金衢盆地的沉积相

Sedimentary Facies and Evolution of Tectonic Environments in the Jinhua-Quzhou Basin,Zhejiang Province

金衢盆地发育在古生代变质褶皱基底之上 ,前中生代的构造格架和地质特征对金衢盆地的形成与演化具有很大的影响。通过对金衢盆地的古地理环境、沉积构造、沉积中心以及岩相变化的研究 ;分析了金衢盆地的形成与演化历史 ,讨论了晚中生代—新生代的构造环境演化。研究表明 :①金衢盆地是由挤压到拉张形成的断陷盆地 ,盆地边界大多为正断层 ;②地层序列在盆内不同位置变化较大 ;③沉积相 :金衢盆地各时段沉积相的展布各具特色 ,并且演化序列比较清晰 ;冲积扇相以冲积扇裙的形式分布于盆地南北两缘 ,且有一定差异 ;河流及沙洲相分布于盆地中部 ,即衢县和龙游之间的区段 ;三角洲相主要有扇三角洲、辫状三角洲及正常三角洲 ;研究区发育湖泊相 ,其中滨浅湖和半深湖占绝对优势。

Jinhua-QuzhouBasin developed on the metamorphosed basement of Palaeozoic fold, and its formation and development was greatly influenced by pre-mesozoic tectonic framework and geological characteristics. In this paper, the author studied paleogeographic environment, sedimentary structure, depocenter and paleolithological changes etc., analyzed Jinhua-Quzhou Basin's history of formation and evolution and discussed its evolution of tectonic setting from Late-Mesozoic to Cenozoic. From what was studied, four conclusions have been reached: ①Jinhua-Quzhou basin was a fault basin because of compression and then extention; and its boundaries were mostly normal faults. ②In different areas of the basin, there were different stratigraphic sequences. ③Sedimentary facies: the distribution of Jinhua-Quzhou Basin's sedimentary facies varied in different stages, and to some extent, the evolution sequences were clear. Alluvial fan facies spread in northern and southern borders of Jinhua-Quzhou basin as alluvial fan apron with some differences. River facies and sand bank facies distributed in the middle of Jinhua-Quzhou Basin, locating in sectors between Quxian and Longyou. Delta facies included fan delta, braided delta and normal delta. Also, in areas we studied, there were lake facies, but shore shallow lake subfacies and semi-deep lake subfacies were the most important ones.