Structural style and evolution of the Gulf of Lion Oligo-Miocene rifting: role of the Pyrenean orogeny     

M. Sranne  A. Benedicto  P. Labaum  C. Truffert  G. Pascal 《Marine and Petroleum Geology》1995,12(8)

The Gulf of Lion margin results from the Cligo-Aquitanian rifting and Burdigalian crustal separation between continental Europe and Corsica-Sardinia. Immediately before the onset of extension, the area of the Gulf of Lion was affected by the Pyrenean orogeny which controlled the structural style of the evolving margin. During extension, the foreland of the Pyrenean orogen was affected by extensional thin-skinned tectonics. The décollement level ramped down into the basement, in areas where the latter was thickened during orogeny. In this intermediate part, the margin was extended by several crustal-scale low-angle faults, which generated small amounts of syn-rift sedimentation compared with the accumulation of post-rift sediments. However, more than 4 km of syn-rift sediments were deposited in the Camargue basin, which is located at the transition between thin- and thick-skinned extensional systems. Kinematic restorations and stratigraphy suggest a pre-rift surface elevation above sea-level of at least 1 km in the intermediate part of the margin, which is in agreement with reduced syn-rift sedimentation. The slope area extends seaward of the North Pyrenean Fault, a terrane boundary inherited from the Pyrenean collision. This part of the margin was stretched by seaward dipping low-angle block tilting of the upper crust, and antithetic lower crustal and sub-crustal detachment. The lithospheric structures inherited from the Pyrenean orogeny exerted a strong control on the kinematics of the rifting and on the distribution and history of subsidence. Such parameters need to be integrated in the definition of pre-rift initial conditions in future basin-modelling of the Gulf of Lion.  相似文献   

新疆西准噶尔布龙果尔组的建造类型、时代及有关问题研究的新进展   总被引：2，自引：2，他引：0  

李耀西  蓝善先 《新疆地质》1992,(1)

本文对布龙果尔组的建造类型及地质时代进行了论证,认为其应属磨拉石建造叠加坍塌建造的复合型建造,并将其地质时代从晚奥陶世厘正为早志留世早期。此外,首次提出早古生代西准噶尔北部地区有一次造山运动,这次运动北疆邻区称为“艾比湖运动”,其发生的确切时间应为晚奥陶世末期。最后,根据布龙果尔组中出现蛇绿岩套的近源砾石。推断洪古勒楞蛇绿岩的形成年代早于早志留世。可能是奥陶纪。  相似文献   

Tectonometamorphic evolution of an intracontinental orogeny inferred from P–T–t–d paths of the metapelites from the Rehamna massif (Morocco)          下载免费PDF全文

P. Wernert  K. Schulmann  F. Chopin  P. Štípská  D. Bosch  M. El Houicha 《Journal of Metamorphic Geology》2016,34(9):917-940

New petrographic and microstructural observations, mineral equilibria modelling and U/Pb (monazite) geochronological studies were carried out to investigate the relationships between deformation and metamorphism across the Rehamna massif (Moroccan Variscan belt). In this area, typical Barrovian (muscovite to staurolite) zones developed in Cambrian to Carboniferous metasedimentary rocks that are distributed around a dome‐like structure. First assemblages are characterized by the presence of locally preserved andalusite, followed by prograde evolution culminating at 6 kbar and 620 °C in the structurally deepest staurolite zone rocks. This Barrovian sequence was subsequently uplifted to supracrustal levels, heterogeneously reworked at greenschist facies conditions, which was followed locally by static growth of andalusite, indicating heating to 2.5–4 kbar and 530–570 °C. The ²⁰⁶Pb/²³⁸U monazite age of 298.3 ± 4.1 Ma is interpreted as minimum age of peak metamorphic conditions, whereas the ages of 275.8 ± 1.7 Ma and 277.0 ± 1.1 Ma date decompression and heating at low pressure, in agreement with previous dating of Permian granitoids intruding the Rehamna massif. The prograde metamorphism occurred during thickening and associated horizontal flow in the deeper crust (S1 horizontal schistosity). The horizontally disposed metamorphic zones were subsequently uplifted by a regional scale antiform during ongoing N–S compression. The re‐heating of the massif follows late massive E–W shortening, refolding and retrograde shearing of all previous fabrics coevally with regionally important intrusions of Permian granitoids. We argue that metamorphic evolution of the Rehamna massif occurred several hundred kilometres from the convergent plate boundaries in the interior of continental Gondwanan plate. The tectonometamorphic history of the Rehamna massif is put into Palaeozoic plate tectonic perspective and Late Carboniferous reactivation of (Devonian)–Early Carboniferous basins formed during stretching of the north Gondwana margin and formation of the Palaeotethys Ocean. The inherited heat budget of these magma‐rich basins plays a role in the preferential location of this intracontinental orogen. It is shown that rapid transition from lithospheric stretching to compression is characterized by specific HT type of Barrovian metamorphism, which markedly differs from similar Barrovian sequences along Palaeozoic plate boundaries reported from Variscan Europe.  相似文献   

