| The Carlin East deposit is the underground extension of the Carlin deposit, the "type" locality of sedimentary rock-hosted disseminated gold deposits, and is located 20 km to the northwest of the town of Carlin, NV. Ore is dominantly hosted in the upper two sub-units of the Silurian to Devonian Roberts Mountains Formation (stls1 and stls2) and is locally hosted in the Devonian Popovich Formation along structures.; Two types of Jurassic dikes (158 Ma) are present at Carlin East: phlogopite-bearing and hornblende-bearing lamprophyre dikes. Both types of dikes are commonly intensely altered and are locally mineralized with gold where they are cut by faults. Isocon plots of both types of dikes show additions of Au, As, Sb, Hg, Tl, and Se with depletions of CaO, Na2O, MnO, and Ni.; Alteration at Carlin East comprises decarbonatization, silicification, argillization, and dolomitization. Three distinct phases of mineralization were identified.; Geochronological studies were performed at Carlin East using structural relationships, apatite fission-track, and 40Ar/39Ar techniques. (Abstract shortened by UMI.)... |
