Regional variations in illite crystallinity of the Ordovician-Devonian Mathinna Group of northeast Tasmania indicates that metamorphic grade is dominantly anchizonal (200-300°C, sub-greenschist facies) over an area of 80 km x 100 km. The b0 white mica variation (b0 9.020âˆ"0.008Ã…) is characteristic of intermediate pressure Barrovian-type metamorphism. Peak metamorphism does not correlate with stratigraphic position and does not change across most of the large faults, indicating that peak metamorphism occurred after east-directed thrusting and as a result of crustal thickening. Most Devonian granites in northeast Tasmania intruded at much lower pressure than the peak metamorphic conditions, suggesting very rapid unroofing in the Middle Devonian. These results are very similar to the metamorphic characteristics reported from the Lachlan Fold Belt in Victoria. The metamorphic history is used to support a thin-skinned model for the deformation in a tectonic wedge that tapered to the east and was subsequently exhumed by backthrusting to the west.

Item Type:	Refereed Article
Research Division:	Earth Sciences
Research Group:	Geology
Research Field:	Structural Geology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Earth Sciences
UTAS Author:	Berry, RF (Associate Professor Ron Berry)
UTAS Author:	Davidson, GJ (Dr Garry Davidson)
ID Code:	23255
Year Published:	2001
Web of Science® Times Cited:	8
Deposited By:	Centre for Ore Deposit Research - CODES CoE
Deposited On:	2001-08-01
Last Modified:	2002-06-11
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