GRAVITY-GLIDING STRUCTURE IN ANFU,JIANGXI

The Anfu gravity-gliding structure is located in a Paleozoic synclinorium at the southern foot of the Wugong Mountians in western Jiangxi.It is a near- ly E-W-trending thrust-type synclinorial structure.The overlying gliding system is composed mainly of the Upper Permian Leping coal measures and Changxing Formation and the Lower Triassic Daye Formation limestone and sandy shale.The structure consists mainly of the near-E-W-trending Wujia’ ao syncline and the Luojiafang syncline and a series of subsidiary folds on its southern limb.The gentle listric glide fracture surface is a gigantic listrie shear fracture zone or detachment zone composed of a series of shear fracture surfaces.In the north,i.e.in the rear of the gravity gliding structure,the principal glide surfaces all dip to the south at an angle of about 20°,and the dip angle becomes low gradually as it extends to the depth;in the middle part,the glide surface is gentle and dips nearly horizontally;in the south, i.e.in the front of the structure,the glide surface gradually dips to the north and exhibits the features of north-directed imbricate overthrusting. In plan,an arcuate fracture structure is manifest.Along its principal glide surface,there occur shatter breccia or a gliding fracture zone and crumpling zone.The underlying sequence is still composed of the Upper Permian Loping coal measures and Changxing Formation and the Lower Triassic Daye Forma- tion sandy sale and limestone. The Anfu gravity-gliding structure is just located on the southern limb of the Wugongshan major anticline.Its formation and development is obviously closely related to the uplifting of the Wugonshan major anticline and the boun- dary conditions of the fractures to its south.The difference in topography and gravitational unstability resulting from the uplifting of the Wugongshan major anticline to its north are the basic conditions and controlling factors for forming this gliding structure,the long-continued and repeated activities of the fracture zone on the southern margin of the uplift and south-directed successive stepwise subsidence are the prerequisites for xinducing and intensi- fying the gliding. The further understanding of the Anfu gravity-gliding structure is not only of certain theoretical significance but also of special important significance for the prospecting and evaluation the coal field in the area.