摘要

Ping Chau Formation has long been regarded as the youngest formation in Hong Kong since its emergence from Tung Ping Chau, an island on the northeast of Mirs Bay of New Territories. On the basis of field survey, the present study re-collates and re-stipulates typical sedimentary structure and sedimentary environment of Ping Chau Formation at Tung Ping Chau. Furthermore, with combination of geochemical laboratory methods for the first time a systematic analysis of the major and trace elements of Ping Chau Formation, and geochemical characteristics of rare earth elements were studied. The results showed that: Ping Chau Formation was formed in a passive continental margin structural environment; the study area belonged to transition facies ranging from brackish water to fresh water, with salinity increase from bottom to top on the profile showing a tendency of gradual salinization, The sedimentary environment of Ping Chau Formation had an anoxic reducing environment; The study concluded that Ping Chau Formation was formed in a reducing environment of brackish water or shore-shallow lake with low salinity.