【作者】 任升莲；

【导师】 宋传中；

【作者基本信息】 合肥工业大学 ， 矿物学、岩石学、矿床学， 2013， 博士

【摘要】 秦岭造山带是地球表层变形最强烈的地区之一,是扬子和华北两大板块俯冲、碰撞及陆间造山作用的结果。板块汇聚作用引起了华北板块南缘强烈变形,且最终被卷入秦岭造山带中成为造山带的重要组成部分。研究区伏牛山构造带就位于这个特殊的位置,它记录了造山带形成和演化的全部过程。所以,对其变质变形作用细节研究可以恢复板块俯冲碰撞作用、反演古板块的汇聚方式和运动学过程,对建立大陆造山带的结构、演化和动力学模式有重要意义。本文以构造矿物学和板块构造学为指导,以秦岭伏牛山构造带内的洛栾和瓦乔两条断裂带及其影响岩石为标志体,以其构造岩石的宏观、微观及超微变质-变形特征为主要研究内容,以9条横穿伏牛山构造带的横剖面和1条沿构造带的纵剖面为主线,通过重点地段的地质填图、剖面绘制、运动学涡度分析、有限应变测量等构造解析常规方法,分析有关的面理、线理组构、运动学矢量、剪切类型和方式等内容；利用矿物变形与应力关系研究构造岩相带变形的应力、应变状态,估算构造岩相带变形的古应力大小；利用岩石学手段结合不同尺度分析,研究变质岩的矿物成分、结构、构造特征,并确定其分布规律,分析变质相与构造带的关系；利用特征变质矿物研究分析断裂带及两侧变形岩石中特征变质矿物种类、数量及组合关系,解析变形时期构造环境；利用矿物变形特征研究构造岩的变形方式和变形机制,揭示矿物塑性变形序列,特别是特征变质矿物的脆-塑性转换变形机制及影响脆-塑性转换温度、压力、应变速率等因素；通过对变形过程中产生的同构造变质流体的变形特征、成分特征进行分析,探讨其来源及其形成年代；通过对构造带岩石变质与变形特征研究,划分构造带岩石的变质相和变形相,分析同一构造背景下构造带岩石形变与相变之间的关系,建立构造带岩石的变质相-变形相的关系模式。针对秦岭伏牛山构造带的特点,通过大量阅读相关资料和对前人成果的分析总结,了解区域地质背景和研究现状,分析存在的问题,采取大量野外现象观测、室内分析测试和综合研究,尝试用矿物学与构造地质学相结合的研究思路和宏观、微观、超微观变形技术相结合的研究手段和方法,在变形变质岩石学、构造矿物学、构造地质学和地质-热事件年代学等方面做相应的研究,并取得以下创新性研究成果：(1)伏牛山构造带的宏观地质特征伏牛山构造带位于北秦岭北部,北界为洛栾断裂带,南界为瓦乔断裂带。洛栾断裂带作为北秦岭与秦岭北缘的界线,宽十几公里,是由一系列韧性剪切带和夹在其间的岩片组成的构造带。断裂带西窄东宽,总体走向290°,倾向NNE,倾角多为60°。具有四期变形,早期由南向北俯冲,随后产生大规模的左行剪切作用,形成大量的糜棱岩,这期的糜棱岩是本文研究的重点。第三期为弱糜棱岩化作用,最后一期是岩片产生由北向南的逆冲作用。糜棱岩自东向西由粗粒糜棱岩向中粒糜棱岩-细粒糜棱岩变化,分别对应于中下部地壳的变形、上部地壳的下构造层和上部地壳的中上构造层的变形。瓦乔断裂带为伏牛山构造带的南界,是二郎坪岩群与宽坪岩群的界线,宽几公里至十几公里不等,也是由多条韧性剪切带组成。各剪切带产状基本一致,走向290。,倾向NNE,倾角约50°。断裂带内广泛发育糜棱岩、超糜棱岩,糜棱岩矿物σ、δ残斑、石英脉体形态等特征指示其具有由北向南逆冲兼左行平移的特征。(2)伏牛山构造带的显微变形特征伏牛山构造带的岩石主要有糜棱岩、构造片岩、糜棱岩化岩石等。其中糜棱岩按原岩成分的不同分为：长英质糜棱岩、碳酸盐质糜棱岩、镁铁质糜棱岩。通过大量的显微观察和分析,发现整个构造带的矿物组合和矿物变形特征自东向西明显不同,且具有一定的规律。①石英的动态重结晶型式自东向西由高温边界迁移式逐渐转变为亚颗粒式、膨凸式动态重结晶,再往西部又转变为亚颗粒式。②长石的动态重结晶型式自东向西由亚颗粒-膨凸式重结晶逐渐转变为膨凸式重结晶,直至显微碎裂变形,再往西部又转变为塑性变形,出现膨凸式重结晶现象。③黑云母自东向西由浅棕-棕红色半自形细小的片状转变为绿色-棕绿色眼球状残斑,蚀变增强。与此同时,白云母、绿泥石和绿帘石也由少变多。④东部大理岩(碳酸盐)质糜棱岩中的方解石产生了膨凸式重结晶形成了核幔构造,西部的大理岩(碳酸盐)质糜棱岩,只产生了细粒化,并没有明显的重结晶现象。在栾川县庙子出露的灰岩糜棱岩因剪切作用生热而导致隐晶质方解石在强变形域晶体有增大的现象。⑤镁铁质糜棱岩中的角闪石多产生了强烈塑性变形,但动态重结晶现象只有栾川县庙子剖面才能见到,东部角闪石大多数产生绿帘石、绿泥石化,西部角闪石几乎全部阳起石化,显示出韧性剪切使原岩产生了退变质作用。⑥岩石结构和构造自东向西由粒状(柱-粒状)变晶结构、片麻状构造逐渐转变为糜棱结构,片状构造。⑦糜棱岩的类型自东向西也由高温斜长石-钾长石超塑性糜棱岩依次向中温石英-斜长石塑性糜棱岩和中温石英塑性糜棱岩转变,在VII剖面又转向中温石英-斜长石塑性糜棱岩。⑧构造带构造片岩特别发育。东部的构造片岩内残留有较多糜棱结构,说明构造片岩原为糜棱岩经重结晶作用演变成,具有典型的塑性变形特征。而西部的构造片岩则以强烈的构造压扁变形特征为主,兼有剪切作用,矿物颗粒脆性裂纹十分常见,是在脆-韧性条件下形成的半塑性构造岩。说明东段岩石相对西段遭受构造作用的时间更长,层次更深。伏牛山构造带中糜棱岩及构造片岩的矿物变形特征和动态重结晶型式均反映出构造带的温压条件自东向西由高到低,说明伏牛山构造带的东部抬升高于西部。(3)构造岩的变形机制、变形相和矿物塑性变形序列长英质糜棱岩是伏牛山构造带出现最多的一类糜棱岩。东部石英的变形机制为位错攀移成为重要的蠕变机制,为高温塑性变形机制,西部石英则以脆性微破裂、位错滑移与重结晶为主。东部长石的变形机制为位错蠕变为主；西部则以微裂隙、双晶与重结晶为主。因此,东部长英质糜棱岩的形成机制为中地壳偏深的环境下的晶质塑性变形、高温扩散蠕变为主的塑性变形机制；西部则为上地壳下部-中地壳上部环境下的低温扩散蠕变、颗粒边界滑移以及晶质塑性变形控制的塑性变形机制。伏牛山构造带中矿物塑性变形序列为：方解石、黑云母、石英、斜长石、钾长石。伏牛山构造带长英质糜棱岩的变形相变化为：自东向西,依次为二长石变形相、石英斜长石变形相、石英变形相。(4)伏牛山构造带的形成环境1)变质相通过岩石的矿物共生组合分析伏牛山构造带变质相：东部为低角闪岩相,往西逐渐转变为高绿片岩相和低绿片岩相。2)变质变形温度通过变质相、石英动态重结晶型式、石英脉包裹体测温、糜棱岩中的动态重结晶石英分维数、石英组构分析、斜长石和角闪石地质温度计等多种方法的分析和计算,得出伏牛山构造带的形成温度为中温偏高的条件,东部的温度高于西部。洛栾断裂带形成温度范围为300～550℃：瓦乔断裂带形成温度范围为500～550℃。3)压力和应变条件①糜棱岩的动态重结晶石英分维数计算的洛栾断裂带差异应力为0.32～0.41GPa,应变速率值为3.92917E-11～3.17713E-16；瓦乔断裂带的差异应力为32.417～33.524MPa,应变速率值为3.45769E-14～2.14687E-16。两条断裂带的差异应力均表现为自东向西逐渐增大趋势,属于中等应变速率条件。②同构造石英脉的石英晶体位错特征显示：洛栾断裂带具有先挤压后叠加较强剪切改造的特征：瓦乔断裂带则表现出先强烈挤压后叠加弱剪切力为辅的特征。根据位错密度计算的差异应力为：0.71～0.87Gpa,应变速率值为：2.34445E-11～4.05872E-11。③利用角闪石全铝压力计获得洛栾断裂带的压力为：0.75～0.95GPa,瓦乔断裂带的压力为：0.60～0.85GPa。④利用Massonne多硅白云母压力计计算出伏牛山构造带的压力为0.27～0.87GPa。