Genesis of the Taishanmiao Au Deposit in the Ningshan–Zhenan Ore Field, South Qinling Orogen, China: Evidence from Geochemical, Geochronological and S-Pb-H-O Isotopical Study     

GAO Zuoyu  LIU Yunhu  SUN Naiquan  LI Yuntao  LI Bo 《《地质学报》英文版》2022,96(3):993-1009

The Taishanmiao Au deposit is in the western part of the Ningshan–Zhenan ore field, in the South Qinling orogen. Based on geological and geochemical features, we propose that the Taishanmiao Au deposit is a magmatic-hydrothermal type of deposit. All samples have high SiO2, K2O + Na2O contents and differentiation index values, low CaO, MgO, P2O5, and TiO2 contents, are enriched in high field-strength elements, and depleted in large ion lithophile element. The stable isotope δ34S values of pyrite vary from 6.8%–7.8%, and the H-O isotopic compositions of quartz from quartz-pyrite veins indicate the ore-forming fluid is a mixture of a small amount of magmatic-hydrothermal solution and groundwater. Lead isotope ratios of pyrite and silicalite can show that the ore-forming materials were derived from a mixed source containing mantle and crustal materials. At the same time, the LA-ICP-MS U-Pb dating of monzogranite is 198.4 ± 4.2 Ma. Combined with the regional geological background, the intracontinental extension in the late collisional orogeny and large-scale lithospheric thinning associated with mantle uplift may lead to large-scale mineralisation in the region.  相似文献   

青藏高原东缘—扬子特提斯构造域深部结构与地壳形变研究     

王志  王剑  付修根 《地质论评》2021,67(1):1-12

青藏高原东缘和扬子西缘的构造带是中国特提斯构造域的重要组成部分,该构造域受欧亚板块与印度板块陆—陆碰撞、高原隆升、块体裂解或拼接挤压等强烈构造活动的影响,记录和保存了多期次的特提斯构造演化历史痕迹。同时,该研究区域也是中国西部地区地壳形变最强烈的地区之一,其浅表形变特征与深部构造之间存在怎样的关联和制约机制是目前国际地球科学的一个研究热点。本研究依据作者十多年来持续在该区域开展的地质—地球物理研究,通过深部地球物理多参数结构成像、沉积盆地分析、地壳形变和强震孕育机制等综合对比分析,发现在青藏高原东缘的下地壳存在低速和高泊松比异常带,该异常体与来自青藏高原上涌的软流圈热物质汇聚,导致从扬子西缘到青藏高原的下地壳和上地幔的深部结构发生显著变化。沿着龙门山断裂带,中、下地壳存在交叠相间的低速(高泊松比)和高速(低泊松比)区域,这些深部结构分布特征与地表形变及前陆盆地隆坳格局具有较好的一致性。基于上述认识,提出了青藏高原东缘—扬子板块的深部接触模式及其相应的盆山耦合关系,阐明了板块碰撞—耦合的深部动力学过程对剧烈地壳形变、盆地隆坳格局和强震诱发的制约关系。本研究成果将为深入认识青藏高原东缘高原急剧隆升、盆地基底结构与隆拗格局,以及强烈地壳形变的深部动力学机制提供参考信息。  相似文献   

