Characteristics of the Cretaceous alluvial fans in Yongkang and Jinqu Basins, central and western Zhejiang Province
Wu Yinye1, Feng Rongchang1, Yue Ting1,2, Yao Genshun3, Zhang Huiliang3, Ma Liqiao3
1 Research Institute of Petroleum Exploration and Development,PetroChina,Beijing 100083 2 China University of Mining and Technology(Beijing),Beijing 100083 3 Hangzhou Research Institute of Geology,PetroChina,Hangzhou 310012,Zhejiang
Abstract：In Zhejiang Province,southeastern China,there are lots of small Cretaceous sedimentary basins,featured with fluvial and lacustrine red sediments. In this paper,the Tongshanyan outcrop and the Fangyan outcrop,respectively in Yongkang and Yiwu,Jinhua City of Zhejiang Province,were studied. The Zhongdai Formation from Tongshanyan outcrop,in Jinqu Basin, was deposited during the later Early Cretaceous to the earlier Late Cretaceous,while the Fangyan Formation from Fangyan outcrop,in Yongkang Basin,was deposited during the later Early Cretaceous. The continental clastic rocks,in both outcrops,are mainly characterized by alluvial fan and have multiple sets of sedimentary cycle. The main sedimentary characteristics are: the lower part is composed of purplish red massive conglomerate and sandy conglomerate,intercalated with argillaceous siltstone,and locally has purplish red tuff and dark gray basalt;the upper part is composed of brown calcareous siltstone interbedded with argillaceous siltstone,which contains dinosaur fossils “Chilantaisaurus zhejiangensis”. The alluvial fan sedimentary structures are developed,such as large-scale cross beddings. It deposits the slot-flow and braided-channel facies in fan root, while the flake or sheet sandstone facies in middle fan. The latter may be interpreted as sheet flood deposits, and would have the potential to be good oil or gas reservoirs. This paper will be helpful to study the sedimentary characteristics and formation of the root to middle alluvial fan deposits in the small sedimentary basins in the southern China.
Wu Yinye,Feng Rongchang,Yue Ting et al. Characteristics of the Cretaceous alluvial fans in Yongkang and Jinqu Basins, central and western Zhejiang Province[J]. JOPC, 2015, 17(2): 160-171.
