ネパール中央西部,アルン川流域西部のチュリア(シワリク)層群

抄録・要旨

In the present study area, the Churia Group is divided into the Arung Khola, Binal Khola, Chitwan and Deorali Formations in ascending order which attains a total thickness from 3,000 to 5,000 meters and ranges in age from about 16 Ma to Recent. In the adjoining area to the east, TOKUOKA et al. (1986) have established the standard stratigraphy of the Churia Group on the basis of paleomagnetic study. The stratigraphy and structures are very well traceable to the present study area. The lower member of the Arung Khola Formation is distributed to the north of Central Churia Thrust (C.C.T), whereas the strata from the middle member of the Arung Khola Formation to the top of the Deorali Formation occur to the south of the Thrust.The C.C.T. has an E-W trend and is very well exposed at two locations, where the steeply dipping Arung Khola Formation of the northern belt is thrust over the gently dipping Deorali Formation of the southern belt. At Parewa Pahar Khola, one meter wide zone of fault-clay has been developed along the thrust. Some basaltic fragments have been discovered from the fault-clay. These fragments are interpreted to have been sqeezed out from the deeper part along the thrust plane.