Abstract Carlin, epithermal, and orogenic gold deposits, today mined almost exclusively for their gold content, have similar suites of anomalous trace elements that reflect similar low-salinity ore fluids and thermal conditions of metal transport and deposition. Many of these trace elements are commonly referred to as critical or near-critical elements or metals and have been locally recovered, although typically in small amounts, by historic mining activities. These elements include As, Bi, Hg, In, Sb, Se, Te, Tl, and W. Most of these elements are now solely recovered as by-products from the milling of large-tonnage, base metal-rich ore deposits, such as porphyry and volcanogenic massive sulfide deposits. A combination of dominance of the world market by a single country for a single commodity and a growing demand for many of the critical to near-critical elements could lead to future recovery of such elements from select epithermal, orogenic, or Carlin-type gold deposits. Antimony continues to be recovered from some orogenic gold deposits and tellurium could potentially be a primary commodity from some such deposits. Tellurium and indium in sphalerite-rich ores have been recovered in the past and could be future commodities recovered from epithermal ores. Carlin-type gold deposits in Nevada are enriched in and may be a future source for As, Hg, Sb, and/or Tl. Some of the Devonian carbonaceous host rocks in the Carlin districts are sufficiently enriched in many trace elements, including Hg, Se, and V, such that they also could become resources. Thallium may be locally enriched to economic levels in Carlin-type deposits and it has been produced from Carlin-like deposits elsewhere in the world (e.g., Alsar, southern Macedonia; Lanmuchang, Guizhou province, China). Mercury continues to be recovered from shallow-level epithermal deposits, as well as a by-product of many Carlin-type deposits where refractory ore is roasted to oxidize carbon and pyrite, and mercury is then captured in air pollution control devices.

ABSTRACT We will embark on a five-day journey through northern, western, and central Sonora, in which we will see excellent examples of mostly Mesozoic to Cenozoic tectonics, sedimentation, and metallogeny. On Day 1, we will visit the porphyry copper deposit at Ajo, Arizona, and several Pleistocene cinder cones and maar craters in the Pinacate Biosphere Reserve. On Day 2, we will see L- and L-S tectonites at the type locality of the Mojave-Sonora megashear in Sierra Los Tanques, Noche Buena orogenic gold deposit, Ediacaran Gamuza beds in Caborca, and have an overview of the Carnero detachment fault on the south side of Sierra La Gloria. Day 3 will explore faults and related sedimentary and volcanic rocks associated with the late Miocene oblique opening of the Gulf of California rift and visit outcrops that record late Miocene timing constraints for flooding of the Gulf of California seaway, including several localities on southern Isla Tiburón accessible only by boat. Day 4 will visit exposures of Permian sedimentary to Paleogene igneous rocks in Hermosillo (Cerro La Campana); Puerto del Sol detachment fault zone; Aconchi batholith and a hot spring localized on a Basin and Range normal fault; Santa Elena low-sulfidation epithermal gold mine; and the Upper Jurassic Cucurpe Formation. On Day 5, we will visit several exposures of different crustal levels of the Magdalena-Madera metamorphic core complex, including the spectacular stretched pebble conglomerates in Arroyo Amolares.