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Newly-recognised Continental Fragments Rifted from the West Australian Margin
Citation
Williams, SE and Whittaker, J and Muller, RD, Newly-recognised Continental Fragments Rifted from the West Australian Margin, The Sedimentary Basins of Western Australia IV: Proceedings of the Petroleum Exploration Society of Australia Symposium, 18-21 August 2013, Perth, WA, pp. 1-9. (2013) [Refereed Conference Paper]
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Abstract
The southwest Australian margin formed at the nexus of
rifting and breakup between India, Australia and Antarctica
in the Early Cretaceous. Studying the basin evolution along
this margin has been hampered by a lack of data from the
offshore Perth Abyssal Plain (PAP), and from the conjugate
Greater Indian margin, which was highly deformed during
collision with Eurasia. Here, we present new data (magnetic
anomaly profile data, swath bathymetry, and dredge
samples) constraining the evolution of the PAP, collected
during voyage ss2011/v06 of the RV Southern Surveyor in
late 2011.
The Batavia Knoll (BK) and Gulden Draak Knoll (GDK)
are two prominent, previously unsampled bathymetric
features located >1600 km offshore Australia that have been
assumed to be igneous features. Successful dredges on the
western flanks of both knolls recovered continental basement
rocks, revealing that both knolls are microcontinents. We
use quantitative analysis of shiptrack magnetic profiles
combined with satellite gravity anomalies to estimate the
extent and spatial variation in thickness of the continental
crust. Sediment thickness estimates are made using depths to
magnetic sources for shiptrack profiles.
The geophysical data provide evidence for basin structures
within the knolls of a similar scale to those imaged within
other fragments of stretched continental crust such as the
Naturaliste Plateau. Interpretation of previously unidentified
M-series anomalies in the Perth Abyssal Plain, combined
with dredge data, support a reconstruction model where the
BK and GDKs are microcontinents that initially rifted with
Greater India during breakup with Australia at ~130 Ma. As
seafloor spreading ceased in the PAP at about 105–100 Ma,
a westward ridge jump led to the rifting of the BK and GDK
from Greater India.
Item Details
| Item Type: | Refereed Conference Paper |
|---|---|
| Keywords: | plate tectonics, magnetics |
| Research Division: | Earth Sciences |
| Research Group: | Geology |
| Research Field: | Structural geology and tectonics |
| Objective Division: | Expanding Knowledge |
| Objective Group: | Expanding knowledge |
| Objective Field: | Expanding knowledge in the earth sciences |
| UTAS Author: | Whittaker, J (Associate Professor Jo Whittaker) |
| ID Code: | 86220 |
| Year Published: | 2013 |
| Deposited By: | IMAS Research and Education Centre |
| Deposited On: | 2013-08-29 |
| Last Modified: | 2014-09-11 |
| Downloads: | 0 |
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