Assays from a mapping and sampling program conducted in the Kyrgyz Republic by White Cliff Minerals (ASX: WCN) have identified new outcropping gold and copper mineralisation up to four kilometres east of the company’s high-grade Aucu project.
The mapping showed multiple new shear zones while the rock samples identified significant gold and copper mineralisation, with assays of up to 6.7 grams per tonne gold and 7.8% copper.
The mineralisation is believed to be associated with porphyry and overlying sandstones, occurring within shear zones in both lithologies and as a layer of thermally-altered, magnetite-rich skarn sandwiched between the sandstone and porphyry.
White Cliff managing director Todd Hibberd said the results confirm the scale of Aucu’s copper-gold system extends west-to-east, but is still untested to the south.
“The current geological interpretation is that the whole area is underlain by a larger mineralised system with an upper zone of structurally-controlled epithermal gold mineralisation within a broad copper porphyry alteration zone,” he said.
“[We know the] gold mineralisation now extends at least 8km from west to east and is currently open to the west, south and north and there is the possibility that further mineralised porphyries exist to the east.”
White Cliff’s mapping and rock sampling program was based on the results of an extensive soil geochemistry survey completed in December, which delineated the core of Aucu’s 1km-wide copper porphyry system.
The survey identified copper-magnetite, skarn-style mineralisation along the contact of the mineralised porphyry and the overlying limestone, believed to be generated by the interaction of hot mineralised fluids with the colder limestone.
Grades recorded in the soil samples were up to 0.7% copper.
In contrast, the survey found gold mineralisation had formed up to 4km from the core of the system at lower temperatures as the mineralised fluids flowed out and away from the central porphyry.
The mineralisation was reported to have developed strongly within the sandstone due to its brittle and layered nature.
The results also showed a strong association between gold mineralisation within epithermal veins and the distribution of anomalous arsenic results in the soil samples.
White Cliff holds a 90% interest in the Aucu project, which is located over 57 square kilometres of land approximately 350km west-southwest of the capital city of Bishkek.
Drilling at Aucu from 2014 to 2016 defined a gold deposit containing the current inferred resource of 2.95 million tonnes at 5.1g/t gold for 484,000 ounces of gold, and 700,000t at 0.51% copper for 4,000t of copper.
Drilling also defined a significant copper deposit at surface consisting of 16.5Mt at 0.36% copper for 60,000t of copper.
Extensive mineralisation is known to occur around both deposits, demonstrating potential for the project to be “significantly expanded” over time.
At midday, shares in White Cliff Minerals were trading 14.29% higher at $0.016.