공시 • Feb 10
Astro Resources NL Announces Assay Results and Downhole Geophysical Surveys of the Georgina Project in the Northern Territory
Astro Resources NL announced that latest exploration results have further upgraded the prospectivity of its 80%-owned Georgina IOCG Project in the Northern Territory, with assay results returned from diamond drilling at the Banks and Leichhardt West prospects, and downhole geophysical surveying completed. Assay results have been received for two diamond drill holes completed by previous owner, Greenvale Energy, at the Banks and Leichhardt West prospects in mid-2022. Visual results reported by GRV indicated that both holes intersected trace to minor chalcopyrite (copper mineral) mineralisation in prospective altered host-rocks. Laboratory assay results have now confirmed these visual observations of copper, as well as revealing anomalous levels of other elements commonly associated with IOCG deposits (e.g. bismuth which is commonly associated with Tennant Creek style IOCG deposits). Results include: Leichhardt West hole KNXLW001RDD intersected 0.22% Cu from 536.05-536.3m associated with elevated bismuth and silver. Leichhardt West hole KNXLW001RDD intersected 0.15% Cu from 600-600.8m (end of hole) associated with elevated bismuth and silver. General increased anomalism in copper, bismuth and silver observed in spatial association with modelled 3D gravity and magnetic anomalies. Banks hole KNXBA001RDD intersected elevated copper, bismuth and silver from 433-440m. The results are considered highly significant as they suggest the drilling may have intersected rocks peripheral to an IOCG system, indicate a hydrothermal component to the Banks and Leichhardt West prospects, and illustrate compelling similarity to Tennant Creek IOCG deposits. Highly-regarded contractor, Gap Geophysics, was engaged to conduct a downhole survey campaign at Astro's highly prospective Central Tenement, comprising both a triaxial magnetic survey and EM. All three holes drilled in the Central Tenement area were surveyed as part of the campaign, with the Banks hole surveyed to 445m depth, Leichhardt West hole to 600m and Leichhardt East hole to 365m. The main objective of the survey was to characterise the magnetic characteristics of the holes, as magnetic surveying is one of the principal tools utilised in IOCG exploration. Magnetics are important for several reasons, including that remanent magnetism (a permanent magnetic field direction recorded in magnetic minerals) is observed in some IOCG deposits, such as at Tennant Creek. Furthermore, magnetic characteristics of overlying `cover' rock types (such as the Helen Springs Volcanics, observed in all holes drilled to date at Georgina), may have a `masking' or influencing effect on the response of underlying host rocks in surface geophysical data. To complement data collected from the downhole surveys, a selection of drill samples displaying magnetic properties will be sent to CSIRO for magnetic remanence testwork. In addition to triaxial magnetic surveying, downhole EM was also conducted. Downhole EM is designed to test for off-hole conductors, which may be the result of sulphide mineralisation. Downhole magnetic responses were observed in basement rocks of all three holes, with downhole EM data yet to be finalised and interpreted. Following completion of the Leichhardt East drillhole KNXLE001RDD in December 2022, work has been prioritised on mark-up and processing of drill core. As announced previously, this hole intersected anomalous copper mineralisation as bornite and chalcopyrite, ironstones with sulphide veining, and widespread chlorite and hematite IOCG-style alteration. Since completion, the hole has undergone detailed geological logging, with bulk density and magnetic susceptibility measurements taken. The drill core will be cut, sampled and dispatched for assay in the current month. The Leichhardt East drilling is supported by an NT Government grant, following a successful application under Round 15 of the Resourcing the Territory Geophysics and Drilling Collaborations Program. As part of grant funding conditions, half-core must be supplied to the NT Geological Survey. The remaining half-core will be sampled for magnetic remanence testing at CSIRO, petrographical thin section preparation for microscopy and conventional multi-element assay including fire assay for gold. Once the Company has received final data from the surveys and magnetic remanence testwork, Leichhardt East assays and petrography, a holistic review of the whole Central Tenement area will be conducted. This will include a broader review of elevated magnetic and gravity responses interpreted to be prospective for IOCG style mineralisation, supported by the rock types, alteration and geochemistry results received for drill holes completed to date.