Tesorito Gold Porphyry Drilling Delivers 582m @ 0.94g/t Gold
Los Cerros Limited (ASX: LCL) has drilled an outstanding intercept of 460.9m @ 1.11g/t Au from surface within a broader intercept of 582.3 @ 0.94g/t Au from surface in Tesorito South diamond drill hole TS-DH16, within the 100% owned Quinchia Gold Project in Colombia.
Management says the result is significantly better than the best drill intercepts to date, and elevated Tesorito South to a globally significant recent gold porphyry discovery.
Porphyry associated mineralisation is now demonstrated to continue below and south-west of a fault structure at 356m downhole, introducing opportunity for more deep mineralisation in all directions.
Whilst gold mineralisation started from surface, the drill core reveals higher grade mineralisation of the target porphyry suite from 90m down hole as indicated by increased porphyry signatures such as vein density and including: 254m @ 1.61g/t Au from 92m which includes an even higher grade interval of 116m @ 2.32g/t Au and 0.12% Cu from 132m.
Within this interval is a 34m zone grading 3.03g/t Au and 0.12% Cu, the highest grade porphyry style mineralisation intersected at Tesorito South to date. The drill hole continued through the porphyry suite of mineralised andesites, magmatic breccias and diorites down to 356m where it crossed a fault, as expected.
TS-DH16 was drilled in the same fence line as TS-DH07, which was drilled in 20172 and generated 253m @ 1.01g/t Au from surface, with a higher grade zone of 64m @ 1.67g/t Au from 144m. The higher grade zone of TS-DH16 (254m @ 1.61g/t Au) is thought to be a much thicker extension of the high grade zone encountered in TS-DH07.
In previous drilling, the above-mentioned fault marked the end of the zone of interest, with unmineralised units encountered to the west of the fault at depth. However, mineralisation in TS-DH16 continued for another 226m below and south-west of the fault (to 582.3m downhole), albeit at lower average grade, but with some zones of interest such as:
- 20.4m @ 0.51g/t Au from 380m in porphyritic andesite
- 13.7m @ 0.51g/t Au from 447.2m in porphyritic andesite
- 12.0m @ 0.51g/t Au from 510m in breccia contact with diorite
- 6.2m @ 0.52g/t Au from 554m in breccia
The 12m and 6.2m intervals are within a porphyry suite of magmatic breccias and porphyritic diorite over a 119.3m interval from 463m to 582.3m and show encouraging porphyry signatures and vein densit.
Managing Director, Jason Stirbinskis, said that at this stage it is inconclusive if the 119.3m interval represents the faulted extension of the Tesorito South porphyry suite or a separate porphyry suite.
He said these results at depth have greatly enhanced the potential for Tesorito to be further expanded to the south-west, and will require a more thorough assessment, including multi-element analysis, to better understand the relationship between this new porphyry suite and the Tesorito South porphyry.
Below 582.3m to EOH at 690m, the drill cut country rock andesites which carry low grade gold mineralisation to 629m.
“On a gram-metre basis TS-DH16 is the best hole ever recorded in the entire Quinchia district and has raised exciting questions about the potential scale of this gold system,” Mr Stirbinskis said.
“The near surface (first 411m of this hole) has expanded to the south-west the modelled gold envelopes described by the high grade intercepts reported in the TS-DH02, ’14, ’11, ’15 drill fence and mineralisation still remains open to the south west. Follow-up drilling will further explore this region of relatively sparse data.
“The company will offer further detail on interpretation of the porphyry suite intercepted below and south-west of the fault in coming weeks as we assimilate new drill data as it arrives.”
Assays remain pending for an additional four completed holes at Tesorito South (TS-DH17, 18, 20 and 21) all of which tested the lateral and depth extensions of the porphyry system. Tesorito South is developing into an exciting addition to the mid-Cauca porphyry belt which hosts many multi-million ounce gold porphyry discoveries.