川西马尔康片麻岩穹隆与伟晶岩型锂矿的构造成因   总被引：1，自引：0，他引：1  

郑艺龙  许志琴  高文琦  郑碧海  高建国  闫浩瑜 《地质学报》2021,95(10):3069-3084

片麻岩穹隆是造山折返过程形成的重要构造样式.马尔康锂矿床位于松潘-甘孜造山带腹地的马尔康片麻岩穹隆中,其核部为太阳河花岗闪长岩和可尔因花岗岩、幔部由经过变质作用的晚三叠世深海—半深海复理石和浊积岩组成,大量含锂伟晶岩脉侵位于红柱石-十字石变质带中.通过野外地质调查和构造分析,在马尔康片麻岩穹隆中识别出三期构造变形叠加于造山早期大规模收缩变形之上:第一期变形(D1)为南向的大型高温拆离剪切带(马尔康拆离断层,MRKD);第二期变形(D2)为马尔康"穹隆构造";第三期变形(D3)为后期叠加的新生代近东西向逆冲断层.新的锆石U-Pb年代学数据表明太阳河和可尔因岩体的结晶年龄分别为226～212 Ma与224～218 Ma,马尔康拆离断层中平行剪切面理的同构造变形伟晶岩脉形成于约212～207 Ma,而未变形含锂伟晶岩脉则形成于200～190 Ma之间.研究表明,马尔康片麻岩穹隆在造山早期伴随220～212 Ma的花岗岩侵位,形成中低压巴罗式变质作用;在挤压向伸展转换过程(212～207 Ma)中,形成向南剪切的拆离断层以及变质核杂岩构造,致使花岗岩浆底辟上涌和片麻岩穹隆的形成;200～190Ma以来,马尔康片麻岩穹隆的继续上隆,大量网状伟晶岩(包括含锂伟晶岩)侵位在幔部变质沉积岩中,岩体顶部聚集流体经结晶分异作用和高温萃取作用形成锂矿床.本文指出,马尔康片麻岩穹隆由于新生代逆冲作用,使北侧的可尔因和太阳河岩体抬升,南侧厚层晚三叠世幔部变质带埋深,为伟晶岩型锂矿床的保存创造了有利条件.  相似文献   

复合造山作用和中国中央造山带的科学问题   总被引：19，自引：5，他引：14       下载免费PDF全文

杨经绥许志琴  马昌前吴才来张建新  王宗起王国灿张宏飞  董云鹏赖绍聪 《中国地质》2010,37(1):1-11

在全球大陆范围内,广泛分布的造山带纪录了板块汇聚的历史和碰撞造山的过程,因此,造山带的研究一直是地球科学经久不衰的重要领域。研究表明,世界上许多造山带是长期活动(300Ma)的复合造山带,活动域的宽度可超过1000km,并具有造山前的热结构,是大陆生长的最好见证。近10年来,全球造山带的研究已摆脱传统地质学和经典板块观念的束缚,面临一个新的起点,即由单一造山带向复合造山带研究转轨,由造山类型、造山作用向造山动力学研究聚焦。复合造山带长期活动的原因、大陆增生机制、造山带的流变学结构和造山热对造山作用的控制等已成为当前大陆复合造山带研究的关键科学问题,复合造山动力学已成为当今地球科学前沿——大陆动力学研究的重要内容。中国中央造山带位于北中国板块与南中国板块之间,是中国大陆上一条十分醒目而又极其重要的巨型(长5000km)构造带。中央造山带是经历了大致600Ma的活动历史,泥盆纪和三叠纪的两次碰撞造山以及白垩纪以来的陆内造山过程而构筑成的典型"复合造山带"。在全球复合造山带中,中国中央巨型造山带具有结构复杂性、活动长期性和非原地型,造山过程多期性以及造山带拼贴与大陆增生方式特殊性的特点,特别是世界最大规模的中央超高压变质带及其两期超高压变质作用的发现,揭示了中央造山带的形成还经历了板块汇聚边界洋壳/陆壳深俯冲至100km以上的地幔深处的两次壮观地质事件,使中央造山带成为全球造山带中最为精彩和不可多得的典型,与青藏高原一样,被国内外地学家们誉为当今中国地学研究的"瑰宝"。中国中央巨型复合造山带可以作为研究复合造山过程与复合造山动力学的重大地学问题的范例,重要的核心科学问题是:中国中央巨型复合造山带的早古生代和三叠纪陆块汇聚、碰撞造山过程以及中新生代陆内造山与周缘盆地互馈;两期高压-超高压变质带的时空关系、形成条件和洋壳/陆壳的俯冲-深俯冲与折返动力学机制;揭示和探讨中国中央复合造山带的长期活动性,造山作用的多期性和叠置性,造山热结构以及复合造山过程;洋壳/陆壳深俯冲、复合造山与大陆增生理论的创新。此外,中央复合造山带的研究对于金属矿产资源的开拓、周缘中新生代盆地含油气资源的战略前景以及现今南北中国的气候、环境、人文、地理、生态和灾害的制约提供新的科学依据与动力学背景。  相似文献   

