Coastal foraminifera from the Iranian coast of Makran, Oman Sea (Chabahar Bay to Gawater Bay) as an indicator of tsunamis

Abstract

Extreme coastal inundation associated with the 2004 Indian Ocean and 1945 Makran tsunamigenic-earthquakes highlight the risk of tsunamis to coastlines of the northern Oman Sea. Foraminifera have been used as indicators of paleotsunamis in the past where allochthonous tests, found in low-energy environments such as in coastal lagoons, ponds, and marshes, indicate marine overwash. In this study, we constrain the modern distributions of foraminifera from coastal Iran so that they may be used to identify and interpret (e.g. assess provenance) paleotsunami deposits in the geologic record. We collected surface sediment samples from sixteen sites within the study area from Chabahar to Gawater Bays on the Makran coast of Iran, selecting locations impacted by the 1945 Makran tsunami. Foraminifera obtained from these locations are dominated by intertidal, subtidal, and supratidal species, with minor abundances of planktic taxa. Samples collected from study locations are characterized by abundances of iron-stained and heavily corroded (e.g. edge rounded and pitted) individuals. Cluster analysis was used to determine three foraminiferal assemblages within the Makran coastal zone: subtidal, intertidal and supratidal. Characterizing modern distributions of foraminifera along the Makran coast of Iran will aid in identifying the provenance of older overwash deposits previously identified in this region