On July 1, 2019, Barrick's Goldstrike and Newmont's Carlin operation were contributed to the Nevada Gold Mines joint venture and are now collectively referred to as Carlin.
Barrick is the operator of the Nevada Gold Mines LLC joint venture and owns 61.5%, with Newmont owning the remaining 38.5% of the joint venture.
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Summary:
The mineralization of Gold Quarry is generally bounded on the northwest by the northeast-striking Chukar-Alunite Fault zone, and on the southeast by the north–northeast-striking Deep Sulfide Feeder Fault zone. Mineralization is preferentially located in the hanging wall of the Chukar-Alunite Fault Zone and in the footwall of the Good Hope Fault. Gold mineralization is disseminated, with higher gold grades concentrated adjacent to structures.
Ten geologically distinctive mineral zones have been defined, referred to as Quarry Main, Deep West, Deep Sulfide Feeder, Chukar North, Chukar South, Good Hope, Mac, Magpie, Southwest, and Wedge.
Six major lithologic units are recognized in the Gold Quarry deposit from surface mapping and drill hole logging: Tertiary Carlin, Devonian Slaven, Devonian Rodeo Creek, Devonian Popovich, Silurian Roberts Mountains, and Ordovician Hanson Creek Formations.
The four main gold-hosting lithologies are:
• Silty limestone sections of the Roberts Mountains Formation;
• The upper 90 metres of the Popovich Formation consisting of silty limestone and calcarenite;
• Siltstone, siliceous mudstone, and cherty siltstone of the Rodeo Creek Formation; and
• About 60 metres of upper-plate sedimentary rocks of the Marys Mountain sequence that consists of limy mudstone and siltstone.
Detailed surface mapping and drill hole interpretation indicates that there are four dominant fault sets at Gold Quarry. These include (from youngest to oldest): north striking basin-bounding, normal faults (Grey, and Tuff Faults), northeast-striking normal faults (Chukar, Alunite, Bad Attitude, and Deep Sulfide Feeder Faults), northwest-striking Good Hope reverse Fault, and low-angle Roberts Mountains thrust.
Oxide gold ore consists of minute particles of finely-disseminated native gold within the host rock. Oxidization of portions of the deposit may have occurred as a result of late hydrothermal acidleaching and supergene leaching of the original refractory material. Oxide material is subdivided into oxide carbonate (OC) and oxide siliceous (OS) styles, based on the presence of carbonates. Refractory mineralization is subdivided into silica sulfide refractory (SSR), carbon sulfide refractory (CSR), and unoxidized carbonate (UC). Refractory conditions of each type are due to a combination of silica ± pyrite encapsulation of gold ± the presence of naturally activated organic carbon ± the presence of carbonate. These represent the unoxidized portions of the Gold Quarry deposit. Mineralization is associated with As, Sb and Hg.
Sulfidation, decalcification, and dolomitization of the Popovich and Roberts Mountains limestones and silicification of the Rodeo Creek siliciclastic rocks are the dominant alteration types associated with mineralization. Barite and clay-altered intrusive rocks have been noted in association with the Alunite and Good Hope Faults.