Exploration company Meteoric Resources (ASX: MEI) has commenced a drilling campaign at the Juruena copper-gold porphyry target within Brazil’s Alta Floresta Belt.
Comprising three drill holes (each averaging a depth of 1,200m) for a total 3,600m, the campaign will test a large chargeability anomaly defined by a deep induced polarisation (IP) survey conducted last year.
The drill target is believed to lie beneath a historic shallow IP anomaly, major gold artisanal workings, a giant soil copper-molybdenum-gold anomaly, and fertile porphyry intrusive rocks.
Historic drill holes into the shallow anomaly intersected strong hydrothermal alteration, typical porphyry-like veins, porphyry intrusive rocks and highly anomalous copper-gold values, confirming the potential for Juruena to host a giant porphyry system at depth.
Previous geology, geochemistry, and geophysical data has demonstrated the discovery could be part of a large, well-preserved magmatic-hydrothermal system, encompassing several gold and base-metal-related deposits.
It is believed to host outcropping, high-grade, low-to-intermediate sulphidation deposits and a potential copper-gold porphyry source existing 500m below the surface.
Definitive drill target
Meteoric managing director Dr Andrew Tunks said last year’s deep IP survey provided a definitive drill target for the current campaign.
“Our geology team has drawn together many lines of geological evidence to interpret a significant copper-gold porphyry system at depth which we believe is related to the outcropping high-grade epithermal gold deposits at Juruena,” he said.
“The first of three holes has targeted the central portion of the IP chargeability anomaly and the Juruena Fault [and] the full program is expected to take at least three months to complete.”
Drilling at Juruena has largely concentrated on epithermal gold targets at Dona Maria, Querosene and Crentes.
The high-grade Dona Maria and Querosene are believed to have a structure, hydrothermal alteration and metal association typical of an intermediate sulphidation style of deposit with gold silver and tellurium content.
Crentes exhibits a different metal association and structural characteristic where the gold is closely related to copper mineralisation, molybdenum values are significant, and the major host rock is a hydrothermal breccia.
The project’s Uiliam-Mauro prospects have not traditionally been a long-term focus for companies exploring Juruena, however a shallow IP survey carried out by US-based Lago Dourado Minerals over the greater area has shown an IP chargeability anomaly centred on the target.
The anomaly was coincident with a large-zoned copper-gold-molybdenum soil geochemistry anomaly and although the results were not economic, they were considered interesting due to the close association between anomalous copper values with porphyry intrusive rocks and alteration.