塔中地区中—上奥陶统内波内潮汐沉积与油气勘探

现代海底普遍发育由内波、内潮汐引起的深水牵引流,内波、内潮汐不仅可形成各种小规模、分散的深水牵引流沉积,而且还可建造千米级的大型沉积物波。在古代地层记录中已发现各种厘米级的内波、内潮汐沉积单元,但尚未发现内波成因的大型沉积物波。通过对塔中地区中—上奥陶统碎屑岩段岩心观察和地震剖面的系统分析,发现了该岩段内由内波和内潮汐作用形成的各种牵引流沉积构造单元。已识别出4种内波、内潮汐沉积微相类型及5种基本垂向沉积层序,同时还在研究区中一上奥陶统陆坡相中识别出了内波成因的大型沉积物波。这些内波、内潮汐沉积具有较好的油气潜能,是该区中—上奥陶统潜在的油气勘探新领域。

Middle-Upper Ordovician Internal-wave and Internal-tide Deposits and Their Significance of Petroleum Geology in the Central Tarim Basin

Internal-wave and internal-tide deposits are a new type of deep-water traction current ones found and studied during the last 10 years Deep-water traction currents of internal-wave/ internal-tide ongin are well developed on modern sea floors of the oceans,They can not only produce cm-sized sedimentary structures but also build huge kin-sized sediment waves.Most of these sediment waves migrate up towards slopes.In an- cient stratigraphic record,small-scaled sedimentation units of internal-wave/internal-tide origin have been recognized but large-scaled sediment waves of internal-wave ongin have not Based on detailed studies of rock cores and seismic profiles, different kinds of internal-wave/internal-tide deposits have been recognized in the Middle-Upper Ordovician clastic rock members in the central Tarim Basin.Four basic sedimentary microfacies and five vertical successions of internal-wave/in- ternal-tide deposits have been recognized and summarized. Especially,according on detailed studies of seismic profiles, the large-scared upslope-migrating sediment wave,which can be explained as the origin of internal waves,was discovered in the Middle-Upper Ordovician continental slope facies These internal-wave/internal-tide deposits have good capability of reservoirs and may be a new potential field of petroleum explo- ration in this study area.