THE THIN SKIN TYPE NAPPE STRUCTURES IN MALAN, WESTERN BEIJING COAL FIELD

The thin skin type nappe structures in Malan are composed of F₀₉ and F₀₁ faults,which form the boundary faults and main slip plane of top and bottom nappes respectively,including fourteen fault chip sheets between them.They were disappeared downward on the sliding plane of basement,forming the typical Jura Mountain type thin skin structure.The exotic block got nappe and slip from northwest to southeast,with the sliding distance over 7 km,the length of strata shortened about 5 times and the thickness of strata increased 3 times.The nappe structures,which generated in the middle-late period of Yanshan movement between J₃t and K₁d,cut down and superimposed on the slide-stacking structure system created in the early F₁.The regularities of structural development have important significance for the coal exploration.