                                          Denise K. Honn
                  University of Nevada, Las Vegas
                               Geoscience Department

Useful Remote Sensing and GIS links:

Go to Keck Library!

Go to National atlas of the United States (USGS)!

Go to the Nevada Bureau of Mines and Geology!

A bit about myself:

BSc from Washington State University, 2003.

MSc from University of Nevada, Las Vegas, 2005.

Currently at UNLV working with Dr. Eugene I. Smith towards my Ph.D.

Current Projects:

Nested Calderas of the Northern Kawich Range, central Nevada

Five calderas were discovered in the northern Kawich Range, central Nevada. These calderas are filled with intracaldera rhyolite tuffs and caldera collapse breccias. Based on ⁴⁰Ar / ³⁹Ar dating of sanidine and crosscutting relations, the calderas erupted in the following order from oldest to youngest: Clifford Spring (23.67 ± 0.09 Ma), Tobe Spring (22.77 ± 0.07 Ma), Cow Canyon (22.78 ± 0.07 Ma), Bellehelen (22.87 ± 0.16 Ma), and Warm Springs. Welded tuff lithologies of collapse breccia blocks show that these calderas represent separate events and not a single caldera with piecemeal collapse. Geochemistry shows that the five intracaldera tuffs are chemically similar and therefore cogenetic. The five tuffs are also similar to the Pahranagat Formation and the Pyramid Spring tuff. To explain the eruption of at least seven tuffs of very similar chemistry over a period of 1.06 m.y, a new model for magma production in northern Nye County during the Tertiary ignimbrite flare-up is presented. This model calls for a heat surge producing greater than 50 % partial melting of the lower crust producing rhyolitic melt batches of similar chemistry. Cooling of the crust due to these voluminous eruptions resulted in the suppression of the ignimbrite flare up.

Volcanoes of the McCullough Range, southern Nevada: a window into the pre-extensional history of the Colorado River Extensional Corridor.

The McCullough Range is a geologically unique part of the Colorado River extensional corridor. The McCullough Range has been relatively un-deformed internally by Basin and Range extension though most other ranges underwent strong extensional deformation exemplified by mid-tertiary faulting. Thus, the volcanic centers within the McCullough Range are relatively well preserved providing an exceptional opportunity to study the pre-extensional volcanic history of the Colorado River extensional corridor. The range harbors at least 4 volcanic centers; the McCullough Pass caldera, the Sloan Sag, the central McCullough Range stratovolcano, and the Henderson Caldera. The McCullough Pass caldera is a club shaped depression formed by the eruption of the McCullough Pass tuff at 14 Ma (Smith et al., 1988; Sanford, 2000; Spell et al., 2001). The Sloan Sag is a 13.5 km diameter volcano-tectonic depression of the Hidden Valley volcanics filled by mid-Miocene andesite and dacite domes, flows and the pyroclastic flows of the Sloan volcanics (Bridwell, 1994). The central McCullough Range is predominantly composed of a stratovolcano (12 to 15 Ma) with a 2500- to 3000- m thick section of andesite interbedded with thin conglomerates, debris flows and sandstones derived from the volcano (Boland, 1996). The stratovolcano is flanked to the north by the Henderson caldera. The Henderson Caldera is exposed as the northern most extent of the northern McCullough Range, contiguous to and partly underlying the southern reaches of the city of Henderson. The exposed caldera consists of biotite dacite and hornblende andesite domes and flows, pumice rich ash-flow tuff, and mesobreccia deposits. The ongoing study of the Henderson Caldera and other volcanic centers of the McCullough Range provide geologic data to the scientific research of the developing Sloan Canyon National Conservation Area as well as continue to provide insight into the evolution of the Colorado River extensional corridor.