共查询到20条相似文献，搜索用时 250 毫秒
1.
H.J. Zwart 《Tectonophysics》1986,129(1-4)
The main outlines of the geology of the Variscan part of the Pyrenees are discussed. Rocks involved in this cycle are high-grade basement gneisses, Palaeozoic sediments and their metamorphic equivalents, late intrusive granodiorites and early, pre-Variscan granites. The main features of the stratigraphy of the Palaeozoic are given.Structures fall into two domains: a low-grade suprastructure, essentially with steep folds and cleavages, and a high-grade infrastructure with dominantly low-dipping foliations. An important phase of early, pre-cleavage folding occurs in low-grade rocks mainly along the southern border of the Axial zone. In high-grade rocks most structures and the metamorphism postdate the main cleavage phase in low-grade rocks. The influence of the Alpine orogeny on the Variscan structures consists mainly of faults, steep, reverse faults in the northern, and south-directed thrusts in the southern part of the Pyrenees. Metamorphism took place under high geothermal gradients and low pressures, as indicated by the abundant occurrence of andalusite and cordierite 相似文献
2.
Hicham Si Mhamdi Mohammed Raji Soufiane Maimouni Mostafa Oukassou 《Arabian Journal of Geosciences》2017,10(5):125
The Paleozoic massif of Tichka in the southern part of the Western High Atlas of Morocco constitutes a structural transition between the Meseta and the Anti-Atlas domains. It was affected by a complex network of fractures noticeable at different scales. Using Landsat ETM+ imagery permits detecting the main fracture directions. Various techniques of lineament’s extraction were applied, including the colored compositions, spectral band ratios, and directional filters applied to the principal component analysis. Lineament’s extraction is based on visual interpretation and completed by field observations. The resulted map allows recognizing at least four trending fracture system, with average N-S, NE-SW, E-W, and NW-SE orientations. The surrounding rocks of the granitic massif show a high fracture density. Tectonic indicators show that this massif is initially affected by NW-SE Variscan tectonic extension, followed by NW-SE Variscan compression. This regime is being maintained until the late Variscan period corresponding to the relaxation of the NW-SE major Variscan stress. A clockwise rotation of the latter stress, which became N-S to NNE-SSW, related to the late Variscan deformation, is responsible for reworking preexisting faults. 相似文献
3.
M. Carracedo J. L. Paquette A. Alonso Olazabal J. F. Santos Zalduegui S. García de Madinabeitia M. Tiepolo J. I. Gil Ibarguchi 《International Journal of Earth Sciences》2009,98(7):1609-1624
The first U–Pb geochronological results on the magmatic alignment of the Los Pedroches batholith are presented. The batholith
is composed of a main granodioritic unit, several granite plutons and an important acid to basic dyke complex, all of them
intrusive after the main Variscan regional deformation phase, D1, along the boundary between the Ossa-Morena and Central Iberian
zones (SW Iberian Massif). Zircons from samples on both extremes of the granodiorite massif record nearly simultaneous magmatic
crystallization at ca. 308 Ma, while the emplacement of granite plutons was diachronic between 314 and 304 Ma. The U–Pb results
combined with new field and textural observations allow to better constrain the age of Variscan deformations D2 and D3 across
the region, while the age of D1 remains imprecise. Transcurrent D2 shearing-tightening of D1 folds occurred around 314 Ma
(lower Westphalian) in relation to the emplacement of the first granitic magmas. D3 faults and shear bands bearing a strong
extensional component developed at ca. 308 Ma (upper Westphalian), associated to the intrusion of the main granodiorite pluton
(granodiorite) of the batholith. Together with available geochemical and geophysical information, these results point to the
Variscan reactivation of lithospheric fractures at the origin and subsequent emplacement of hybrid magmas within this sector
of the Massif. 相似文献
4.
