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1.
滇西北金顶超大型铅锌矿田位于青藏高原东南缘兰坪中-新生代盆地中部,是三江成矿带中南段最典型的密西西比河谷型(MVT)矿床之一,其构造控矿和盆地流体成矿特征明显受控于印度-欧亚大陆碰撞有关的区域挤压构造。近年来,矿床浅部地质条件与资源状况已被充分揭露,但其深部地质结构、构造控矿差异性仍不清楚,这也制约了成矿预测和找矿新发现。本文以矿田东北部的跑马坪大型隐伏矿床为研究对象,利用三维地质建模及空间分析方法,识别矿化空间变化及其与断层、不整合面和地层岩性的配置关系,分析构造控矿规律及可能的流体运聚趋势。结果表明,跑马坪铅锌矿床的成矿作用与近E-W向挤压构造对中新统金顶砂泥岩(Mio-j)与上三叠统三合洞组(T_(3)s)不整合面的差异性破坏关系密切,近NS和NE向逆断层与NW向走滑-掀斜断层组合是最重要的控矿构造。其中,近NE向逆断层与不整合面是成矿流体运聚的主要通道,而近于平行的NW向走滑-掀斜断层上盘的T_(3)s高孔渗性角砾状灰岩、含灰岩角砾砂岩及裂隙带因为富含H_(2)S等还原性流体而成为与Mio-j富含金属氧化性盆地卤水混合和金属沉淀就位的最有利空间。由此,逆断层和走滑-掀斜断层组合、特定地层岩性与不整合面联合控制了流体汇聚与混合成矿作用,断层沟通了同位叠加的上三叠统油气藏储层和渐新统-中新统盆地卤水(带),这是铅锌成矿的关键。该成矿模型在金顶矿田及邻区与类似地区均具有普遍指导意义。最后,本文预测沿跑马坪矿区深部及其南北侧延伸区域还存在多条NE向隐伏控矿断层,其成矿潜力大,是下一步找矿勘查的有利靶区。  相似文献   

2.
云南金顶超大型铅锌矿床的成矿地质背景   总被引:17,自引:1,他引:17  
采用构造-沉积综合分析的方法,研究了金顶超大型铅锌矿床成矿的盆地、构造和深部地质背景。研究表明,控矿的古新世-中始新世盆地为走滑拉张盆地,研究区先后经历了古新世-中始新世早期的走滑和拉伸,中始新世-渐新世的挤压推覆和中新世的隆升和走滑,分析了盆地演化、沉积体系、同生断裂活动和逆冲推覆等对金顶超大型铅锌矿床的控制作用,探讨了可能的成矿过程。  相似文献   

3.
青海杂多地区新生代构造特征与两种类型矿床的关系   总被引:9,自引:2,他引:7  
青海南部存在着巨大的成矿潜力,研究该区的构造变形与成矿作用的关系,对于认识区内众多矿床(化)的构造背景和控矿要素具有重要意义.新生代的走滑断裂和逆冲推覆构造是大陆碰撞造山带成矿理论中晚碰撞阶段在青藏高原东、北缘的重要构造形式.走滑断裂呈北西向,控制着藏东一系列走滑拉分盆地和斑岩的产出;逆冲推覆构造走向北西,整体自南向北呈现很好的分带特征,可分为根带、中带和前锋带.研究区存在两种类型矿床,分别为走滑断裂控制的斑岩型矿床和逆冲推覆构造控制的热液型矿床.其中,切过地壳尺度的走滑断裂因减压作用导致含水地幔的部分熔融,进而导致富含挥发分的含矿斑岩上涌、侵位,形成纳日贡玛斑岩型钼(铜)矿;逆冲推覆作用是流体长距离迁移的动力来源,逆冲推覆构造前锋带的逆冲断层上(下)盘破碎带或次级断层附近是成矿流体迁移的疏导系统和金属汇聚、淀积的重要场所.  相似文献   

