Paper No. 186-12
Presentation Time: 8:00 AM-5:30 PM
SEM ANALYSIS AND U-PB DETRITAL ZIRCON DATING OF SAND FROM AN ACTIVE DUNE SYSTEM NEAR TONOPAH, NEVADA
Tonopah is a small town in the south-central portion of Nevada with a rich history of silver mining and a star sand dune complex just west of town known as Crescent (Tonopah) Sand Dunes. Because sand dunes accumulate sediments from broad geographic areas, sands from these environments are often used as a standard to describe the area’s surrounding geology. While extensive studies have been conducted documenting the geochemical and mineralogical characteristics of sands from large sand dune systems in the Basin and Range of the western United States, there have been few studies investigating the Crescent Sand Dunes. Oglesbee et al. (2019) inspected numerous characteristics of these sands (grain size, mineral abundances, bulk element compositions, etc.) to serve as an environmental reference for Tonopah and the greater area. Although the data from this reference material suggests these sands to be most chemically similar to nearby Miocene-aged volcanic deposits, it is still relatively unclear whether these sands originate from these rocks or another primary source. The presented research aims to further constrain the possible primary sources of the Crescent Dune sands by using scanning electron microscope (SEM) analyses and U-Pb dating of detrital zircons. Initial SEM imaging indicates a wide range of sand grain roundedness, shape, and texture. Preliminary SEM imaging also reveals widely present lithics with varying vesiculated textures. U-Pb dating of the detrital zircons in the Crescent Dune sands will yield a crystallization age that can be compared to the well-documented igneous rocks nearby. Further results from the SEM and U-Pb dating of zircons combined with previous reference material will aid in establishing primary sediment sources that contribute to the formation of the Crescent Sand Dunes. Data from this research may also be useful for investigating sediment movement and desertification in a world increasingly affected by climate change.