The newly discovered major thrustbelt in the Jiamusi-Yitong fault zone in Siping city of Jilin province has well developed thrusts

cataclasite

and folds.In areas near the eastern and western main boundary faults

secondary faults are distributed intensively

and folds are dominated by closed vertical bends

while in the central part of the thrustbelt

the strata occurrence is gentle with few faults and folds

indicating that the main boundary faults are the area of compressive stress concentration.Most of the faults thrust towards the 110°-130° irection.According to the relationship of cutting and overlaying between the thrusts and the Mesozoic-Cenozoic strata

the Jiamusi-Yitong fault zone is considered to have experienced at least two periods of strong obduction since the Cretaceous:the first occurred in late Late Cretaceous

when the major thrustbelt was formed;and the second occurred at the end of Oligocene.According to field survey results and basin data

the formation and evolution of Jiamusi-Yitong fault zone can be divided into five stages:namely sinistral strike-slip(early K

1

)

regional stretch(later K

1

-early K

2

)

compressive and thrusting(late K

2

)

fault depression(E)

and compressive inversion(the end of E

3

).