{"id":2345,"date":"2019-10-02T19:50:21","date_gmt":"2019-10-02T19:50:21","guid":{"rendered":"https:\/\/www.gsnv.org\/shop\/geology-of-the-redline-gold-skarn-deposit-converse-project-humboldt-county-nevada\/"},"modified":"2020-02-24T18:17:08","modified_gmt":"2020-02-24T18:17:08","slug":"geology-of-the-redline-gold-skarn-deposit-converse-project-humboldt-county-nevada","status":"publish","type":"product","link":"https:\/\/www.gsnv.org\/shop\/geology-of-the-redline-gold-skarn-deposit-converse-project-humboldt-county-nevada\/","title":{"rendered":"Geology of the Redline Gold Skarn Deposit, Converse Project, Humboldt county, Nevada"},"content":{"rendered":"","protected":false},"excerpt":{"rendered":"

ABSTRACT
\nThe Redline low-grade Au skarn deposits are located on the
\nConverse property, 18 miles (29 km) northwest of Battle Mountain,
\nNV, and nine miles (14.5 km) south of the Lone Tree mine. The project
\nis a joint venture between Newmont Gold Company and the Nike
\nJoint Venture (50% each). The Nike JV consists of UUS Inc. (a subsidiary
\nof Cameco Corp.) and Romarco Nevada (50% each).
\nGeophysical work and drilling by UUS resulted in discovery of significant
\nmineralization in 1995. Drilling to date consists of 102
\nholes, generally on 200- to 400-ft (61- to 122-m) centers. As at year
\nend 1998, in situ geologic resources at a cutoff grade of 0.015 oz
\nAu\/ton (0.51 g Au\/t), without engineering or economic implications,
\nare: Indicated 48 million tons at 0.024 oz Au\/ton for 1.2 million
\nounces Au (44 M tonnes at 0.83 g Au\/t for 36 tonnes Au) plus
\nInferred 35 million tons at 0.023 oz Au\/ton for 0.8 million ounces
\n(31 M tonnes at 0.80 g Au\/t for 25 tonnes Au).
\nTwo main zones of Au mineralization, North and South
\nRedline, underlie two bedrock hills which are entirely covered by
\nalluvium. Depth to bedrock is as little as 28 ft (8.5 m) at North
\nRedline and 121 ft (37 m) at South Redline, and ranges to over 800
\nft (240 m) in the paleovalley between the hills. The Au deposits
\noccur in a calc-silicate alteration system which surrounds an inferred
\nstock of quartz monzodiorite to granodiorite porphyry, the Redline
\nporphyry. The stock is 1,500 to 2,000 ft (450 to 600 m) in diameter
\nand occurs at the intersection of a northwest-trending aeromagnetic
\nhigh and a north-south aeromagnetic linear. A dike-like arm of the
\nstock extends north-northeast from the northeast corner of the pluton.
\nThe calc-silicate alteration halo ranges from 800 to 1,400 ft (240
\nto 430 m) in width with a vertical extent of over 950 ft (290 m). Host
\nrocks comprise a receptive unit of calcareous sandstone and siltstone
\nwithin the Mississippian, Pennsylvanian, and Permian Havallah
\nsequence. Alteration assemblages include pyroxene hornfels, pyroxene>
\ngarnet skarn, biotite hornfels, and quartz hornfels, with a retrograde
\noverprint of amphibole, epidote, chlorite, calcite, quartz and
\nsulfide minerals. Biotite and quartz hornfels are early in the alteration
\nsequence and are overprinted by the much more abundant
\npyroxene hornfels. Light green to grass green diopsidic pyroxene is
\nthe dominant hornfels mineral. Pyroxene-garnet skarn replaces
\nhornfels but is greatly subordinate to hornfels in volume; skarn
\npyroxene is dark green and hedenbergitic. The garnet:pyroxene ratio
\nin skarn is <1:10. Local variations in the garnet:pyroxene ratio are\npresent in relation to the stock contact and certain dikes, but a broad\nconsistent zonation in the ratio has not been recognized.\nSulfide minerals include pyrrhotite, chalcopyrite, pyrite, molybdenite,\nand others. Sulfide content is low, generally <0.5%. A Re-Os\nage date of 41.0\u00b10.2 Ma obtained from a sample of molybdenite from\nSouth Redline is believed to date the age of Au mineralization. Gold\ncommonly occurs as free particles. Gold is presumed to be part of the\nretrograde assemblage and seems to be most strongly associated with\nchalcopyrite and chlorite. The southwest margin of the stock is\naffected by silica-secondary biotite alteration and contains low-grade\nAu values. A late sericite-chlorite-calcite alteration-brecciation event\noccurs on the west side of South Redline.\nGold mineralization is strongest in the middle to outer portions\nof the calc-silicate alteration halo. The mineralized bodies generally\ndip west at 15\u00a1 to 35\u00a1, subparallel with bedding in the sandstone.\nThe distribution of mineralized rocks in map view suggests partial\ncontrol of Au deposition by a north-south pre-mineral structure on\nthe east side of the Redline porphyry. The Redline system shows a\nsomewhat telescoped horizontal geochemical zonation pattern. Gold\nis associated with elevated Cu. Concentrations of Ag, Zn, Pb, Sb,\nand As occur progressively more distal from the stock, with considerable\noverlap between elements. One drill hole intersects a sulfideenriched\nzone outside the calc-silicate halo which is enriched in Au,\nPb, Zn, and As. Avertical geochemical zonation pattern is evident in\nmany drill holes.\n<\/p>\n","protected":false},"featured_media":4042,"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\/2345"}],"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=2345"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/media\/4042"}],"wp:attachment":[{"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/media?parent=2345"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/product_cat?post=2345"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/product_tag?post=2345"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}