Abstract: The Changlin Formation in the Huangtang area, Fujian Province developed bedded siliceous rocks consisting of thin-layered tuff and producing siliceous sponge spicules and siliceous calcareous algaes. The sedimentary environment of the siliceous rocks is complex and their origin is still under debate. Here, based on our field geological survey and petrographic study, as well as analyses of major elements, rare earth elements and trace elements, we show that the siliceous rocks have similar phase behavior as non-hydrothermal siliceous rocks in the Fe-Mn-Al diagram. Moreover, findings of enrichment of Mo, V and LREEs, weak negative Eu anomalies and U/Th values concur with typical biogenic characteristics, while microscopic characteristics show influence of volcanic activity. In the major element discrimination diagrams including Fe2O3/TiO2Al2O3/(Al2O3+Fe2O3), TFe2O3/(100SiO2)Al2O3/(100SiO2) and (La/Ce)NAl2O3/(Al2O3+Fe2O3) diagrams, the siliceous rocks are consistent with continental shelf. Geochemical indicators such as high ΣREE value and values of Ceanom, MnO/TiO2 and (La/Yb)N, all indicate that the siliceous rocks deposited in the shallow sea continental shelf under anoxic condition, affected by terrigenous material in the Huangtang area. Combining other researchers work, we believe that transgression in the study area began in the Late Jurassic accompanied by small-scale volcanic activities in an overall reducing environment, producing isolated deep water areas. Our research may guide future developments in petroleum geology assessment of prospective regions in Fujian and Zhejiang Provinces. 

Key words: southeastern China, Changlin Group, siliceous rocks, geochemistry, depositional environment