通过上述不同方法得出伏牛山构造带岩石的变质变形的温压条件基本相同,均表现出东部温压条件高于西部。说明东段抬升强,西段抬升弱。(5)构造带运动学特征伏牛山构造带两条主要断裂带的岩石有限应变测量结果显示其运动学特征各自不同：洛栾断裂带单剪作用较强,而瓦乔断裂带以纯剪作用为主。洛栾断裂带岩石的付林系数K值为：1.68-15.13,应变椭球体的形态属于雪茄状,反映出其以剪切拉伸变形为主,且西段强于东段：涡度分析(WK>0.75)显示洛栾断裂带具有简单剪切为主的性质。瓦乔断裂带的付林参数K在0-1之间,应变椭球体为扁椭球状,属压扁型应变。反映出瓦乔断裂带的岩石变形以压扁为主。涡度分析也显示瓦乔断裂带以纯剪性质为主。(6)伏牛山构造带年代学特征同构造石英脉的ESR测年结果显示：在372.9±30.0Ma时洛栾断裂带产生剪切走滑作用,瓦乔断裂带韧性剪切走滑的年龄是275.0±20.0Ma。所测218.0±20.0Ma、120Ma、71.6±7.0Ma的年龄则反映了扬子、华北两大板块印支晚期全面闭合以及燕山期的构造-热事件在北秦岭也产生了一定的影响。北秦岭各构造带在时代上自北向南依次变新,说明是自北向南演化的。(7)伏牛山构造带岩石变质相与变形相的对应关系伏牛山构造的岩石变质相和变形相有明显的对应关系：长英质糜棱岩变形相自东向西依次为二长石变形相、石英斜长石变形相、石英变形相。在地壳层次上表现为从中地壳到上地壳层次。矿物共生组合显示出东部岩石的变质相为低角闪岩相,往西逐渐转变为高绿片岩相和低绿片岩相。从东往西,变质变形条件由高到低。总之,本文以伏牛山构造带中具有特殊构造作用的洛栾断裂带、瓦乔断裂带和受其影响的宽坪岩块、二郎坪岩块北缘、栾川岩片、陶湾岩片、石人山岩块南缘为切入点,通过分析伏牛山构造带岩石的变形细节和应变特征,确定华北板块南缘的变形作用、构造型式,恢复其所在岩相带、主压应力方位及作用方式；通过研究伏牛山构造带岩石的变质特点、形成方式、机理、环境,分析断裂带对其周边岩石的变质-变形影响,建立岩石变质相-变形相的耦合关系等,从构造矿物变质-变形过程、形成方式的角度进一步认识秦岭造山带中大型剪切带在造山过程中的应力、应变状态及演化,利用矿物学-岩石学-微观构造地质学的研究内容和方法,建立板块运动与大陆边缘变质-变形模式,为探索大陆造山带的结构、演化和动力学问题,提供可靠的、精细的支撑数据和资料。更多还原

【Abstract】 Qinling orogenic belt is one of the most intense areas of deformation on the earth surface.It’s the result of the collision and the intracontinental orogeny between Yangtze and North China Blocks. The southern margin of the North China Block strongly deformed because of the plate convergence,and everntually be involved in Qinling orogenic belt as an important part. The study area-Funiushan tectonic belt located here, which records the whole process of the orogenic belt’s formation and evolution.So the detail study of its metamorphic and its deformation can help to restore the subduction collsion,to inverse the way the paleoplate converged and moved, which is very important for the establishment of the structure, evolution and dynamics mode in the continental orogenic.This article is based on structural mineralogy and plate tectonics.lt takes Luoluan and Waqiao fault belts,among Qinling-Funiu mountain tectonic belt,and those influenced rocks as markers. The major studies are the macro,micro and ultra-micro metamorphic and deformation characteristics of crystalline rock in this area.Thi-s article focuses on nine cross sections and a longitudinal section-of petrologic combining the analysis of diverse scales to study mineral composition, minerals structure and texture of metamorphic rocks and find out its regularities of distribution to analysi-s the relation between metamorphic facies and tectonic belts. Study diagnostic metamorphic mineral in deformation rocks among fault zone and its two sides,to analysis its type,counts and symbiotic relationship and finally resolving tectonic setting during M-etamorphosis Period.Take advantage of mineral deformation characteristics to study the deformation pattern and mechanism of the tectonic rock, to reveal mineral plastic deformation sequence,especially the diagnostic metamorphic mineral’s crisp-plastic convert deformation mechanism and its influencing factors,such as the temperature,pressure,strain rate and other factors.With the analysis of the deformation and compositional characteristics of the syntectonic metamorphic fluid which formed during the deformation process.we try to get its source and formation