Carboniferous to Lower Permian stratigraphy of the southern Tamworth Belt, southern New England Orogen, Australia: Boundary sequences of the Werrie and Rouchel blocks

Abstract

Carboniferous to Lower Permian successions along the western border of the Tamworth Belt between Wallabadah and Muswellbrook were remapped to clarify the stratigraphy and establish a boundary between the Werrie and Rouchel blocks. The boundary, located at the Waverley Fault, separates Carboniferous sequences containing different formations and volcanic members. SHRIMP AS3 dating of volcanic members indicates that successions within the Rouchel and Gresford blocks were deposited, uplifted and eroded at different times. The lacustrine Woodton Formation in the Werrie block, previously considered Carboniferous, is earliest Permian (Asselian) from palaeobotanical and SHRIMP AS3 evidence. Stratigraphic and palaeoenvironmental differences between the Werrie and Rouchel blocks suggest that they were not directly juxtaposed during the greater part of the Carboniferous, supporting palaeomagnetic evidence that blocks within the Tamworth Belt are allochthonous. Superposition of the western extremity of the Waverley Fault by Lower Permian (Sakmarian) formations and intrusion of folded and faulted Devonian to Lower Permian successions by the Barrington Tops Granodiorite (ca 280 Ma) indicate that the Werrie, Rouchel and Gresford blocks were subjected to tectonism before the Late Permian Hunter – Bowen Orogeny.

Key words:

• Carboniferous
• New England Orogen
• Permian
• Rouchel block
• SHRIMP
• stratigraphy
• Tamworth Belt
• uranium – lead dating
• Werrie block

Acknowledgements

This research was funded by Large ARC Grant A39917100. David Keith, University of New England, is thanked for the loan of thin-sections and access to palaeobotanical specimens. Rodney Gould kindly identified the palaeobotanical specimens. Mark Dawson and Ken McDonald, New South Wales Mineral Resources, Armidale, provided access to compilations of geological maps and conversion of grid data. Bill Collins is thanked for the use of unpublished data and Phil Schmidt for advice on palaeomagnetics. Irene Wainwright carried out the XRF analyses. Mineral Resources New South Wales, particularly John Watkins, is thanked for supporting the cost of publication of Plate 1. Constructive comments on the manuscript by Dick Glen, Barrie McKelvey and Albert Brakel are greatly appreciated.

Notes

*Appendix 3 and Tables 2 – 23 [indicated by an asterisk (*) in the text and listed at the end of the paper] are Supplementary Papers; copies may be obtained from the Geological Society of Australia's website (www.gsa.org.au) or from the National Library of Australia's Pandora archive (http://nla.gov.au/nla.arc-25194).