【摘要】 我们把沉积盆地的演化分为建设期和改造期两大阶段,并提出原型盆地恢复的两项主要任务为:重塑盆地建设期的种种特征(包括盆地边界、沉积环境、大地构造背景等)和研究盆地改造期的构造演化特征。对四川海相原型盆地原始边界的地震层析成像研究表明,其结晶基底的北界位于秦岭—大别山造山带下,西北界在松潘—甘孜造山带下,西界和西南界大致与三江造山带东缘重合,东南界大致由华南造山带中的吴川—四会—郴州—江山—绍兴断裂通过。四川海相原型盆地的建设期分为3个阶段:地壳形成阶段(太古代—新元古代中期),边缘裂解阶段(新元古代晚期—寒武纪)和聚合扩边阶段(奥陶纪—二叠纪中期);改造期分为两个阶段:陆内张裂阶段(中晚二叠世)和陆内挤压阶段(三叠纪至白垩纪)。四川海相原型盆地在中生代受到周缘几条大型造山带的改造,构造变形由造山带向盆地内部传播。这些造山带活动的起始和终结的时间各有不同,影响的空间范围和变形强度也不尽相同,其中来自东南沿海方向的挤压活动影响范围最大,变形强度在发育厚皮构造的基底卷入带最强,发育薄皮构造的盖层滑脱带次之,盆地中心的宽缓褶皱带(川中隆起带)最弱。四川海相原型盆地的建设期形成了有利于海相烃源岩的沉积条件(海底火山活动为提高海洋生产力提供了丰富的营养,并为烃源岩堆积保存提供了缺氧环境),四川海相原型盆地的改造期对烃源岩既有正面影响,也有负面影响。正面影响包括:张裂活动使海底地貌高差增大,形成有利于烃源岩聚集的缺氧环境,构造稳定带有利于烃源岩的保存;负面影响包括:基底卷入带中的烃源岩会被剥蚀,当前陆带埋深过大时,或热—构造活动强烈时,烃源岩热演化将进入过成熟阶段。更多还原

【Abstract】 Evolution of a sedimentary basin could be divided into two stages:constructing stage and reworking stage.To restore the proto-type basin has to recurrence the basin characters(original boundary,sedimentary environment,tectonic setting,etc.)in the constructing stage and to reveal tectonic evolution process in the reworking stage.The seismic topographic images revealed that the original boundary of the crystalline basement of proto-Sichuan Basin went beneath the Qinling-Dabieshan orogenic belt in the north,beneath the Songpan-Ganzi orogenic belt in the northwest,along the eastern margin of the Three-river orogenic belt in the west and southwest,and along the Wuchuan-Sihui-Chenzhou-Jiangshan-Shaoxing fault in the Hua’nan orogenic belt in the south east. The constructing stage of the marine proto-Sichuan Basin could be divided into three substages: crust-forming sub-stage(Archean to middle Neo-proterozoic),rifting sub-stage(late Neoproterozoic) and basin enlarging sub-stage(Ordovician to Middle Permian).The reworking stage of the marine proto-Sichuan Basin could be divided into two sub-stages:intra-continental rifting sub-stage(Middle to Late Permian)and intra-continental compressing sub-stage(Triassic to Cretaceous).The proto-Sichuan Basin was reworked at margins by several orogenic belts in the Mesozoic.The Basin-ward deformation propagated from those orogenic belts in different periods and impacted basin in different regions.The deformation extent is the greatest where crystalline basement was involved into thrust,and is the smallest in the basin center where developed only gentle fold. The constructing sub-stage provided favorable condition for marine source deposits.For example,submarine volcanism provided abundant nutrition favoring marine productivity,and anoxic environment favoring accumulation and preservation of source rock.The reworking substage affected the source rocks both positively and negatively.For example,rifting enhanced the submarine relief and caused anoxic environment favoring source rock accumulation and preservation.Uplift during thrusting and folding could cause erosion of source rocks,while gentle folding or less deformed area could preserve source rocks.Suitable bury depth in foreland basin could bring source rock into oil window,while ultra-deep burning could bring source rock into post-mature condition.更多还原