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The Willyama Complex Setting the scene. 3 main c. 1820 Ma cratons Separated by central Australian orogens.

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Presentation on theme: "The Willyama Complex Setting the scene. 3 main c. 1820 Ma cratons Separated by central Australian orogens."— Presentation transcript:

1 The Willyama Complex Setting the scene

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3 3 main c Ma cratons Separated by central Australian orogens

4 Curnamona Province Palaeoproterozoic metamorphic basement Palaeoproterozoic metamorphic basement Adelaidean sedimentary rocks Adelaidean sedimentary rocks Mesozoic & Cenozoic Mesozoic & Cenozoic

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6 Willyama Complex Focus of an enormous amount of work Ag-Pb-Zn orebody Focus of an enormous amount of work Ag-Pb-Zn orebody Greenschist to granulite facies inliers -fault contact or unconformably overlain by Adelaidean rocks Greenschist to granulite facies inliers -fault contact or unconformably overlain by Adelaidean rocks Metasediments, orthogneiss, granite and amphibolite bodies Metasediments, orthogneiss, granite and amphibolite bodies All multiply deformed All multiply deformed

7 Basement rocks Detailed mapping revealed a stratigraphy within the Willyama Complex metaseds Detailed mapping revealed a stratigraphy within the Willyama Complex metaseds Can see sedimentary features preserved through effects of metamorphism - give way up features - use marker horizons Can see sedimentary features preserved through effects of metamorphism - give way up features - use marker horizons Need to establish timing and nature of rock bodies - sedimentary or igneous? Oldest rocks Ma Oldest rocks Ma Deformed and metamorphosed at c Ma Deformed and metamorphosed at c Ma

8 General progression Upper units - turbidites and other clastic sediments Upper units - turbidites and other clastic sediments chemical sediments Quartzofeldspathic gneiss with BIF lower units of composite gneiss (migmatite, schist)

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10 Multiple deformation events See effects of 2 or three regionally penetrative deformation events See effects of 2 or three regionally penetrative deformation events Early, bedding parallel foliation deformed by folds with a steeply-dipping axial plane Early, bedding parallel foliation deformed by folds with a steeply-dipping axial plane Retrograde shear zones - D3 Retrograde shear zones - D3 Then effects of another two vents that deformed the Adelaidean series Then effects of another two vents that deformed the Adelaidean series

11 Metamorphic grade Greenschist to granulite facies means overall block tilt Greenschist to granulite facies means overall block tilt Weekeroo - and-st-g-bi-mu q schists honest amphibolite facies conditions Weekeroo - and-st-g-bi-mu q schists honest amphibolite facies conditions Peak conditions early Peak conditions early S1, S2 cut by RSZ S1, S2 cut by RSZ And -> sill -> ky And -> sill -> ky

12 Adelaidean Series of Neoproterozoic to Cambrian basins throughout Australia Series of Neoproterozoic to Cambrian basins throughout Australia Willyama Complex acted as basement and source - see distinctive cobbles in the Adelaidean rocks Willyama Complex acted as basement and source - see distinctive cobbles in the Adelaidean rocks Quartzites±magnetite, dolomites, siltstones are the main lithologies Quartzites±magnetite, dolomites, siltstones are the main lithologies

13 series 5 main lithostratigraphic units 5 main lithostratigraphic units Hawker Group - Cambrian limestone and shale Hawker Group - Cambrian limestone and shale Wilpena Group- shale, silstone,sandstone Wilpena Group- shale, silstone,sandstone Umberatana Group- massive tillites, sandstone and arkoses; laminated silts, shales, carbonates; marine glacials, red sandstone and siltstone Umberatana Group- massive tillites, sandstone and arkoses; laminated silts, shales, carbonates; marine glacials, red sandstone and siltstone Burra Group - basal sandstone - conglomerate passes into argillite-carbonate sequence Burra Group - basal sandstone - conglomerate passes into argillite-carbonate sequence Callana Beds - volcanics, conglomerates, limestone and sandstone unconformable on Mt Painter Callana Beds - volcanics, conglomerates, limestone and sandstone unconformable on Mt Painter

14 Mesozoic and Tertiary Mesozoic - eastern Australia flooded by shallow seas - GAB and dinosaur fossils Mesozoic - eastern Australia flooded by shallow seas - GAB and dinosaur fossils Tertiary - developed laterites, break- aways, opals Tertiary - developed laterites, break- aways, opals

15 And the job to do Information Research Process Define the task Define the task Locate the information Locate the information Selection - what information is relevant to the defining stage Selection - what information is relevant to the defining stage Organizing - how to use the information Organizing - how to use the information Presentation - how to communicate the information to the target audience Presentation - how to communicate the information to the target audience Assessing/reflection - how well did I answer the question; what did I learn Assessing/reflection - how well did I answer the question; what did I learn

16 20 minute task Group 1&2 Flow diagram to identify igneous rocks Group min review - 2 good points, 2 ways to improve Group 1&2 Flow diagram to identify igneous rocks Group min review - 2 good points, 2 ways to improve Group 4 & 5 - sedimentary (Group 6) Group 4 & 5 - sedimentary (Group 6) Group 7 &8 - metamorphic rocks (Group 9) Group 7 &8 - metamorphic rocks (Group 9)


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