The PACE Initiative drilling collaboration proposal DPY3-06 was formulated to drill test three gravity - (magnetic) anomalies seen along the buried Benagerie Ridge area of the Curnamona Province of South Australia, on EL 3019 (Quinyambie Station)...
The PACE Initiative drilling collaboration proposal DPY3-06 was formulated to drill test three gravity - (magnetic) anomalies seen along the buried Benagerie Ridge area of the Curnamona Province of South Australia, on EL 3019 (Quinyambie Station) which is situated about 130 km north-northwest of Broken Hill. The targeted mineralisation is of the iron oxide - associated copper-gold (IOCG) style, possibly occurring in association with inferred Mesoproterozoic basement volcanic and intrusive acid igneous rocks. One vertical rotary mud/diamond cored drillhole was completed on each of the three targeted anomalies, for an aggregate drill penetration of 1128.2 m, including 633.2 m of coring. In each case, the depth of cover proved to be less than expected (by around 75 m on average), and the basement lithology encountered is a massive, reddened quartz-feldspar porphyritic rhyolite or green/grey dacite that does not contain significant veining or brecciation. Only very minor fracture-filling thin veins reflecting weak quartz - sericite - carbonate - pyrite alteration were seen in the drill cores. Assaying of 2 m drillhole samples for a suite of metallic elements returned very low values throughout, with a maximum gold value of 78 ppb in BRD003 corresponding with a 4 mm wide vein running subparallel to the core axis below 334.8 m depth. Specific gravity measurements that were done on basement rhyolite cores from 2 of the PACE drillholes averaged 2.60 g/cubic cm, a value which is similar to results obtained from other previously drilled nearby holes. Simple gravity modelling was performed using actual depths to basement, specific gravity values for cover sediments (2.0) and basement (2.60), plus a range of plausible ridge-flank slope angles, and the models indicated that the observed gravity anomalies of 1-2 mGal may be due solely to basement topographic effects. The lack of proximal indicators of mineralisation in the PACE hole basement drill cores supports this hypothesis at this stage.
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