Untangling Sea Level and Sediment Supply History of the Panther Tongue Delta, Utah, USA

Abstract

The Panther Tongue is a fluvio-deltaic parasequence in the lower part of the Star Point Sandstone formation in the Wasatch Plateau, central Utah, deposited during the late Cretaceous period. The sedimentology of the Panther Tongue and adjacent beach ridges parasequence has been extensively described by Hwang & Heller (2002) and Hampson et al. (2011). This study aims to produce an estimate of the magnitude of the sediment supply and the sea level fluctuations at the time when the Panther Tongue delta was formed. First, two delta sections and a beach ridges section were constructed by interpreting and correlating available logs, using the Manti geological map (Witkind et al., 1987) and geological interpretations from Hwang & Heller (2002) and Hampson et al. (2011). Next, a numerical delta and beach ridges model ‘2DStratSim’ in MATLAB was used to simulate the delta and beach ridges sections. Forward simulations with different sea level and sediment supply scenarios were run in order to determine a model that best fits the constructed delta and beach ridges sections. The input variables of the best matching simulation are the following. The relative sea level falls 28 meters over 80 000 years. The sea level decreases 4 meters over the first 40 000 years and 24 meters over the next 40 000 years. The average bed sediment load supply is 0,03 m3/s. The average suspended sediment load supply is 0,04 m3/s. The bed sediment load supply varies between 0,15 m3/s and 0,005 m3/s. The suspended sediment load supply varies between 0,1 m3/s and 0,005 m3/s. The total bed sediment volume was 1,92??10?^11 m3. The average suspended sediment load supply was 0,04 m3/s. The total suspended sediment volume was 1,55??10?^11 m3/s.