Olistostrome and its implications to geological disaster on coastal area with special reference to the Bantimala tectonic complex, Pangkep Regency South Sulawesi Province

Abstract

Olistostrome is clastic sedimentary rock, its formation related to tectonic activity along the plate subduction edge on the front region of the accretion prism. Its formation is a submarine landslide with a mudflow sediment mass. The material components can be mixed from various continental and oceanic sources. As in the complex area of Bantimala tectonics, olistostrome shows typical properties of ugly sorting, floating rock blocks in the sandy matrix, tectonite textures, and constituent rocks generally in the form of metamorphic rocks of subduction and plate collision. The criterion shows the submarine sludge deposits formed in the subduction tectonic area of the marine trough environment where there is an increase in slope due to subduction accretion. This study aims to examine the characteristics of olistostrome as a landslide deposit in the subduction zone about the correlation of disaster in convergent tectonic areas in the present. In the area of Bantimala, the exposure of olistostrome rock is large enough with large dimensions with a mega-landslide. This can happen by earthquakes or critical slope in the past. This phenomenon can be a reference to disaster present-day in subduction areas, as in the island arc of Indonesia, which is a collision area of three plates very vulnerable to this disaster. A submarine landslide can cause disaster to infrastructure, telecommunication cable, gas hydrate dissolution, tsunami disaster and environmental destruction of marine benthos.