4:45 PM - 5:00 PM
[SVC41-54] The characteristics of seismic stratigraphic facies of Kikai submarine caldera and off the southern Kyusyu
Keywords:Caldera, Sesimic Reflection Survey, Sesimic Sequence Stratigraphy
The results of the high resolution seismic reflection profiles around Kikai caldera and off the southern Kyusyu reveal seismic stratigraphic facies and the geologic structures. Several seismic units characterized by distinctive seismic facies were recognized around Kikai caldera, and these were deformed by faults accompanied with caldera collapse and also slump structures which are widely shown in the vicinity of the caldera. These facies of the units are considered to represent the variations of pyroclastic materials in association with stages of the volcanic activities, and also the deformation of these units can allow us to discuss the caldera formation process. Several uniform units are recognized in the profiles of the northern side of Kikai caldera where is off the southern Kyusyu, and are believed to be primary and secondary deposits supplied by the southern Kyusyu volcanoes including Aira caldera and Ata caldera located in the Kagoshima-bay. In these units has some sequence stratigraphic surfaces and system tracts accompanied with the Quaternary eustatic sea level change and possible subsidence. We will discuss the activities of these caldera volcanoes of the south of the Kyusyu from these stratigraphic structures and sequence pattern of deposits supplied by both of the Kikai caldera and the southern Kyusyu volcanoes.