age.Through the study for tectonic rock’s metamorphism and deformation characteristics,we divided the metamorphism and deformation facies in the tectonic belt,and we analyzed the relationship between deformation and phase transition of the tectonic rock in the context of syntectonic,and then establish their relationship schema.For the features of the Qinling-Funiushan tectonic belt, reading a lot and summarying the previous research achievements, we understood the regional geological background, the research status and the existing problems.With a large number of wild phenomenon observations and laboratory analysises,we tried a combination of mineralogical and structural geology and a combination of macro,micro and ultra-micro deformation technology to do the researches.And so we achieved the following innovative research results on deformation-metamorphic petrology,tectonic mineralogy,structural geology and geological-hot chronology of events:(1) macro geological characteristics of Funiushan tectonic beltFuniushan tectonic belt is located on the north margin of the North Qinling, bounded by Luo-Luan fault in the north and Wa-Qiao fault belt in the south.As the boundary fault of north Qinling and the northern margin of Qinling tectonic belt, Luoluan fault zone is a tectonic belt composed by a serious of ductile shear zone and the pieces of rock stuck in between with a dozen kilometers wide. It general strike in290°,trend NNE, and inclination to60°and has four phases of deformation. Early subduction from south to north followed by large scale left-lateral slip with many mylonites forming. The third deformation is weak mylonitization and the last deformation is thrusting from north to south. From east to west, the fine-grained mylonite gradually changed into medium-grained and coarse-grained mylonite, which respectively compare to the mylonite in the middle and lower structural layer of the crust, the lower structural layer of the upper crust, and the middle and upper of the upper crust.As the boundary of the Erlangping group and Kuanping group, the Waqiao fault is located in the southern margin of Funiushan tectonic belt with a dozen kilometers wide and it is also composed by many ductile shear zones and brittle-ductile shear zones, which basically have the same occurrence(crosspitch:290°,trend:NNE, inclination:50°). Mylonite, ultramylonite, mylonite mineral σ、δ porphyroclastics,the quartz veins and many other features extensively developed in the fault zone, indicating that the fault zone thrust from the north to the south with sinistral component.(2) microscopic deformation characteristics of Funiushan tectonic belt Rocks in Funiu tectonic belt are mainly mylonite, tectonic schist, mylonitization rock. According to the different components of original rocks, Mylonites are divided into felsic mylonite, carbonate mylonite, mafic mylonite. Through microscopic observation and analysis, we found the entire structure with mineral assemblages and mineral deformation characteristics significantly different from east to west, and with some regularity.①Types of quartz dynamically recrystallization from east to west change from grain boundary migration recrystallization to subgrain rotation recrystallization, then to bulging recrystallization, but transformed into subgrain rotation recrystallization in the west part.