Abstract:

Through sandbox modeling experiment the strain data were measured to analyze the deformation features of Triassic and Jurassic strata in mid-Qilian orogenic belt. The results show that the deformation feature of Jurassic is obviously different from that of Triassic.Triassic is a set of offshore sediments with sandstone and limestone and mudstone, and the mudstone was green with carbonaceous and calcareous cementation;Jurassic is a set of lacustrine sediments mainly composed by mudstone and sandstone and bearing coal.Triassic sandstones are mostly feldspar-quartz fine-sandstones, and Jurassic sandstones are argillaceous sandstones or gray-wackes with a lot of cuttings.During the late period of Indosinian movement,Triassic shows brittle fault-block motion features and develop fractures and folds, of which the axial planes are vertical,and the hinges strike east to west resulting from north-south direction extrusion;Jurassic develop tight folds because of the intensive squeezing action in Yanshanian.

Key words: mid-Qilian orogenic belt, deformation feature, strain