The importance of sea-level and climate change, including changing wind energy, on the evolution of a coastal estuary

Abstract

123. km of high-resolution 2-D seismic lines and 6 sediment cores up to 16. m in length were collected from Copano Bay, Texas. These data were used to examine the role of climate and sea-level changes in the evolution of the bay. Paleogeographic maps of the bay were constructed to show how the bay evolved through time. The overall transgression was punctuated by five environmental changes within Copano Bay over the past 9.6. ky. The largest environmental change occurred at 8.2. ka when the bay-head delta back-stepped approximately 7.5. km as a result of a 0.4-1.2. m rapid rise in sea level. With a well constrained model of how the bay changed through time, textural data from the most continuous record of middle-bay deposits was used to produce a proxy for wind strength over the last 8.2. ky. Our wind strength proxy reveals that Copano Bay experienced relatively tranquil winds during the early Holocene followed by its windiest conditions from 5.2 to 4.1. ka and a return to more tranquil winds during the late Holocene. The wind strength proxy was compared with other published paleo-climatic records for the region and a reasonable correlation was found between periods of higher wind energy and drier climate. This study illustrates that despite their complex depositional systems and many sediment and water sources, a system-wide approach to studying an estuary can still be used to extract paleoclimate archives from estuarine deposits. Show more