The Tennant Creek mineral field in central Northern Territory has been one of the largest producers of gold and copper in the Northern Territory. The Rover mineral field, located ~80 km to the southwest of Tennant Creek and covered by up to several hundred metres of the Wiso Basin, is generally interpreted as an analogue of the Tennant Creek mineral field. This report reviews geology and mineral deposits in both mineral fields to determine how appropriate this analogy is and identify ares of future research to reduce exploration uncertainty and develop new concepts for exploration in the Rover (and Tennant Creek) mineral fields.
The Tennant Creek field is hosted by the ~1860 Ma turbiditic Warramunga Formation, which contains only minor volcaniclastic rocks. In contrast, although much of the lithologies in the Rover field appear to be turbiditic sedimentary rocks similar to the Warramuga Formation, intermediate to felsic volcanic and volcaniclastic rocks appear to be an important component of the Rover field. SHRIMP zircon U-Pb analyses of these rocks indicate emplacement ages of 1855-1850 Ma, younger than the Warramunga Formation. These volcanic rocks are within error of granites and quartz-feldspar porphyry sills and dikes of the Tennant Creek Supersuite that intrude both the Tennant Creek and Rover fields. The volcanic rocks appear to be slighly older than the ~1840 Ma Ooradidgee Group that overlies the Warramunga Formation further to the north and east.
The copper-gold mineral deposits in the Rover field (e.g. Rover 1 and Explorer 142) appear to be analogous to deposits in the Tennant Creek field, although one of the more significant deposits, Explorer 108, differs substantially. This deposit is dominated by zinc and lead and is hosted by a brecciated dolomite alteration zone, both of which are not common in the Tennant Creek field. The association of the deposit with magnetite, talc and chlorite is similar to the Tennant Creek field, and the lead isotopic compositions of the nearby Curiosity deposit are similar to some deposits in the Tennant Creek field. Hence, these two deposits are likely to be part of the Tennant Creek family and better understanding of Explorer 108 may contribute to new exploration plays in Tennant Creek.
Based on these preliminary results, a joint Northern Territory Geological Survey-Geoscience Australia research program, in collaboration with Castile Resources, in the Rover field is proposed to: (1) better refine the timing of sedimentation and magmatism in the Rover and Tennant Creek fields through round-robin SHRIMP U-Pb geochronology, (2) document the relative and absolute timing of structural elements in the Rover field, (3) establish the absolute and relative ages of mineralisation, and (4) document the geology and mineralisation characteristics (including alteration, paragenesis, isotopes, etc) of the Rover 1 and Explorer 108 deposits.
Presented at the Annual Geoscience Exploration Seminar (AGES) 2020
