Geochemical characteristics and structural setting of lithium–caesium–tantalum pegmatites of the Dorchap Dyke Swarm, northeast Victoria, Australia

The Dorchap Dyke Swarm hosts the first recorded occurrence of lithium–caesium–tantalum (LCT) pegmatites in Victoria, Australia. Syn-orogenic emplacement pegmatite dykes occurred along a northwest-trending shear system during Benambran Orogeny. Pegmatites are derived from fractionated melt associated with Mount Wills Granite, which is an S-type, peraluminous granite originating supracrustal melting Ordovician sedimentary sequences. A distinct, eastward-oriented fractionation trend across has highlighted 20 × 8 km highly zone northeastern Range, includes spodumene- and petalite-bearing pegmatites. distinct pattern elemental enrichment (P > Cs Be Nb ≥ Ta Li Sn) observed strongly Swarm. Subsequent metasomatic fluid movements hydrothermal overprinting have resulted redistribution mobile elements either as alteration species or some instances development exomorphic halos. Additionally, regional overprint, likely subsequent metamorphism primary petalite to spodumene plus quartz, cookeite. Bulk rock geochemical data suggest syn-collisional setting for dyke intrusion, consistent inferred tectonic central Lachlan Fold Belt at time emplacement. Pegmatite locally contain overprinted structural foliation, deformed metasediments may indicate that was syngenetic folding compression surrounding Omeo Metamorphic Complex immediately following Bindian Orogeny.KEY POINTSDorchap Li–Cs–Ta Australia.Pegmatites were emplaced synchronous Orogeny.Dorchap geochemically correlated Granite.