Tasmanian Geological Survey TASMANIA DEVELOPMENT Record 1995/01 AND RESOURCES Tasgo NGMA Project Sub-Project 1: Geological Synthesis Explanatory notes for the Time–Space Diagram and Stratotectonic Elements Map of Tasmania by D. B. Seymour and C. R. Calver Tasmanian Geological Survey Record 1995/01 1 CONTENTS INTRODUCTION ..................................................................................................................... 4 KING ISLAND.......................................................................................................................... 5 ?Mesoproterozoic ............................................................................................................... 5 Neoproterozoic orogenesis and granitoid intrusive rocks ................................................ 5 ?Neoproterozoic sequences ................................................................................................ 5 Early Carboniferous granitoid intrusive rocks ................................................................ 6 ROCKY CAPE ELEMENT....................................................................................................... 7 ?Mesoproterozoic: Rocky Cape Group ............................................................................... 7 Burnie and Oonah Formations ........................................................................................ 7 Smithton Synclinorium .................................................................................................... 7 Ahrberg Group .................................................................................................................. 9 Regional deformation and metamorphism ...................................................................... 9 Introduction: the Penguin and Delamerian Orogenies ............................................ 9 Arthur Lineament ...................................................................................................... 9 Relationship to the Scopus Formation ...................................................................... 10 Dolerite dyke swarms ........................................................................................................ 11 Wurawina Supergroup ..................................................................................................... 11 Devonian deformation ...................................................................................................... 12 Devonian–Carboniferous granitoids ................................................................................ 12 Granitoid-related mineralisation............................................................................... 12 DUNDAS ELEMENT ............................................................................................................... 13 Introduction ...................................................................................................................... 13 Neoproterozoic sequences .................................................................................................. 13 Oonah Formation........................................................................................................ 13 Success Creek Group.................................................................................................. 14 Crimson Creek Formation ......................................................................................... 15 ?Allochthonous sequences ................................................................................................. 15 Mafic volcanics and associated rocks......................................................................... 15 Ultramafic–mafic complexes...................................................................................... 15 Post-collisional Middle Cambrian sequences .................................................................. 16 Introduction ................................................................................................................ 16 Mt Read Volcanics and associated rocks................................................................... 16 Mineralisation in the Mt Read Volcanics.................................................................. 17 Lower Dundas Group ................................................................................................. 17 Late Cambrian–Early Ordovician siliciclastic sequences ............................................... 18 Introduction ................................................................................................................ 18 Owen Group ................................................................................................................ 18 Upper Dundas Group ................................................................................................. 19 Professor Range–Mt Zeehan area.............................................................................. 19 Cambrian deformation ..................................................................................................... 20 Gordon and Eldon Groups ............................................................................................... 20 Devonian deformation ...................................................................................................... 21 Devonian–Carboniferous intrusive rocks ......................................................................... 21 Granitoid-related mineralisation............................................................................... 22 Southern extensions of the Dundas Element ................................................................... 22 ?Mesoproterozoic units............................................................................................... 22 ?Neoproterozoic sequences......................................................................................... 23 ?Allochthonous units .................................................................................................. 23 Middle Cambrian units .............................................................................................. 23 Wurawina Supergroup ............................................................................................... 24 Devonian intrusive rocks ........................................................................................... 24 Tasmanian Geological Survey Record 1995/01 2 SHEFFIELD ELEMENT.......................................................................................................... 25 Introduction ...................................................................................................................... 25 Burnie Formation ............................................................................................................. 25 ?Early Cambrian sequences ............................................................................................. 25 Middle to Late Cambrian fossiliferous sequences ........................................................... 26 Late Cambrian–Early Ordovician siliciclastic sequences ............................................... 27 Gordon and Eldon Groups ............................................................................................... 28 Devonian and earlier deformation ................................................................................... 29 Devonian granitoid rocks ................................................................................................. 31 Granitoid-related mineralisation............................................................................... 31 TYENNAN ELEMENT............................................................................................................. 32 Metamorphic rocks ............................................................................................................ 32 ?Neoproterozoic sequences ................................................................................................ 33 ?Middle Cambrian intrusive rocks ................................................................................... 34 Ordovician–Early Devonian sedimentary successions .................................................... 34 Devonian deformation ...................................................................................................... 35 Devonian granitoid rocks ................................................................................................. 35 ADAMSFIELD–JUBILEE ELEMENT.................................................................................... 37 Late Proterozoic successions ............................................................................................. 37 Deformation of Proterozoic rocks ...................................................................................... 37 Cambrian successions ...................................................................................................... 37 Late Middle to early Late Cambrian deformation .......................................................... 38 Wurawina Supergroup ..................................................................................................... 38 Devonian deformation ...................................................................................................... 39 TECTONIC SYNTHESIS OF WESTERN TASMANIA.......................................................... 40 NORTHEAST TASMANIA ELEMENT..................................................................................