Citation

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Shergold, J.H., 1991. The Pacoota Sandstone, Amadeus Basin, Northern Territory: stratigraphy and palaeontology. Bulletin  237. Bureau of Mineral Resources, Geology and Geophysics, Canberra.

Abstract

The Pacoota Sandstone is a thick (up to 850 m) deposit of siliciclastic rocks straddling the Cambrian- Ordovician boundary in the Amadeus Basin of central Australia. It is economically the most important hydrocarbon reservoir of the basin, contains a potentially significant reserve of phosphorite, and may be an important aquifer. The internal stratigraphy of the Pacoota Sandstone, not previously documented in detail on a basin-wide scale, is based here on a sequence of four informally defined sedimentary packages, separated by unconformity or disconformity. The age and stratigraphic distribution of these sequences is measured against a preliminary and equally informal biostratigraphic scheme, which involves body-fossil and ichnofossil assemblages. Although a late Cambrian-early Ordovician age has long been known, it is now possible to date the sequences, at least to stage-level of resolution. Sequence 1, characterised by channel-fill sediments at several localities, is Payntonian to early Datsonian (latest Cambrian). It overlies earlier Upper Cambrian (Mindyallan) formations with regional unconformity, and it, in turn, is overlain unconformably by Sequence 2. The latter is a tidal and storm-dominated sequence with concentrations of the Skolithos ichnocoenosis, but lacking age-diagnostic body fossils. It is separated by a further major unconformity from Sequence 3, comprising predominantly phosphatic and glauconitic clastic sediments of latest Warendian (late Tremadoc) age, which thus indirectly date Sequence 2 also. Sequence 4, which may be disconformable, at least in part on Sequence 3, again has storm and tidally dominated sandstones rich in ichnofossils, but impoverished in body fossils. The limited fauna that does occur dates this sequence at the Tremadoc/Arenig transition. The Pacoota Sandstone is in places unconformably overlain by the Horn Valley Siltstone, of early Arenig age.
Google map showing geographic bounding box with values North bound -23.0 East bound 136.5 West bound 127.5 South bound -25.0
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Product Type/Sub Type

dataset - GA Publication - Bulletin

Constraints

license
Creative Commons Attribution 3.0 Australia Licence

IP Owner

Commonwealth of Australia (Geoscience Australia)

Author(s)

Date (publication)

1991

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dataset

Topic Category

geoscientificInformation

Keywords

GA Publication
Bulletin
palaeontology
stratigraphy
Earth Sciences

Resource Language

English

Resource Character Set

utf8

Resource Security Classification

unclassified

Geographic Extent

North bound
-23.0
East bound
136.5
West bound
127.5
South bound
-25.0

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Unknown

Digital Transfer Options

onLine

DISTRIBUTION Format

pdf

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Organisation Name
Geoscience Australia
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Canberra
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ACT
Postal Code
2601
Country
Australia
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Metadata File Identifier

a05f7892-7f9a-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 Date Stamp

1996-10-29

METADATA SECURITY CLASSIFICATION

unclassified

Metadata Contact

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pointOfContact
Organisation Name
Geoscience Australia
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address
Downloads
For information on acquiring this product,
please contact Geoscience Australia Client Services via:

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1800 800 173 (within Australia);
 
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