Final Report Stratigraphic Drilling on the Redbank Trend 2021 NTGS Geophysics and Drilling Collaboration Program Redbank Project

Abstract

The source of high-grade copper mineralisation in breccia pipes at Redbank has remained a mystery after 100 years of prospecting, exploration, and small-scale mining. Several exploration models have been proposed for the source of mineralisation beneath the known breccia pipes that commonly invoke an underlying, deep seated magmatic source driving mineralised fluids to the surface. No source model has ever been systematically tested. With an eye to regional scale - and to lateral and vertical extent - Redbank has completed magneto-telluric (MT) and airborne EM surveys during 2021 with the aim of advancing discovery pathways. Redbank support a stratabound base metals exploration model to be tested at the Redbank Project. Potential exists at favourable lithologic and structural trap sites in near-surface proximity of breccia pipes through sub-horizontal fluid pathways. These accumulations may be tabular in nature, follow fold axes, or even exist in failed petroleum reservoirs at horizons (+250m) within the Wollogorang Formation or deeper units. Fluid movement may also be driven by lithostatic or hydrostatic pressure in the basin sediments. Such trap sites could potentially host significant accumulations of copper mineralisation that would support larger scale mining operations. Historical work has been comparatively limited given wide-spread breccia pipe occurrence and focused primarily on detecting or investigating localised breccia pipes - often over a relatively small area of tenure (ELR 94). Drilling has been similarly restrained and only very limited drilling completed in the 1970's actually tested depths greater than 250m. To date, deep drilling has not determined a base depth extent for these breccia pipes. In addition, very little is known about any deep magmatic source that may have driven mineralising fluids along structural or stratigraphic pathways within the southern McArthur Basin. In 2020, after 4 years of study and $100mil of taxpayer funds, Geoscience Australia - through Exploring For The Future funding - drew significant attention to the Redbank area's potential to host a Tier 1 mineral deposit. More recently, studies commissioned by CSIRO have shed new light on the oil and gas generative potential of the Tawallah Group in the Redbank district. As industry assimilates the significance and magnitude of these high-level studies, and both demand and commodity prices continue to rise, big miners are awakening to the renewed prospectivity of this region. This report provides a summary of the oriented stratigraphic diamond drill hole completed in late 2021 by Redbank Operations Pty Ltd on ELR 94 in the Wollogorang district of the southern McArthur Basin, Northern Territory of Australia. This drilling was partially funded by the Northern Territory Government DITT as part of the Resourcing the Territory / Geophysics and Drilling Collaborations Program (Round 14: 2021). The drill hole (identified as 21STRAT01) was positioned with the aid of combined surface geological mapping, historical drilling results and recent geophysical data. The objective for 21STRAT01 was to provide diamond core for stratigraphic profiling of the Gold Creek Volcanics, Wollogorang Formation, Settlement Creek Dolerite, and the Aquarium Formation. Additionally, 21STRAT01 was intended to provide fresh core samples for: the application of modern multi-element geochemical techniques, hydrocarbon and physical rock studies; to increase knowledge of the deeper host Paleoproterozoic-aged stratigraphy of the Tawallah Group at Redbank and in the south-east McArthur Basin where very little modern information exists; to increase understanding of the timing and controls on the formation of sedimentary-hosted metal systems. Given its stratigraphic purpose and the other outcomes required of this drill hole, a critical design element was to site 21STRAT01 in a location unlikely to intersect mineralisation or associated alteration. 21STRAT01 commenced on 26th August 2021 and reached its final depth of 700.05m on October 24th, 2021 (HQ gauge core 0.0m - 496.25m and NQ2 gauge core 496.25m - 700.05m). All core was geologically logged photographed and cut at Redbank, with magnetic susceptibility, conductivity, velocity and XRF data also captured on site. A complete oriented half core set with metre marks was dispatched to the NTGS Core Library in Winnellie on 3rd December 2021.