姚荣辉,张 波.武威盆地西缘覆盖区构造特征的地球物理证据[J].甘肃地质,2023,(1):1-9
武威盆地西缘覆盖区构造特征的地球物理证据
Structural Characteristics from Geophysical Evidence of the Coverage Area in the Western Margin of the Wuwei Basin
  
DOI:
中文关键词:  武威盆地  二维地震  覆盖区  隐伏构造  地球物理  甘肃
英文关键词:Wuwei Basin  2D seismic survey  hidden structure  Gansu
基金项目:中国地质调查局项目“武威—固原地貌边界带基础地质调查项目”(DD20190018)
作者单位
姚荣辉 甘肃省地矿局第二地勘院甘肃 兰州 730020 
张 波 甘肃省地矿局第二地勘院甘肃 兰州 730020 
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中文摘要:
      武威盆地是河西走廊主要的含油气盆地,也是古生界页岩气勘探的热点区域。由于武威盆地为第四系所覆盖,盆地的结构和构造存在争议。为研究武威盆地西部的地质结构和构造特征,利用二维地震和已有的1 ∶ 5万航磁、1 ∶ 20万重力、钻孔,采用钻孔约束下的重磁震联合反演,对武威盆地西部的结构和构造进行了厘定。研究表明:武威盆地西部的基底岩性复杂,寒武系变质岩、加里东期中酸性岩浆岩交互分布,岩性变化大;盖层以第四系、新近系为主,第四系厚度多在200 m以上;武威盆地西缘可分为古生代—中生代、新近纪、第四系等三个构造活动阶段,古生代—中生代经历了早寒武世NE—SW向伸展变形、侏罗纪末—白垩纪初NE—SW地壳缩短变形、早白垩世NE—SW伸展变形等三个阶段的构造变形,在新近纪晚期经历了伸展断陷过程,在第四纪经历了快速堆积过程;新近系和寒武系之间的区域不整合界面表明,至少在晚中新世(11. 2 Ma)之前,武威盆地西部仍处于准平原化阶段,对晚中新世之前的沉积进行了剥蚀、夷平,造成了武威盆地西部地层分布的不连续;中新世之前,武威盆地西部和北祁连山是连为一体的,即武威盆地在发生相对沉降之前是青藏高原的一部分。
英文摘要:
      Wuwei Basin is an important hydrocarbon-bearing basin in the Hexi Corridor area and a key basin for Paleozoic shale gas exploration. Because the Wuwei Basin is covered by the Quaternary, the structure of the basin is disputed. In order to study the tectonic characteristics of the western Wuwei Basin, the author used two-dimensional seismic and the existing 1∶ 50 000 aeromagnetic and 1∶ 200 000 gravity exploration results, drilling holes. The research results in this paper show that the basement lithology in the west of the Wuwei Basin is complex, Cambrian metamorphic rocks and Caledonian intermediate-acid magmatic rocks are alternately distributed, and the facies change is large. The caprock of the basin is mainly Quaternary and Neogene, and the thickness of Quaternary is more than 200 m. The western margin of the Wuwei Basin can be divided into three stages of tectonic activity: Paleozoic-Neogene, Neogene, and Quaternary. During the Paleozoic-Neogene period, the western part of the Wuwei Basin experienced the Early Cambrian NE-SW-trending extensional deformation, the late Jurassic-early Cretaceous NE-SW crustal shortening deformation, and the Early Cretaceous NE-SW extensional deformation. During the Late Neogene, the Wuwei Basin experienced an extensional fault depression process. During the Quaternary period, the study area underwent rapid accumulation processes. The regional unconformity interface between Neogene and Cambrian indicates that at least before the Late Miocene (11. 2Ma), the western Wuwei Basin was still in the stage of quasi-plainization, and the sediments before the Late Miocene were denuded and flattened , resulting in discontinuous stratigraphic distribution in the west of Wuwei Basin. Before the Miocene, the western part of the Wuwei Basin and the North Qilian Mountains were integrated, that is, the Wuwei Basin was part of the Qinghai-Tibet Plateau before the relative subsidence occurred.
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