Study On Sedimentary Environment Of Port Island Formation In Hong Kong Global Geopark

Hong Kong Global Geopark is located in the eastern part of Hong Kong.Port Island is a part of the sedimentary area in the geopark,the previous studies about geology are quite few.Under the support from the project of the "Port Island and Bluff Head 1:10000 Geological Mapping",this paper mainly deals with the sedimentary environment of Port Island of Hong Kong Global Geopark.Based on the field investigation and sample collection and indoor research,the sedimentary environment in Port Island is analyzed in terms of sedimentology petrology,stratigraphy,geochemisty,the major results are as follows:(1)The Port Island Formation is composed of rhythmic layers,dominated by siltstone,fine-grained sandstone and conglomerate.The Long Harbour Formation is dominated by rhyolitic brecciated welded tuff and sedimentary tuff.The sedimentary structures in Port Island include parallel bedding,cross-bedding,yielding trace fossils.(2)According to the lithological composition,sedimentary structures,petrological properties,and thin section analysis,as well as the contact between Port Island Formation and Long Harbour Formation,the sedimentary environment of the Port Island Formation should be the arid-semi-arid oxidizing fluvial environment.The sandstone of Port Island Formation belongs to fluvial facies,some tuffaceous content in rocks indicates that some local volcanic activities happen simultaneously.