内蒙古达茂旗北部岩浆活动与铜、金成矿作用 总被引：2，自引：0，他引：2
内蒙古达茂旗北部岩浆岩分布广泛,以加里东期和华力西晚期为主。加里东期侵入岩以闪长岩、石英闪长岩及斜长花岗岩为主;华力西晚期侵入岩以闪长岩、石英闪长岩、黑云母花岗岩、二长花岗岩及钾长花岗岩为主。经研究发现,铜矿化多与闪长岩、石英闪长岩及花岗闪长岩有关;金矿化多与石英闪长岩、斜长花岗岩及黑云母花岗岩有关;铜、金矿床(点)均产于岩体内或其外接触带的火山岩中,暗示铜、金矿(点)的形成与岩浆活动密切相关。进一步研究发现本区铜、金矿化主要受华力西晚期岩浆活动控制。通过对研究区成矿地质背景的讨论及与斑岩型铜、金矿床地质特征的对比,指出本区具备寻找斑岩型铜、金矿床的潜力。 相似文献
5.
茂林岩体位于安徽南部江南隆起带北侧石台—泾县褶皱带,内部相为二长花岗岩,边缘相为细粒花岗闪长岩,后期有花岗闪长斑岩等脉岩侵入,岩石属于钙碱性岩系列,其中Cu、Mo、Ag丰度较高。茂林岩体与周边发现的矿床（点）均存在一定的成因联系,找矿潜力较大。北东向断裂及南北向断裂构造与浅成相二长花岗岩、花岗闪长岩岩株及岩脉接触部位是周边寻找斑岩型钼矿的有利部位,岩体晚期花岗闪长斑岩岩脉是寻找铜、铅矿的潜力区。 相似文献
6.
大兴安岭铜钼矿床主要与古生代和中生代浅成侵入岩和火山-次火山岩有关,矿床形成于陆缘岩浆岩带、造山带和深大断裂带中.成矿期主要为加里东期、华力西期和燕山期.矿化围岩为花岗闪长岩、花岗闪长玢岩、二长花岗岩、安山岩、英安岩、流纹岩、安山玢岩、流纹斑岩和火山碎屑岩.围岩蚀变主要有硅化、绢云母化、钾长石化、水白云母化、伊利石化、绿泥石化、碳酸岩化.矿石中主要工业元素为Cu和Mo,伴生有益组分为Ag、Au、Re等.成矿类型有：①斑岩型铜钼矿床;②火山-次火山热液型铜钼矿床.大兴安岭铜钼矿床主要由陆缘岩浆岩带、造山带、深大断裂带的火山-次火山作用及小型侵入作用形成,成矿流体沿着火山机构、岩浆侵入构造、区域构造等运移,热动力、压力、扩散力等使成矿流体产生上升运动和局部循环运动,成矿流体的迁移、萃取、扩散、交代作用等使成矿物质产生富集. 相似文献
7.
海沟金矿床具有多源、多期、多阶段成矿特点,成矿主要与燕山早期花岗闪长岩及闪长玢岩有关.成矿物质主要来自中元古界色洛河群,也有部分来自岩浆岩.成矿水为岩浆水和大气降水的混合.成矿热源为燕山期花岗闪长岩.成因类型应属混合岩化热液型铀金大型矿床. 相似文献
8.
9.
满都拉地区地处达茂旗—白乃庙Cu-Au多金属成矿带,区内地层主要为古生界及中新生界,断裂构造主要为NE向、NW向及近WE向,岩浆岩以华力西晚期为主。区内铜矿床类型较丰富,有斑岩型、热液型和火山块状硫化物型。铜矿床主要产于上石炭统本巴图组及下二叠统大石寨组中,受NW向及近EW向断裂控制,与华力西岩浆活动密切相关。文章认为区域上近EW向的上石炭统—下二叠统火山岩-碎屑岩-碳酸盐岩系,是本区的最佳找矿地段,华力西晚期岩浆岩及其与地层的接触带是找矿的重要标志。 相似文献
10.
