Abstract Title: INTERRELATION OF CARLIN-TYPE Au DEPOSITS, EOCENE MAGMATISM, 
LATE PROTEROZOIC RIFTING, RUBY MTS CORE COMPLEX DEVELOPMENT, AND FOUNDERING OF 
THE LARAMIDE SHALLOW SLAB

Abstract Author(s): Henry, Christopher D. (University of Nevada) - Ressel, 
Michael W. (Newmont Mining Corporation)  

Abstract: Relations of the giant Carlin trend (CT) Au deposits of Nv to several 
late Proterozoic to Eocene tectonic-magmatic features raise a wide range of 
basic to applied questions to be addressed by Earthscope. Au production from 
the CT, a 60-km-long NNW alignment of major Eocene deposits that probably 
overlies a late Proterozoic rift, makes the US the worldÕs third leading 
producer. The sources of heat, fluids, and Au remain controversial, although 
geologic and geophysical data indicate that Eocene plutons underlie the CT at 
upper to probably mid-crustal depths and were likely heat sources. The origin 
of Eocene magmatism is enigmatic. The best interpretation is that foundering of 
the subhorizontal Laramide slab along an ENE axis induced asthenospheric 
upwelling and magmatism along its trailing edge from Wa southward into Nv 
(Humphreys, 1995). The CT lies ~60 km WNW of the NNE-striking RM, which lay at 
probable 13- to 20-km-depths in the Eocene when the CT deposits formed. Eocene 
plutons in the RM are likely mid-crustal analogs to the postulated CT plutons. 
RM unroofing is interpreted to have occurred along a shallowly WNW-dipping 
detachment that should have extended beneath the CT and beneath other Eocene 
igneous centers south of the CT. Detachment could have separated the CT and 
igneous centers from their lower crustal and mantle roots. However, 
magnetotelluric data indicate the RM are bounded by high-angle structures on 
both sides (Wannamaker and Doerner, 2002). Deciphering these complex mantle and 
crustal structures will require the full range of Earthscope examination.