②Types of feldspar dynamically recrystallization from east to west change from subgrain rotation recrystallization to bulging recrystallization, but transformed back to s bulging recrystallization in the west part.③Biotite from east to west changes from a light brown-brown hypidiomorphic into tiny flakes green-brownish green augen porphyroclasts, alteration increased. At the same time, muscovite, chlorite and epidote increased. ④The calcite in eastern marble (carbonate) mylonite occurred bulging recrystallization formed the core-mantle structure, but only found fine graining in western marble (carbonate) mylonite, and no significant recrystallization. Aphanitic calcite crystals in Limestone mylonite in Miaozi strong fields has increased due to heat caused shear effect at Miaozi area in Luanchuan County.⑤Hornblende in mafic mylonite occurred a strong plastic deformation, but the dynamic recrystallization only observed in Miaozi profile. Most of the eastern amphibole occurred epidotization and chloritization, Almost all western amphibole occurred actinolition, showing retrograde metamorphism of the original rocks due to ductile shear.⑥Rock texture and structure from east to west change from granoblastic texture and gneiss ic structure gradually into mylonitic texture, schistose structure.⑦Types of mylonite from east to west change from a high-temperature plagioclase K-feldspar superplastic mylonite to the medium temperature quartz-plagioclase plastic mylonite and medium temperature quartz plasticity mylonite, then turn back to the medium temperature quartz-plagioclase plastic mylonite⑧Tectonic schists are particularly developed. Eastern schists have more remaining mylonitic structure inside, indicating tectonic schists are mylonite originally by recrystallization, with the typical plastic deformation. The western schists subjected intense flattening and shearing, brittle crack of mineral particles are very common, are semiplastic tectonic rocks formed under the brittle-ductile conditions. It indicates that eastern schists are suffered tectonism longer and deeper.Mineral deformation characteristics and types of dynamic recrystallization of mylonite and schist in Funiushan tectonic belt shows the temperature and pressure conditions are decreasing from east to west, indicating the eastern uplift is higher than the west in Funiushan tectonic belt.(3) Deformation mechanism, deformation facies and mineral plastic deformation sequence of tectonic rocks.Felsic mylonite is the most common in Funiushan tectonic belt. Dislocation climb creep has become an important deformation mechanism of eastern quartz. It is a high-temperature plastic deformation mechanisms. However the deformation mechanism of western quartz is based brittle microfracture, dislocation glide and recrystallization. The deformation mechanism of eastern feldspar is dislocation creep in main; but microfractures, twinning and recrystallization are common in western feldspar. Therefore, the deformation mechanism of felsic mylonite in east part is formed in the middle crust environment, which mainly