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Corundum (sapphire) and zircon relationships, Lava Plains gem fields, NE Australia: integrated mineralogy, geochemistry, age determination, genesis and geographical typing

Citation

Sutherland, FL and Coenraads, RR and Abduriyim, A and Meffre, S and Hoskin, PWO and Giuliani, G and Beattie, R and Wuhrer, R and Sutherland, GB, Corundum (sapphire) and zircon relationships, Lava Plains gem fields, NE Australia: integrated mineralogy, geochemistry, age determination, genesis and geographical typing, Mineralogical Magazine, 79, (3) pp. 545-581. ISSN 0026-461X (2015) [Refereed Article]

Copyright Statement

Copyright 2015 The Mineralogical Society

DOI: doi:10.1180/minmag.2015.079.3.04

Abstract

Gem minerals at Lava Plains, northeast Queensland, offer further insights into mantle-crustal gemformation under young basalt fields. Combined mineralogy, U-Pb age determination, oxygen isotope and petrological data on megacrysts and meta-aluminosilicate xenoliths establish a geochemical evolution in sapphire, zircon formation between 5 to 2 Ma. Sapphire megacrysts with magmatic signatures (Fe/Mg ∼1001000, Ga/Mg 318) grew with ∼3 Ma micro-zircons of both mantle (δ18O 4.55.6%) and crustal (δ18O 9.510.1) affinities. Zircon megacrysts (31 Ma) show mantle and crustal characteristics, but most grew at crustal temperatures (600800C). Xenolith studies suggest hydrous silicate melts and fluids initiated from amphibolized mantle infiltrated into kyanite+sapphire granulitic crust (800C, 0.7 GPa). This metasomatized the sapphire (Fe/Mg ∼50120, Ga/Mg ∼311), left relict metastable sillimanite-corundum-quartz and produced minerals enriched in high field strength, large ion lithophile and rare earth elements. The gem suite suggests a syenitic parentage before its basaltic transport. Geographical trace-element typing of the sapphire megacrysts against other eastern Australian sapphires suggests a phonolitic involvement.

Item Details

Item Type:Refereed Article
Keywords:sapphire, zircon, U-Pb age determination, trace elements, oxygen isotopes, basalt, syenite, lithosphere
Research Division:Earth Sciences
Research Group:Geology
Research Field:Tectonics
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Meffre, S (Dr Sebastien Meffre)
ID Code:105860
Year Published:2015
Web of Science® Times Cited:8
Deposited By:Centre for Ore Deposit Research - CODES CoE
Deposited On:2016-01-18
Last Modified:2016-05-24
Downloads:0

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