Los Cerros Limited (ASX: LCL) announced that an exceptionally wide gold intercept was returned from the first diamond hole, TS-DH08 at the southern Tesorito anomaly within its Quinchia gold project in Colombia.
The company reported that TS-DH08 returned 230m @ 1.0g/t gold from surface (uncut) including 18m @ 2.0g/t Au from surface including 6m @ 4.1g/t Au from 6m; and 116m @ 1.38 g/t Au from 114m including 74m @ 1.6g/t Au from 114m including 4m @ 3.18 g/t Au from 148, and 2m @ 9.58g/t Au from 176m within 6m @ 4.86 g/t Au from 174m.
With this new result, gold mineralisation exceeding 1g/t Au has been demonstrated by three separate diamond holes to exceed 230m downhole thickness, over an area of 300m x 250m, and remaining open in all directions.
Previously announced results include 384m @ 1.01g/t from 16m incl 29.3m @ 1.9g/t Au from 136.75m in TS-DH02; and 253.1m @ 1.01g/t Au from 2.9m incl 64m @ 1.67g/t Au from 144m in TS-DH07.
LCL said that the assays support interpretation of the cap of the porphyry core at the southern anomaly starting from around 100-150m below surface.
The company reported that the significant new development is the presence of primary bornite, banded veining, and anomalous copper, indications of increased potential for copper mineralisation to develop at depth. LCL said that there is emerging evidence of scale and continuity of both near surface high grade epithermal and deeper porphyry style mineralisation.
Los Cerros said that the current Hole TS-DH09 exploring untested northern Tesorito anomaly is currently at 329m depth. The company said that the drill rig will then be moved back to the southern anomaly to further develop epithermal and porphyry strike and depth extensions.
The Quinchia Portfolio is located in central west Colombia, 100km south of Medellin, in the department of Risaralda.
The Quinchia Portfolio is located within the same structural trend (Mid-Cauca porphyry gold belt) as the Marmato Gold Mine and the La Colosa gold project which hosts gold resources of 14 million and 29 million ounces respectively.
The Quinchia Portfolio covers 10,542Ha consisting of granted titles and applications and includes deposits and targets such as Miraflores, Chuscal, Dosquebradas, and Tesorito. Approximately 40,000m of drilling has occurred at Quinchia and includes an established 877koz Resource and 457koz Reserve at Miraflores.
At the Chuscal target, a maiden drilling program was completed January 2020, and drilling is scheduled to re-commence in October 2020.
There are several other targets within the region including the Dosquebradas deposit which has an Inferred Resource of 459,000 ounces grading 0.71g/t Au8.
Drilling at Tesorito
The company is currently drilling Tesorito near surface porphyry which is located 3km of Miraflores target.
LCL had previously reported results from the drill holes TS-DH02 and TS-DH07, which included 384m @ 1.01g/t from 16m incl 29.3m @ 1.9g/t Au from 136.75m in TS-DH02; and 253.1m @ 1.01g/t Au from 2.9m incl 64m @ 1.67g/t Au from 144m in TS-DH07.
The company has now announced the results from the Tesorito hole TS-DH08, the first hole of LCL’s current expanded drilling program. Earlier drill holes TS-DH02 and TS-DH07 are located on either side of the recently completed hole.
High-grade results from TS-DH08
LCL announced that the results from TC-DH08 further demonstrate the potential for both deeper extensions of gold-copper porphyry and near surface high grade epithermal gold.
Los Cerros reported that hole TS-DH08 entered mineralisation immediately at surface with 18m @ 2.0g/t Au including an interval of 6m @ 4.1g/t Au from 6m correlating to a mapped epithermal vein.
The company said that porphyry mineralisation with epithermal vein overprinting continued for 230m down hole before altered country rock was encountered from 277m to end of hole at 325.5m.
LCL announced that the drill hole is interpreted to have entered the cupola (porphyry cap) of the potassic core at 110m as evidenced by banded veining, UST4 textures and the presence of primary bornite, a copper mineral classically associated with porphyry gold-copper deposits, all suggesting strong assay results in this zone.
This was subsequently validated with intercepts of 4m @ 3.18g/t Au from 148m and 6m @ 4.8g/t Au from 174m including 2m @ 9.58g/t Au from 176m, all within 116m @ 1.38g/t Au from 114m. The potassic altered core is interpreted to be the cause of the magnetic anomaly.
More than 1g/t Au from 3 holes
LCL noted that down hole thicknesses exceeding 230m of gold mineralisation of 1g/t or above, essentially from surface, have now been described in three drill holes over an area of 300m x 250m.
The company said that whilst a general NNE trend to the mineralised porphyry is likely, the 3D geometry of the porphyry system is yet to be determined. The company said that the next Tesorito drill holes (after the current TS-DH09) will focus on determining its strike, width and depth continuity.
Latest updates and next steps
Los Cerros reported that the drill rig is currently drilling hole TS-DH09 to test the northern Tesorito target located 200m north of hole TS-DH08, where a previously undrilled zone of anomalous gold and molybdenum in soils occurs concurrent with a magnetic high.
The company said that the rig will then return to the southern target to further test extensions to the higher-grade porphyry core both laterally and at depth.
LCL announced that additional drilling is required to systematically test the nature and extent of both the higher-grade mineralization that appears to be associated with EW trending sheeted veins, as well as the broader intercepts of NNE-trending moderate-grades related to the porphyry-style mineralization.
The company said that the objective of the proposed program is to test continuity of wide high grade intersections in holes TS-DH02 and TS-DH07 to potentially guide resource targeted drilling in a second phase drilling program, and to test the northern gold-molybdenum soil geochemistry anomaly.
Los Cerros’ Managing Director Jason Stirbinskis said: “This is a highly encouraging start to the drill campaign as it not only provides a sense of near-surface porphyry mineralised volume given similar results of nearby holes, but has also hinted to further potential at depth.
Primary bornite is a copper rich mineral species, its presence, based on visual logs, correlates to elevated copper in assays and has raised the possibility of more copper occurrences as we chase depth extensions in subsequent drilling.
In this regard, it is interesting to note that TS-DH02 recorded an intersection near end of hole, of 35m grading 0.19% Cu from 365.5m downhole including 0.7m at 2.63% Cu from 390.8m downhole depth3, some 90m deeper than the depth of TS-DH08. Similarly, we cannot rule out the presence of another porphyry pulse enriched in copper below our current drilling.
The 18m intersection grading 2.0g/t Au from surface including 6m @ 4.1g/t Au also provides encouragement to further pursue the east-west trending epithermal veins for high grade gold resources to supplement existing resources and reserves at the nearby Miraflores deposit.
The presence of banded veins, UST textures and primary bornite are typical of the core of many porphyry copper gold deposits including the multi-million ounce Nuevo Chaquiro5 deposit located 51km to our north, where both our Senior Geologists have worked”.