Geophysics and Drilling Collaboration Final report for Gecko Deeps K44 Project ML 23969

Abstract

The drilling was partially funded by the Northern Territory Government under the CORE (Creating Opportunities for Resources Exploration) initiative and the Geophysics and Drilling Collaborations Program (Round 8, 2015-16). A single hole, GODD032, was drilled at Gecko K44 Deeps target for a total of 1,279 metres. Drilling was conducted between 8 - 30 July 2015. The hole intersected fine-grained siliclastic sequence of greenish to grey laminated siltstone and shale, massive sandstones and greywackes of the Warramunga Formation. Mineralized intermediate dikes (diorite?) are intersected from 968m - 998.2m (900m below surface). GODD032 intersected alteration associated with known mineralized ironstone in the TCMF. The most extensive alterations is chlorite-sericite-quartz with approx 500m thick surrounding the major fault. Away from the centre, the alteration grades to chlorite-sericite-quartz, chlorite-quartz to quartz-chlorite. Locally, interbedded sandstone and siltstone have been altered selectively to a chlorite-sericite assemblage on the coarser unit, and quartz-hematite assemblage (with purplish tint) in siltstone. Pervasive quartz-dolomite alteration was intersected at 1175m (10.1m thick) above the ironstone producing characteristic white to locally pink networks of dolomite veins and stringers. Mineralisation in GODD032 has been categorised into two zones: the Shallow Copper-rich zone and the Deep ironstone zone. The Shallow Copper-rich zone intersected multiple zones of sulfide-rich veins at shallow depth (~100m below surface). The copper mineralisation is associated with quartz-chalcopyrite veins analogous to the recently discovered Goanna mineralisation some 800m to the east. The deep ironstone zone occur in the footwall of a major fault. The ironstone intersected at 1191.5m (approx 1km below surface) comprises 4.2m of hematite-quartz-jasper, locally exhibiting colloform texture, and 2m of hematite-chlorite-quartz from 1228.3m. The ironstons zones however failed to return significant intersections. GODD032 is the deepest hole drilled in the TCMF to date (total drilled 1,279m, equivalent to 1.1 km vertical extent). Alteration and mineralisation at depth suggest that hydrothermal fluids passed through the rock, which could indicate a possible near-miss adjacent to Au-Cu mineralisation.