退积型扇三角洲高分辨率层序地层学研究

以川西拗陷中段须四下段退积型扇三角洲沉积体系为研究对象，采用地震、测井、录井、露头资料综合研究方法，运用高分辨率层序地层学理论，划分出了四、五、六三个级别的基准面旋回，并分析了各相带不同级别旋回的特征。在此基础上，总结了退积型扇三角洲沉积体系横向和纵向上旋回的分布规律，提出了基准面旋回分布模式。研究认为，川西坳陷中段须四下段为一个四级基准面旋回，其上升半旋回代表一个典型的退积型扇三角洲沉积体系；退积型扇三角洲平原相以基准面上升半旋回为主，其前缘相的旋回类型较丰富；西部龙门山冲断带主要发育上升半旋回，凹陷区为上升半旋回为主的完整旋回，而在远离物源的东部斜坡带多发育近似对称的完整旋回。

HIGH-RESOLUTION SEQUENCE STRATIGRAPHY FOR RETROGRADTIONAL FAN DELTAS

The theory and technology of the highresolution sequence stratigraphy, According to data of seismic, logging and outcrops, the authors study retrogradational Fan Deltas in the lower section of T3X4 in the middle part of West Sichuan Depression, threegrade baselevel cycle secquence is figured out in the section: the forth, the fifth, and the sixth class cycle secquence,and the characteristics of these different grade baselevel cycle secquence is analized. On the, basis, the distribution law of the baselevel cycle secquence in horizone and lengthways inside retrogradational Fan Delta is summarized, and the distribution model of baselevel cycle secquence is put forward. The lower section of T3X4 can be regarded as a forth class cycle secquence, and the rising cycle is a typical model of retrogradational Fan Deltas. The retrogradational Fan Delta plain is dominated by the semirising cycle base level, but the retrogradational Fan Delta front develops all kinds of baselevel cycles. The western Longmen Mountain thrusting belt develops the semirising cycle, the integrated cycles exists in the depression area and the Eastern slope far form the source area,the former develops the incomplete symmetry dominated by uprising semicycle and the latter develop the completenearly symmetry type.