Storm surge deposition by hurricane ike on the mcfaddin national wildlife refuge, Texas: Implications for paleotempestology studies

摘要

Hurricane Ike made landfall at Galveston, Texas on September 13, 2008. A storm surge in excess of 3 m struck the upper Texas coast, situated in the northeast quadrant of the landfalling hurricane. The storm surge caused widespread flooding many tens of kilometers inland and transported large amounts of offshore and littoral sediments into nearshore subaerial environments. This study documents the character of storm surge sedimentation on the McFaddin National Wildlife Refuge, which includes extensive palustrine marshes and large brackish lakes. The storm surge deposit exhibits two distinct styles of sedimentation: a thick, sandy washover fan, extending about 150 m inland, deposited as traction load; and a thinner, finer, more organic-rich blanket of sediments extending more than 2.7 km inland, deposited from suspension. Cores collected from the bed of Clam Lake, a large brackish lake on the refuge, approximately four weeks before and 16 weeks after Hurricane Ike's landfall, show that the storm surge deposited a 10-cm-thick sediment layer onto the lake bed. Lithologically, the deposit was similar to lake-bed sediments and did not form a distinct layer in cores, but it was distinguished by abundant offshore foraminifers. However, examination of a lake-bed core for earlier hurricane deposits revealed that foraminifers are not well preserved, and it was concluded that Clam Lake was unsuitable for paleotempestology studies based on lithologie and foraminiferal evidence of hurricane strikes. The study shows that storm surge sedimentation can extend a considerable distance inland, with the implication that paleotempestology studies could be conducted farther inland than in previous studies if sites suitable for long-term preservation of foraminifers are available.