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SHRIMP U-Pb detrital zircon ages from Proterozoic and Early Palaeozoic sandstones and their bearing on the early geological evolution of Tasmania

Black, Lance; Calver, Clive; Seymour, David B; Reed, A.

Description

Detrital zircons from 13 Late Mesoproterozoic to Early Neoproterozoic sandstones and two Palaeozoic sandstones from Tasmania were dated in order to improve constraints on depositional ages, to test correlation between Proterozoic inliers, and to characterise source regions. These include successions considered to be the oldest presently exposed in Tasmania. Typical features of the age distributions of the Proterozoic rocks are prominent data concentrations at 1800-1650 Ma and 1450-1400 Ma, and...[Show more]

dc.contributor.authorBlack, Lance
dc.contributor.authorCalver, Clive
dc.contributor.authorSeymour, David B
dc.contributor.authorReed, A.
dc.date.accessioned2015-12-13T22:50:33Z
dc.date.available2015-12-13T22:50:33Z
dc.identifier.issn0812-0099
dc.identifier.urihttp://hdl.handle.net/1885/80834
dc.description.abstractDetrital zircons from 13 Late Mesoproterozoic to Early Neoproterozoic sandstones and two Palaeozoic sandstones from Tasmania were dated in order to improve constraints on depositional ages, to test correlation between Proterozoic inliers, and to characterise source regions. These include successions considered to be the oldest presently exposed in Tasmania. Typical features of the age distributions of the Proterozoic rocks are prominent data concentrations at 1800-1650 Ma and 1450-1400 Ma, and a minor spread of Archaean ages. Statistical testing of the similarity of the age profiles shows that widespread quartzarenaceous samples from the Detention Subgroup, Needles Quartzite and from the Tyennan region are strongly similar, consistent with broad correlation. Relatively large differences are seen between the Detention Subgroup and the conformable, stratigraphically higher Jacob Quartzite, which contains an additional spread of 1300-1000 Ma zircons suggestive of a Grenvillian source. Age profiles of the quartzarenites and quartzwacke turbidites (Oonah Formation and correlatives) cannot be readily differentiated. The Oonah Formation likewise includes samples with and without Grenvillian ages, and there is no 750 Ma zircon population that would be expected if the turbidites were genetically related to the Wickham Orogeny, The simplest interpretation is that the quartzarenites (Rocky Cape Group and correlatives) and the turbidites (Oonah Formation and correlates) are lateral equivalents, although a younger (post-Wickham Orogeny) age for the Oonah Formation cannot be discounted. A maximum age of ca 1000 Ma is inferred for the Oonah Formation, Rocky Cape Group and correlatives. A minimum age of ca 750 Ma is provided by the basal age of the overlying Togarl Group and correlatives. In a metasediment from western King Island, the youngest detrital zircons are ca 1350 Ma, allowing a pre-Grenvillian depositional age as suggested by previous dating of metamorphic monazite. However, the age profile of this sample is not dissimilar to the other Tasmanian successions that are inferred to be 1000-750 Ma. The Wings Sandstone, of southern Tasmania, contains an unusual profile dominated by Grenvillian ages, consistent with an allochthonous origin. Basement ages that broadly match the age spectra of the Tasmanian Proterozoic sediments are found in southwestern Laurentia, consistent with mutual proximity in Rodinia reconstructions, The Palaeozoic sandstones, from the turbiditic Mathinna Supergroup of northeastern Tasmania, have zircon age profiles typical of the Lachlan Fold Belt, with a predominant latest Neoproterozoic-Early Cambrian component and a lesser, broad Proterozoic data concentration at ca 1000 Ma. Western Tasmania was not a significant part of the source area for these rocks.
dc.publisherBlackwell Publishing Ltd
dc.sourceAustralian Journal of Earth Sciences
dc.subjectKeywords: Paleozoic; Proterozoic; sandstone; SHRIMP dating; uranium-lead dating; Australasia; Australia; Eastern Hemisphere; Tasmania; World Geochronology; Provenance; SHRIMP; Tasmania; Uranium-lead dating; Zircon
dc.titleSHRIMP U-Pb detrital zircon ages from Proterozoic and Early Palaeozoic sandstones and their bearing on the early geological evolution of Tasmania
dc.typeJournal article
local.description.notesImported from ARIES
local.description.refereedYes
local.identifier.citationvolume51
dc.date.issued2004
local.identifier.absfor040203 - Isotope Geochemistry
local.identifier.ariespublicationMigratedxPub9128
local.type.statusPublished Version
local.contributor.affiliationBlack, Lance, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationCalver, Clive, Mineral Resources Tasmania
local.contributor.affiliationSeymour, David B, Mineral Resources Tasmania
local.contributor.affiliationReed, A., Southern Ocean Science Pty Ltd
local.bibliographicCitation.startpage885
local.bibliographicCitation.lastpage900
local.identifier.doi10.1111/j.1400-0952.2004.01091.x
dc.date.updated2015-12-11T10:41:01Z
local.identifier.scopusID2-s2.0-15844384036
CollectionsANU Research Publications

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