4.
金顶铅锌矿床是一个以沉积岩(灰岩与砂岩)为寄主岩石的超大型铅锌矿床。本文在对矿区构造和矿床基本特点研究的基础上,重点阐述了两种不同类型矿体(砂岩型和灰岩型)的构造类型、矿石显微构造及矿石组构的特点。本文研究表明,极其发育的断裂构造系统是兰坪盆地地质构造发育的基本特点,在盆地边缘、盆地内部普遍发育了具有薄皮式逆冲断层和推覆构造组合特点的成矿前断裂,它们造成矿区内大规模地层倒转与堆叠现象;盆地中发育了由构造角砾岩与透镜体带构成、宽度达近3km的NE-NNE向成矿期中轴断裂,它控制着矿体或矿床的发育与分布;近SN方向的成矿后地堑构造对于矿床具有破坏作用,并使之剥露于地表。金顶铅锌矿床主要有两种重要的矿床类型,即板状或层状砂岩型矿床和角砾状灰岩型矿床,它们分别位于白垩系钙质长石石英砂岩与三叠系沥青质灰岩构成的两个逆冲席体内。以凤凰山矿区为典型,金顶铅锌矿床具有3层结构:上部的三叠系白云质灰岩岩盖,中部的砂岩型矿体和下部的灰岩型矿体,三者之间被两条作为圈闭存在的重要逆冲断层带间隔。砂岩型矿体与灰岩型矿体之间由几个角砾岩筒连接,作为成矿时期的矿液运移通道存在。破裂与微破裂构造、块状构造、对生脉状构造及假晶构造等是最常见的显微构造型式,它们的存在揭示出破裂与碎裂、充填和交代作用过程在铅锌矿化过程中均起着重要的作用。金顶铅锌矿床的形成与就位,直接受构造作用控制。成矿前的逆冲推覆作用为高压成矿流体的形成以及成矿圈闭的发育创造了条件,成矿期中轴断裂的活动性促使成矿流体向上运移,而灰岩与砂岩的物理性质(包括孔隙度/渗透率以及力学属性)则制约了两种不同类型矿体的出现。致密的灰岩渗透率较低,含矿流体加热了灰岩并使之软化,同时高流体压力使得围岩易碎,形成由早期到晚期的细角砾岩、粗角砾岩和破裂,成矿物质同时沉淀结晶,胶结围岩角砾形成角砾型灰岩矿体。高压流体通过流体通道进入低孔隙度的砂岩后,便迅速弥散于其中,沿着颗粒边界或裂隙充填,并交代岩石中的钾长石碎屑及方解石胶结物,形成块状的砂岩型矿体。  相似文献   

5.
阿吾拉勒成矿带是西天山重要成矿带之一,经历了多期构造作用,并伴生多期成矿作用。本文对成矿带内查岗诺尔矿区及邻区构造变形特征以及变形序列精细解析,探讨构造变形对铁矿的成矿作用以及后期改造作用的影响,为西天山地区铁矿床成因和找矿方向提供新启示。野外构造观察发现,研究区断裂构造主要分为NW-NWW向高角度韧性-韧脆性走滑断层及逆冲推覆断层,以近EW向、近SN向为主的高角度共轭脆(韧)性走滑断层和近SN向脆性右行走滑断层。年代学研究表明,断层分别形成于燕山晚期-喜马拉雅早期、喜马拉雅中期和喜马拉雅晚期,均为成矿期-成矿期后的构造记录。早期高角度韧性-韧脆性走滑断层是区域性控矿构造,而逆冲推覆断层是矿区主导控制性构造;中期共轭脆(韧)性走滑断层对矿体具有较为强烈的破坏和改造作用;晚期脆性右行走滑断层对矿体影响较小。查岗诺尔和智博矿区的断裂构造主要表现为对矿体的破坏和改造作用,而在松湖和塔尔塔格矿区,韧性-韧脆性剪切带是主要的控矿构造。主矿脉与构造密切伴生,具体表现为与成矿作用密切相关的磁铁矿化、绿泥石绿帘石化、碳酸盐化等蚀变多沿构造裂隙发生。  相似文献   

6.
<正>1.刘俊来等(Mineralium Deposita,2010,45:567-582),砂岩型铅锌矿床中方铅矿成矿过程的破裂机制:以云南金顶大型硫化物矿床为例第一作者联系方式:刘俊来,中国地质大学地质过程与矿产资源国家重点实验室,北京100083云南金顶超大型铅锌矿床主要有两种矿床类型,即板状或层状砂岩型矿床和角砾状灰岩型矿床。构造分析表明,逆冲断层与穹窿构造是控制铅锌矿化作用的主要构造。具有3层结构的这两种矿床保存在金顶穹窿构造格架内的两条逆冲席体内。砂岩型矿床形成穹窿的岩盖,灰岩型矿床集中在砂岩型矿床岩  相似文献   

