Based on geological features and location, the Los Helados deposit is classified as a porphyry Cu–Au system. Porphyries are well documented along the Andes and represent a widespread type of deposit in Chile.

The Los Helados project area is underlain most extensively by Permo-Triassic rocks assigned to the Choiyoi Group that form the Andean basement in the region.

The Los Helados porphyry Cu-Au system is exposed in a high-elevation, northwestfacing cirque with high topographic relief. The bottom of the elongated cirque, where the uppermost part of the deposit is exposed at surface, is at 4500 metres above sea level, while the sides of the valley rise steeply above to 5300 metres on the eastern side: a difference of at least 800 metres. The abundant rock exposures on this steep eastern slope provide the best outcrop for mapping geological relationships at surface, including excellent alteration vectors towards the largely covered deposit in the cirque bottom.

The host rocks to the deposit are largely Permo-Triassic in age. Granite is the oldest, and most regionally extensive unit. It is intruded by a tonalitic- to dioritic intrusive complex as well as fine-grained andesite dykes, typical of the Permo-Triassic in the region. A rhyodacitic to rhyolitic feldspar-phyric intrusion has previously been interpreted to pre-date the mafic units, however recent work suggest that the rhyodacitic intrusion is a pre-mineral porphyry of Eocene to Late Oligoce ........

The main conclusions and recommendations from the block cave geomechanics study were:

- Based on empirical methods, caving of the Los Helados rock mass can be achieved with a minimum hydraulic radius (HR) of 39. This equates to a cave initiation footprint of approximately 135 x 185 m. It is concluded that cave initiation can be successfully achieved at Los Helados given the rock mass conditions and proposed mining footprints.

- The rock mass characteristics suggest that unassisted cave propagation may be an issue at Los Helados, with a planned lift height of 1,000 m. The proposed height/width ratios of the cave are 0.56 to 2.75, depending on which side of the cave is considered. This indicates that there could be a risk of cave-stalling, depending on the initiation strategy. The proposed single lift of more than 800 m over the full footprint area is greater than what has currently been done in other existing traditional block cave operations. In order to ensure cave propagation of the proposed 1,000 m column, the design will incorporate a HF preconditioning lift located at 3,840 mRL. HQ diameter preconditioning holes will be drilled on a 70 m x 82 m grid spacing, using 300 m upholes and 300 m down-holes. To complete the full column HF, two design options are possible. Both options will have the same lower HF level at 3,840 masl. The difference between the two options is that one has a second HF lift at 4,120 masl and the second option assumes 500 m do ........

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