Variable Response of Coastal Environments of the Northwestern Gulf of Mexico To Sea-Level Rise and Climate Change: Implications For Future Change

• Main Authors: Anderson, John B., Wallace, Davin J., Simms, Alexander R., Rodriguez, Antonio B., Milliken, Kristy T.
• Format: Text
• Language: unknown
• Published: The Aquila Digital Community 2014
• Subjects: Climate change; Coastal response; Gulf of Mexico; Sea-level; Earth Sciences; Geology; Physical Sciences and Mathematics; Antarc*; Antarctica; Ice Sheet
• Online Access: https://aquila.usm.edu/fac_pubs/19917; https://doi-org.lynx.lib.usm.edu/10.1016/j.margeo.2013.12.008

The results from nearly three decades of marine geological research in the northwestern Gulf of Mexico are compiled in an effort to understand those factors (e.g., sea-level rise, sediment supply, subsidence, antecedent topography) that influenced coastal evolution during the last eustatic cycle (~ 120 ka to Present). Armed with this information, we evaluate coastal response to variable sea-level rise of the Holocene and accelerated rise during historical time to gain a better understanding of how the coast is likely to respond to future changes. The early Holocene evolution of northwestern Gulf of Mexico bays was punctuated by rapid and possibly synchronous flooding events that are interpreted as resulting from episodes of rapid sea-level rise. Two of these events, one between ~ 8.4 and 8.0 ka and the other between ~ 7.4 and 6.8 ka, were associated with known episodes of ice sheet retreat in North America and Antarctica, respectively. During the middle and late Holocene, the east Texas and western Louisiana coasts experienced episodes of stability and growth followed by rapid shoreline retreat, while the central Texas coast remained relatively stable. This variability in coastal response to sea-level rise resulted mainly from differences in sediment supply and the highly irregular antecedent topography on which coastal environments formed. Sand that nourished the evolving east and south Texas, as well as westernmost Louisiana, coasts was derived mainly from transgressive ravinement of deltas that were formed during the falling stage of sea level (MIS5e–MIS2). The loci of these deltas controlled the spatial variability of this offshore sand supply. Sand supply to the central Texas coast has been dominated by converging longshore currents and throughout the middle to late Holocene was large enough to keep pace with sea-level rise. Moreover, sand supply from rivers has varied considerably in response to climate change. During the early Holocene, when the average rate of linear sea-level rise was 4.2 mm/yr, the ...