Class
Article
College
College of Science
Faculty Mentor
Tammy Rittenour
Presentation Type
Oral Presentation
Abstract
Sand dunes are threshold systems capable of recording past changes in effective moisture and aridity, and sensitive to sustained, decadal-scale drought. Records of past drought can provide a reference to past climate variability and expected extremes in an area. Such records provide data for climate modeling refinement, and regional and community adaptive planning. We use optically stimulated luminescence (OSL) dating and radiocarbon ages from charcoal to investigate eolian activity in two dune fields in southern Utah, located 250 km apart in the central Colorado Plateau. Dune forms in this semi-arid region have been mapped and auger samples obtained from mapped units, typically to depths of 3.5 m with two OSL samples from each core. With OSL ages, chronostratigraphic reconstructions are based on grain size analysis, geochemistry, organic and magnetic properties, and identification of paleosols (representing periods of dune stability). Kanab dune field, located 13 km northwest of Kanab, Utah, covers approximately 12.5 km2 and is oriented WSW with active and stabilized parabolic dune forms and sand sheets. Initial OSL results from the windward (presumed older) end of the dune field have identified at least four periods of dune activation between 8 and 0.7 ka. San Rafael Desert dune field, located approximately 25 km southwest of Green River, Utah is composed of multiple dune fields encompassing a greater area (>2500 km2). Linear sand ridges, oriented NNE dominate here, with barchanoid and parabolic dunes present. Preliminary OSL ages identify at least five periods of dune formation between 13 and 0.5 ka. We interpret coeval dune activity the dune fields to represent persistent (at least decadal scale) regional droughts. Chronologically distinct patterns of dune activity are interpreted to reflect local disturbances impacting vegetative cover. Further analyses will refine chronologies of both sites for regional comparison and with existing Holocene climate records.
Location
Room 421
Start Date
4-12-2018 12:00 PM
End Date
4-12-2018 1:15 PM
Holocene chronostratigraphy and paleoclimate implications of dune fields across southern Utah
Room 421
Sand dunes are threshold systems capable of recording past changes in effective moisture and aridity, and sensitive to sustained, decadal-scale drought. Records of past drought can provide a reference to past climate variability and expected extremes in an area. Such records provide data for climate modeling refinement, and regional and community adaptive planning. We use optically stimulated luminescence (OSL) dating and radiocarbon ages from charcoal to investigate eolian activity in two dune fields in southern Utah, located 250 km apart in the central Colorado Plateau. Dune forms in this semi-arid region have been mapped and auger samples obtained from mapped units, typically to depths of 3.5 m with two OSL samples from each core. With OSL ages, chronostratigraphic reconstructions are based on grain size analysis, geochemistry, organic and magnetic properties, and identification of paleosols (representing periods of dune stability). Kanab dune field, located 13 km northwest of Kanab, Utah, covers approximately 12.5 km2 and is oriented WSW with active and stabilized parabolic dune forms and sand sheets. Initial OSL results from the windward (presumed older) end of the dune field have identified at least four periods of dune activation between 8 and 0.7 ka. San Rafael Desert dune field, located approximately 25 km southwest of Green River, Utah is composed of multiple dune fields encompassing a greater area (>2500 km2). Linear sand ridges, oriented NNE dominate here, with barchanoid and parabolic dunes present. Preliminary OSL ages identify at least five periods of dune formation between 13 and 0.5 ka. We interpret coeval dune activity the dune fields to represent persistent (at least decadal scale) regional droughts. Chronologically distinct patterns of dune activity are interpreted to reflect local disturbances impacting vegetative cover. Further analyses will refine chronologies of both sites for regional comparison and with existing Holocene climate records.