***************************************************************** From: Calvin Miller <calvin.miller@xxxxxxxxxxxxxx> ***************************************************************** A volcanic/plutonic field trip that may of interest to some (22-23 March). Register through GSA (Cordilleran section) web site (http://www.geosociety.org/sectdiv/cord/08mtg/index.htm); contact any of leaders for more information. Calvin Miller ------------------ Field Trip #11: Spirit Mountain Batholith and Secret Pass Volcanic Center: Magmatism in the Uppermost Crust, Colorado River Extensional Corridor, Nevada-Arizona. Sat.-Sun., 22-23 March (2 days). Nicholas Lang, University of Tennessee-Knoxville, +1-865-974-6008; B.J. Walker, Oregon State University; +1-541-737-1201; Lily Claiborne, Vanderbilt University, +1-615-322-2140; Calvin F. Miller, Vanderbilt University, +1-615-322-2232; Rick Hazlett, Pomona College, +1-909-621-8675. Cost: $US210. Min: 13; Max: 22. We will examine spectacular cross-sectional views of a Miocene batholithic complex and coeval eruptive center in southeast Nevada and northwest Arizona, respectively. We will emphasize the storage transport, fractionation, and eruption processes at a range of depths exposed by extension-related tilting. The shallow to mid-crustal Spirit Mountain batholith reveals evidence for multiple replenishment and rejuvenation over a 2-m.y. period, with extensive coarse cumulate granites and leucogranite (high-silica rhyolites) sheets, mafic-felsic mingling and mixing, and a major dike swarm. The roots of the possibly related Secret Pass Canyon volcanic center comprise a large, very shallow, composite laccolith and smaller dikes, sills, and a volcanic neck, with intriguing field relationships with the volcanic sequence that it intrudes and underlies. The sequence includes volcanogenic sediments, ignimbrites, domes, and block-and-ash flow deposits. ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
