Please use this identifier to cite or link to this item: https://hdl.handle.net/2440/116579
Type: Thesis
Title: S-type granite formation at Vivonne Bay, Kangaroo Island
Author: Mitchell, S. F.
Issue Date: 1990
School/Discipline: School of Physical Sciences
Abstract: Demonstrating a genetic association between a granite and the surrounding country rock by field relationships is usually difficult. However, wave cut platform exposures at Vivonne Bay, Kangaroo Island, display a variety of granites, each of which has evolved under different but related processes. Both field relationships and geochemical analyses were used to describe the granite-migmatite association and allow the processes of formation to be assessed. There are five major granite lithologies recognised along the Vivonne Bay section, viz; biotite granite, garnet granite, leucocratic granite, felsic granite and porphyritic granite. Field relationships indicate that the leucocratic granite, felsic granite and garnet granite are small (<200m) intrusives, while the porphyritic granite is a kilometre scale intrusion which forms the "core" of the section. The small scale (<200m) biotite granite is intimately associated with a biotite metasediment and granitised metasediment (or subgranite). The level of metamorphism of the metasediments is very high, reaching migmatite grade in most parts of the section, and is proportional to the proximity of the porphyritic granite core. Geochemical analyses indicate two major trends. The first trend suggests the intrusive granites form a fractionation relationship and the second trend implies that the biotite granite is the product of partial melting of the metasediments. Mass balance modeling and an analysis of the trace element distribution reinforced the suggested trends. This study concluded that the granites at Vivonne Bay represent four different stages in melt evolution; Stage 1: Unsegregated partial melting of the metasediments producing a subgranite Stage 2: Metre scale segregations of partial melt from the metasediments producing a biotite granite Stage 3: Kilometre scale pluton accumulations of biotite granite melts producing a porphyritic granite Stage 4: Fractionation from the porphyritic granite producing a garnet granite.
Dissertation Note: Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1990
Where: Kanmantoo Trough, Kangaroo Island, South Australia
Keywords: Honours; Geology; granite genesis; petrology;, mineralogy; geochemistry; melt evolution stages
Description: This item is only available electronically.
Provenance: This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the author of this thesis and do not wish it to be made publicly available, or you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals
Appears in Collections:School of Physical Sciences

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