Acquired in April 2011, AuRico Gold’s El Chanate Mine is located 37 km northeast of Caborca in Sonora State, Mexico. The Mine consists of an open pit, crusher, heap leach pads, process plant located on 3,665 hectares encompassed within 19 mineral concessions.
Historical workings suggest the area has been mined for gold since the early 19th century. The current open-pit mine has now been developed below the level of those historical small-scale mine workings.The open-pit mine plan covers an area approximately 1,700 metres long, 780 metres wide, and 280 metres deep. El Chanate utilizes conventional three stage crushing and heap leaching, with gold bearing solutions being processed in an ADR plant, followed by electro-winning and refining.
El Chanate’s main structural feature is the Chanate fault zone, a 7 km-long northwest-striking, variably southwest-dipping structure. The area is underlain by deformed sedimentary rocks of the Late Jurassic-Early Cretaceous Bisbee Group and the Late Cretaceous Chanate Group, which locally are overlain by andesites of the Cretaceous El Charro volcanic complex.
The sedimentary strata are locally intruded by andesitic sills and dikes, a microporphyritic latite, and a diorite stock. These strata comprise mudstone, siltstone, sandstone, conglomerate, shale, and limestone.
Sandstone, conglomerate, and lesser mudstone that lie above the Chanate fault are of the Middle Cretaceous Chanate Group. Below the fault, siltstone and sandstone lenses are assigned to the Arroyo Sasabe Formation of the Lower Cretaceous Bisbee Group.
Alteration and mineralization associated with the Chanate fault zone are exposed across a northwest strike length of over 3.5 km. The rock units in this zone are altered to varying degrees by sericite, pyrite, ankerite, and quartz veining.
In surface outcrops the mineralized zone is distinguished by its bleached appearance relative to unmineralized rock. Sub-parallel sheeted zones of quartz veinlets form thick, mineralized lenses, within a larger area of sub-economic but anomalous gold concentrations.
Drill-hole data indicate the mineralized lenses are sub-horizontal to gently southwest-dipping, and are often parallel to the Chanate fault and the steep normal faults. The Chanate fault zone itself is generally weakly mineralized, while rock units in the adjacent hanging and footwalls are well mineralized.