In this paper influences of boundary directions on strikes of normal faults in extension basin are discussed according to five planar sandbox experimental models of different boundary geometries. The dimension of rig used in this study is 150(length)?40(width)?20(highness)cm. Incohesive dry quartz sand of 300-600uaverage grain size is used in experiments, which has a linear Navier-Coulomb behaviour with inner friction angles of 31 to 33?.Experiments are conducted in constant displacement rates of 4.48?10-3s-1-8.33?10-3s-1. It is indicated that extensional deformation of one direction can produce normal faults of different strike directions because of variation in directions of extensional boundary. Normal faults of different strikes in extensional rifting basins are not surely caused by regional tectonic stresses of different directions or structural deformations of multiphase. Strikes of normal faults in extensional rifting basins are dependent on the direction of extensional boundary and the tectonic extension direction. Effects of extensional boundary decrease with increase in distances from the boundary. Strikes of normal faults near extensional boundary are controlled mainly by its directions and can approximately reflect them. Strikes of normal faults in inner parts of the extensional rifting are mainly controlled by tectonic extensional direction and trend to the direction normal to it and mainly reflect extensional direction. Variations in directions of extensional boundary of rifting basins can cause changes of strikes of normal faults. Strikes of the normal faults caused by roll-over deformation above listric normal faults are constantly parallel to strikes of boundary faults.
Zhou Jianxun,Qi Jiangfu. INFLUENCES OF DIRECTION OF EXTENSIONAL BOUNDARY ON STRIKES OF NORMAL FAULTS IN EXTENSION BASIN: INSIGHTS FROM PLANE SANDBOX EXPERIMENTS[J]. Chinese Journal of Geology, 1999, (4): 491-497,450.