Abstract

A prominent sandstone breccia crops out in the Pacoota Sandstone, Western MacDonnell Ranges, Northern Territory. The breccia occurs as discontinuous lenses which grade laterally, through incipient breccia and disrupted sandstone beds, into the enclosing sandstone sequence. This sequence consists of interbedded well-sorted silicia-cemented and poorly sorted friable quartzose sandstones; these two sandstone types also constitute, respectively, the clasts and matrix of the breccia. The clasts are rectangular (joint-bounded) and broken rectangular in shape, ranging up to 1 m in length. The matrix is predominantly massive, but convolute bedding is locally present. Similar sandstone breccias are known from three other localities in the region, all at the same stratigraphic level within the Pacoota Sandstone. Petrographic data indicate that the clast sandstone was cemented and strained prior to brecciation, whilst the matrix sandstone retained a largely cohesionless state and failed in a quasi-liquid manner. It is concluded that the brecciation occurred in situ at a considerable depth in a sedimentary pile, and resulted from the rotation and fragmentation of joint blocks of silica-cemented sandstone in the interbedded mobile matrix sandstone. Pore-water pressures are thought to have played an important role in the mobilization of the matrix sandstone.
Google map showing geographic bounding box with values North bound -23.5 East bound 133.2 West bound 132.0 South bound -24.5
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Product Type/Sub Type

nonGeographicDataset

Constraints

Creative Commons Attribution 4.0 International Licence

IP Owner

Commonwealth of Australia (Geoscience Australia)

Author(s)

Date (publication)

1976-01-01T00:00:00

Product Type

nonGeographicDataset

Topic Category

geoscientificInformation

GA Catalogue Number

80901 Product http://www.ga.gov.au/metadata-gateway/metadata/record/80901/

Keywords

GA Publication
Journal
NT
Earth Sciences

Resource Language

English

Resource Character Set

utf8

Resource Security Classification

unclassified

Geographic Extent

North bound
-23.5
East bound
133.2
West bound
132.0
South bound
-24.5

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

fae9173a-6f62-71e4-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
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