Stratigraphic and petrologic response to Late Pan-African movement in Shidian area, western Yunnan Province

There are a few outcrops of Cambrian strata in Baoshan block, and hence researches in this aspect are limited. Controversy has long existed over the contact relationship between Cambrian and Ordovician strata. Some hold the opinion of conformable contact, others argue for pseudoconformity, and due to the insufficient work, no final conclusion has been reached. During the 1:50000 regional survey performed in Shidian area of Baoshan City, the authors found that Ordovician strata are commonly missing in this area, and Middle Ordovician strata only exist in Banpo area of Shidian. In Dazhai area, Middle-Upper Ordovician Pupiao Formation overlies Upper Cambrian Baoshan Formation in parallel unconformity. In combination with the existent Late Cambrain-Early Ordovician magmatic activities, the authors hold that these phenomena represent the long-distance response to Late Pan-African movement.