Exploration – Overview
Like Cactus, the Parks/Salyer Project and Cactus Northeast Extension both extend over a portion of the large porphyry copper system that has been dismembered and displaced by tertiary extensional faulting. Major host rocks at Cactus are precambrian oracle granite and laramide monzonite porphyry and quartz monzonite porphyry. The porphyries intruded the older rocks to form mixed breccias; monolithic breccias and occur as large masses, poorly defined dike-like masses; and thin well-defined but discontinuous dikes. The mineralization is structurally complex with intense fracturing, faulting, and both pre-mineral and post-mineral brecciation.
The long section below displays the horst and graben fault block geometries and mineralization interpretations from the Parks/Salyer deposit to the NE Extension. NE movement along the basement fault was accommodated by block rotation and the formation of NW trending normal faults resulting in the formation of horst and graben blocks. The copper box indicates Arizona Sonoran controlled property boundaries. The existing Cactus West pit is displayed on the long section below.
Recent ASCU exploration programs centered on definition and infill core drilling around the Parks/Salyer Project, which led to a maiden mineral resource of 2.9 billion pounds of copper at 1.015% Total Copper, issued on September 28, 2022. In 2019, two vertical PQ core holes were drilled into the East mineralized zone for verification of grade and for metallurgical testing as part of the evaluation program prior to purchase. One additional vertical PQ core hole was drilled into Cactus East in 2020 for further metallurgical testing, for a total of 5,768 ft (1,758 m). Five angled HQ core holes totaling 9,252 ft (2,820 m) were drilled in late 2019 and 2020 around the northern and western edges of Cactus East to define and expand mineralization. Also in 2020, 11 angled HQ core holes totaling 15,377 ft (4,687 m) were drilled around the perimeter of the West Pit to further define and expand Cactus West mineralization beyond the pit limits. Infill drilling continues on the Cactus East and West deposits to convert inferred resources defined in the PEA to indicated. In 2019, 55 surface sonic drill holes totaling 5,120 ft of 6-inch diameter holes were drilled across the Cactus Stockpile Project to support an initial resource based on approximately 750 ft (229 m) spaced drilling. Through late 2020 and 2021, an infill surface sonic drill program was undertaken to reduce the spacing to 400 ft (122 m). The resource database for the Stockpile Project resource contains 210 holes. Drilling of an additional 332 holes on the Project in 2021 further reduced the drill spacing to 200 ft (61 m), which will be incorporated into the resource database.
Located 1.3 miles down trend to the southwest from Cactus, ASCU’s 100%-owned Parks/Salyer Project is at an exploration stage. The Project is located on Arizona Sonoran-owned land contiguous to Cactus and provides an opportunity to organically grow Arizona Sonoran’s copper resources and mine life at the Project, leveraging off planned Cactus infrastructure and equipment.
The Company conducted an ionic leach soil geochemistry program over the Parks/Salyer property in 2019 on 325ft (100m) spacing. This confirmed soil geochemistry across the property for copper, molybdenum, silver and gold and a general northeast trend of the higher anomalous values. The Company followed up this work with two diamond drill holes in 2020. This extended the mineralization a further 900-1000ft (275-300m) to the northeast of previously drilled mineralization. A further two holes were drilled in late 2021 extending mineralization again, another 500ft (150m) to the north. As of 1H2022, the Company completed drilling a 12-hole exploration program, following up on four historic diamond holes, which tested the extension of the porphyry copper system from the southern border of its Parks/Salyer property, along the mine trend towards the Cactus Project.
On a preliminary basis, P/S demonstrates a scalable underground opportunity for further expansion of leachable inventory at Cactus. In September, the Company declared maiden Inferred mineral resources of 143.6 million tons at 1.015% Cu at Parks/Salyer for 1.46 million tons of contained copper and included:
- 2.46 Billion pounds of 1.066% total soluble copper (leachable)
- 0.45 Billion pounds of 0.804% total copper (primary sulphide)
Inferred Resources at Parks/Salyer are comprised of oxide, enriched and primary mineral zones; the oxides and enriched material is considered amenable to heap leach processing methods. Please refer to the PR dated September 28, 2022.
Cactus NE Extension
The NE Extension is located 3,000 ft (915 m) to the northeast of Cactus East. ASARCO defined the mineralized zone with wide spaced exploration drilling (> 1,000 ft, 305 m) in 1962 and 1963 as part of the initial property wide exploration program. The table below shows significant intercepts of the main holes drilled into the NE Extension.
|From (ft)||To (ft)||Length (ft)||TCu (%)||Mineral