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 T3X4 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 T3X4 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.