HR: 0800h
AN: OS31A-0169    [Abstracts]
TI: Comparative Sedimentology of Recent and Ancient Tsunami Deposits in Sri Lanka
AU: * Jackson, K L
EM: kjackson@rsmas.miami.edu
AF: University of Miami - RSMAS/MGG, 4600 Rickenbacker Cswy, Miami, FL 33149, United States
AU: Amelung, F
EM: famelung@rsmas.miami.edu
AF: University of Miami - RSMAS/MGG, 4600 Rickenbacker Cswy, Miami, FL 33149, United States
AU: Eberli, G P
EM: geberli@rsmas.miami.edu
AF: University of Miami - RSMAS/MGG, 4600 Rickenbacker Cswy, Miami, FL 33149, United States
AU: Jayasena, H
EM: cjayasena@pdn.ac.lk
AF: Dept. of Geology, University of Peradeniya, 4/22 Pitakanda Rd, Anniewatta, Kandy, N/A, Sri Lanka
AU: Kehelpannala, K
EM: kvwilbert@hotmail.com
AF: Institute of Fundamental Studies, Hantana Rd, Kandy, N/A, Sri Lanka
AU: Moore, A L
EM: moorean@earlham.edu
AF: Dept. of Geosciences, Earlham College, 801 National Rd West, Richmond, IN 47374- 4095, United States
AU: Peterson, L C
EM: lpeterson@rsmas.miami.edu
AF: University of Miami - RSMAS/MGG, 4600 Rickenbacker Cswy, Miami, FL 33149, United States
AU: Rankey, E C
EM: grankey@rsmas.miami.edu
AF: University of Miami - RSMAS/MGG, 4600 Rickenbacker Cswy, Miami, FL 33149, United States
AU: Swart, P K
EM: pswart@rsmas.miami.edu
AF: University of Miami - RSMAS/MGG, 4600 Rickenbacker Cswy, Miami, FL 33149, United States
AB: Sri Lankan coastal lagoon sediments contain two coarse sand deposits that are 3690 to 4570 radiocarbon years and display an analogous sedimentary signature to the 2004 tsunami deposit. Based on similar internal stratigraphy, grain size, composition, and age dating, these coarse sand deposits are interpreted to represent paleotsunami deposits. Sediment cores collected during two field campaigns to Karagan Lagoon, located on the southeastern coastline of Sri Lanka, were sampled along parallel and perpendicular transects to the coastline. The cores feature mud-dominated background sedimentation, interrupted by two coarse quartz sand layers with sharp erosive bases at approximately 50 to 80 cm depth. The layers are identified in 4 cores though the vertical thicknesses vary and the layers are not laterally continuous. Cores located closer to the lagoon mouth and the coastline in the direction from which the tsunami arrived contain more sand layers while cores farther away from the tsunami entry point have little to no tsunami deposits preserved. The 2004 tsunami layer is characterized by inversely graded, coarse quartz sand that fines slightly at the top of the core. Below the 2004 layer are approximately 30 cm of normal lagoon sedimentation consisting of organic-rich mud interspersed with brackish molluscs. From 50 to 80 cm, there are two deposits that interrupt the sequence of normal lagoon sedimentation and display similar internal stratigraphy in terms of grain size and type to the 2004 deposit. These deeper deposits are approximately 10 cm thick and are composed of inversely graded, coarse quartz sand intermixed with some silt and shell fragments. The 2004 tsunami deposit in Karagan Lagoon provides a modern analog by which we can interpret the deeper sand layers.
DE: 1861 Sedimentation (4863)
DE: 4239 Limnology (0458, 1845, 4942)
DE: 4564 Tsunamis and storm surges
DE: 7221 Paleoseismology (8036)
DE: 9340 Indian Ocean
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting