Stratigraphic relationship between microlandform in the southern coastal plain of El Salvador, Central America, and the TBJ tephra erupted from Ilopango Caldera in the 3rd to 6th century

- Group Presentations of Micro-landform and Geography, 4th

Abstract

Microlandform in the Rio Lempa delta, southern coast of El Salvador, Central America, was identified by aerial photo interpretation, and stratigraphy between the microlandform and TBJ tephra erupted from Ilopango Caldera in the 3rd to 6th century was clarified. The results demonstrated that a coastal sandbar surrounding Jiquilisco Bay, which called San Juan del Gozo Peninsula, was formed after the Ilopango eruption. On the other hand, a micro-highland in the Rio Lempa delta and islands in the Jiquilisco Bay are the remnant of old sandbar which existed before the eruption and was eroded after the lagoon was enlarged seaward by the formation of new sandbar. Mangrove peat in the northern coast of the Jiquilisco Bay intercalates inorganic muddy sand deposited after the eruption. These results suggest that sediment supply to the lower Rio Lempa and nothern coast of Jiquilisco Bay could be increased.