The Meandu Creek Bentonite, Queensland

摘要: Remnant ash particles, vitric lapilli and pumice fragments established that the economic clay deposit at Meandu Creek was formed by devitrification alteration of pyroclastic material. The assemblage trace elements niobium, zirconium yttrium suggested parent more akin in composition to alkali‐acid volcanic rocks than basaltic lavas blanketed surrounding highlands.Variations composition, pre‐depositional diagenetic history were responsible for subdivision into three horizons characterised different minerals.Hydrated halloysite, allophane gibbsite basal horizon subaerial weathering ash, subsequently deposited preserved an aqueous environment. Montmorillonite α‐cristobalite central produced place under conditions impeded drainage. Kaolinite upper montmorillonite a freely leached