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Gem-bearing basaltic volcanism, Barrington, New South Wales: Cenozoic evolution, based on basalt K-Ar ages and zircon fission track and U-Pb isotope dating

Sutherland, F L; Fanning, Christopher

Description

Barrington shield volcano was active for 55 million years, based on basalt K-Ar and zircon fission track dating. Activity in the northeast, at 59 Ma, preceded more substantial activity between 55 and 51 Ma and more limited activity on western and southern flanks after 45 Ma. Eruptions brought up megacrystic gemstones (ruby, sapphire and zircon) throughout the volcanism, particularly during quieter eruptive periods. Zircon fission track dating (thermal reset ages) indicates gem-bearing eruptions...[Show more]

dc.contributor.authorSutherland, F L
dc.contributor.authorFanning, Christopher
dc.date.accessioned2015-12-13T23:20:42Z
dc.identifier.issn0812-0099
dc.identifier.urihttp://hdl.handle.net/1885/90827
dc.description.abstractBarrington shield volcano was active for 55 million years, based on basalt K-Ar and zircon fission track dating. Activity in the northeast, at 59 Ma, preceded more substantial activity between 55 and 51 Ma and more limited activity on western and southern flanks after 45 Ma. Eruptions brought up megacrystic gemstones (ruby, sapphire and zircon) throughout the volcanism, particularly during quieter eruptive periods. Zircon fission track dating (thermal reset ages) indicates gem-bearing eruptions at 57, 43, 38, 28 and 4-5 Ma, while U-Pb Isotope SHRIMP dating suggests two main periods of zircon crystallisation between 60 and 50 Ma and 46-45 Ma. Zircons show growth and sector twinning typical of magmatic crystallisation and include low-U, moderate U and high-U types. The 46 Ma high-U zircons exhibit trace and rare-earth element patterns that approach those of zircon inclusions in sapphires and may mark a sapphire formation time at Barrington. Two Barrington basaltic episodes include primary lavas with trace-element signatures suggesting amphibole/apatite-enriched lithospheric mantle sources. Other basalts less-enriched in Th, Sr, P and light rare-earth elements have trace-element ratios that overlap those of HIMU-related South Tasman basalts. Zircon and sapphire formation is attributed to crystallisation from minor felsic melts derived by incipient melting of amphibole-enriched mantle during lesser thermal activity. Ruby from Barrington volcano is a metamorphic type, and a metamorphic/metasomatic origin associated with basement ultramafic bodies is favoured. Migratory plate/plume paths constructed through Barrington basaltic episodes intersect approximately 80% of dated Palaeogene basaltic activity (65-30 Ma) along the Tasman margin (27-37°S) supporting a migratory plume-linked origin. Neogene Barrington activity dwindled to sporadic gem-bearing eruptions, the last possibly marking a minor plume trace. The present subdued thermal profile in northeastern New South Wales mantle suggests future Barrington activity will be minimal.
dc.publisherBlackwell Publishing Ltd
dc.sourceAustralian Journal of Earth Sciences
dc.subjectKeywords: Cenozoic; fission track dating; gemstone; potassium-argon dating; ruby; sapphire; uranium series dating; zircon; Australia Basalt; Cenozoic; Fission track dating; Potassuim-argon dating; Ruby; Sapphire; Uranium-lead dating; Zircon
dc.titleGem-bearing basaltic volcanism, Barrington, New South Wales: Cenozoic evolution, based on basalt K-Ar ages and zircon fission track and U-Pb isotope dating
dc.typeJournal article
local.description.notesImported from ARIES
local.description.refereedYes
local.identifier.citationvolume48
dc.date.issued2001
local.identifier.absfor040307 - Ore Deposit Petrology
local.identifier.ariespublicationMigratedxPub21301
local.type.statusPublished Version
local.contributor.affiliationSutherland, F L, Australian Museum
local.contributor.affiliationFanning, Christopher, College of Physical and Mathematical Sciences, ANU
local.description.embargo2037-12-31
local.bibliographicCitation.startpage221
local.bibliographicCitation.lastpage237
local.identifier.doi10.1046/j.1440-0952.2001.00851.x
dc.date.updated2015-12-12T09:04:15Z
local.identifier.scopusID2-s2.0-0035067360
CollectionsANU Research Publications

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