The spilite-keratophyre association of West Tasmania and the ore deposits at Mt. Lyell, Rosebery and Hercules ...

• Main Author: Solomon, M
• Format: Thesis
• Language: unknown
• Published: University Of Tasmania 2023
• Subjects: Hercules; King Island; Iceland
• Online Access: https://dx.doi.org/10.25959/23248049.v1; https://figshare.utas.edu.au/articles/thesis/The_spilite-keratophyre_association_of_West_Tasmania_and_the_ore_deposits_at_Mt_Lyell_Rosebery_and_Hercules/23248049/1

Western Tasmania was the site of geosynclinal sedimentation during the Cambrian and the Late Precambrian. In the Early Cambrian there was a marked change from Precambrian ( ?) deposition of sandstones, mudstones and dolomite to a typical synorogenic greywacke sedimentation that continued into the Upper Cambrian. This change was accompanied by extrusion of spilitic and keratophyric volcanics. The basic volcanics are best exposed on King Island and include pillow lavas, breccias called isolated-pillow, broken-pillow, and broken-flow breccias and also tuffs similar to palagonite tuffs in Iceland and \aquagene tuffs\" in British Columbia. The pillows (which develop by a combination of surface tension and gravitational effects) and also the finely globular tuffs indicate an aqueous environment. The spilites contain three principal types: (a) picrite ( b) tholeiitic and (c) augite-rich. They are generally low in titania and rich in alumina. Differentiation is characterised by iron enrichment but follows neither ...