四川盆地德阳—安岳裂陷晚震旦世—早寒武世沉积演化特征与有利勘探方向

安岳大气田的发现，推动了板内裂陷动力学及沉积充填过程研究，但目前有关德阳—安岳裂陷成因及演化认识尚存争议。通过大量地震资料解释，结合最新钻井资料，系统研究了裂陷演化成因及沉积充填特征，指出有利勘探区带。主要认识为：①德阳—安岳裂陷形成于晚震旦世—早寒武世，具有“北沉降、南侵蚀”差异演化特征。裂陷由北往南张裂，灯二期台地边缘在绵阳—蓬莱—大足—资阳地区发育；灯四期裂陷进一步向南延伸到泸州地区；灯影末期，裂陷北部沉降，中南部抬升剥蚀，部分地区灯三段和灯四段剥蚀殆尽。②德阳—安岳裂陷灯影末期北部沉降大于南部，沉降中心在绵阳—成都一带；麦地坪末期北部继续沉降，南部开始出现沉降；筇竹寺期形成绵阳—成都、宜宾—泸州南北2个沉降中心。③德阳—安岳裂陷周缘形成侵蚀型、加积型和退积型3类台缘储层，叠合寒武系麦地坪组—筇竹寺组厚层烃源岩，形成了蓬莱—剑阁—老关庙地区和资阳—威远地区2个有利勘探区带，勘探面积达3×10⁴ km²。

Sedimentary evolution characteristics and favorable exploration directions of Deyang-Anyue Rift within the Sichuan Basin in Late Sinian-Early Cambrian

The discovery of Anyue giant gas field has promoted the research on in-plate fracture dynamics and se-dimentary filling process,but the current understanding of the origin and revolution of Deyang-Anyue Rift remains controversial. By interpreting large amounts of seismic data and combining latest drilling data, this paper systematically studied the origin, revolution and sedimentary filling characteristics of the rift and identified favorable exploration zones. The conclusions are as follows: Deyang-Anyue Rift was formed during Late Sinian-Early Cambrian epoch, with a differential evolution characteristic of “sedimentation in the north, erosion in the south”. The rift fractured from north to south, and platform margins were developed in the second member of Dengying Formation in Mianyang-Penglai-Dazu-Ziyang region. In the fourth member of Dengying Formation, the rift further extended south to Luzhou area. In the late depositional stage of Dengying Formation, the northern part of the rift went through sedimentation, and the southern part went through uplift and denudation, resulting in erosion of the third and fourth members of Dengying Formation in some areas. In the late depositional stage of Dengying Formation, the sedimentation volume of the northern part of Deyang-Anyue Rift was bigger than that of the southern part, and the deposition center was located in Mianyang-Chengdu region. During the late depositional stage of Maidiping Formation, sedimentation continued in the northern part and occurred in the southern part. In the depositional period of Qiongzhusi Formation, two deposition centers were formed, with Mianyang-Chengdu in the South and Yibin-Luzhou in the North. Three types of reservoirs related to platform margins were developed, including erosion type, aggradation type and retrogradation type. Combined with the thick source rocks of Maidiping-Qiongzhusi formations, two favorable exploration zones were developed in Penglai-Laoguanmiao of Jiange region and Ziyang-Weiyuan region, the exploration area of which reaches 30 000 km².