Waratah and Luina Mapping Waratah and Luina Mapping

The project area includes the historic Magnet silver-lead deposit, the Cleveland copper-tin deposit, the Mt Bischoff tin deposit, numerous smaller mines and prospects and is a focus for current exploration. It also extends to remote and poorly known country in the upper Heazlewood River and upper Whyte River valleys.

This geologically complex region is a key area for understanding western Tasmanian geology. A probable Early Cambrian volcanosedimentary broken formation, the Luina Group, appears to have been obducted over the more siliceous, turbiditic Neoproterozoic Oonah Formation and Mt Bischoff inlier. The Luina Group encloses the Heazlewood River, Whyte River and Magnet mafic-ultramafic complexes; the latter two are being mapped in detail for the first time. Much of the mineralisation is related to Devonian granite, which new gravity data suggests may extend, at shallow depth, further north than previously thought. The new fieldwork has also identified reactive carbonate horizons in the Oonah Formation and Luina Group.

Project outline:

Fieldwork by two geologists commenced in December 2012, and due to climate, terrain and vegetation has been largely restricted to summer and early autumn, over two field seasons. Some new track-cutting, clearing of existing tracks, and remote area walk-in field camps have been required. Mapping was assisted by airborne magnetic and radiometrics and a newly commissioned LIDAR survey.

The existing Luina 1:25,000 map sheet will be revised and the Waratah sheet published in 2014/15. Several hundred rock samples have been collected for petrography and geochemistry to complement the mapping. A specific sub-project will define the geochemical characteristics of the Luina Group and compare it to Early Cambrian rock units elsewhere in Tasmania (such as the Crimson Creek Formation to the south), to help resolve some long debated stratigraphic problems. U-Pb ICPMS detrital zircon age dating work has been completed for the key sedimentary units at Waratah in order to characterise the provenance of obducted sequences.