Strain coupling between upper mantle and lower crust: natural example from the Běstvina granulite body, Bohemian Massif     

M. MACHEK  S. ULRICH  V. JANOU&#;EK 《Journal of Metamorphic Geology》2009,27(9):721-737

Strain patterns within mantle rocks and surrounding coarse‐grained felsic granulites from the Kutná Hora Crystalline Complex in the Variscan Bohemian Massif have been studied in order to assess their strain coupling. The studied rock association occurs within low‐strain domains surrounded by fine‐grained granulite and migmatite. The Doubrava peridotite contains closely spaced and steeply dipping layers of garnet clinopyroxenite, which are parallel to the NE–SW‐striking, high‐temperature foliation in nearby granulites, while the Úhrov peridotite lacks such layering. The Spa?ice eclogite is not associated with peridotite and shows upright folds of alternating coarse‐ and fine‐grained varieties bearing NE–SW‐striking axial planes. Electron back‐scattered diffraction measurements revealed full strain coupling between clinopyroxenites and coarse‐grained granulites in the S₁ fabric that is superposed on the S₀ fabric preserved in peridotites. The B‐type olivine lattice preferred orientation (LPO) characterizes the S₀ fabric in peridotites and its reworking is strongly controlled by the presence of macroscopic clinopyroxenite layering. The S₁ in clinopyroxenites and coarse‐grained granulites is associated with the LS‐type clinopyroxene LPO and prism <c> slip in quartz respectively. While the S₁ fabric in these rock types is accompanied invariably by a sub‐vertical stretching lineation, the S₁ fabric developed in reworked Úhrov peridotite is associated with strongly planar axial (010) type of olivine LPO. The peridotites with the S₀ fabric are interpreted to be relicts of a fore‐arc mantle wedge hydrated to a various extent above the Saxothuringian subduction zone. The prograde metamorphism recorded in peridotites and eclogites occurred presumably during mantle wedge flow and was reaching UHP conditions. Strain coupling in the S₁ fabric between clinopyroxenites and granulites at Doubrava and upright folding of eclogites at Spa?ice document a link between tectonic and magmatic processes during orogenic thickening, coeval with intrusions of the arc‐related calcalkaline suites of the Central Bohemian Plutonic Complex (c. 360–345 Ma). Juxtaposition of peridotites and granulites could be explained by a rheological heterogeneity connected to the development of clinopyroxenite layering in the upper mantle and a previously published model of a lithospheric‐scale transpressional arc system. It invokes vertical shearing along NE–SW trending, sub‐vertical foliations in the upper mantle that could have led to an emplacement of mantle bodies into the granulitized, orogenic root in the sub‐arc region. Clearly, such a transpressional arc system could represent an important pathway for an emplacement of deep‐seated rocks in the orogenic lower crust.  相似文献   

古深断裂活化与燕山期陆内造山运动——以川南—滇东和中扬子褶皱-冲断系为例   总被引：18，自引：1，他引：18  

吴根耀 《大地构造与成矿学》2001,25(3):246-253

基于花岗岩侵入、构造变形和磨拉石建造(或长期隆起)提出川南—滇东和中扬子地区侏罗-白垩纪时发生造山事件。分析了造山带的内部结构、范围和动力机制,发现川南—滇东褶皱-冲断系为北东向及近南北向断裂控制发育,其西以滇中古陆块与燕山期消减型造山带相隔;中扬子褶皱-冲断系为北西向断裂控制发育,向南西扩展时止于黄陵古陆核。两者均属印支运动后出现的中国—东南亚次大陆外侧的新特提斯洋消减,及嗣后的碰撞激活拼合大陆内的古深断裂活化而发生的燕山期陆内造山运动,构成中国大地构造演化的一个显著特色。  相似文献   

Thermal controls on flexure of underthrust continental lithosphere     

C. David Brown 《Geophysical Journal International》2001,146(3):813-826

  相似文献