{"id":2307,"date":"2019-10-02T19:49:19","date_gmt":"2019-10-02T19:49:19","guid":{"rendered":"https:\/\/www.gsnv.org\/shop\/shear-hosted-copper-mineralization-within-the-atacama-fault-zone-el-salado-district-northern-chile\/"},"modified":"2020-02-24T18:16:56","modified_gmt":"2020-02-24T18:16:56","slug":"shear-hosted-copper-mineralization-within-the-atacama-fault-zone-el-salado-district-northern-chile","status":"publish","type":"product","link":"https:\/\/www.gsnv.org\/shop\/shear-hosted-copper-mineralization-within-the-atacama-fault-zone-el-salado-district-northern-chile\/","title":{"rendered":"Shear-Hosted Copper Mineralization Within the Atacama Fault Zone, El Salado District, Northern Chile"},"content":{"rendered":"","protected":false},"excerpt":{"rendered":"<p>The El Salado district is located 35 km east of Cha\u0096aral<br \/>\nin the Coastal Range of northern Chile (Fig. 1). The district is<br \/>\nincluded in a group of vein and manto-type copper deposits<br \/>\nspatially related to the Atacama Fault Zone (AFZ) that comprise<br \/>\nthe Coastal Range copper province (Espinoza et al.,<br \/>\n1996). Two major strike-slip faults, the central and east<br \/>\nstrands of the AFZ, bound the district (Fig. 2). Subsidiary<br \/>\nfaults and shears host extensive copper vein mineralization in<br \/>\na >10 km2 area that comprises the district. Minor production<br \/>\nis derived from several vein deposits and reworking of old<br \/>\nmine dumps. Oxide copper ore is processed at the stateowned<br \/>\nENAMI heap leach facility in the town of El Salado.<br \/>\nAthick sequence of submarine (?) meta-andesite and siliciclastic<br \/>\nrocks (>1500 m) assigned to the Early Cretaceous<br \/>\nBandurrias Formation (Mercado, 1977) are the principal host<br \/>\nrocks for copper-mineralized veins. Dark-green to black,<br \/>\nfine-grained to aphanitic andesite and minor porphyritic<br \/>\nandesite comprise the volcanic unit. The massive andesite is<br \/>\nstrongly fractured throughout the district and in outcrop<br \/>\nappears structureless. Flow layering, pillow structures, and<br \/>\nvesicular or amygdaloidal horizons are absent making structural<br \/>\ninterpretation difficult. Several lenses of thin-bedded<br \/>\nplatey limestone, up to 30 meters thick, are interstratified<br \/>\nwith the andesite on the west side of the district, adjacent to<br \/>\nthe central Atacama fault. The limestone is highly recrystallized<br \/>\nand locally displays strong ductile deformation. The<br \/>\nupper sedimentary unit consists of poorly- bedded indurated<br \/>\nquartz sandstone with minor chert, argillite, and volcaniclastic<br \/>\ninterbeds. Within the district the Bandurrias Formation<br \/>\nstrikes north-northeast and dips moderately (40-65\u00a1) eastward,<br \/>\nexcept near the central Atacama fault where deformed<br \/>\nlimestone beds are vertically dipping or overturned (cross<br \/>\nsection on Fig. 2). About 1.0 km north of the Tulipan mine,<br \/>\nfolded quartz sandstone and chert beds interfinger with massive<br \/>\nandesite, suggesting a gradational change from volcanic<br \/>\nto detrital deposition.<br \/>\nPre- and post-mineral dikes and small stocks of intermediate<br \/>\ncomposition have intruded the volcanic-sedimentary<br \/>\nsequence. A prominent andesite porphyry dike and numerous<br \/>\nmonzonite porphyry dikes were emplaced along the Santo<br \/>\nDomingo fault in the center of the district, and some dikes<br \/>\ncontain trace amounts of chalcopyrite. Small fine-grained<br \/>\nandesite dikes are common on the east side of the district and<br \/>\na large altered diorite dike cuts massive andesite near the central<br \/>\nAtacama fault. Though some intrusive rocks are locally<br \/>\naltered and weakly mineralized, a clear genetic relationship<br \/>\nbetween copper mineralization and specific intrusions has not<br \/>\nbeen established. Hornblende phenocrysts from a small plug<br \/>\nof weakly altered diorite porphyry cutting Bandurrias<br \/>\nandesite in the southern part of the district yielded a 40Ar\/39Ar<br \/>\nplateau age of 107.4\u00b11.1 Ma. Diorite and granodiorite of the<br \/>\nCretaceous (127 Ma) Las Tazas pluton crop out extensively<br \/>\naround El Salado.<\/p>\n","protected":false},"featured_media":4112,"comment_status":"closed","ping_status":"closed","template":"","meta":{"pmpro_default_level":""},"product_cat":[154],"product_tag":[],"_links":{"self":[{"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/product\/2307"}],"collection":[{"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/comments?post=2307"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/media\/4112"}],"wp:attachment":[{"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/media?parent=2307"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/product_cat?post=2307"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/product_tag?post=2307"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}