Abstract

Two new U-Pb dates (sensitive high-resolution ion microprobe on zircon) have an important bearing on the age of the Marinoan (Elatina) glaciation, a presumed global chronostratigraphic marker that has been previously poorly constrained in terms of its numerical age. In the Grassy Group of King Island, intermediate sills dated as 575 ± 3 Ma intrude an Elatina-equivalent diamictite (the Cottons Breccia), cap carbonate, and postglacial shale. The sills are locally vesicular, stratigraphically limited, probably intruded at shallow depth, and probably closely postdate the end of Marinoan glaciation. In the Togari Group of northwest Tasmania, a rhyodacite flow dated as 582 ± 4 Ma underlies the Croles Hill Diamictite, which is at least partly glaciogenic. No cap carbonate is known from the Croles Hill Diamictite, but in other respects its stratigraphic setting is similar to the Cottons Breccia. The two dates together support a significantly younger age (ca. 580 Ma) for the Marinoan glaciation than some previous estimates, and suggest correlation with the Gaskiers Formation of Newfoundland. The new data cannot exclude the possibility of a ca. 620 Ma age for the Marinoan glaciation, as suggested by recent evidence from outside Australia, but this would require a more complex and much less probable interpretation of the Tasmanian stratigraphic relationships.
Google map showing geographic bounding box with values North bound -40.0 East bound 150.0 West bound 144.0 South bound -44.0

Product Type/Sub Type

nonGeographicDataset

Constraints

Creative Commons Attribution 4.0 International Licence

IP Owner

Commonwealth of Australia (Geoscience Australia)

Author(s)

Date (publication)

2004-01-01T00:00:00

Product Type

nonGeographicDataset

Topic Category

geoscientificInformation

GA Catalogue Number

71034 Product http://www.ga.gov.au/metadata-gateway/metadata/record/71034/

Keywords

External Publication
Scientific Journal Paper
AU-TAS
Earth Sciences

Resource Language

English

Resource Character Set

utf8

Resource Security Classification

unclassified

Geographic Extent

North bound
-40.0
East bound
150.0
West bound
144.0
South bound
-44.0

Digital Transfer Options

onLine

Distributor

Role
distributor
Organisation Name
Commonwealth of Australia (Geoscience Australia)
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address

Metadata File Identifier

a05f7892-f998-7506-e044-00144fdd4fa6

Metadata Standard Name

ANZLIC Metadata Profile: An Australian/New Zealand Profile of AS/NZS ISO 19115:2005, Geographic information - Metadata

Metadata Standard Version

1.1

METADATA SECURITY CLASSIFICATION

unclassified

Metadata Contact

Role
pointOfContact
Organisation Name
Commonwealth of Australia (Geoscience Australia)
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address