A middle Cambrian shallow water trilobite fauna from the Comstock Formation, near Queenstown, western Tasmania

Abstract

A limestone lens within the Comstock Formation, from low in the Tyndall Group near the Lyell Comstock Mine near Queenstown, western Tasmania, contains a small trilobite fauna. The trilobites include Ammagnostus cf. laiwuensis, Kootenia sp., Sudanomocarina? sp. and a possible member of the Monkaspidae. These suggest an age somewhere in the range from the upper Ptychagnostus atavus Zone to the Lejopyge laevigata Zone, with regional stratigraphic correlations suggesting the latter zone. This is only the second Tasmanian Cambrian fossil assemblage described from limestone; almost all previously described Tasmanian Cambrian faunas are found in siltstones and shales.

KEY WORDS:

• Comstock Formation
• middle Cambrian
• Tasmania
• trilobites
• limestone

ACKNOWLEDGEMENTS

The late Kerry Reid, Chief Geologist of the former Mt Lyell Mining and Railway Company, is thanked for his assistance in obtaining the fossils. The early part of this work was supported by an ARC grant to JBJ. John Laurie (Geoscience Australia) is thanked for comments on an earlier version of this paper. Lin Tian Rui's visit to Australia was partly funded by the then Applied Geology Research Group, University of South Australia. The assistance of the present and former curators, Sue Cameron, Penny Williamson, Kathy Stait, Fernando Della Pasqua and Isabella von Lichtan of the Department of Earth Sciences, University of Tasmania, is gratefully acknowledged. Clive Calver and an anonymous referee are thanked for constructive reviews.