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1.
甘肃桦树沟(铁)铜矿床的成因机制 总被引：4，自引：0，他引：4
矿床地质地球化学特征研究结果表明，随着古陆边缘弧－槽－盆体系的发生与发展，元古代基底火山（沉积）岩系经深循环水（海水）－热系统的作用，成矿物质被浸出和搬运，并经海底喷溢作用沉淀于海盆洼地中形成桦树沟矿床含铜建造，后期变质作用使成矿物质活化、转移和富集。桦树沟矿床为喷气（流）沉积－变质改造型（铁）铜矿床。 相似文献
2.
湖南桃江半边山先寒武纪马底驿组陆屑风暴岩 总被引：2，自引：1，他引：2
本区马底驿组陆屑风暴岩的沉积构造非常清晰,其中有丘状交错层理、差异层理、层面构造、袋模、渠模、韵律层理和多种准同时变形构造.剖面可分为由块状层和韵律层组成的八个一级韵律,块状层为含砾泥质粉砂岩,韵律层由一系列二级韵律组成.根据沉积构造特征,自下而上划分为:斜坡带风暴浊流沉积、外陆棚风暴碎屑流沉积和陆棚风暴碎屑流沉积,海水逐渐变浅,为一海退层序。 相似文献
3.
摘要：采用非线性有限元数值模拟技术和方法,研究大巴山前陆构造带应力场、位移场和形变场的流变学特征,分析叠加褶皱的相干形式和联合弧的形态特征,展现了大巴山弧形构造的发育、演化过程,提供了一组与大巴山前陆叠加构造相适应的边界外力和约束条件。研究表明:(1)模型选用的蠕变材料在变形过程中,应力场的变化非常缓慢,使得我们有条件通过应力迹线去研究构造变形的形态特征。(2)大巴山弧形构造带早晚两期褶皱的干涉形式大致为构造横跨叠加、斜跨叠加和共轴叠加三种。(3)大巴山弧形构造带形成的关键条件是北东向区域应力的作用和东西两个基底构造结的存在;而与大巴山弧联合构成收敛双弧的川东弧形构造带主要为来自南东方向的动力作用所致。 相似文献
4.
论武都复合型斜叠弧形构造及其控矿作用 总被引：3，自引：0，他引：3
摘 要 武都弧形构造构成西秦岭地区主要构造格局它是由礼县弧、武都弧、文县弧和白
马弧构成的一个复合型斜叠弧形构造系统其弧顶呈 NE 向斜叠东翼向 NE 向收敛归并西
翼向 NW 向散开。其主要活动时期为燕山晚期—喜马拉雅期是在 SN 向挤压构造应力场作
用下并受到东部 NE 向龙门山构造带和西部康藏地块的边界约束作用地壳表层发生由北
向南的不均匀推挤而形成的。它对区内金矿床具有重要的控制作用表现出明显的构造成矿
专属性且具有显著的弧顶控矿的特点。 相似文献
5.
地月系统不同成因环形构造及其影像特征 总被引：2，自引：0，他引：2
环形构造是一种常见的地质现象,特别是在月球上分布更为普遍。本文论述了三种成因的环形构造,即:侵入岩成因的环形构造,火山成因的环形构造,以及小天体撞击形成的撞击坑。文中详细介绍了它们的成因与结构特征,指出侵入岩成因的环形构造主要由岩浆冷凝收缩形成,在遥感影像上主要表现为影像色调的不同;火山成因的环形构造为火山口,在遥感影像上具有环形结构;而小天体撞击形成的撞击坑形态复杂,如碗形坑、中心锥环形坑与多环撞击坑,撞击坑的坑沿外缓内陡,遥感影像上表现为环形或弧形构造,有些撞击坑具有辐射纹。 相似文献
6.