7.
兰坪金顶铅锌矿床泥底辟流体成矿特征初探   总被引:2,自引:0,他引:2  
兰坪金顶铅锌矿床的成矿过程与油气的生成有许多相似之处,泥底辟构造在金顶铅锌矿床的成矿过程中起着极为重要的作用。首先,随着泥底辟的上侵,塑性泥流夹带大量气体到构造圈闭中释放压力,扩大成矿空间;其次,流体的去气作用在构造圈闭中进行一系列的强改造活动,进而促使铅锌矿体的形成。文章通过对金顶铅锌矿床形成有关的泥底辟流体的来源、流体形成原因、流体在张性-挤压走滑盆地阶段的演化及金顶铅锌矿床成矿的泥底辟流体特征的分析,认为兰坪金顶铅锌矿床的形成与泥底辟构造密切相关,该矿床具泥底辟流体的成矿特征。  相似文献   

8.
地处青藏高原东、北缘的兰坪、玉树及沱沱河地区,广泛发育包括金顶超大型矿床在内的大量新生代Pb、Zn、Cu多金属矿床.这些矿床均产于该高原东缘晚碰撞构造转换环境,主体赋存于第三纪前陆盆地内部,以沉积岩容矿,与岩浆活动无关,受逆冲推覆构造系统控制,显著区别于世界已知的各类以沉积岩容矿的贱金属矿床.研究表明,伴随印度.亚洲大陆碰撞造山而产生一系列逆冲断裂系,将前陆盆地侧缘的中生代地层切割成叠置的构造岩片,并推覆叠置于盆地沉积地层之上,形成单冲式或对冲式逆冲推覆构造系统,并控制了Pb-Zn-Ag-C矿床的形成与发育.根据逆冲推覆构造控矿式样和矿化特征,可以识别出4种矿床式:①产于逆冲推覆构造系统前锋带"构造穹隆 岩性圈闭"内的金顶式Zn-Pb矿床;②受控于前锋带冲起构造的河西.三山式Pb-Zn-Ag-Cu矿床;③产于主逆冲断裂带派生的次级断层或平移断层内的富隆厂式Ag-Cu或Cu矿床;④产于主逆冲断裂上盘灰岩层间破碎带内的东莫扎抓式Pb-Zn矿床.这些矿床的矿体多受不同级次的断裂控制,多孔砂岩、白云岩化灰岩及构造破碎带是有利矿化部位.多数矿体显示开放空间充填成矿特点,少数显示层控性,属后生成矿.金属矿物组合主要为低Fe闪锌矿 方铅矿 黄铁矿组合及低温Cu硫化物(黝铜矿系列为主) Ag硫化物(辉银矿、黝银矿、汞银矿) 方铅矿±闪锌矿组合,脉石矿物组合主要为方解石±重晶石±萤石±白云石±天青石,局部见沥青.成矿流体以盐水体系为主,盐度w(NaCleq)变化于1%~28.0%之间,成矿温度较低,通常在80~190 ℃,显示盆地卤水±大气降水的特点.逆冲推覆构造系统对矿床的控制主要体现在:其深部拆离滑脱带可能是流体流长距离侧向迁移的优选通道,主逆冲断裂是成矿流体垂向运移和向上排泄的主要途径,浅部各类样式的逆冲构造是流体汇聚的主要场所.成矿物质以盆地沉积岩贡献为主,部分可能来自幔源岩石.矿床金属组合可能与成矿流体迁移-汇聚过程中流经岩石的性质有关:矿区发育灰岩建造时,出现Zn-Pb(Zn多于Pb)矿化;若发育碎屑岩建造,尤其是红层,则出现Cu-Ag(-Pb)矿化.因此,笔者将这种逆冲推覆构造控制的新类型矿床称之为造山型Pb-Zn-Ag-Cu矿床,其成矿模式可表述为:伴随着印度-亚洲大陆持续碰撞,青藏高原东、北缘中生代构造岩片向盆地中央推覆并置,形成单冲式或对冲式逆冲推覆构造系统,流体从造山带沿拆离滑脱带长距离向前陆盆地方向运移,运移过程中淋滤围岩的金属物质,通过主逆冲断裂垂向沟通,进入浅部各式逆冲构造部位从而形成不同样式的矿床.经综合分析,提出了青藏高原东、北缘受逆冲推覆构造控制的贱金属矿床的勘查要素.  相似文献   

