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Evolution and emplacement of high fluorine rhyolites in the Mesoproterozoic Gawler silicic large igneous province, South Australia

Citation

Agangi, A and Kamenetsky, VS and McPhie, J, Evolution and emplacement of high fluorine rhyolites in the Mesoproterozoic Gawler silicic large igneous province, South Australia, Precambrian Research, 208-211 pp. 124-144. ISSN 0301-9268 (2012) [Refereed Article]

Copyright Statement

Copyright 2012 Elsevier B.V.

DOI: doi:10.1016/j.precamres.2012.03.011

Abstract

The Gawler Range Volcanics (GRV) and the Hiltaba Suite (HS) of South Australia form a silicic-dominated large igneous province (the Gawler SLIP) emplaced in an intracontinental setting during the Mesoproterozoic. Emplacement of the GRV lasted for a short period of time (∼2Ma), and can be separated into two main phases. The first phase (lower GRV) is composed of thick (≤3km) sequences erupted from distinct centres, and includes small to moderate volume (up to >150km 3) felsic lavas, ignimbrites, and minor mafic and intermediate lavas. The upper GRV include extensive felsic lavas that are up to >1000 of km 3 in volume and >200km across. Using well preserved, quartz-hosted melt inclusions, we investigated the composition of the lower GRV, including major, trace, and volatile elements. The results indicate high concentrations of K 2O (≤7-8wt.%), rare earth and high field strength elements, and low concentrations of Ca, Mg, Ni, Cr, Sr and Ba in comparison with felsic continental crust. Overall, melt inclusion compositions match whole-rock geochemical characteristics. We demonstrate that the GRV magma was F-rich (≤1.3wt.%), and had high temperature for a silicic magma. High F concentrations and high temperature would have resulted in lower than usual polymerisation of the melt and relatively low viscosity. These characteristics help explain how very voluminous felsic magma was erupted effusively and emplaced as lavas. Other intracontinental SLIP contain extensive felsic lavas and ignimbrites which appear to share similar geochemical characteristics. We also show that selective alteration caused depletion of whole-rock compositions in some trace elements, namely Pb, U, and Sn. © 2012 Elsevier B.V.

Item Details

Item Type:Refereed Article
Research Division:Earth Sciences
Research Group:Geology
Research Field:Volcanology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Agangi, A (Mr Andrea Agangi)
Author:Kamenetsky, VS (Professor Vadim Kamenetsky)
Author:McPhie, J (Professor Jocelyn McPhie)
ID Code:81347
Year Published:2012
Funding Support:Australian Research Council (CE0561595)
Web of Science® Times Cited:11
Deposited By:Centre for Ore Deposit Research - CODES CoE
Deposited On:2012-12-01
Last Modified:2013-04-03
Downloads:0

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