On October 24, 2017, Angkor announced the results of its 2017 exploration program at Okalla.
Drilling commenced on July 2, 2017, on Angkor’s Banlung Tenement on which the two prospects, Okalla West and Okalla East, are located. The two prospects are approximately 7 kilometres apart. Both are hosted by intrusive rock complexes connected along a regional structural corridor. Phase 1 drilling was conducted to determine the structure and type of mineralization of the targets over a gold anomaly devoid of outcrop.
Highlights of these results include:
- 562.2m of drilling completed, with 439.2m at Okalla West and 123.0m at Okalla East.
- Drilling confirms the existence of gold veins in faults at Okalla West.
- Okalla West hole OKW17-003D returned 2.05 gpt Au (gold) and 4.55 gpt Ag (silver) over 1.65 metres at 45.35m.
- Okalla West hole OKW17-005D returned 6.17 gpt Au and 8.2 gpt Ag over 0.75m at 39.6m.
- Rocks within the intrusive complex at Okalla West show them to be alkaline in nature indicating that gold mineralization would likely be related to alkaline magmatism.
- Okalla East hole BL17-048D returned 0.88 gpt Au and 0.14% ppm Cu (copper) over 10.0m from 26.0m to 36.0m.
- Okalla East hole BL17-049D has one significant intercept from 32 to 37 metres. The 5m run returned a weighted average of 0.31 gpt Au with 0.25% Cu.
OKALLA WEST – Summary of 2017 Results
Angkor Gold’s modest Phase 1 drill program has proved the existence of gold veins in faults in the Okalla West intrusive complex. The Okalla West gold veins display multiple occurrences of vein development and gold mineralization that is fault controlled. Observations and results include:
- Veins in faults hosted by late monzonite intrusive phase.
- Sulphides including pyrite and chalcopyrite accompany gold in mineralized veins.
- Bismuth, tellurium, arsenic, lead and zinc elevated in gold intercepts.
- Vein banding and brecciation indicate more than one gold mineralizing pulse in vein formation.
At the Okalla West prospect, Angkor drilled nine holes totalling 439.2 metres as part of its Phase 1 drill program. The program contributed to the understanding of geology and structure, and demonstrated the existence of gold mineralized veins in faults in the Okalla West intrusive complex.
The drilling was designed to test surface gold anomalies from the pit and auger hole program completed earlier this year (see press release dated March 6, 2017). Drill holes OKW17001D, OKW17003D and OKW17005D intersected banded quartz veins with both pyrite and sometimes chalcopyrite in fault/shear zones as wide as 10 metres at an approximate depth of 40m. The vein intercepts were from 0.75m to 1.6m within the fault/shear zones. All vein hosting fault/shear zones are within a previously unknown monzonite intrusive rock discovered by the drill program. OKW17-003D has eight faults/shears in monzonite from 10cm to 150cm over 15.7m of core length. OKW17-005D has five fault/shear zones in monzonite from 20cm to 370cm in width over 11.6 metres of core length.
While faulting and/or mineralization was observed, no significant results were reported for holes OKW17-001D, OKW17-002D, OKW17-004D and OKW17-006D to OKW17-009D.
OKALLA EAST PROSPECT
Angkor is exploring the Okalla East area, seven km from Okalla West, as a porphyry copper gold molybdenum style occurrence. The first hole this year, BL17-048D was drilled to follow-up on a highly prospective gold intercept of 1 metre topcut at 34.29 gpt Au from Angkor’s 2011 drill program. (see: http://www.angkorgold.ca/diamond-drill-results-from-okalla-prospect-cambodia/)
An examination of hole BL17-048D shows numerous cross-cutting veins and fractures throughout almost the entire 50 metre length of the hole. Many of the veins/fractures contain medium grained pyrite with some chalcopyrite. A total of 123.0 metres were drilled at Okalla East. A map of drill hole locations accompanies the press release.
BL17-048D resulted in a weighted average of 0.88 gpt Au and 0.14% Cu over 10.0 metres from 26.0 to 36.0 metres. The core is medium grained diorite, diorite breccia and microdiorite with pyrite in narrow veins and pyrite with minor chalcopyrite as disseminations.
BL17-049D has one significant intercept from 32 to 37 metres. The five-metre run returned a weighted average of 0.31 gpt Au with 0.25 %Cu. It was collared 30m west of the first hole to test the along strike extension. This hole displayed massive coarse-grained pyrite in narrow (<1 cm) fractures in the upper portion of the hole transitioning downward into abundant open fractures containing chalcopyrite and pyrite with minor molybdenite to the bottom of the hole. The diorite hosting this mineralization is cut by two felsic dikes which are also mineralized.
A previous petrographic study of angular surface gold grains from pit concentrates display secondary gold growth indicating a local source of gold being leached from the fault zones, carried upward by groundwater and deposited onto the surface of the gold grains.
Petrographic work on rocks within the intrusive complex show them to be alkaline in nature indicting that gold mineralization is likely related to alkaline magmatism. One feature of this style of mineralization is the low quartz content of the vein system. As predicted, the quartz veins encountered are not robust. Vein intercepts are all less than 40m from surface and about 30m below the saprolite/bedrock interface. Phase 2 drilling will target the fault/vein zones at a minimum depth of 75 metres below the bedrock interface to avoid the influence of leaching ground waters.
The entire license area has been the subject of an aeromagnetic survey, satellite imagery geological interpretation, with reconnaissance field truth mapping and multi-element stream sediment geochemical survey, taking samples from catchments of roughly 1km2 extent. These efforts highlighted several areas as specific targets for further more intensive work. On 3 separate locations, a ‘C’ zone augered geochemical survey was undertaken, coupled with detailed geological mapping. On each of Okan East (781 samples) and Okan West (781 samples) prospects, this covered an area of 1km x 1km, sampling at 25m centres along lines at 100m intervals, both north-south and east-west. On Okalla, pilot ‘B’ zone (1570 samples) and pilot ‘C’ zone augered sampling programs were run in parallel over a restricted area of 1.5km x 1.0km, mostly on east-west lines. The ‘B’ zone samples were collected at 20m intervals on lines 100m apart, the ‘C’ zone sampling at 100m intervals on a square grid. Although it is inept statistically, the results were combined in a single population (!) and an IP survey run over the restricted target area indicated.
A later ‘C’ zone auger survey (3535 samples) was run over an expanded, area of 4.2km2. This showed much the same pattern, although the anomalies were, unsurprisingly, crisper. As deforestation by the local farmers exposed more outcrop, a much broader geochemical and detailed mapping target emerged, and after some experimentation, a termite mound geochemical survey (8270 samples) was done over 22.0 km2, taking samples from all termite mounds within 20m corridors spaced 200m apart, both north-south and east-west; and a reflected light spectroscopic survey of clay alteration has been done. Many, but not all, of the targets indicated by IP were diamond drilled. Several holes were drilled on quartz vein showings in artisanal workings, and most were drilled on quartz-flooded breccia targets beneath the primary strong Au-Cu-Mo geochemical anomalies. A total of 6642m was drilled on the prospect in 38 holes.
An IP survey has been started on the Okalla and Okalla East prospects, overlapping north into Banlung North tenement on Okalla North. All 3 of these, together with Katieng in the latter tenement, have identical magnetic signatures, suggesting that the Okalla East and north prospects are similar diorites, which could also host mineralization. The survey was interrupted by the onset of the monsoons and will recommence once the rains are over.