Palaeogeographic setting of a deep-water trilobite fauna from the Early Devonian (Pragian) of the Upper Yarra, central Victoria. Phacopidae of Victoria, Part 3

Abstract

A Pragian (Early Devonian) trilobite fauna from the Norton Gully Formation in the Upper Yarra area of central Victoria consists exclusively of the phacopid Prokops moorei sp. nov., a species with a highly variable visual surface including greatly reduced and blind morphologies. Several trilobites are preserved as moult assemblages, but most occur as isolated tergites on bedding-planes crowded with dacryoconarids and small bivalves. The autecology and taphofacies of the fauna indicate a deep-water setting, with the biofacies associations closely resembling deep-water assemblages described from Devonian sequences elsewhere. The distributions of laterally equivalent late Pragian facies from eastern areas of the Melbourne Zone indicate an inclined shelf between Lilydale and the Upper Yarra area, deepening eastwards from shoreline to outer shelf settings. To the northwest and northeast of the Upper Yarra area, the shelf was bounded by tectonically active margins associated with the converging Benambra Terrain, and to the south by the Waratah Bay Platform.

Key words:

• Devonian
• Pragian
• trilobites
• Prokops
• Phacopidae
• palaeogeography
• Victoria
• Australia