Alan R. Wallace

Interests: 

Economic geology

Regional geology

Contact: 

775-784-5789

Education

Experience

I have worked for the USGS in Denver and Reno since 1978, following several years of work in the private sector. My USGS research focuses on the regional geologic setting of areas that contain mineral deposits or ground-water resources. Projects range from regional mapping to deposit-scale ore genesis studies, as well as regional and local mineral assessment investigations. Specific studies have included: mineral deposits of the Colorado mineral belt, rift-margin tectonics and fluorite deposits of the Rio Grande rift, volcanism, sedimentation, and tectonism along the northern Nevada rift, genesis of sedimentary rock-hosted gold deposits, and mineral assessments of the Humboldt River Basin (NV) and the southern Rocky Mountains. Study areas principally have been in Colorado, Nevada, New Mexico, and Utah, with one project in the Altiplano of Bolivia. I am on the Graduate Faculty in the Department of Geological Sciences and the Hydrological Sciences Program at the University of Nevada, Reno, where I work with graduate students and faculty on a variety of geological, geochemical, and hydrologic projects.

Current Activities

My current research focuses on the landscape evolution of the northern Great Basin over the past 20 million years. This field-based work has several components, including:

1) Miocene and Pliocene sedimentation, tectonism, and erosion in northeastern Nevada, the origin and evolution of the Humboldt River, and the roles of these processes on the formation, exposure, burial, and supergene weathering of major Carlin-type and epithermal gold deposits in the region.  This work is being expanded to a much broader part of the Great Basin to determine time-space domains of Cenozoic processes that may have modified or concealed mineral deposits, depending on the age of a deposit relative to that of the various processes.

2) The evolution of sedimentary basins and faulting, and how these processes affected ground-water resources in the Great Basin. These results are being applied to dewatering of large open-pit gold deposits and to regional evaluations of ground-water withdrawal for export to large metropolitan areas.

3) The evolution of Miocene freshwater lakes in the Great Basin, and determining why some lakes produced world-class diatomite deposits and others did not. Factors included nutrient inflow and availability, tectonic activity during lake formation, climate change, and the roles of coeval volcanic processes.