New Zealand Journal of Geology and Geophysics abstracts

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Diagenetic history of Triassic sandstone from the Beacon Supergroup in central Victoria Land, Antarctica

Matthias Bernet*
Reinhard Gaupp^†

Institut für Geowissenschaften
Johannes-Gutenberg Universität
Mainz, Germany
matthias.bernet@aya.yale.edu

^*Present address: State University of New York, New Paltz, USA.
^†Present address: Institut für Geowissenschaften, Friedrich Schiller Universität, Jena, Germany.

Abstract  The diagenetic history of Triassic sandstone from the Beacon Supergroup, Victoria Land, Antarctica, can be divided into three main phases of shallow burial diagenesis, contact diagenesis (temperatures of 200–300°C), and post-contact diagenesis, on the basis of petrographic and geochemical analyses. Shallow burial diagenesis is characterised by minor compaction, K-feldspar alteration to illite, and quartz cementation. Contact diagenesis is related to emplacement of dolerite intrusions and basalt flows during Gondwana break-up at 180 Ma. This high-temperature diagenetic phase is dominated by zeolite cementation, even in sandstone poor in zeolite precursor materials. Elevated thermal conditions associated with the igneous intrusions are suggested by increased illite crystallinity, but strong evidence for contact metamorphism is missing. Post-contact diagenesis is signified by zeolite and K-feldspar dissolution, and local quartz, calcite cementation, and minor albite and K-feldspar precipitation. This diagenetic phase is possibly related to renewed (hydro-) thermal activity in Victoria Land in association with rifting of New Zealand and Australia from Antarctica at c. 96 Ma.

Keywords  contact diagenesis; zeolite cementation; dolerite intrusion; Beacon Supergroup; Antarctica

G04040; Received 18 October 2004; accepted 5 May 2005; Online publication date 22 August 2005
New Zealand Journal of Geology & Geophysics, 2005, Vol. 48: 447–458
0028–8306/05/4803–0447© The Royal Society of New Zealand 2005

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