区域挤压体制下盆-山耦合关系探讨——以河西走廊和北祁连山为例

The basin-range coupling under the regional compressional regimes: Examples from the Hexi Corridor Basin and North Qilian Mountains

关键词:  河西走廊  北祁连山  盆地  断裂

Key words:  Hexi Corridor  North Qilian Mountains  basin  fault

摘要:

笔者在盆-山构造及构造地貌发育的基础上,对研究区构造和沉积记录进行了分析,进而探讨了新生代以来河西走廊与北祁连山的耦合关系。区内盆地和山脉是于38Ma前在准平原基础上发育起来的;38~17Ma,研究区处于挤压凹陷状态,随着Ⅰ级夷平面解体而盆地范围扩大;17Ma以来,盆地南缘不断抬升,沉积中心向北迁移,于4.96~3.66Ma、0.93~0.84Ma和中更新世末-晚更新世初形成向北推进的Ⅱ级、Ⅲ级、Ⅳ级夷平面。盆山构造的运动方式有前展式、掀斜式和对冲式3种。前展式是盆山演化的主要方式且发生时代相对较早,后两者明显活动于0.93~0.84Ma,其中掀斜式运动是盆地内横向隆起形成的主要原因,而对冲式运动的标志是盆地北缘龙首山、合黎山的隆起。

Abstract:

The coupling relationship between the Hexi Corridor Basin and North Qilian Mountains is discussed in terms of tectonic and depositional records in the study areas from the Cenozoic onwards. The basin and mountains initiated on the ground of paraplains during 38 Ma B.P. The basin area increased due to the compressional regimes of the study areas and disintegration of I-order planation surfaces during 38-17 Ma. After that, the southern margin of the basin was constantly uplifted and the depocenter migrated northwards. The northward prograded II-, III- and IV-order planation surfaces appeared during 4.96-3.66 Ma, 0.93-0.84 Ma, and the latest stage of the middle Pleistocene to the early stage of the late Pleistocene, respectively. The movement styles of the basin-range structures include piggback, tilting and ramping types. The former one may act as the main style in early stages of the basin evolution, whereas the latter two were active during 0.93-0.84 Ma. The tilting-type movement is responsible for the formation of the transverse uplifts within the basin while the ramping-type movement is manifested in the uplift of the Longshou Mountains and Heli Mountains in the northern part of the basin.