摘要:四川盆地位于扬子板块西缘和青藏高原东缘，地震勘探资料等揭示盆地前寒武纪基底保存完整的古俯冲带和地堑—地垒结构，说明盆地基底后期构造活动非常稳定；显生宙以来经历晚震旦世—石炭纪、二叠纪—中三叠世两幕克拉通边缘强拉张—强挤压，而克拉通内弱拉张—弱挤压的构造演化过程，体现出盆地内部稳定性结构沉积演化特征。克拉通内弱拉张初期以海相碳酸盐岩大面积稳定沉积（即震旦系灯影组和二叠系栖霞—茅口组）和随后的风化壳岩溶作用（即桐湾期、东吴期等不整合面）为特征，弱拉张期以拉张槽（如：绵阳—长宁拉张槽和开江—梁平拉张槽等）的形成为典型特征；弱挤压则以古隆起（如：加里东期乐山—龙女寺古隆起、印支期泸州古隆起等）的发育为典型特征。四川盆地晚三叠世后的前陆盆地演化阶段受控于其周缘造山带逆冲推覆构造活动，是现今地貌和构造盆地的主要建造期，形成了四川盆地周缘突变（线型）和渐变（弥散型）两种盆山结构。盆地西边界（龙门山）和北边界（米仓山—大巴山）即是线型突变边界，也是扬子地块（板块）的边界，边界几何形状和扬子板块刚性特征对盆山系统结构—构造特征等有较大的控制作用；四川盆地的东边界（齐岳山—大娄山）和西南边界（大凉山）即是渐变弥散型边界，同时也是板（陆）块内部的边界，它们受控于邻区（盆外）的构造变形和盆内沉积盖层中滑脱层的分布特征。受控于盆地（克拉通）周缘活动，四川盆地垂向上前寒武纪基底与盖层、盖层内早期和晚期构造具解耦特征。基底与盖层构造的解耦有利于盆地内部前寒武纪基底结构构造的保存和盖层内大型隆—坳结构的形成演化；盖层内早期和晚期构造的解耦有利于早期构造免遭后期破环，对深层油气藏的保存意义重大。总之，四川盆地可能是具独特形成过程和特征的叠合盆地新类型，其突出特征表现为周缘活动、内部稳定及早期和晚期构造解耦。
关键词: 强拉张—强挤压/
弱拉张—弱挤压/
突变型盆山结构/
渐变型盆山结构/
构造解耦/
叠合盆地
Abstract:The Sichuan Basin locates at the eastern margin of the Tibetan Plateau, and the western margin of the Yangtze plate, of which the recent seismic data show the intact Pre-Sinian structures of the plaeo-subduction and rifts, indicating of long-term tectonic quiescence of the basement. The Sichuan Basin（marine craton）has experienced two-episodes of weak extension-weak shortening across the craton（basin）, combined with intensive extension-intensive shortening in the（craton）basin′s periphery during Phanerozoic time. The two-episodes are Late Sinian（Edicarian）to Carboniferous epoch, and Permian to Middle Triassic epoch. Both of the extensional episodes are characterized with deposits of marine platform facies （e.g., the Upper Sinian Dengying Formation, Middle Permian Qixia and Maokou Formations）, and subsequent karstification as a result of uplifting and erosion. While both of the extensional episodes are dominated with intracratonic sags in the Sichuan Basin （e.g., the Early Cambrian Mianyang-Changning sag, the Late Permian to Early Triassic Kaijiang-Liangping sag）. In subsequent, the evolution of Sichuan Basin is characterized with foreland basin controlled by the basin-mountain systems around the basin, as margin-plate basin-mountain systems and interior-plate basin-mountain systems. The former systems are the Longmenshan, Micang-Dabashan basin-mountain systems at western and northern margins of Yangtze plate, their evolutions are controlled by the geometry of plate margin and competence of basement. In contrast, the latter one consists of the Qiyueshan-Daloushan, Daliangshan basin-mountain systems at the eastern and southwestern margins of Yangtze plate, their evolutions are controlled by detachment of incompetent layers of the basin. Thus, we argued that tectonic decouple occurred across the Sichuan Basin between the Pre-Sinian basement and sedimentary cover, as well as among the sedimentary cover, respectively. The tectonic decouple between the basement and overlying strata facilitated development of basin-scaled paleo-uplift and depression, and preservation of the pre-Sinian structures of plaeo-subduction and rifts. The tectonic decouple among sedimentary strata（cover）further facilitated early structures without deformation by subsequent tectonics, indicative of high-quality preservation for hydrocarbon in deep strata. In general, the Sichuan Basin may indicate a unique type of superimposed sedimentary basin, as formation and evolution mainly controlled by its peripheric tectonics.
Key words:Intensive extension-intensive shortening/
Weak extension-weak shortening/
Margin-plate basin-mountain system/
Interior-plate basin-mountain system/
Tectonic?decouple/
Superimposed basin
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