZA
dc.description.abstractThe Koperberg Suite intrusion at Jubilee, Namaqualand varies in composition from anorthosite, through mica diorite to pyroxene leucodiorite and pyroxene diorite. Detailed mapping and petrological studies of these rocks indicate that they were sequentially emplaced into the Concordia Granite country rocks, and that each of the rock types represent discrete magmatic events. The sequence of intrusion is from more acidic to more basic. Whole-rock geochemical analyses indicate that these rocks represent cumulates involving variable proportions of plagioclase, orthopyroxene, mica, quartz, oxides and immiscible sulphides. These cumulate phases intruded into the Concordia Granite at the time of peak of metamorphism and deformation in the Okiep Copper District, i.e, about 1030Ma ago, At the time of intrusion, the country rocks were under going partial melting under high grade (granulite facies) metamorphic conditions. and granitic anatects were present in the crust. Hybridisation of basic magma and granitic melts occurred within the shear zones along which the basic magmas ascended. The En content of orthopyroxene in the Koperberg Suite exceeds the An content of plagioclase. This is atypical of basic intrusions and is a consequence of this mixing. Mixing calculations based on the initial 87Sr/86Srratio (Ru) of the Jubilee samples at 1030Ma, imply high levels of assimilation (as much as 80% assimilation in the case of anorthositic rocks) between a granitic component, similar in composition to the Nababeep Gneiss and a mantle-derived basic magma. Sulphide mineralisation was initiated by the assimilation process, which caused the separation of immiscible sulphides from the hybridised magma. Subsequent oxidation of the original sulphide assemblage produced bornite, chalcopyrite and Ti-poor magnetite.en_ZA
dc.description.librarianAndrew Chakane 2019en_ZA
dc.identifier.urihttps://hdl.handle.net/10539/26642
dc.language.isoenen_ZA
dc.subjectPetrology -- South Africa.en_ZA
dc.subjectMetamorphic rocks -- South Africa.en_ZA
dc.subjectIntrusions (Geology) -- South Africa.en_ZA
dc.subjectCopper mines and mining -- South Africa.en_ZA
dc.subjectPetrogenesis -- South Africa.en_ZA
dc.titleThe petrogenesis of the Koperberg suite in the jubilee mine, Namaqualand.en_ZA
dc.typeThesisen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
Van Zwieten AJM_The petrogenesis of the Koperberg.pdf
Size:
3.95 MB
Format:
Adobe Portable Document Format
Description:
Download
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
license.txt
Size:
1.71 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
ETD Collection