台湾海峡西部地震地层分析

SEISMIC STRATIGRAPHIC ANALYSIS OF THE WEST-ERN TAIWAN STRAIT

利用在台湾海峡西部采集的近万公里地震反射资料及围区地质、钻井及地震资料,对晋江凹陷和九龙江凹陷地震反射剖面进行了较详细的描述与分析,以及地震层序和地震相划分,对各地震层序及地震相分别进行了地质年代与沉积相探讨,并首次把九龙江凹陷T_3~0—T_g超层序解释为中生代地层的不同见解,这对研究该区海域沉积史、生油气史、油气储层和盖层,以及进一步开展油气勘探有十分重要的意义。

A seismic stratigraphic analysis of the Jinjiang Depression and Jiulong-jiang Depression was done based on about 10000km of seismic data collected in the western Taiwan Strait and on various geological, drilling and seismic data obtained in adjacent region. Five major unconformities ( T10, T20, T30, T40 and Tg) are defined in accordence with the accoustic signatures. Analysis suggests that T10, T20, T30, T40 and Tg belong to Quaternary, Pliocene, Miocene, Eocene and bottom of the Upper Cretaceous respectively. Some researchers whereas believe that T30 and Tg of the Jiulongjiang Depression are the bottom 昽f Upper Tertiary and Mesozoic respectively. Based on the seismic reflection signatures, we defined two super-seismic sequences, I(seafloor-T30 ) and II(T30-Tg) and subdivided Sequence II into Subsequences II1 and II2 . Based on parameters such as amplitude and seismic facies, we identified a series of seismic facies such as moderate-strong amplitude and continuity facies, moderate-strong amplitude and moderate continuity facies, moderate amplitude and continuity facies, moderate-weak amplitude and moderate continuity facies, moderate-weak amplitude and continuity facies, weak amplitude and continuity facies, amplitude-variable facies and mixed reflection facies. Accordingly, sedimentary facies such as deltaic facies, littoral facies, littoral sandbar facies, neritic sand and mudstone facies and neritic mudstone facies are inferred existing in the western Taiwan Strait. These results are of great importance in studies of the history of sedimentation, hydrocarbon genesis, hydrocarbon reservoirs and caprocks in this region.