Date of Award

5-2021

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Earth and Environmental Studies

Thesis Sponsor/Dissertation Chair/Project Chair

Jorge Lorenzo-Trueba

Committee Member

Sandra Passchier

Committee Member

Josh Galster

Abstract

The sedimentary record of fluvio-deltaic environments holds clues to past climate and sea level change. Although theories for stratigraphic interpretation generally rely upon the assumption that the fluvial surface responds uniformly to sea level changes, recent theoretical work suggests that changes in the relief and concavity of the fluvial surface can influence the propagation of sea level information upstream, and result in geologically long-lived lags in the system response. We test this theoretical result using measurements from an evolving experimental delta subject to sea-level cycles. As predicted by the theoretical results, during sea-level fall the relief increases and the fluvial surface curves concave down, whereas during sea level rise the relief decreases and the fluvial surface curves concave up. Although the changes in relief and concavity of the fluvial surface are subtle, these dynamics result in the upper portion of the profile being out phase by approximately half a period with respect to changes in sea level, whereas the nearshore region is in phase. Overall, these results suggest that changes in the upper portion of the fluvio-deltaic surface do not necessarily reflect synchronous changes in sea level, which has implications for the reconstruction of the paleo sea level record.

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