New Zealand Journal of Geology and Geophysics abstracts

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Diorite and gabbro of the Dromedary mafic complex, South Victoria Land, Antarctica

G. SIMPSON¹
T. ASLUND²

Geology Department
University of Otago
P.O. Box 56
Dunedin, New Zealand

¹Present address: Institut für Mineralogie und Petrographie, ETH-Zentrum, Sonneggstr. 5, CH-8092 Zürich, Switzerland.

²Present address: Department of Earth Sciences, Monash University, Clayton, Victoria, Australia.

Abstract  The syntectonic Dromedary mafic complex is a well-preserved mafic body which was emplaced into Koettlitz Group metasediments during widespread late Proterozoic-Paleozoic granitoid plutonism, metamorphism, and deformation in South Victoria Land, Antarctica.

The 4 x 9 km pluton is reversely zoned. It consists of a core of calc-alkaline cumulate and noncumulate gabbros--comprising gabbro, olivine gabbro, anorthosite, norite, and pyroxenite--surrounded by an outer margin of homogeneous pyroxene-bearing diorite. All rocks have undergone varying degrees of metamorphic reconstitution. The resulting assemblages are strongly controlled by original rock composition. Field relationships and geochemical data suggest that the diorite and gabbro are coeval and cogenetic.

The Dromedary mafic complex has geochemical signatures distinct from most other nearby dioritic bodies. It does, however, plot as an extension of syntectonic granitoids from the Dry Valley region.

Keywords  mafic complex; gabbro; diorite; reversely zoned pluton; syntectonic; Antarctica

New Zealand Journal of Geology and Geophysics, 1996, Vol. 39: 403-414

0028-8306/96/3903-0403 $2.50/0 (c) The Royal Society of New Zealand 1996

PDF file of entire paper: medium quality (3288K); (scanned from paper original: notes about this process)

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