Seismic imaging and crustal architecture across the Lachlan Transverse Zone, a cross-cutting feature of eastern Australia  

Authors / CoAuthors

Finlayson, D.M. | Korsch, R.J. | Glen, R.A. | Leven, J.H. | Johnstone, D.W.

Abstract

A two-dimensional crustal velocity model has been derived from 1997 wide-angle seismic profiling across the Lachlan Transverse Zone (LTZ) in the eastern Lachlan Orogen. The LTZ is considered to be a significant early tectonic feature controlling structural evolution in eastern Australia. The 364 km north-south profile passed from Ordovician volcanic and volcaniclastic rocks (Molong Volcanic Belt of the Macquarie Arc) in the north across the LTZ into Ordovician turbidites and Early Devonian intrusive granitoids in the south. The velocity model highlights significant lateral variations in sub-surface crustal architecture within the upper and middle crust. In particular, there is a higher P-wave velocity (6.24-6.32 km/s) unit identified in the upper crust under the arc at 5 to15 km depth that is not seen south of the LTZ. Near-surface P-wave velocities within the LTZ are markedly less than those along other parts of the profile and these are attributed to mid-Miocene volcanic centres. In the middle and lower crust there are also poorly defined velocity features that we also interpret to be related to the LTZ. The interpreted Moho depth increases from 37 km in the north to 47 km in the south above an underlying upper mantle with a P-wave velocity of 8.19 km/s. The seismic data indicate significant differences in crustal architecture between the northern and southern parts of the profile within the upper and middle crust, with associated strong indications that the LTZ may also have through-going crustal features to Moho depths.

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nonGeographicDataset

eCat Id

36228

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Keywords

• External PublicationScientific Journal Paper

( Theme )

• seismics

( Theme )

• structural geology

• AU-NSW

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_Internal

Publication Date

2001-02-20T00:00:00

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Australian Government Security ClassificationSystem    

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Creative Commons Attribution 4.0 International Licence    

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geoscientificInformation

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[-36.0, -32.0, 148.0, 150.0]

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