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Fractionation vs. magma mixing in the Wangrah Suite A-type granites, Lachlan Fold Belt, Australia: Experimental constraints

Klimm, Kevin; Holtz, Francois; King, Penelope

Description

The Wangrah Suite granites (Lachlan Fold Belt, Australia) reflect different stages of differentiation in the magmatic history of an A-type plutonic suite. In this study we use experimentally determined phase equilibria of four natural A-type granitic compositions of the Wangrah Suite to constrain phases and phase compositions involved in fractionation processes. Each composition represents a distinct granite intrusion in the Wangrah Suite. The intrusions are the Danswell Creek (DCG), Wangrah...[Show more]

dc.contributor.authorKlimm, Kevin
dc.contributor.authorHoltz, Francois
dc.contributor.authorKing, Penelope
dc.date.accessioned2015-12-13T22:53:55Z
dc.identifier.issn0024-4937
dc.identifier.urihttp://hdl.handle.net/1885/82029
dc.description.abstractThe Wangrah Suite granites (Lachlan Fold Belt, Australia) reflect different stages of differentiation in the magmatic history of an A-type plutonic suite. In this study we use experimentally determined phase equilibria of four natural A-type granitic compositions of the Wangrah Suite to constrain phases and phase compositions involved in fractionation processes. Each composition represents a distinct granite intrusion in the Wangrah Suite. The intrusions are the Danswell Creek (DCG), Wangrah (WG), Eastwood (EG) and Dunskeig Granite (DG), ordered from "most mafic" to "most felsic" by increasing SiO2 and decreasing FeOtotal. Experimental investigation show that the initial water content in melts from DCG is between 2-3 wt. % H2O. If the DCG is viewed as the parental magma for the Wangrah Suite, then (1) fractionation of magnetite, orthopyroxene and plagioclase (∼ 20 wt. %) of the DCG composition, leads to compositions similar to that of the EG; (2) further fractionation of plagioclase, quartz, K-feldspar and biotite (∼ 40 wt. %) from the EG composition, leads to the DG composition. These fractionation steps can occur nearly isobarically and are confirmed by bulk rock Ba, Sr, Rb and Zr concentrations. In contrast, the generation of the most abundant WG composition cannot be explained by fractional crystallisation from the DCG at isobaric conditions because of the high K2O content of this granite. Magma Mixing could be the process to explain the chemical distinctiveness of the Wangrah Granite from all the other granites of the Wangrah Suite.
dc.publisherElsevier
dc.sourceLithos
dc.subjectKeywords: fractional crystallization; fractionation; granite; igneous intrusion; magma; magmatic differentiation; mixing; phase equilibrium; water content; Australasia; Australia; Lachlan Fold Belt A-type granite; Australia; Crystallisation; Experiments; Fractional crystallisation; Magma-mixing
dc.titleFractionation vs. magma mixing in the Wangrah Suite A-type granites, Lachlan Fold Belt, Australia: Experimental constraints
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume102
dc.date.issued2008
local.identifier.absfor040300 - GEOLOGY
local.identifier.ariespublicationf5625xPUB10331
local.type.statusPublished Version
local.contributor.affiliationKlimm, Kevin, Universitat Hannover
local.contributor.affiliationHoltz, Francois, Universitat Hannover
local.contributor.affiliationKing, Penelope, College of Physical and Mathematical Sciences, ANU
local.description.embargo2037-12-31
local.bibliographicCitation.issue3-4
local.bibliographicCitation.startpage415
local.bibliographicCitation.lastpage434
local.identifier.doi10.1016/j.lithos.2007.07.018
local.identifier.absseo970104 - Expanding Knowledge in the Earth Sciences
dc.date.updated2015-12-11T11:00:43Z
local.identifier.scopusID2-s2.0-42949170053
CollectionsANU Research Publications

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