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Regional metamorphism of the Mathinna Group, northeast Tasmania
journal contribution
posted on 2023-05-16, 13:18 authored by Patison, NL, Ronald BerryRonald Berry, Davidson, GJ, Taylor, BP, Bottrill, RS, Manzi, B, Ryba, J, Shepherd, RERegional 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 9.020∓0.008Å) 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.
History
Publication title
Australian Journal of Earth SciencesVolume
48Pagination
281-292ISSN
0812-0099Department/School
School of Natural SciencesPublisher
Blackwell Science AsiaPlace of publication
Carlton, Victoria, AustraliaRepository Status
- Restricted