周王断裂野外构造特征对其形成演化的指示

Field structural characteristics of Zhouwang Fault and implications for its formation and evolution

周王断裂是长江中下游地区重要的边界断裂之一,厘定其构造演化特征有助于更好地认识长江中下游地区的成矿构造背景。文章通过详细的野外观察和大比例尺剖面测量,发现周王断裂地表由一系列小规模断层组成,而且其出露位置由西向东不断向北迁移,延伸方向也由近东西向转变为北东东—南西西向。周王断裂并不是地表上白垩统与古生界地层之间的界线,而是宣城盆地基底与南侧皖南褶皱-逆冲带的接触界线,其形成主要是利用早中生代褶皱中的逆断层和顺层断层再次活动而形成正断层;由于被上白垩统地层覆盖,周王断裂表现为一条隐伏断裂。

The Zhouwang Fault is one of the important boundary faults in the middle and lower reaches of the Yangtze River,of which tectonic evolution characteristics is helpful to better understand the metallogenic tectonic background of the middle and lower reaches of the Yangtze River.Based on detailed field observation and large-scale cross-sectional survey,this study finds that the Zhouwang Fault is composed of a series of small-scale faults on the surface,crops out towards the north,from west to east,and the striking direction is changed from nearly E-W to NEE-SWW trending.The Zhouwang Fault is not the boundary between the Upper Cretaceous and the Paleozoic strata on the surface,but the contact boundary between the Xuancheng Basin basement and the fold-and-thrust belt in South Anhui,which formed as a normal fault by using the previous thrust faults and the bedding faults in the Early Mesozoic folds.Because of being covered by the Upper Cretaceous strata,the Zhouwang Fault is a buried fault.