塔里木盆地中央隆起带东段“帚状构造”特征及其形成动力学机制

CHARACTERISTICS OF THE “BRUSH STRUCTURE SYSTEM” AND A PRIMARY ANALYSIS ON ITS FORMATION DYNAMIC MECHANISM IN THE EASTERN CENTRAL UPLIFT BELT, TARIM BASIN

断裂是塔中隆起带东段构造变形的主要方式,也是控制油气成藏与分布的重要因素,其形成机制和过程一直存有争议。文章从李四光教授构造体系理论出发,通过综合解析塔中隆起带东段断裂的几何学、运动学及动力学特征,探讨了塔里木盆地中央隆起带东部"帚状构造体系"形成的地球动力学模型。研究结果显示:塔里木盆地古生代以来受天山、西昆仑山和阿尔金山三大褶皱山系的影响,伴随盆地三个"伸展-聚敛"构造旋回的发展和演化;中央隆起带东段的塔中Ⅰ号断裂、塔中10号断裂、塔中Ⅱ号断裂和卡塔克南缘断裂等断裂于加里东早期产生,并于随后多次活动,它们在剖面上呈现"Y"字型结构,平面上向东南收敛、向西北撒开,和南侧的塘南断裂及车尔臣断裂共同构成"帚状构造"体系;加里东运动以来,该构造体系先后经历了张扭性(加里东早期)→压扭性(加里东中期)→张扭性(海西早起)→压扭性(海西晚期)两大应力场的转换,并于海西晚期基本定型,同时在其周邻地区产生北东、北东东向的次级的、低序次的断裂体系。

Fault is the main type of structural deformation in the eastern part of the middle uplift zone in the Tarim basin, and it is also an important factor controlling hydrocarbon accumulation and distribution. Based on the structural system theory of Professor J.S.Lee, and through the comprehensive analysis of geometry, kinematics and dynamics characteristics of faults in the eastern part of central uplift belt in the Tarim basin, the geodynamics models of "brush structural system" are discussed in this paper. Research results show that: since the early paleozoicera, affected by the three orogenic belts of the Southern Tianshan mountain in the north, the Kunlun mountain in the southwest and the Altun mountain in the southeast and along with the evolutionary process of the three great extension-convergent tectonic cycles, faults, such as the Central Tarim Fault Ⅰ, the Central Tarim Fault 10, the Central Tarim Fault Ⅱ, the Katak southern edge faults and so on, were generated successively and had been active many times. They present as "Y" type structure on the profile, and constrict to the SE direction and spread out to the NW direction on plane, forming as the "brush structure system" together with the Tangnan strike-slip fault and Cheerchen strike-slip fault on the south side. Ever since the early time of Caledonian orogeny, the "brush structure system" experienced two regional stress field conversion history of the tenso-shear stage(early Caledonian orogeny)→ the compresso-shear stage(moddle Caledonian orogeny)→the tenso-shear stage(early Hercynian orogeny) and the compresso-shear stage(late Hercynian orogeny), and basically finalized the design by the time of late Hercynian orogeny, in the meantime, many lower generation faults of NE trend and NEE trend were generated.