⁴⁰Ar-³⁹Ar Chronology and Petrology of the Miocene Rift-related Volcanism of Daniell Peninsula (Northern Victoria Land, Antarctica)

I. Nardini¹, P. Armienti¹, S. Rocchi¹ & R. Burgess²

¹Dipartimento di Scienze della Terra, Università di Pisa, Via S. Maria 53, 56126 Pisa - Italy
²Department of of Earth Science, University of of Manchester, Oxford Road, Manchester M13 9PL - UK

Received 24 January 2002; accepted in revised form 27 May 2003
 

Abstract - New geochemical data and ⁴⁰Ar-³⁹Ar age determinations are presented for volcanic rocks from the Daniell Peninsula of the Hallett volcanic province (McMurdo Volcanic Group). The Daniell Peninsula is mainly made up by overlapping shields and includes a stratovolcano in its southern termination. Analyses reveal an association of transitional to mildly alkaline and alkaline rocks, ranging from olivine-tholeiites and alkali basalts to peralkaline trachytes and rhyolites, and from picrites to trachytes and phonolites. Similar products were emitted contemporaneously at Coulman Island and in the adjacent Melbourne volcanic province. Volcanic activity in the Daniell Peninsula is largely contemporaneous also with the acidic peralkaline volcanism of the nearby Malta Plateau and covers a time span between 11.9 and 5.3 Ma, with the oldest products typically cropping out in the stratovolcano of Mandible Cirque and at the western margins of the peninsula. Geochemical modelling indicates that northern Victoria Land basaltic magmas may represent low-degree partial melts (<3%) of a garnet-pyroxenite source (T>1500°C and P=3.2-3.5 Gpa) with REE contents similar to pyroxenite found as xenoliths in basic magmas.

 

*Corresponding author (nardini@dst.unipi.it)