CARBONATE STORM DEPOSITS (TEMPESTITES) OF MIDDLE TO UPPER CAMBRIAN AGE IN THE HELAN MOUNTAINS, NORTHWEST CHINA

Storm-influenced shelf carbonate deposits are well developed in the Mi ddle Lo Upper Cambrian of the Helan Mountains, north-est China. The st orm-influenced sequences can be divided into four major kinds of facie s based on their lithologic and petrographic characteristics. They are : 1) supra-intertidal stromatolite-tempestite association, 2) barrier skeletal-oolitic tempestite association, 3) upper shelf proximal micri te-tempestite association, and 4) lower or distal shelf shale-micrite tempestite association. Lithofacies changes and tempestite relationshi ps indicate that the shelf deepened to the south. Vertical frequencies in the sequence of storm deposits display cyclic changes on different orders. These cycles and cyclic orders reflect distinct episodic stor m events.