THERMAL HISTORY AND TECTONO-GEOMORPHIC EVOLUTION OF PANSHAN PLUTON AT SOUTHERN MARGIN OF THE YANSHAN OROGENIC BELT

The thermal history and uplifting of the Pangshan pluton at the southern margin of the Yanshan orogenic belt were studied in detail by thermochronological dating.It was revealed that the Panshan pluton was intruded at a depth of about 10km before 226.48Ma. This was followed by a rapid cooling at a rate of 10.22℃/Ma during 226.48~204.95 Ma subsequently, it was uplifted 2.5km in the period of 204.95~118Ma at a rate of 0.028mm/a, 1.33km in the period of 118~80Ma at a rate 0.035mm/a, approximately 7km during 80~35 Ma at a rate of 0.08 mm/a, and about 0.5km since 35Ma at a rate of 0.014mm/a.The ring structures system surrounding the pluton formed a little earlier than 226.48Ma, and the boundary normal fault between it and the North China Basin was formed and became active mainly during 80~35Ma.