9.
赵发勇铅锌矿床位于三江成矿带中段昌都地区,铅锌矿化发育在新生代区域逆冲推覆构造中,以逆冲断层相关的古溶洞构造为主要控矿构造,代表了逆冲褶皱系MVT铅锌矿床中一种新的成矿模式——溶洞控矿成矿模式。因此,笔者在对赵发勇矿区详细地质填图基础上,对其成矿流体特征、成矿期方解石和硫化物的同位素组成进行了系统研究,以期对逆冲褶皱系MVT铅锌矿床中这一新成矿模式的成因机制进行探讨。赵发勇铅锌矿床矿体呈漏斗状-筒状发育在逆(冲)断层上、下盘的下二叠统和上三叠统灰岩古溶洞中,以角砾状、块状和皮壳状为主要矿石构造,以方铅矿、闪锌矿为主要矿石矿物,经历了硫化物期(I)和硫化物-碳酸盐期(II)两期成矿过程。I期成矿流体总体具低温度(130~140℃)、高盐度(23%~24%NaCl eq.)特征,部分呈现中高温度(约高达400℃)、中低盐度(约低达8%NaCleq.)特征;δDV-SMOW值介于–147‰~–94‰,δ18O流体值介于1.25‰~13.62‰;同成矿期方解石δ13CV-PDB值为–2.4‰~5.1‰,δ18OV-SMOW值为15.1‰~27.4‰。两期硫化物δ34S均为负值(–15.1‰~–1.6‰), 206Pb/204Pb、207Pb/204Pb、208Pb/204Pb组成分别为18.703 0~18.966 2、15.638 9~15.687 2、38.554 8~38.924 0。研究表明, I期铅锌矿化由①封存在地层中的蒸发浓缩的海水或/和区域古近纪—新近纪盆地下渗的盆地卤水形成的低温度、高盐度的本地流体和②由区域或矿区地层释放的蒸发浓缩海水和变质基底释放的变质水混合而成的中低温、中高盐度的区域流体两种流体组成;两期矿化的成矿金属来自造山带中从基底变质岩到盖层灰岩或/和碎屑岩等在内的多套地层,还原硫来自古近纪—新近纪盆地卤水中的硫酸盐±灰岩地层封存水中的硫酸盐的细菌还原作用;富还原硫的本地流体和富金属物质的区域流体的混合是铅锌硫化物沉淀的主要机制。结合对三江带区域溶洞控矿MVT铅锌矿床研究认识,笔者初步建立了逆冲褶皱系溶洞控矿MVT铅锌矿床成矿模型。  相似文献   

10.
青海玉树地区的东莫扎抓和莫海拉亨铅锌矿床位于青藏高原金沙江缝合带和班公湖-怒江缝合带夹持的羌塘地体东北缘,是"三江"北段铜铅锌多金属成矿带铅锌矿床的典型代表,处于玉树逆冲推覆构造带的前锋带位置,但矿床与逆冲推覆构造之间的关系并不明确。野外研究表明,方解石为乳白色,结晶粗,呈不规则状、囊状,被后期矿化所穿切,形成于挤压(逆冲推覆阶段)到拉伸(成矿阶段)的过渡阶段,是联系逆冲推覆构造与铅锌矿床之间的"纽带"。本文对该阶段方解石开展了Rb-Sr和Sm-Nd等时线方法定年,测定东莫扎抓铅锌矿床过渡阶段的年龄为35.2~35.5 Ma,平均为35.4 Ma,与其成矿时代35 Ma非常接近;测定莫海拉亨铅锌矿床过渡阶段的年龄为34.0~34.6 Ma,平均为34.3 Ma,与其成矿时代33 Ma也非常接近。结合区域成矿地质背景,建立了玉树地区铅锌矿床从逆冲推覆阶段到成矿阶段的构造控矿模式:伴随着印度-亚洲大陆持续碰撞,青藏高原北缘中生代构造岩片向盆地中央推覆叠置,形成逆冲推覆构造(37~40 Ma),之后处于由挤压到拉伸的松弛状态,早期造山带流体、盆地流体混合形成巨晶方解石脉(34~35 Ma),最后,流体从造山带沿拆离滑脱带长距离向前陆盆地方向运移,运移过程中淋滤围岩的金属物质,并与先期造山带流体混合,形成富铅、锌的成矿流体,通过主逆冲断裂垂向沟通,进入浅部的反冲断层形成铅锌矿床(33~35 Ma)。  相似文献   

