赣东北-皖南元古代造山带构造格架及演化

Tectonic Features and Evolution of the Proterozoic Orogenic Belt between Northeastern Jiangxi and Southern Anhui

赣东北-皖南元古代造山带位于扬子板块南缘江南造山带东段,经历了晋宁早期俯冲和晚期碰撞两个造山阶段,自北 而南可划分为九岭褶皱变形区、鄣公山构造混杂岩带、江山-绍兴对接带,其间均以区域性构造带相隔,变形强度依次增强,中 元古代变质地层分属于史密斯、有限史密斯、非史密斯地层范畴,难以建立总体地层层序而区别于传统的"史密斯"地层;同 时,该套地层又形成于元古代扬子、华夏两板块的张开-闭合过程中的统一大地构造背景下,存在着一定的必然联系而有别于 "地体构造"、"构造混杂岩";依据地层组成结合岩石化学研究,在"构造混杂岩"基础上建立了"双列岛弧"的"沟弧盆体系"模 式。

The Proterozoic erogenic belt between northeastern Jiangxi and southern Anhui is located in the east part of Jiangnan oro-genic belt on the southern margin of Yangtze plate. The belt has undergone two orogenic stages, namely subduction of early Jingning period and collision of late Jingning period. From north to south it can be divided into Jiuling folded deformation area, Zhanggongshan tectonic melange zone and Jiangshan-Shaoxing end-to-end joint zone. Spaced by regional tectonic zones, these units have been deformed in turn in an increasingly stronger trend. The Middle Proterozoic metamorphic strata belong to Smith Strata, limited Smith Strata and Non-Smith Strata respectively, and hence it is difficult to set up a complete stratigraphic sequence to distinguish them from the traditional 'Smith' Strata. Moreover, this set of stratawas formed under the united geotectonic background during the opening and closing of the Yangtze plate and the Cathaysian plate, and therefore some certain connections exist between them. All this distinguishes them from the 'geological body tectonics' and 'tectonic melange'. According to stratigraphic compositionand lithochemistry, a'trench-arc-basin system' model for the dual-arrangedisland arc is established on the basis of the 'tectonic melange'.