Transform structures in the northern part of Songliao Basin include transform faultsand transform zones. The transform faults are orthogonal to or obligue to normal faults.Their geometric forms were largely determined by the geometric forms and displacementso f the normal faults that controlled thd depression. The faults

resulted from the activationo f the pre-existing faults or weak belts on the basement

were the fundamental factor thatdivided fault-depressed basins into blocks from south to north

and discontinuous in axis.Transform zones are structural systems which adjusted extensional deformation during theevolution of rift-basin. The transform zones could be divided into synthetic collateral

synthetic overlap

synthetic approach

conjugate divergent

conjugate convergent and conjugate collateral types. All of the above mentioned faults

zones and normal faults formedin rifting stage.