三亚崖州湾海域上新世以来地震层序地层研究

On seismic sequence stratigraphy since the Pliocene in Yazhou Bay,Sanya,Hainan Island

地质环境的稳定是支持人类社会生存和发展的基础条件之一,对三亚崖州湾海域地层地震相和沉积相进行研究,对该地区的演化过程及未来演化趋势具有科学意义。根据二维地震资料,以层序地层学为理论指导将崖州湾海域地层划分出3个三级层序,自下而上依次命名为SQA、SQB、SQC。在SQA和SQB层序内部以最大海侵面为界划分了海侵体系域和高位体系域,SQC层序还未发育完全,只存在海侵体系域。在研究区的层序地层格架内识别出平行-亚平行反射地震相、下凹状地震相和前积反射地震相3种地震相类型。根据地震相展布特征,认为崖州湾海域沉积地层主要发育三角洲、滨海及浅海3种沉积相类型。上新世以来随着海平面的升降、气候变化及受其影响的物源供给水平变化,研究区由浅海相过渡到三角洲相,最后到现在的滨海相。

The stability of the geological environment is an important prerequisite for the development of the marine economy in China.It is of scientific significance to this region's environmental evolution and future trend.In sequence stratigraphy,based on the 2D seismic data,the strata in the marine area of Yazhou Bay could be divided into three third-level sequences,namely,SQA,SQB,and SQC from the bottom to top.In the SQA and SQB sequences,transgressive and highstand systems tracts are divided by the maximum transgressive surface,and the SQC sequence is not fully developed except for the transgressive system tract.In the sequence stratigraphic framework of the study area,three types of seismic facies,i.e.,parallel sub-parallel reflection facies,depressed reflection facies,and progradational reflection facies,were recognized from the sequence.The pattern of seismic facies distribution shows that the sedimentary strata in Yazhou Bay developed mainly coastal,shore,and shallow marine types.Since the Pliocene,the sedimentation evolved landward from shallow sea to delta,and finally to the coastal facies.The controlled factors in the study area are mainly climate change and sea level fluctuation.