Gernold Zulauf 《International Journal of Earth Sciences》1993,82(3):489-504
Investigations of brittle deformation structures, present within the crystalline rocks of the Bavarian Oberpfalz, reveal a complex late to post-Variscan crustal evolution. Upper Carboniferous (mainly Westphalian) granites were emplaced into semibrittle to brittle rocks of the ZEV (zone of Erbendorf-Vohenstrauß) and the EGZ (Erbendorf greenschist unit), respectively. From both the alignment of the granites and the direction of granite-related tension gashes a north-east-south-west extension must be assumed for the period of magmatic activities. Apart from the granite intrusions, rapid crustal uplift (about 1.5 km/my) led to an increase in the geothermal gradient from < 30 °C/km (late Variscan pre-granitic) to > 40 °C/km (late Variscan post-granitic). The increased geothermal gradient persisted during the succeeding reverse faulting which results from late Carboniferous (probably Stephanian) east-west and northeast-south-west compression. Although not evidenced directly in the area considered, strike-slip faults seem to have played an important part during the late Variscan crustal evolution, particularly in the Early Permian. The strike-slip events indicate further crustal shortening and indentation under north-south compression.A similar indentation was present in Cretaceous time. After a weak phase of Early Cretaceous reverse faulting, which results from north-south compression, strike-slip faults formed under north-west-south-east and north-south compression. All these faults, in particular the strike-slip faults, seem to be related to the Cretaceous and lowermost Tertiary convergence of the Alpine/Carpathian orogeny.A late stage of crustal extension, characterized by a radial stress tensor (2 = 3), is indicated through high angle normal faults which probably formed during the subsidence of the adjacent Neogene Eger Graben. 相似文献
11.
多宝山铜矿硫同位素空间分布特征 总被引：4，自引：0，他引：4
多宝山铜矿是一大型斑岩铜矿床.矿床位于大兴安岭隆起带与松辽沉降带的接舍部位.矿区出露的地层主要是奥陶系中统多宝山组地层岩性主要为安山岩、凝灰岩、凝灰质砂岩、砂岩;侵入岩主要是华力西晚期花岗闪长斑岩和花岗闪长岩;围绕花岗闪长斑岩体具有蚀变分带现象,由内向外分为钾化带-绢云母化带-青磐岩化带,矿体多产于绢云母化带内;研究表明,多宝山铜矿形成于中低温条件下,矿体内金属硫化物具有分带性,由矿体中心向边缘依次是斑铜矿-黄铜矿-黄铁矿.文章对多宝山铜矿硫同位素空问分布特征以及与矿体富集部位的对应关系进行了分析,并解释了形成这一现象的原因. 相似文献
12.
西藏多不杂斑岩铜金矿床地质与蚀变 总被引：7，自引：0，他引：7
[摘 要]西藏多不杂斑岩铜金矿是近年来新发现的一个矿床,位于班公湖-怒江成矿带西段。多不杂矿床内发育三期花岗闪长斑岩,侵入到侏罗系曲色组变砂岩中,北东向断层是多不杂矿床的主要控岩断层。多不杂矿床由内向外发育钾化、绢英岩化、青磐岩化,钾化主要发育于第一期花岗闪长斑岩出露区域,绢英岩化环绕钾化带发育,并叠加在钾化带之上,青磐岩化在矿床西侧的玄武安山岩和南侧的火山角砾岩中呈团块状发育。多不杂矿床的的铜矿化以黄铜矿矿化为主,金矿化与铜矿化密切共生。黄铜矿化主要发育于第一期花岗闪长斑岩及其与变砂岩接触带内,第一期花岗闪长斑岩为多不杂矿床的成矿斑岩。 相似文献
13.
AbstractDetailed mapping of the prc-Variscan rocks exposed in the Southern Central Pyrenees reveals the occurrence of extensional tectonic contacts overprinted by main phase and pre-main phase folds. The interpretation of the former contacts as normal faults and the reinterpretation of other contacts described in the literature lead us to suggest an extensional event during Devonian and/or early Carboniferous times, prior to the contrac-tional Variscan paroxysm. 相似文献
14.
15.
通过二道沟金矿区火山—侵入杂岩、构造、矿床的研究,认为成矿与早白垩世斑状花岗间长岩同源;矿脉与岩脉、爆破岩伴生,时空关系密切;结合矿石、矿物、测温资料,确认二道沟金矿为岩浆中温热液金矿床。 相似文献
16.