11.
International unity is becoming ever stronger in this country owing to an increasing similarity in the development of the cultural environment. This comprises the provision of all the country's republics with a sufficient number of schools, theatres, and other institutions and cultural information media in accordance with the needs of the population. An important part is played by the rise in ‘the general educational level, as well as the level of professional qualifications and skills. Among all the Soviet nations and nationalities, this rise being more rapid among formerly backward peoples. Prominent among the factors of internationalization is the progressive development of the nationalities’ cultural resources, while professional culture is being increasingly brought within the reach of the masses.The implementation of the nationalities policy promotes the all-round development of all Soviet nations and nationalities, their drawing together, the upsurge of the individual capabilities of every Soviet citizen.  相似文献   

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Chronological analyses of correlations between certain global repeating events (mass extinctions of marine organisms, meteorite impacts, and flashes in the frequency of geomagnetic reversals) during the Phanerozoic Eon and the motion of the solar system in the Galaxy are presented for five rotationally symmetrical models for the regular Galactic gravitational field. Thirteen of sixteen mass-extinction events can be described by a repetition interval of 183±3 million years. This is in agreement with the anomalistic period (interval between two subsequent passages of the Sun through the apocenter of its Galactic orbit) in the model of Allen and Martos. The positions of the minima and maxima in Gaussian functions approximating the frequency distribution for geomagnetic reversals also agree with the times of passage of the Sun through the apocenter and pericenter, respectively, of its Galactic orbit in this model. The maximum in the distribution of the deviations of the dates of mass extinctions from the nearest dates of impacts of large, crater-forming bodies is close to zero, providing evidence that many such events are correlated. As a rule, extinctions follow impact events. The impacts of large bodies have occurred most often when the solar system passes through the Galactic plane, while mass extinctions occur more often at some distance from the Galactic plane (about 40 pc). As a rule, intervals of increases in the frequency of geomagnetic reversals coincide with dates of impacts of large bodies. At the same time, these intervals do not show a clear correlation with the dates of mass extinctions. The intensity of mass extinctions, like the energy released by impacts, is consistently higher in periods when the Sun is moving from the apocenter toward the pericenter of its orbit, than when it is moving from the pericenter toward the apocenter. Thus, there is evidence for a variety of relationships between repeating global events in the Phanerozoic and the motion of the Sun in the Galaxy. Long-period variations in the frequency of geomagnetic reversals are correlated with the orbital motion of the Sun, and increases in the frequency of geomagnetic reversals are correlated with impacts. Mass extinctions are correlated with the impacts of large bodies, whose motions may have been perturbed by clouds of interstellar material concentrated toward the Galactic plane and by the shock front associated with the Perseus spiral arm, through which the solar system passes. The velocity of the Sun relative to the spiral pattern is estimated.  相似文献   

14.
It is known from observations that the center of mass of the Moon does not coincide with the geometric center of its figure, and the line connecting these two centers is not aligned with the direction toward the center of the Earth, instead deviating toward the Southeast. This stationary deviation of the axis of the inertia ellipsoid of the Moon to the South of the direction toward the Earth is analyzed. A system of five linear differential equations describing the physical libration of the Moon in latitude is considered, and these equations are derived using a new vector method taking into account perturbations from the Earth and partly from the Sun. The characteristic equation of this system is obtained, and all five oscillation frequencies are found. Special attention is paid to the fifth (zero) frequency, for which the solution of the latitude libration equations are stationary and represents a previously unknown additional motion of the rotational axis of theMoon in a cone with a small opening angle. In contrast to the astronomical precession of the Earth, the rotation of the angular-velocity vector is in the positive direction (counter-clockwise), with the period T 3 = 27.32 days. On this basis, this phenomenon has been named “quasi-precession.” This quasi-precession leads to a stationary inclination of the major axis of the inertia ellipsoid of theMoon to the South (for an observer on Earth), making it possible to explain one component of the observed deviation of the center of mass of the Moon from the direction toward the Earth. The opening angle of the quasiprecession cone is approximately 0.834″.  相似文献   

