南盘江地区紫云变形带分段特征

利用实测南盘江地区紫云变形带(镇宁-桑郎一段)的几条构造剖面及前人资料,分析了沿紫云变形带不同段落的几何学特征、变形样式及运动学特征.紫云变形带上的分段运动特点十分显著.北段(大花哨段)变形卷入地层主要为二叠系-三叠系,变形样式以一系列倾角较缓的逆冲断层和箱状、尖棱褶皱为主,表现出卷入地层相对较新、主滑脱面相对较浅(下三叠统)的表皮逆冲构造的特点.南段(紫云段)变形卷入地层为中泥盆统-三叠系,变形样式以一系列高角度逆冲断层、构造直立带和尖棱状褶皱、揉皱为主,表现为卷入地层相对较早、主滑脱面相对较深(中泥盆统)的薄皮大型倒转背斜.这种差异是由北段位于威宁断陷带和广西裂谷带的交接部位,裂陷较浅,沉积以刚性较强的浅水碳酸盐沉积为主;而南段位于广西裂谷带内,沉积以较软的盆地相泥岩、硅质岩为主造成的.解剖变形带不同段落的沉积、变形特征可更好地研究变形带不同部位的构造特征.

Characteristics of the segments of the Ziyun deformation belt in the Nanpanjiang area, Guizhou, China

By using several structural sections concerning the Ziyun deformation zone(from Zhenning to Sanglang area) in the Nanpanjiang area,this paper discusses the geometry and deformation styles and kinematics character in different segments.Segmentstion is characteristic in the Ziyun deformation zone.In the north section,it is dominated by the shallow-level thrust structure involved in the strata in Permian-Triassic epoch.Their deformation styles are mainly thrust faults and box-or sharp-type folds.Such phenomenon reflects that their slide-planes are relatively shallow(Lower Permian series).Whereas in the south section,the segmentation is controlled by the large scale thinskinned inversed anticlines involved in the strata in Devonian-Triassic epoch,so their deformation order is deeper than the former.Their deformation styles are mainly high-angle thrust faults and steep-dip zones and sharp-type folds.These show that their slide-planes are relatively deeper(Middle Devonian series).These differences are caused by different sediments formed in different rift sections.The north section is located in the transition zone between the Weining rift and Guangxi rift forming the shallow-water carbonate,but the south section is located in the Guangxi rift forming the mudstone and silicalite.By analyzing the character of the sediment type and the deformation style in different sections,people can further understand the structural character in different sections.