中上扬子地区碎屑岩—碳酸盐岩混积相发育特征及组合模式研究

Research of the Mixed Model and Developmental Characteristic of the Clastic-carbonatite Diamictite Facies in the Middle of Yangzi Area

混合沉积是沉积学中一个新的研究领域,研究区古生界沉积岩石类型多样,碳酸盐岩和碎屑岩交替出现,为混合沉积的研究提供了良好的实例。在古生代地层沉积格架系统研究基础上,对研究区各时期沉积格局及演化规律进行分析。经过基础性研究后,认为研究区发育以晚奥陶世、早志留世沉积为代表的碎屑岩—碳酸盐岩混积台地以及以早寒武世沉积为代表的碎屑岩—碳酸盐岩混积陆棚沉积2种混积相。碎屑岩—碳酸盐岩混积台地是主要发育于陆源碎屑滨浅海、砂泥质潮坪与碳酸盐缓坡或台地的过渡地带的台地沉积。混积陆棚是指同时发育碎屑岩与碳酸盐岩2种沉积的陆棚。研究区混合沉积主要发育于早古生代早期的镶边碳酸盐岩台地—欠补偿盆地组合和泥盆纪—二叠纪碎屑岩潮坪—碳酸盐岩台地组合内。

The mixed sedimentation was a new research field for the sedimentology. In the study area,the Paleozoic sedimentary rocks have various types. The elastic rock and carbonatite were alternately developed,and it provided a good case study for the research of mixed sedimentation. Based on the research of the Paleozoic depositional framework, we analyzed the depositional pattern and sedimentary evolution of the study area. Two mixed sedimentary facies were proposed for the study area,i, e. , clastic-carbonatite mixed platform facies in the late Ordovician and early Silurian,and the clastic-carbonatite mixed continental shelf in early Cambrian. The clastic-carbonatite mixed platform facies was developed in the transitional area among the terrigenous elastic offshore, arenaceous pelitic tidal flat and carbonatite slope or platform. The mixed sedimentary continental shelf was a kind of continental shelf developed with the elastic rock and carbonatite. In the study area, the mixed sedimentation was mainly developed in the early Paleozoic carbonatite platform with edges-undercompensation basin combination,and the Devonian-Permian elastic tidal flat-ear- bonatite platform combination.