PRELIMINARY ANALYSIS OF THE TECTONIC ACTIVITIES OF BABAOSHAN AND HUANGZHUANG-GAOLIYING FAULTS IN BEIJING AREA

The tectonic activities of Babaoshan and Huangzhuang-Gaoliying faults are studied,based on new geological data obtained recently.During Cenozoic time Huangzhuang-Gaoliying fault is the main western boundary fault of Beijing Depression and the activity of Huangzhuang-Gaoliying fault was stronger than that of Babaoshan fault.The former be-haves the feature that the high activity part of the fault has changed from the south to the North with the time.Both of the faults are active in Quaternary, but the strong active period of Babaoshan fault was mainly in the Early Pleistocene and activity became very weak later.Till the Middle Pleistocene, Huangzhuang-Gaoliying fault was still very active, its north-ern segment till the Late Pleistocene, even Holocene.In general, the activity of the southern segment of Huangzhuang-Gaoliying fault is weaker than that of the northern one;the ac-tive time of the southern ceased early, but the northern lasted to very late;and the active character of the middle and the southern was dextral-slip, the northern mainly the dip-slip.