论文部分内容阅读
北疆可划分为三个各具不同特征的大地构造发展阶段,即地槽阶段、地台阶段和地洼阶段。根据地质发展史和构造特征的不同,本区现阶段可划分为三个构造区,即阿尔泰地洼区、准噶尔地洼区和天山地洼区。它们是由后海西地台转化而来的地洼区。 控制北疆各地洼区的形成演化的重要因素,一是地壳结构的不均一性:北疆中部存在厚度相对较小,但较为“稳定”的前寒武纪刚性基底,其周围存在厚度大、但较软弱的海西古地槽褶皱带,它对本区地洼区的形成演化起决定作用;二是“壳幔混熔层”的存在和分布状况:“壳幔混熔层”与地幔活动紧密相关,它的存在对北疆地壳运动和岩浆作用有重大影响;三是北疆各相邻壳体的相对推挤作用。由于地壳膨胀造成侧向的挤压作用,加上相邻壳体的阻挡作用或主动的挤压作用,致形成各种褶皱和断裂及由其组成的各种构造系。 北疆早更新世以来所形成的构造,主要是由于天山地洼区地壳的急激膨胀和来自南北方壳体不同程度的挤压作用所造成。
North Xinjiang can be divided into three different characteristics of the tectonic development stage, namely the geotrake stage, platform stage and depression stage. According to the different geologic history and tectonic characteristics, the present stage of this area can be divided into three tectonic zones, that is, the Altai-Diwa area, the Zungwa-diwa area and the Tianshan-diwa area. They are converted from the post-Hercyn out in the depression area. One of the important factors controlling the formation and evolution of the depression area in the northern part of the country is the heterogeneity of the crustal structure. Precambrian rigid substrates with a relatively small but relatively “stable” thickness exist in the central part of the northern part of Xinjiang, However, the weaker Hercynian geosyncline fold belt plays a decisive role in the formation and evolution of the depression zone in this area. Second, the existence and distribution of “crust-mantle mixed layer”: “crust-mantle mixed layer” and mantle activity Which is closely related to the existence of the North China crustal movement and magmatism have a significant impact; third is the relative movement of the adjacent shell north. Lateral crushing due to crustal expansion, coupled with the blocking or pro-active squeezing action of adjacent shells, results in the formation of various folds and faults and various structural systems formed therefrom. The structure formed since the Early Pleistocene in the northern Xinjiang is mainly caused by the sudden expansion of the crust of the Tianshan depression and the extrusion of different degrees from the northern and southern shells.