15.
从榴辉岩与围岩的关系论苏鲁榴辉岩的形成与折返   总被引:4,自引:1,他引:4       下载免费PDF全文
位于华北和扬子两板块碰撞带中的苏鲁榴辉岩形成的温压条件不但是超高压,而且是高温。榴辉岩的PTt轨迹表明其为陆-陆磁撞俯冲带的产物。榴辉岩的区域性围岩花岗质片麻岩为新元古代同碰撞期花岗岩,榴辉岩及其他直接围岩皆呈包体存在于其中,并见新元古代花岗岩呈脉状侵入榴辉岩包体中。区域性围岩新元古代花岗岩的锆石中发现有柯石英、绿辉石等包裹体,表明新元古代花岗岩的组成物质也经受过超高压变质作用,且榴辉岩与围岩新元古代花岗岩的锆石U-Pb体系同位素年龄基本相同。但新元古代花岗岩所记录的变质作用和变形作用期次(或阶段)却少于榴辉岩。椐上述可得如下推断:超高压榴辉岩与新元古代花岗岩岩浆是同时在碰撞带底部(俯冲板块前部)形成的;榴辉岩的第一折返阶段是由新元古代花岗岩岩浆携带上升的,其第二折返阶段是和新元古代花岗岩一起由逆冲及区域性隆起而上升,遭受剥蚀。  相似文献   

16.
某高速公路下伏煤矿采空区稳定性分析   总被引:10,自引:0,他引:10  
在论述某高速公路下伏砦脖煤矿采空区地质、采矿和工程地质特征的基础上, 进行了稳定性数值模拟分析, 定性与定量地分析与评价了该煤矿采空区的地表变形特征及稳定性。研究结果表明: 该煤矿采空区的变形尚未完成, 对拟建的高速公路将产生很大的危害, 必须采取相应的工程治理措施。   相似文献   

17.
摩擦桩基桩土间极限摩阻力取值问题探讨   总被引:1,自引:0,他引:1  
陈银生 《世界地质》1999,18(1):54-59
通过对广珠东线高速公路横沥大桥的试桩及土体的工程地质条件分析,总结出影响摩擦桩基桩土间极限摩阻力取值的一般问题以及解决问题的方法和措施。  相似文献   

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In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations, 80–50%; and 9stations, < 50%. A map has been devised of thesusceptibility of the materials through which thesouth-eastern Andalusian road network crosses,together with an inventory of the damage caused byinstability phenomena on banks and cuttings of theroad network during the winter of 1996–1997. Therelationships between the rainfall during the studyperiod, the damage caused to the road network and thesusceptibility of the materials affected are analysed.The results indicate that there is a clearcorrespondence between the rainfall recorded and thesusceptibility of the materials with the inventorieddamage. It is concluded that the widespread seriousdamage caused in early 1997 to the roads andsurrounding areas in the Alpujarra region and thecoast of the Province of Granada was mainly caused bythe extraordinarily heavy rains. However, considerablyless damage was observed where the susceptibility ofthe terrain is low, thus highlighting the extremeusefulness of terrain-susceptibility maps for riskprevention and territorial planning.  相似文献   

20.
We first re-examined the apparent polar wander curves for stable Eurasia and Africa since the Triassic. These curves were then combined together with curves of North and South America according to the kinematics of the Atlantic ocean and a synthetic polar wander curve was given. Then, most of the paleomagnetic results from the Tethys mobile belt, from the Atlantic to the Pamirs, were analysed.Several groups of plates, microplates and blocks can be seen. First, relatively stable regions like Maghreb and Sicily, which have not moved much. Then we have a group formed by Iberia, Sardinia, Italy and, to a lesser extent, Corsica and the Western and Central Alps. For these blocks, movements are anticlockwise rotations chiefly driven by the anticlockwise rotation of Africa, but they are sometimes stronger.To the east, a major change takes place. The north of the Aegean Sea and the Ionian zone are clockwise rotated and these rotations are recent: Oligocene-Miocene for the first part, Pliocene to the present for the second part.A major problem arises in Turkey, Caucasus and Iran. Paleomagnetic results indicate a position far to the south of Eurasia, and, at the same time, geological evidence is in favour of a position close to Eurasia. We discuss these discrepancies.  相似文献   

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