Petrology of the halite-bearing Carribuddy Formation, Canning Basin, Western Australia

Abstract

Abstract The Carribuddy Formation [Upper Ordovician to (?) Lower Devonian] is halite-bearing, dolomitic, and partly red. The low bromine content of the halite accords with the absence of potassium salts in the study area, but the geochemistry is probably complex. The overlying Tandalgoo Red Beds [(?) Lower Devonian] are mainly sandstone, and represent a later influx of clastic material, some of which may have been deposited subaerially. The Carribuddy halite is colourless to red-brown. Coloration may have been caused by precipitation of ferric hydrate, a precursor of hematite, from percolating oxygenated waters which dissolved and reprecipitated the halite. Differences in bromine content between red-brown and colourless halite from the same cores suggest that much of the colourless halite was not dissolved, but the data are too sparse to be conclusive. The sequence of main authigenic minerals within the halite beds and veins seems to have been (i) halite, (ii) dolomite and anhydrite, (iii) quartz, (iv) hematite pigment and euhedra. Colour patterns in halite veins indicate that the vein minerals have not moved since their emplacement and pigmentation before the Middle Devonian. Some pigment in the red beds with the halite could have been transported to the basin, but most of it was probably formed in place by diagenesis.