Distribution of Foraminifera and Ostracoda in the Kameshwaram Coast, Nagapattinam, South India: Implications for Recogni
Paleo-tsunamis are commonly recognized by the presence of marine sand sheets with microfossils typical of lagoons, estuaries and tidal marshes. Sediment sub-samples recovered from trenches located 500–700 m away from present day shoreline at Kameshwaram,
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Distribution of Foraminifera and Ostracoda in the Kameshwaram Coast, Nagapattinam, South India: Implications for Recognition of Overwash/Extreme Wave Event Deposits P. Elakkiya, S.M. Hussain, and K. Elumalai
Abstract Paleo-tsunamis are commonly recognized by the presence of marine sand sheets with microfossils typical of lagoons, estuaries and tidal marshes. Sediment sub-samples recovered from trenches located 500–700 m away from present day shoreline at Kameshwaram, near Nagapattinam, Tamil Nadu, Southeast Coast of India, show lithological variation and the occurrences of microfossils typical of offshore regions. The assemblage of foraminifera, ostracoda and their distribution pattern in the tsunami inundated area of Kameshwaram coast is discussed. The following species are identified at a depth of 39–43 cm: Ammonia beccarii, Globigerina bulloides, Quinqueloculina sp., Spiroloculina orbis, Propontocypris bengalensis, Propontocypris crocata and Phlyctenophora orientalis. These species might have been brought by the high energy tsunami waves, which might be a 2004 tsunami deposit. However, from the depth of 0–39 cm and 43–80 cm, the sediment is un-fossiliferous. Based on carapace-valve ratio, a higher rate of sedimentation is inferred. This preliminary work on foraminiferal and ostracod distribution refers that the paleo-tsunami sediments originated from coastal to inner shelf environments.
7.1
Introduction
In the past, southeast of India especially the Tamil Nadu State ignored the possible threats from tsunami and large earthquakes. However, on December 26th 2004, the southeast coast of India was affected by a tsunami along with Srilanka, Thailand and other coastal SE Asian countries. It had caused 1,000’s of fatalities and huge economic loses in Tamil Nadu alone. There were many earthquakes since then that forced issuance of announcements on possible tsunami.
P. Elakkiya • S.M. Hussain (*) • K. Elumalai Department of Geology, University of Madras, Guindy Campus, Chennai 600 025, India e-mail: [email protected] Mu. Ramkumar (ed.), On a Sustainable Future of the Earth’s Natural Resources, Springer Earth System Sciences, DOI 10.1007/978-3-642-32917-3_7, # Springer-Verlag Berlin Heidelberg 2013
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Tamil Nadu has no historical records of tsunami and any significant local seismic activity. Geologic records of past tsunami, if any, may help in identifying the threat of the coastal area of Tamil Nadu to tsunami. Many authors have studied the historical hazards through documentation of depositional characteristics of sediments (Darienzo and Peterson 1995; Atwater and Hemphill-Haley 1996; Benson et al. 1997; Bourgeois and Minoura 1997; Hutchinson et al. 1997; Liu and Fearn 2000; Donnelly et al. 2001; Hayne and Chappell 2001; Peters et al. 2001; Jankaew et al. 2008; Monecke et al. 2008; Pinegina et al. 2003; McMurtry et al. 2004). Atwater and Moore (1992) and Kalsey et al. (2005) identified 12 paleotsunamis in Bradley Lake, coastal lake, in Oregon, during the past 4,600 years. The analy
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