Seismic sequence and stratigraphic sequence characteristics in fuqing-pingtan sea area

摘要

The technology of high-resolution seismic exploration is a cost-effective way to carry out the shallow geological exploration. The detection researches are conducted on the stratigraphic sequence of Fuqing-Pingtan sea area with adoption of DAS-1 high-resolution digital seismograph. With the interpretation of multi-channel seismic data, 7 reflection interfaces are divided as: T10, T11, T20, T30, T40, T50 and Tg, based on seismic reflection and reflection interface characteristics. Among them, interface T30 is an angular unconformity one, and taking T30 as a boundary, the sedimentary strata in this area can be divided into two major sets, that is, a strong tectonic movement has taken place between them. Tg is the acoustic basement for seismic exploration. Based on the division principle of seismic sequence, the seismic reflection layers over the basement reflection interface can be divided into 7 different seismic sequences from top to bottom in this area, marked as follows: Ⅰ (submarine～T10), Ⅱ (T10～T11), Ⅲ (T11～t20),Ⅳ(T20~T30), Ⅴ (T30~T40), Ⅵ (T30, T40~T50) and Ⅶ (T50~Tg). With comparison analysis on known geological data in the study area and adjacent areas, the geological ages of different seismic sequences in this sea area can be determined basically as Q3~Q4, Q2, N2, N1, E2, E1 and K2. The sedimentary basement in the study area may consist of intermediate-acid volcanic formed in Mesozoic (J3～K1) and intermediate-acid intrusive rock or migmatite primarily comprised of granite in Yanshan era.