【作者】 金宠；

【导师】 李三忠；

【作者基本信息】 中国海洋大学 ， 海洋地质， 2010， 博士

【摘要】 本文通过对华南陆块,特别是中、上扬子地块地层间角度不整合时空分布规律的系统调查和研究,确立了雪峰陆内构造系统中各期构造事件的影响范围以及构造事件造成的不整合的属性；通过野外地质调查和地球物理资料解释相结合,明确了雪峰陆内构造系统内各构造带的滑脱层和整体逆冲推滑体系特征,并根据构造样式对该构造系统进行了构造单元新划分。最后,结合华南周缘造山带构造演化历史分析和华南东部广泛的岩浆岩产出规律,从大陆动力学角度,探讨了雪峰陆内构造系统格局、形成与演化,及其陆内构造形变的动力机制。最终,得出以下几点新认识和新结论：1)雪峰陆内递进变形有两个阶段：自加里东运动以来的幕次递进变形,和晚三叠末期以来的连续扩展递进变形。加里东构造事件影响西界为修水-沅陵-麻阳-三都一线；印支构造事件影响西界为慈利-保靖-三都断裂；燕山构造事件影响扩展至华蓥山断裂。而自晚三叠世末期以来,雪峰陆内构造系统变形时间自东向西逐渐变新。2)确立了中、上扬子地区多套滑脱层次的存在,将沉积盖层中的滑脱层划分出上、中、下三套滑脱组合：二叠统或下三叠统为滑脱面的上滑脱组合；以中下志留统为滑脱面的中滑脱系统和以下寒武统或震旦系底为滑脱面的下滑脱组合。雪峰西侧的北段,上述滑脱层在剖面上表现为跃层向北西拓展的特征,同时主滑脱层从东南向北西表现为由中下组合—中组合—中上组合逐级抬升。3)雪峰陆内构造系统加里东期第二幕逆冲作用,主体上向西逆冲,但在雪峰基底隆升构造带出现向东的反冲。印支-燕山期,雪峰陆内构造系统持续向北西拓展、逆冲推滑,雪峰基底隆升带从而表现为不对称的复合扇状背冲结构。雪峰西侧北段有自南东向北西发育冲断—断弯—断展—滑脱—共轭膝折几种推滑构造样式；而在雪峰西侧南段的贵州地区由于先存断裂的影响,只在黔中地区发育以下寒武统和上二叠统为滑脱层的薄皮推滑构造。虽然雪峰陆内构造系统不同构造单元受不同构造事件叠加情况有着相互叠加并穿时演变的特征,但总体上自东而西依次递进发展。雪峰核部隆起带及东侧主要变形构造样式为叠加于加里东构造之上的印支-燕山期逆冲推覆构造系,雪峰山西侧主体为燕山期推滑褶皱带。4)紫云-罗甸断裂是雪峰陆内构造系统西南界的分划构造,断裂北部的构造与其南部的构造截然不同,并且由北西段向东南段可分为背冲、对冲、叠瓦逆冲和楔冲四种结构样式,该断裂深部和浅部脱藕,深部表现为倾向西南的正断,而断层北侧浅部主要表现为向西南的逆冲,表现出燕山期东部雪峰山基底隆升带对其的挤压影响。5)结合断裂定型和活动年代、变形传递速率、岩浆岩年代和地球化学特征、太平洋板块运动历史对照,本文认为加里东事件、印支事件和燕山事件均为陆内构造事件,其中加里东事件可能为陆内地块间汇聚而产生；印支事件是三面板块挤压围限下的陆内地壳叠置作用产生；而燕山期,湘赣地区岩石圈的减薄是雪峰山及其西侧向西逆冲推滑的直接动力,而湘赣地区岩石圈的减薄事件与太平洋板块运动方向的转变和板缘的远程效应有关。更多还原

【Abstract】 This thesis investigates ranges and distribution of disconformity influenced by each tectonic events since Caledonian period on the basis of a comprehensive fieldwork to angular disconformities and structures; Besides, combined field geological surveys with geophysical data interpretation, the whole detachment is analyzed as well as the entire thrust-decollement system in the Xuefeng intracontinental tectonic system. Thirdly, tectonic units are subdivided in the principle of structure style. At last, by a comparison with tectonic events and magmatism in the surroundings of South China, a geodynamic model of thrusting and decollement in the Xuefeng intracontinental tectonic system is proposed. The major conclusions are presented as follows. 1) Progressive deformation in the Xuefeng intracontinental tectonic system refers to double meanings:①Caledonian progressive deformation from one stage to another, and②diachronous progressive deformation since late-Triassic. The Caledonian and Indosinian deformations are constrained at the east of the Xiushui-Mayang-Sandu line and at the east of the Cili-Baojing-Sandu Fault, respectively.But the Yanshanian deformation range propagated westward to the Huayingshan Fault from the southeast continental margin. Therefore, it is obvious that the diachronously progressive deformation propagated from east to west since the late Triassic.2) Multi-layer detachment fault system are identified and the involved layers can be divided into the upper group, the middle group and the lower group. The upper group is made up of Upper Permian and Lower Triassic. The middle group consists of Lower Silurian. Lower Cambrian and Lower Sinian constitute the lower group. In the northwest of the Xuefeng uplift belt, the major detachment faults propagated vertically by jumping from the lower group to the middle group and to the upper group from SE to NW.3) In the second stage of Caledonian movement, top-to-west thrusting developed in the study area except top-to-east thrusting east of the Xuefeng uplift. During Indosinian and Yanshannian period, thrusting and uplifting continued to develop westward while the Xuefeng uplift belt formed a large-scale, asymmetrical, fan-shaped pop-up structure. Structures in the Xuefeng uplift and its east part resulted from superimposition between Caledonian structures and Indosinian-Yanshannian structures. To the northwest of the Xuefeng uplift belt, the thrust-decollement style varied with "thrust-fault-bending-fault-propagation-detachment-conjugate kink" from east to west. However, thin-skin thrusts and decollements, which were only produced in the Qianzhong uplift on the southwest of the Xuefeng uplift belt (Guizhou), were the result of Yanshannian movement.4) The Ziyun-Luodian Fault is a southeast boundary fault of the Xuefeng intracontinental tectonic system, which includes various structures on each segement. Furthermore, this fault can be divided into 4 segments, and pop-up structures, ramp-faults, imbricate thrustings and wedge-thrustings are identified. Shallow structure of the Fault was a series of top-to-southwest thrust faults which were decoupled with one large-scale normal fault of the fault at depth, Its shallow thrusting is related to the Yanshannian extrusion of the Precambrian basement from the Xuefeng uplift belt. 5) Combined with timing of major faulting, deformation propagation velocity, as well as timing and geochemical characteristics of magmatism and the evolution of the ancient Pacific Plate, it is deduced that Caledonian, Indosinian and Yanshannian events in south China are all intracontinental events. Caledonian event is probably caused by convergence of two intracontinental blocks, i.e. Cathaycian and Yangtze Blocks. Indosinian event, however, is a result of crust overriding under the far-field compression induced from three continental margins. Mesozoic lithospheric thinning of South China, which relates with changes of subduction direction of the ancient Pacific Plate, may make direct influence on the thrust- decollement system during Yanshannian period.更多还原