Analogue experiments for the Shuangyushi area in the north western Sichuan Foreland Basin and their implications
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摘要: 基于川西北前陆双鱼石地区地震构造解释和砂箱物理模拟实验等,揭示川西北前陆盆地构造变形特征、过程与形成演化机制。标准模型、标准地层模型和断坪-断坡结构模型物理模拟实验揭示出川西北双鱼石地区具有双重构造扩展变形特征,受底部滑脱层系和断坡结构带联合控制,其深部物质变形形成典型冲起构造。断坡结构带对上覆下古生界构造变形及其断裂发育具有重要控制作用,部分断裂体系易于形成高效的下寒武统筇竹寺组源岩-古生界储层“源-储”输导体系。前陆扩展变形带逆断层与相关冲起构造易于形成深部隐伏的双重构造,前陆盆地隐伏构造由新生代晚期构造扩展变形形成,但其构造变形相对较弱,因而具有较佳的晚期油气保存富集条件。“自然界原型到实验模型”的砂箱物理模拟为解译前陆盆地演化过程及其油气富集等提供了独立有效的手段。Abstract: In this study, we conducted three sets of analouge experiments, i.e., the pilot experiment with homogeneous quartz sand with frontal ramp, scaled experiments with embedded layer of silicone and/or frontal ramp, for the Shuangyushi area in the north western Sichuan Foreland Basin.It suggests that the north western Sichuan Foreland Basin is dominated with two-layer style of deformation, in particular, with pop-up in deep strata which is controlled by the basal decollement and frontal ramp.It should be noted that the frontal ramp has significant influence on the undistributed deformation and related fault-style occurred at the overlying sequences, which are in favor of formation for a pathway system between Lower Cambrian Qiongzhushi Formation and Mesozoic carbonate/dolomite reservoir.In contrast to duplex as a result of multistage deformation in the thrust-and-fold-belt, the north western Sichuan Foreland Basin is characterized with gentle deformation, as a result of forelandward propagation deformation in Cenozoic, and thus with a better quality of hydrocarbon preservation.Analogue experiments have been a powerful and indispensable tool to help us understand the thrust-fold-belt and foreland basin, as well as their hydrocarbon accumulation, from nature to models.
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图 6 双鱼石地区典型剖面构造解释及其变形模型对比图
a.Inline-1260测线构造解释及其变形模式图;b.Inline-1940测线构造解释及其变形模式图;P1l.下二叠统梁山组;P2w.上二叠统吴家坪组;其他地层代号说明同图 1
Figure 6. Diagram of typical section structure explanation and comparison of its deformation model in the Shuangyushi area
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