Precambrian Tasmania: a Thin-skinned Devil

Abstract

An interpretation of geological and geophysical data is presented to suggest that the Precambrian rocks of Tasmania comprise a series of Palaeozoic thrust slices embedded in the western part of the Lachlan Fold Belt and the eastern part of the Kanmantoo Fold Belt. This interpretation contrasts with previous interpretations which regarded the Precambrian rocks as the basement on which the Palaeozoic rocks formed.In western Tasmania, east-or west-facing thrusts and involving detached Precambrian blocks occur in discrete zones. Westfacing thrusts only occur northwest of an axis from Elliott Bay in southwest Tasmania to Penguin in northern Tasmania. This thrust system overlaps an older east-facing system which becomes more intense eastward but which may be recognised across the entire island.

SHRIMP U–Pb detrital zircon ages from Proterozoic and Early Palaeozoic sandstones and their bearing on the early geological evolution of Tasmania

“…Some or all of the inliers may be allochthonous terranes that accreted onto the Tasman Fold Belt in the Early Palaeozoic (Leaman 1992; Powell 1992; Elliott et al . 1993; Leaman et al . 1994).…”

“…In Tasmania there are a number of spatially or structurally separated Proterozoic inliers (or terranes), many of which have been suggested to be allochthonous blocks (Leaman 1992; Powell 1992; Elliott et al . 1993; Leaman et al . 1994; Meffre et al .…”

Linking mainland Australia and Tasmania using ambient seismic noise tomography: Implications for the tectonic evolution of the east Gondwana margin

“…A diverse range of techniques have so far been exploited to infer information on crustal structure and composition beneath Bass Strait, mainly in studies focusing on similarities recognised in the geology (Crawford and Berry, 1992;Powell and Baillie, 1992;Reed, 2001;Cayley, 2011) and in geophysical, geochemical and other types of data in Tasmania and/or mainland Australia. Geophysical methods include potential field imaging and modelling (e.g., Leaman et al, 1994;Gunn et al, 1997aGunn et al, , 1997bMorse et al, 2009;McLean et al, 2010), seismic reflection profiling (Drummond et al, 2000;Cayley et al, 2011) and seismic tomography (Rawlinson and Kennett, 2008). Palaeomagnetic evidence in the form of magnetic remanence (Li et al, 1997) has also been used.…”

High-frequency ambient noise tomography of southeast Australia: New constraints on Tasmania's tectonic past

“…More than two decades ago it was postulated that the Tamar River marks the approximate location of a crustal‐scale suture zone [ Williams , 1989] ‐ sometimes referred to as the Tamar Fracture System ‐ between ETT and WTT. This idea has since been questioned [ Leaman et al , 1994; Reed , 2001; Rawlinson et al , 2010], and the observed changes in stratigraphy that gave rise to the original hypothesis are now interpreted as being related to thin‐skinned (near‐surface) tectonic processes [ Leaman et al , 1994].…”