四川海相克拉通盆地显生宙演化阶段及其特征

发布时间：2018-07-31 06:02

【摘要】：四川叠合盆地是在四川海相克拉通盆地基础上形成的。本文利用最新的钻井资料、地震资料及其研究成果,详细阐述了四川海相克拉通盆地在显生宙的演化阶段及其特征。研究结果发现,四川海相克拉通盆地显生宙演化可分为早晚两期,早期为晚震旦世-石炭纪,晚期为二叠纪-中三叠世。两期克拉通演化都经历了早期弱拉张,后期弱挤压阶段。弱拉张初始阶段都有一次海相碳酸盐岩的大面积稳定沉积(震旦系灯影组和二叠系栖霞-茅口组)和随后的隆升剥蚀作用及风化壳岩溶作用。其后进入弱拉张期,发育拉张槽,拉张强度最大的部位均位于克拉通的西北部,都是从克拉通的西北部边缘向克拉通内部减弱。然而,两期拉张槽的充填特征不同,早寒武世绵阳-长宁拉张槽是补偿型充填,与拉张槽周缘相比,拉张槽内沉积厚度巨大;晚二叠世-早三叠世开江-梁平拉张槽为欠补偿型充填,与拉张槽周缘相比,拉张槽内沉积厚度非常薄。拉张期结束后进入弱挤压阶段,形成古隆起,挤压强度最大的部位均位于克拉通的西南部,都是从克拉通的西南边缘向克拉通内部减弱。弱拉张阶段的拉张槽与弱挤压阶段的古隆起均为大角度相交关系;然而,拉张槽和古隆起的规模差别较大,早寒武世绵阳-长宁拉张槽面积约5.4×10~4km~2,对应的加里东期乐山-龙女寺古隆起面积6×10~4km~2;晚二叠世-早三叠世开江-梁平拉张槽面积约2.0×10~4km~2,对应的印支期开江古隆起面积0.8×10~4km~2;晚二叠世-早三叠世蓬溪-武胜拉张槽面积约1.5×10~4km~2,对应的印支期泸州古隆起面积4.2×10~4km~2。绵阳-长宁拉张槽的规模比开江-梁平拉张槽、蓬溪-武胜拉张槽要大,乐山-龙女寺古隆起的规模也大于泸州-开江古隆起的规模。四川海相克拉通盆地显生宙演化特征在很大程度上控制了四川叠合盆地海相油气地质条件的发育和油气藏的形成分布。
[Abstract]:Sichuan superimposed basin was formed on the basis of Sichuan marine craton basin. Based on the latest drilling data, seismic data and their research results, the evolution stage and characteristics of Sichuan marine craton basin in Phanerozoic are described in detail in this paper. The results show that the Phanerozoic evolution of the marine craton basin in Sichuan Province can be divided into two stages: the late Sinian Carboniferous and the late Permian-Middle Triassic. Both stages of craton evolution have experienced early weak tensioning and late weak compression. There is a large area stable deposit of marine carbonate rocks (Dengying formation of Sinian system and Qixia-maokou formation of Permian system) and subsequent uplift and denudation and weathering crust karstification in the initial stage of weak tension. After that, the tensioning trough developed, and the most tensional positions were located in the northwestern part of the craton, which weakened from the northwestern margin of the craton to the interior of the craton. However, the filling characteristics of the two extensional grooves are different. The early Cambrian Mianyang-Changning extensional trough is a compensatory filling, and the sedimentary thickness in the tensioning trough is huge compared with the surrounding margin of the tensioning trough. The late Permian-early Triassic Kaijiang-Liangping extensional trough is undercompensated filling, and the sedimentary thickness of the tensioning trough is very thin compared with the margin of the extensional trough. At the end of the extensional period, it entered the stage of weak extrusion and formed paleouplift. The most extruded parts are located in the southwest of the craton, and are weakened from the southwestern margin of the craton to the interior of the craton. The relation between the tensioning trough in the weak tensioning stage and the paleo uplift in the weak extrusion stage is large angle intersecting, however, the scale of the tensioning trough and the paleouplift is quite different. The area of the early Cambrian Mianyang-Changning extensional trough is about 5.4 脳 104km2, the corresponding area of the Caledonian Leshan-Longnusi ancient uplift is 6 脳 10104km2, the area of the late Permian-early Triassic Kaijiang-Liangping extensional trough is about 2.0 脳 104km2and the corresponding area of the Indosinian Kaijiang uplift is 0.8 脳 104km2. In the late Permian-early Triassic Pengxi-Wusheng extension trough area is about 1.5 脳 10 ~ 4 km ~ 2, corresponding to the Indosinian Luzhou paleouplift area 4.2 脳 10 ~ (4) km ~ (-1) ~ (2). The scale of the extension trough of Mianyang-Changning is larger than that of Kaijiang-Liangping and Pengxi-Wusheng. The scale of ancient uplift of Leshan-Longnusi is larger than that of Luzhou-Kaijiang. The characteristics of Phanerozoic evolution in Sichuan marine craton basin control to a great extent the development of marine oil and gas geological conditions and the formation and distribution of oil and gas reservoirs in Sichuan superimposed basin.
【作者单位】：油气藏地质及开发工程国家重点实验室(成都理工大学);中国石油川庆钻探工程有限公司地球物理勘探公司;中国石油西南油气田分公司勘探开发研究院;
【基金】：国家自然科学重点基金项目(41230313) 中国地质调查局项目(121201021000150009) 国家“973”项目(2012CB214805)联合资助
【分类号】：P534.4;P618.13

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