Citation

Meixner, A.J. & Hoatson, D.M., 2004. Geophysical interpretation of Proterozoic mafic-ultramafic intrusions in the Arunta Region, central Australia. Record  2003/029. Geoscience Australia, Canberra.

Abstract

The purpose of this study was to follow on from previous work by Hoatson & Stewart (2001), who summarised the field relationships and mineralisation features of 16 Proterozoic mafic -ultramafic intrusions in the Arunta Region of central Australia. The major aims of this study were to investigate various geophysical datasets in order to define the total sub-cropping extent of the outcropping intrusions, as well as to identify other previously unknown mafic-ultramafic intrusions concealed beneath alluvial cover. Various data enhancements and imaging processes were applied to grids of the magnetic, gravity and gamma-ray spectrometric data, while 2-D computer modelling was carried out on the magnetic data. From these manipulations of the data it was possible to define various features of the outcropping intrusions. These feautures included: total sub-cropping extent; depth of burial beneath alluvial cover; internal structure; spatial association with faults and; the orientation of the intrusions. The larger outcropping intrusions exhibited a high gravity response, but the internal structure of the intrusions could not be determined due to the sparse gravity station spacing. However, the magnetic response of the the intrusions were variable and were more sensitive to the composition, metamorphic grade and post emplacement deformation. Generally the lower the metamorphic grade, the easier it was to determine magnetic signatures originating from primary igneous features such as macroscopic layering and contrasting rock compositions. The high-grade, intensely deformed intrusions exhibit more complex magnetic signatures and are less readily differentiated from country rock. The majority of the 14 outcropping intrusions investigated have sub-cropping extents far exceeding the outcropping component. The depth of burial for the sub-cropping intrusions was less than 120m. A number of previously unknown concealed mafic-ultramfic intrusions were identified based on their gravity and magnetic signatures. A series of bodies were identified on a prominent east-west trending gravity ridge on which the Andrew Yound Hills mafic intrusion outcrops. These bodies have similar magnetic character to the Andrew Yound Hills intrusion and are probably related. A series of ovoid shaped magnetic highs, located east of the Mount Hay Granulite, were also identified as possible plug-like mafic intrusions. The study highlighted the defeciency of the existing gravity data, which consists mostly of 11 km station spacing. This sparsity of gravity data does not allow the determination of internal composition based on density variations for the larger bodies, while smaller bodies are generally not imaged.
Google map showing geographic bounding box with values North bound -22.0 East bound 136.5 West bound 129.5 South bound -24.0
Downloads
For information on acquiring this product,
please contact the Geoscience Australia Sales Centre via:

fax:
+61 2 6249 9960; or
phone:
1800 800 173 (within Australia);
 
+61 2 6249 9966 (outside Australia).

Please note that support hours are 9 am to 5 pm weekdays

Product Type/Sub Type

dataset - GA Publication - Record

Constraints

license
Creative Commons Attribution 3.0 Australia Licence

IP Owner

Commonwealth of Australia (Geoscience Australia)

Author(s)

Date (publication)

2004

Product Type

dataset

Topic Category

geoscientificInformation

Keywords

GA Publication
Record
geology
magnetics
gravity
geophysics
Earth Sciences

Resource Language

English

Resource Character Set

utf8

Resource Security Classification

unclassified

Geographic Extent

North bound
-22.0
East bound
136.5
West bound
129.5
South bound
-24.0

Lineage

Unknown

Digital Transfer Options

onLine

DISTRIBUTION Format

pdf

Distributor

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

Metadata File Identifier

a05f7892-b8d0-7506-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

2003-06-11

METADATA SECURITY CLASSIFICATION

unclassified

Metadata Contact

Role
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 the Geoscience Australia Sales Centre via:

fax:
+61 2 6249 9960; or
phone:
1800 800 173 (within Australia);
 
+61 2 6249 9966 (outside Australia).

Please note that support hours are 9 am to 5 pm weekdays