contain crystalline plastic deformation and high-temperature diffusion creep; in the western, the plastic deformation mechanism is formed in the lower part of the upper crust and the upper part of the middle crust, controlled by low temperature diffusion creep, grain’s boundary slip and plastic deformation of crystalline. The mineral plastic deformation sequence in Funiushan tectonic belt is:calcite-biotite-quartz- plagioclase-K-feldspar.Deformation phase of felsic mylonite in the Funiushan tectonic belt changes from east to west, followed by two-feldspar deformation phase, quartz-plagioclase deformation phase, quartz deformation phase.(4) The environment of deformation in the Funiushan tectonic belt.1) metamorphic faciesMineral assemblages suggested that the metamorphic phase in the east is lower amphibolite phase and to the west it gradually transformed into high greenschist phase and low greenschist. From east to west, the condition of metamorphic-deformation became lower.2) the temperature of metamorphism and deformationThrough calculations and analyze with the methods including metamorphic phase, recrystallization types of quartz, inclusions’temperature in the quartz veins, the fractal dimension of dynamically recrystallized quartz in mylonite, fabric analysis of quartz, geothermometer of plagioclase and hornblende, and so on, we realize that the formation temperature of Funiushan tectonic belt is in medium-high temperature condition, and it higher in the east than in the west. The formation temperature of Luoluan fault is300-550℃, and the Waqiao fault belt is500-550℃.3) pressure and strain condition①mylonite dynamically recrystallized quartz fractal dimension calculation shows the different stress of Luoluan fault belt is0.32～0.41GPa, strain rate is3.92917E-11～3.17713E-16; the different stress of Waqiao fault belt is32.417～33.524MPa, strain rate is3.45769E-142.14687E-16. Two faults are expressed as differential stress increases gradually from east to west trend, belong to medium strain rate conditions.②syntectonic quartz vein quartz dislocations characterized show the Luoluan fault belt has the characteristics of compression first and later superimposed strong shearing; Waqiao fault belt suffered intense compression first, then supplementary weak shearing. According to the dislocation density calculated differential stress is:0.71～0.87Gpa, strain rate is:2.34445E-11～4.05872E-11.③the pressure calculated by the hornblende aluminum geobarometer shows the pressure of Luoluan fault belt and the Waqiao fault belt are0.75-0.95Gpa and0.60-0.85Gpa respectively.④using Massonne Phengite geobarometer calculated the Funiushan tectonic zone pressure is0.27-0.87GPa.Through the different methods calculated the rock metamorphism and deformation temperature and pressure conditions are basically the same of Funiushan tectonic belt, all those results shown the conditions of temperature and pressure is higher in east than the west. They alse suggest the east part uplifts strong, and the west part uplifts weak.