Eocene Magmatism & its Role in Generating Sediment-Hosted Gold Deposits of the Carlin Trend: Emigrant Pass Volcanic Field, Northern Carlin Trend (Beast, Genesis & Betze Post Deposits), Tuscarora Volcanic Field (Mt. Blitzen Volcanic Complex, Tuscarora Epithermal Precious-Metals Deposit)

This three-day trip examines Eocene volcanic and intrusive centers in and around the Carlintrend and the relation of Eocene magmatism and tectonism to Carlin-type deposits (Fig. 1, p.58). Until recently, the prevalent view was that Carlin-type deposits in northern Nevada and Utahwere most likely Cretaceous in age, related to metamorphism and/or extension, and formed atdepths of ~5 km (Kuehn and Rose, 1992; Arehart et al., 1993; Wilson and Parry, 1995; Arehart,1996; Drews-Armitage et al., 1996; Ilchik and Barton, 1997). Our interpretation is that thedeposits are Eocene, that Eocene magmatism was the heat source and possibly the source ofsome metals and fluids, and that the deposits formed at depths no greater than about 2 km(Henry and Boden, 1998; Henry and Ressel, 2000; Ressel et al., 2000a, b). Day 1 examines unal-tered Eocene rocks in the Emigrant Pass volcanic field, which is adjacent to the Carlin trend. Day2 looks at altered and mineralized Eocene dikes in the northern Carlin trend where Eocene intru-sive rocks are intimately associated with ore. Day 3 examines a mix of unaltered and altered-min-eralized rocks in the Tuscarora volcanic field and the Tuscarora epithermal, volcanic-hosted prec-ious metal deposit.