J. -L. Mansy G. M. Manby O. Averbuch M. Everaerts F. Bergerat B. Van Vliet-Lanoe J. Lamarche S. Vandycke 《Tectonophysics》2003,373(1-4):161
The geometry and dynamics of the Mesozoic basins of the Weald–Boulonnais area have been controlled by the distribution of preexisting Variscan structures. The emergent Variscan frontal thrust faults are predominantly E–W oriented in southern England while in northern France they have a largely NW–SE orientation.Extension related to Tethyan and Atlantic opening has reactivated these faults and generated new faults that, together, have conditioned the resultant Mesozoic basin geometries. Jurassic to Cretaceous N–S extension gave the Weald–Boulonnais basin an asymmetric geometry with the greatest subsidence located along its NW margin. Late Cretaceous–Palaeogene N–S oriented Alpine (s.l.) compression inverted the basin and produced an E–W symmetrical anticline associated with many subsidiary anticlines or monoclines and reverse faults. In the Boulonnais extensional and contractional faults that controlled sedimentation and inversion of the Mesozoic basin are examined in the light of new field and reprocessed gravity data to establish possible controls exerted by preexisting Variscan structures. 相似文献
17.
东昆仑祁漫塔格地区野马泉深部的华力西期花岗闪长岩U-Pb年龄及其意义 总被引：3，自引：0，他引：3
野马泉大型矿床是近年来在东昆仑祁漫塔格地区发现的与侵入岩有关的矽卡岩型铁铜多金属矿。利用锆石LA-ICP-MS U-Pb法测得野马泉花岗闪长岩的形成年龄为(392.4±2.2) Ma,属于华力西期。前人利用辉钼矿Re-Os法,获得矽卡岩型铜钼多金属矿石和矽卡岩型钼矿石的等时线年龄分别为(225.0±4.0) Ma(n=7,MSWD=0.24)和(230.1±4.7) Ma(n=5,MSWD=0.12)、在多期热液叠加、多期成矿作用中,早期成矿的热液很可能是野马泉花岗闪长岩(392.4±2.2 Ma)提供的。由于该区有较多的中酸性岩体存在,它们可能为铁铜多金属矿的主要来源,因此确定这些侵入体的形成年龄,对于在该区寻找矽卡岩型铁铜多金属矿具有重要的理论和实践意义。 相似文献
18.
19.
Processing of gravity and magnetic maps shows that the basement of the Upper Rhine Graben area is characterized by a series
of NE–SW trending discontinuities and elongated structures, identified in outcrops in the Vosges, Black Forest, and the Odenwald
Mountains. They form a 40 km wide, N30–40° striking, sinistral wrench-zone that, in the Visean, shifted the Variscan and pre-Variscan
structures by at least 43 km to the NE. Wrenching was associated with emplacement of several generations of plutonic bodies
emplaced in the time range 340–325 Ma. The sub-vertical, NE–SW trending discontinuities in the basement acted as zones of
weakness, susceptible to reactivation by subsequent tectonism. The first reactivation, marked by mineralizations and palaeomagnetic
overprinting along NE–SW faults of the Vosges Mountains, results from the Liassic NW–SE extension contemporaneous with the
break-up of Pangea. The major reactivation occurred during the Late Eocene N–S compression and the Early-Middle Oligocene
E–W extension. The NE–SW striking basement discontinuities were successively reactivated as sinistral strike-slip faults,
and as oblique normal faults. Elongated depocenters appear to form in association with reactivated Variscan wrench faults.
Some of the recent earthquakes are located on NE–SW striking Variscan fault zones, and show sinistral strike-slip focal mechanisms
with the same direction, suggesting also present reactivation. 相似文献
20.
A series of regional deformation phases is described for the metamorphic basement and the Permian cover in an area in the central Orobic Alps, northern Italy. In the basement deformation under low-grade amphibolite metamorphic conditions is followed by a second phase during retrograde greenschist conditions. These two phases predate the deposition of the Permian cover and are of probable Variscan age. An extensional basin formed on the eroded basement during the Late Carboniferous, filled with fan conglomerates and sandstones, and rhyolitic volcanic rocks. Well-preserved brittle extensional faults bound these basins. Further extension deformed basement and cover before the onset of Alpine compressional tectonics. Cover and basement were deformed together during two phases of compressional deformation of post-Triassic age, the first giving rise to tectonic inversion of the older extensional faults, the second to new thrust faults, both associated with south-directed nappe emplacement and regional folding. Foliations develop in the cover only during the first phase of deformation as part of the activity on “shortening faults”. Main activity on the Orobic thrust actually postdates the first phase of thrusting and foliation development in the cover. 相似文献