Contribution of additional sediment to a basin by valley incision and controls on valley preservation in stratigraphy
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In stratigraphy, there have been many studies looking at the geomorphological features generated during sea level variations and the resulting preserved erosional composite unconformities that evolve over time and thus do not correlate to a valley that existed at one given time (Strong & Paola, 2008). Data from the XES 02 experiment that isolated sea level variations from sedimentation and subsidence rates offered a way to look at the exclusive influence of sea level fluctuations on sediment transportation and stratigraphic preservation of valleys (Kim et al., 2006a). This study estimated the amounts of sediment deposited in an experimental basin through time in order to determine (1) the role of valley incision as a basinal sediment source, , and (2) how much of a valley formed during maximum sea level fall is preserved within the basin stratigraphy. Significant valley incision was found during times of rapid sea level fall. Valley incision increased erosion rates up to 5 times those recorded during sea level highs, resulting in a doubling of the basinward sedimentation rates. Stratigraphic preservation of valleys was low, but in those locations where a valley fragment was observed, most of the original valley wall remained. More instances of valley preservation occurred when rapid sea level falls occurred during times of slow, overall sea level rise. Maximum reworking and basinward transport of sediment occurred during rapid sea level falls in an overall falling sea level regime, while preservation of the valleys was greatest during times when rapid falls occurred in an overall rising sea level regime.