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Steps in lithospheric thickness within eastern Australia, evidence from surface wave tomography

journal contribution
posted on 2023-05-16, 22:09 authored by Fishwick, S, Heintz, M, Kennett, BLN, Anya ReadingAnya Reading, Yoshizawa, K
A series of steps in the lithospheric thickness of eastern Australia are revealed by the latest seismic surface wave tomographic model and calculations of the horizontal gradient of shear wave speed. The new images incorporate data from the recent Tasmal experiment, improving resolution in continental Australia. Through comparisons with surface geology and geochemical studies, it is possible to infer that the steps in lithospheric thickness are related to boundaries between blocks of different age. The westernmost boundary marks the edge of the Archaean to Early-Proterozoic core of the continent. A second lithospheric boundary is observed in the central part of east Australia. To the west of this line, geochemical evidence suggests that there is Proterozoic lithospheric mantle, and this boundary may therefore represent the change from Proterozoic to Phanerozoic basement. The structure on the eastern margin of the continent is dominated by slow velocities, suggesting that in this area the continental lithosphere is very thin. There is a strong correlation between the slow wave speeds and the location of both the highest topography and recent volcanic activity. Inland of the continental margin, a zone of strong gradients in the seismic wave speed is observed, indicating a distinct step in lithospheric structure. If the step in lithospheric thickness was in place prior to volcanism, it may have acted as a boundary, with volcanism mainly occurring beneath the thinner lithosphere to the east. Copyright 2008 by the American Geophysical Union.

History

Publication title

Tectonics

Volume

27

Issue

4

Pagination

TC4009

ISSN

0278-7407

Department/School

School of Natural Sciences

Publisher

American Geophysical Union

Place of publication

United States

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the earth sciences

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