(5) the dynamics characteristic of the Funiushan tectonic beltThe finite strain analysis of Funiushan tectonic belt displayed a strong simple shear in the Luoluan fault belt, but pure shear in the Waqiao fault belt. The Fulin coefficient(K) of Luoluan fault is1.68-15.13, strain ellipsoid is cigar-shaped, reflecting shearing extension feature primarily and west part is stronger than east part. Vorticity analysis(WK>0.75) displayed that the Luoluan fault belt possessed dominating simple shear.The Fulin coefficient(K) of the Waqiao fault belt is between0and, strain ellipsoid is flattened ellipsoid-shaped, reflecting flatten strain. Vorticity analysis (WK<0.75) showed Waqiao fault belt possessed dominating pure shear.(6) chronological characteristics of the Funiushan tectonic beltESR dating of syntectonic quartz veins displayed the shear deformation time of the Luoluan and Waqiao fault belt are372.9±30.0Ma and275.0±20.0Ma respectively. The measured218.0±20.0Ma,120Ma,71.6±7.0Ma age reflect the Yangtze and North China plates converged in late Indosinian and Yanshanian structure thermal event also had some impact on the North Qinling tectonic belt. Chronology shows that the evolution from north to south is successive in each northern part of Qinling tectonic belt. Ages from north to south are gradually new.(7) the correspondence between metamorphic facies deformation phase of the Funiushan tectonic beltThe metamorphism phase and deformation phase have obvious correspondence relationships, for example, from the east to the west,felsic mylonite’s deformation phase gradually changed from two-feldspar deformation phase to quartz-plagioclase deformation phase and then to the quartz deformation phase,which corresponds to the changes from the middle crust to the upper crust.Mineral assemblages suggested that the metamorphic phase in the east is lower amphibolite phase and to the west it gradually transformed into high greenschist phase and low greenschist.From east to west, the condition of metamorphic-deformation became lower.In general, the article take the Luoluan fault belt, Waqiao fault belt and Kuanping group, north margin of Erlangping group, Luanchuan slice, Taowan slice, south margin of Shirenshan, which possess particular tectonism in Funiu mountain tectonic belt, as point cuts. The deformation and tectonic patterns in southern margin of North China plate is ascertained and its lithofacies belt, the direction and the way it functions of principal compressive stress is restored by analyzing details of deformation and the features of strain of Funiu mountain tectonic zone. Through studies of characteristics of metamorphism, formation mode, mechanism and environment, the effect in deformation-metamorphism on surrounding rock by fault belts is analysised and coupling between metamorphic facies and deformation facies is established. Stress, state of strain and evolution of Qinling orogenic belt and large shear zone during orogentic process are further recognized by studies of metamorphism and deformation in tectonic minerals and formation mode.Based on research contents and methods in mineralogy, petrology and micro-tectonics, plate movement and metamorphic-deformation patterns of continental margin is set up and it offers reliable and refined supporting datas and materials for exploring structure, evolution and kinetics problems of continental orogenic belt.更多还原