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循化-贵德地区的循化盆地、贵德盆地和同仁盆地与拉鸡山和西秦岭北缘逆冲带相邻分布.盆地沉积地层主要由渐新统西宁群、渐新统上部至上新统贵德群和下更新统组成.它们由不整合界面分隔,划分为3个盆地相.盆地相1为西宁群,盆地相2为贵德群查让组、下东山组、贺尔加组和甘家砾岩组,盆地相3为共和组及下更新统.3个盆地相均在其中下部或底部发育湖泊沉积,向上转变为冲积扇-辫状河平原沉积体系,呈现出粒径向上不断加大的反序、进积沉积序列.盆地沉积、古流和沉积物碎屑成分分析表明,研究区在西宁群(盆地相1)沉积时期发育大型湖泊沉积盆地,盆地沉积物源主要来自于南侧的西秦岭逆冲带,而拉鸡山逆冲带处于沉积基准面之下,接受沉积;在贵德群(盆地相2)沉积时期,逆冲作用向北迁移,拉鸡山逆冲隆升,研究区盆地分割,主要沿拉鸡山逆冲带南北两侧发育点源扩散型冲积扇-辫状河平原沉积.研究区盆山系统演化对青藏高原远端增生过程具有重要的指示意义.研究结果表明,青藏高原新生代向北东的增生作用在渐新世(29～21.4Ma)已抵达西秦岭北缘地区,增生过程主要表现为向北的单向褶皱逆冲增厚隆升和前缘前陆盆地充填;中新世至上新世(20.8～2.6Ma)高原增生作用跨过研究区可能抵达祁连北缘和六盘山地区,增生过程主要表现为双向基底卷入式逆冲增厚隆升和分割式前陆盆地充填;上新世至早更新世(2.6～1.7Ma)高原远端主要表现为区域剥蚀夷平与山间盆地加积充填.
The Xunhua-Youde basin and the Tongren basin are adjacent to the pull-out rock and the north margin of the western Qinling delta in the Xunhua-Guide region, and the sedimentary strata in the basin are mainly composed of the Xining group of the Oligocene, the upper part of the Oligocene, Eighth Regiment and Lower Pleistocene.They are divided into three basin facies by the unconformity interface.The basin facies 1 is Xining group, basin facies 2 is the Gudequn Chariot Formation, the Xiaodongshan formation and the Holga formation And Ganjia conglomerate, the basin facies 3 is the Republican Group and the Lower Pleistocene.The lacustrine sediments developed in the middle, lower and bottom of each of the three basins, and the sedimentary system of alluvial fan-braided river plain turned upwards, The sequence analysis of sedimentary, paleo-current and sedimentary debris in the basin shows that large-scale lacustrine sedimentary basins developed in the depositional period of Xining Group (basin phase 1) in the study area, and the sedimentary sources in the basin mainly come from The western Qinling thrust belt on the south side and the Laji mountain thrust belt are below the sedimentary datum for sedimentation. During the sedimentary period of the Youdequn (basin facies 2), the thrust migration migrated northward and the pull-ge mountain thrust Uplift, basin division of the study area, mainly along the pull Jishan thrust belt north and south on both sides of the hair Point-source diffusive alluvial fan-braided river plain sediments.The evolution of basin-mountain system in the study area is of great significance to the distal hyperplasia of the Tibetan Plateau.The results show that the Mesozoic- 29 ~ 21.4Ma) has arrived in the northern margin of the West Qinling Mountains. The process of accretion is mainly the one-way fold thrust uplift to the north and the filling of the foreland foreland basin. The Miocene-Pliocene (20.8 ~ 2.6Ma) The plateaus may reach the northern edge of Qilian and the Liupanshan area across the study area. The processes of upgrowth mainly include two-way basal inrush thrust thickening and uplifting and split foreland basin filling. During the Pliocene to Early Pleistocene 2.6 ~ 1.7Ma) The distal part of the plateau is mainly characterized by denuded area and accretion fill in the mountain basin.