Abstract: Abundant Early Carboniferous fossils of brachiopods and corals were collected from the formerly Middle Devonian Luoshigou Formation during the geological mapping of the 1:250 000 Chalukou Sheet,Xinjiang.These fossils are dated at the middle Early Carboniferous,and the strata in which the fossils occur are redelineated as the Lower Carboniferous Pasi Group based on the stratigraphic correlation with the Shenxianwan Sheet west of it.This newly-established Pasi Group displays a fault contact with the underlying Lower Silurian Wenquangou Group and an angular unconformable contact with the overlying Lower Jurassic Bagongbulansayi Formation.The discovery of the Early Carboniferous fossils of brachiopods and corals and establishment of the Lower Carboniferous Pasi Group have filled up the space of the Early Carboniferous strata and provided new basic data for the refinement of the stratigraphic sequence framework and evolution on the Tianshuihai microcontinent.