Abstract: The tectonic sedimentary environment in the Ordovician Period of central Xing an Block is attracted widespread attention by geologists. On the basis of regional investigation work, the arc and arcback environment of the study area was firstly verified by the clastic rocks in Toudaoqiao area and invasion rocks in Saqitu area. Then the sedimentary environment and its evolution were introduced in detail through a series of sequence stratigraphic correlation in central Xingan Block during Ordovician. The conclusion showed that there was a slope tilted to NE direction and extended to NE direction in the Ordovician period. A series of shoreshallow sea transgressive clastic rocks were found in Halahahe Formation along the slope. The arc volcanic rocks developed extensively in Duobaoshan Formation. The uplift near the island arc contributed to the SWdirection extension parts of the ZhalantunDuobaoshan arc island. The subsidence appeared far from the island arc, and radiolarian cherts were found locally. The island arc progress was over, and the subsidence and clastic rock appeared again during the sedimentation of Luohe Formation. After several times of uplift and subsidence of the crust, the study area was exposed and denuded finally.

Key words: tectonic environment, arc, sedimentary facies, succession of stratum, Duobaoshan Formation, Xingan block