Magmatism and metamorphism of mafic intrusives of the Dromedary massif, Antarctica
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The area studied is located within the Dromedary massif, southern Victoria Land, Antarctica. The geology of this region includes a number of pre-metamorphic mafic intrusives within Koettlitz Group metasediments, which are the focus of the present study. The Dromedary gabbro is a composite body comprising several tholeiitic anorthositic and gabbroic plutons, and an olivine-bearing alkaline gabbro. Subsequent amphibolite facies metamorphism and deformation of Dromedary gabbro were strongly influenced by original rock composition. The Glee intrusives, a collection of dismembered hybrid intrusive rocks, represent mixing of a mafic magma with a Kspar phenocryst-bearing granitic magma. Glee intrusive whole rock geochemical trends are compatible with trends predicted using a simple linear endmember mixing model. This suggests the Glee mafic endmember was similar in composition to alkaline Dromedary gabbro. Pyroxene-bearing quartz diorite exposed south of Renegar Glacier and diorite intruded into Dromedary gabbro is similar in composition to some Glee intrusives and were possibly also generated by mixing of two magmas. A body of iron-rich nepheline syenite was emplaced into marble northwest of Mt Dromedary. Studies suggest assimilation of marble influenced oxygen isotopic composition of the syenite and encouraged the development of garnet-albite-amphibole coronas around pyroxene, but did not result in generation of substantial quantities of nepheline.
Pre-metamorphic intrusive lithologies exposed in the Mt Dromedary region are compatible with anorogenic magmatism and may represent a rifting or failed rifting event which occurred prior to the compressional "Ross Orogeny".
Pre-metamorphic intrusive lithologies exposed in the Mt Dromedary region are compatible with anorogenic magmatism and may represent a rifting or failed rifting event which occurred prior to the compressional "Ross Orogeny".
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iv, 109 p. : ill. (some col.), maps (some col.) ; 30 cm.
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1990Aslund
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Citation
Aslund, Tania, 1966-, “Magmatism and metamorphism of mafic intrusives of the Dromedary massif, Antarctica,” Otago Geology Theses, accessed February 7, 2025, https://theses.otagogeology.org.nz/items/show/241.