<http://purl.org/dc/terms/description>
"The Longline gold occurrence is located within the Tintina Gold Belt, in the\r\nMoosehorn Range area of west-central Yukon Territory. Gold occurs in sheeted, high-grade\r\n(-30 g/t), shallowly dipping mesothermal quartz veins hosted within mid-Cretaceous\r\nintrusions of the Dawson Range batholith.\r\nFelsic to intermediate intrusions in the Moosehorn Range area are probably closely\r\nrelated; they were emplaced at -96-100 Ma, and have similar geochemical and lead isotopic\r\ncompositions. Geochemistry of the intrusive phases suggests the magmas were mantlederived,\r\nsubduction-related, and extensively contaminated by continental crust. The goldbearing\r\nquartz veins post-date all of these intrusions and are cut by younger mafic dykes.\r\nMetallic minerals inside the veins include galena, sphalerite, arsenopyrite, pyrite,\r\nboulangerite, tetrahedrite, native gold, and scheelite. The alteration assemblage includes\r\nmuscovite, sericite, iron carbonate, pyrite, arsenopyrite, minor clay, quartz, and tourmaline.\r\nVein minerals precipitated from moderately saline fluids, containing H\u20820-C0\u2082-CFi\u2084-NaCl +\r\nN\u2082 , at temperatures of ~260\u00B0-300\u00B0C, pressure of -1.3 - 1.9 kbar, and depth of 5-7 km,\r\nassuming near-lithostatic fluid pressures. Lead isotopic studies indicate the Moosehorn\r\nRange area intrusions are not the source of the metals in the veins and the ultimate source\r\nremains uncertain.\r\nThe veins were emplaced between 92 and 93 Ma along NNW-striking, shallowly\r\nENE-dipping brittle reverse fault structures during a WSW-verging contractional event. The\r\nveins are 1cm to lm thick, sheeted, lens-shaped, banded, and locally connected by subhorizontal\r\ndilational oreshoots, creating a ramp-flat geometry. The long axis of the\r\noreshoots is NNW and slip along the reverse faults was up-dip towards the WSW.\r\nRegional structural context for the formation of the veins is unclear. Prominent\r\nNNW-trending topographic and magnetic lineaments in the area may be dextral strike-slip\r\nfaults along which there may be contractional and dilational jogs. Contraction at a jog in the\r\nvicinity of the Longline property may have generated the structures that host the veins. If so,\r\ndextral strike-slip faults and associated contractional and/or dilational jogs may be an\r\nimportant exploration guide to finding other shallowly dipping auriferous quartz vein\r\nsystems in the region."@en
<https://open.library.ubc.ca/cIRcle/collections/ubctheses/831/items/1.0052774>