Announcement • Jul 28
Inca Minerals Limited Announces Completion of Maiden Australian Drill Program at the Mount Lamb NE Prospect
Inca Minerals Limited announced that a review of drill-hole FW220010, completed at the Mount Lamb NE prospect as part of its maiden reconnaissance drilling program at the Frewena Group Project in the Northern Territory, is now complete. FW220010 was drilled to a total depth of 1,060.4m, comprising a Reverse Circulation (RC) pre-collar of 120.7m and a diamond tail of 939.7m. FW220010 was drilled as an addition to the 2022 program to investigate a gravity anomaly beneath the peak of Mount Lamb that occurs 2.2km WNW of Inca's encouraging drill-holes, FW220007 and FW220009, which intersected zoned haematite and magnetite IOCG-style alteration with visual observations of copper, lead and zinc sulphides. A thick sequence of variably altered, veined and silicified intrusives was intersected in FW220010 from 189m to the end-of-hole (EOH), with these being the first intrusive rocks encountered at the Mount Lamb prospect. Low levels (<1% to 1%) of pyrite, pyrrhotite, chalcopyrite and galena are noted to occur as both disseminations in host rocks and vein-hosted. The RC portion of FW220010 penetrated into Georgina Basin sedimentary units with the switch to diamond coring occurring above the top of the Helen Springs Volcanics. Two metre composite RC samples will be submitted for multi-element analysis. FW220010, an addition to the 2022 reconnaissance drill program, was designed to test a strong gravity anomaly that occurs beneath the peak of Mount Lamb, which is partly offset from the >15km long Mount Lamb magnetic-gravity-conductive trend. The hole was collared approximately 2.2km WNW of Inca's FW220007 and FW220009, and 2.2km north of the government drill-hole, NDIBK04. The gravity anomaly targeted by FW220010 lies adjacent to the large gravity anomaly that was tested by FW220007 and FW220009, where thick intervals of IOCG-style haematite and magnetic alteration were intersected along with visual observations of low levels of copper, lead and zinc sulphides, as announced previously on 6 June and 14 July 2022. Unlike the area targeted by FW220007 and FW220009, the FW220010 target presents much weaker magnetism, with this geophysical signature difference warranting testing during the reconnaissance phase program. The hole was collared close to silica- and iron-rich rock chips with lowly elevated geochemistry, as reported in the ASX announcement dated 24 February 2020, that are thought to have been formed by karst collapse of the limestone-rich Georgina Basin Sediments. The top of the gravity feature intersected by FW220010 is estimated to lie at approximately 550m down-hole depth with a higher tenor core estimated between c. 800-900m down-hole depth. The unconformity between the Georgina Basin sediments and the Helen Springs Volcanics was intersected at 153m and the lower unconformity between the volcanics and basement rocks was intersected at 189m. Notably, at 36m down-hole width, this was the thinnest interval of Helen Springs Volcanics drilled during the 2022 program. As announced 14 July 2022, a thick sequence of altered and silicified, porphyritic intrusive rocks were intersected in FW220010 beneath the Helen Springs Volcanics, with these being the first recorded intrusive rocks at the Mount Lamb prospect. The intrusive composition transitioned downhole from granite to granodiorite, to diorite, to a fine-grained mafic unit, and finally back to diorite by EOH. Broad correlation between this compositional sequence and the gravity anomaly suggests that the gravity feature tested by FW220010 relates to the host rock mineralogy, whereby increasingly mafic lithologies have higher density than more felsic units. Hydrothermal alteration and veining were observed throughout much of FW220010 with widespread silica, chlorite-epidote-sericite and garnet alteration of the intrusive units, as well as lesser degrees of haematite, carbonate, potassium feldspar (kspar) and biotite. Low levels of sulphides including pyrite from trace to locally elevated levels, rare to locally trace chalcopyrite, and rare pyrrhotite and galena were observed throughout the hole as disseminations within the intrusive units and as vein-hosted occurrences. Both disseminations and vein-hosted sulphides occur variably at low levels over large intervals of FW220010. The completion of FW220010 marks the conclusion of Inca's 2022 Frewena reconnaissance drill program with the program a marked success, having confirmed the IOCG (and lesser SEDEX) potential of Inca's land-holding at the four prospects tested so far, being Mount Lamb NE, Mount Lamb SW, Jumping Spider and Roadhouse. The intersection of a distinctly different style of rocks in FW220010 compared with all other holes drilled at Mount Lamb NE and SW not only demonstrates the high geological variety along the prospect trend, but also confirms occurrence of an igneous body in the centre of Mount Lamb, which is confirming its credentials as one of the priority prospects within the entire East Tennant region. The occurrence of magmatic rocks especially those showing widespread alteration, silicification and veining with low levels of metallic sulphides, proximal to thick intervals of zoned haematite and magnetite IOCG-style alteration mimics the schematic magma-derived and surface/basin-derived IOCG models shown in Figure 5 (Barton et al, 2004). It is possible, though not conclusively proved, that the igneous sequence intercepted by FW220010 may relate, directly or indirectly, to the large-scale IOCG-style alteration system at Mount Lamb, potentially being a source of heat, fluids and metals. While the Company notes that visual sulphide estimates undertaken during preliminary core inspection should not be considered a substitute for laboratory analysis, observation of low level (<1%-1%) copper, lead and zinc sulphides occurring in association with strong IOCG-style alteration is a standout success. The occurrence of copper +/- zinc-lead sulphides in all eight holes is a significant result for Inca given the frontier nature of the East Tennant region and that drilling has tested blind, conceptual geophysical targets these targets are no longer conceptual with further exploration strongly warranted. The Company will now focus its attention on completing a detailed study of drill core and expediting core cutting for dispatch of samples for assaying, with current laboratory turnaround times of 8-12 weeks from sample dispatch. As part of Inca's staged, systematic, and results-driven exploration program, the Company intends to carry out a thorough review and interpretation of data acquired at Frewena to determine the best next steps to advance exploration and discovery at the Project.