HOLOCENE CHEMOSTRATIGRAPHY OF SPRING SEDIMENTS IN RANGE CREEK CANYON, UTAH

Range Creek Canyon in southeastern Utah is the location of hundreds of Fremont archeological sites. The Fremont, an indigenous pre-Columbian culture of hunters and farmers, lived in the canyon between 500 AD and 1300 AD. To determine what living conditions were like during Fremont occupation, elemental and grain size data were used to reconstruct the paleoclimate of Billy Slope Bog, a wetland spring within Range Creek Canyon. Specifically, fluctuations in the chemical index of alteration and grain size were hypothesized to be a proxy for precipitation-induced erosion, which would help to characterize moisture availability over the last 8,500 years in the canyon. To validate the results, these proxies would also be compared to pollen-based climate reconstructions of Billy Slope Bog. Additionally, to refine the preexisting chronology of climatic events in the canyon, aluminum, titanium, manganese, and silicon spikes were used to try and identify Mazama tephra layers.

Data was collected using a pXRF spectrometer for the elemental analysis, and grain size data was obtained via laser diffraction analysis. The results showed that the chemical index of alteration had a positive relationship to total pollen influx into Billy Slope Bog, and a negative relationship to mean grain size. This indicates that as precipitation increases, so does vegetation. The increase in vegetation limits the influx of larger grain sizes into Billy Slope Bog. From this data, it was determined that the period in which the Fremont resided in Range Creek Canyon was characterized by drought. Additionally, while a potential location for the Mazama eruption within the core was identified, no volcanic glass was found to confirm its presence.