Mapping undercover: integrated geoscientific interpretation and 3D modelling of a Proterozoic basin
<p>Gravity and 3D modelling combined with geochemical analysis examine the subsurface within and below the poorly exposed Palaeoproterozoic Yerrida Basin in central Western Australia. Understanding the structure of a region is important as key features indicating past geodynamic processes and...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-06-01
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| Series: | Solid Earth |
| Online Access: | https://se.copernicus.org/articles/11/1053/2020/se-11-1053-2020.pdf |
| Summary: | <p>Gravity and 3D modelling combined with geochemical
analysis examine the subsurface within and below the poorly exposed
Palaeoproterozoic Yerrida Basin in central Western Australia. Understanding
the structure of a region is important as key features indicating past
geodynamic processes and tectonic activity can be revealed. However, in
stable, post-depositional tectonic settings only the younger sedimentary
units tend to be widely exposed, rendering direct observation of basement and
intrusive rocks impossible. Geophysical imaging and modelling can reveal the
structure of a region undercover. High-magnitude density anomalies around
the basin cannot be reconciled with current geological knowledge in the case
presented here. The gravity anomalies infer an abundance of buried and
high-density material not indicated by the surface geology. A hypothetical
causative source for the high-magnitude gravity anomalies is mafic rocks
that were intruded and extruded during basin rifting. The simplest and
plausible stratigraphic attribution of these interpreted mafic rocks is to
the Killara Formation within the Mooloogool Group. However, geochemistry
reveals that the Killara Formation is not the only host to mafic rocks
within the region. The mafic rocks present in the Juderina Formation are
largely ignored in descriptions of Yerrida Basin magmatism, and results
indicate that they may be far more substantial than once thought. Sulfur
isotopic data indicate no Archean signature to these mafic rocks, a
somewhat surprising result given the basement to the basin is the Archean
Yilgarn Craton. We propose the source of mafic rocks is vents located to
the north along the Goodin Fault or under the Bryah sub-basin and Padbury
Basin. The conclusion is that the formation of the Yerrida Basin involves a
geodynamic history more complex than previously thought. This result
highlights the value in geophysics and geochemistry in revealing the complexity of
the earlier geodynamic evolution of the basin that may be indiscernible from
surface geology but may have high importance for the tectonic development
of the region and its mineral resources.</p> |
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| ISSN: | 1869-9510 1869-9529 |