Abstract:

According to sequence stratigraphic analysis,4 sequences of thirdorder could be identified from the Low Tertiary in Tangyuan faulted depression.These sequences are different from each other in scale and composition since they underwent different tectonics.In extension rifting background,fault depressed sequences are mainly composed of thick coarse fragments of lowstand system tract(LST);in rapid extension subsiding background,the sequences are characterzed by finegrain in lower part and coarsegrain in upper part;in the compression uplift background,sequence scale is small and lacustrine facies is poorly development.The most favorable sequence types are quickly depressed faulted sequences and quickly faulted depressed sequences,for they both contain best source,reservoir and seal rocks.

Key words: Tangyuan faulteddepression, tectonism, sequence stratigraphy, sequence type