Abstract

Based on analysis results of material composition and other resources of sedimentary rocks in Hà Côi Formation (J1-2 hc) distributed in Ọuảng Ninh province, it was showed that the sedimentary rocks are originated from mixed orogenic sands rich in quartz, they are increasing maturity from the continent block provenances, and affected by recycled orogenic provenances with relation to tectonic settings of a continental passive margin. They were formed in lake, river and swamp environments. In the research area, besides the fossils found as leaf imprints: Coniopteris sp., Equisetites sp., sporomorphs, the trunk fossil discovered in the lower part of the Formation in Móng Cái area enhances biodiversity characteristics of the Formation during hot-dry paleoclimate condition in the Early Jurassic.