P-wave velocity structure of the margin of the southeastern Tsushima Basin in the Japan Sea using ocean bottom seismometers and airguns 总被引：2，自引：0，他引：2
Takeshi Sato Toshinori Sato Masanao Shinohara Ryota Hino Minoru Nishino Toshihiko Kanazawa 《Tectonophysics》2006,412(3-4):159-171
The Tsushima Basin is located in the southwestern Japan Sea, which is a back-arc basin in the northwestern Pacific. Although some geophysical surveys had been conducted to investigate the formation process of the Tsushima Basin, it remains unclear. In 2000, to clarify the formation process of the Tsushima Basin, the seismic velocity structure survey with ocean bottom seismometers and airguns was carried out at the southeastern Tsushima Basin and its margin, which are presumed to be the transition zone of the crustal structure of the southwestern Japan Island Arc. The crustal thickness under the southeastern Tsushima Basin is about 17 km including a 5 km thick sedimentary layer, and 20 km including a 1.5 km thick sedimentary layer under its margin. The whole crustal thickness and thickness of the upper part of the crust increase towards the southwestern Japan Island Arc. On the other hand, thickness of the lower part of the crust seems more uniform than that of the upper part. The crust in the southeastern Tsushima Basin has about 6 km/s layer with the large velocity gradient. Shallow structures of the continental bank show that the accumulation of the sediments started from lower Miocene in the southeastern Tsushima Basin. The crustal structure in southeastern Tsushima Basin is not the oceanic crust, which is formed ocean floor spreading or affected by mantle plume, but the rifted/extended island arc crust because magnitudes of the whole crustal and the upper part of the crustal thickening are larger than that of the lower part of the crustal thickening towards the southwestern Japan Island Arc. In the margin of the southeastern Tsushima Basin, high velocity material does not exist in the lowermost crust. For that reason, the margin is inferred to be a non-volcanic rifted margin. The asymmetric structure in the both margins of the southeastern and Korean Peninsula of the Tsushima Basin indicates that the formation process of the Tsushima Basin may be simple shear style rather than pure shear style. 相似文献
7.
中甸地区甭哥正长岩地球化学特征及其地质意义 总被引：4，自引：0，他引：4
长期以来,甭哥正长岩体被认为是印度—欧亚板块碰撞引起的走滑剪切构造所控制的碱性岩浆活动的产物。本文研究表明甭哥正长岩属钾玄岩系列,富集K2O（5.88%~9.08%）、稀土元素（特别是轻稀土元素）和大离子亲石元素,高场强元素亏损,具有岛弧型微量元素特征。地球化学数据表明原岩于高压条件下发生部分熔融,岩浆源区深度较大,经历了结晶分异作用形成正长岩岩浆。甭哥正长岩的锆石稀释法U-Pb测定年龄为201.4Ma,略晚于中甸弧钙碱性斑岩,其形成的构造环境是弧后拉张环境,甘孜—理塘洋向西低角度俯冲使中甸地区地壳挤压增厚,从而在较深的深度形成原始岩浆。在中甸岛弧岩浆演化后期存在区域性的构造体制转折,从区域性的挤压环境转换成区域性的拉张环境,甭哥岩体的侵位处于两者的过渡时期。 相似文献
8.
V. M. Grannik 《Doklady Earth Sciences》2012,445(2):934-938
It has been established that volcanic rocks of the Schmidt, Rymnik, and Terpeniya terranes are fragments of the compound Early to Late Cretaceous-Paleogene East Sakhalin island arc system of the Sea of Okhotsk region. This island arc paleosystem was composed of back-arc volcano-plutonic belt, frontal volcanic island arc, fore-arc, inter-arc, and back-arc basins, and the Sakhalin marginal paleobasin. The continental volcanic rocks dominate in the back-arc volcano-plutonic belt and frontal volcanic island arc. The petrochemical composition of basalts, basaltic andesites, andesites, and trachytes from the frontal island arc formed in submarine conditions are typical of oceanic island arc or marginal sea rocks (IAB). The petrochemical composition of volcanic rocks from the island arc structures indicates its formation on the heterogeneous basement including the continental and oceanic blocks. 相似文献
9.
滑坡碎屑流对拦挡结构的直接冲击常产生较高的峰值冲击力和冲击能量,导致结构发生破坏而失效;而导引结构通过改变碎屑流的运动路径,可减缓其冲击效应,提高结构抗冲击能力。文章运用三维离散元模拟软件,结合室内休止角试验的结果,校准数值模拟参数,以三种不同导引结构(凹型圆弧、直线型、凸型圆弧)为变量进行数值模拟分析。研究结果表明:凹型圆弧结构B1可以有效地将碎屑流颗粒的冲击力进行转化,结构所受的法向力最小,切向力最大,对颗粒的导引作用最大。经过三种不同导引结构后,颗粒与滑槽之间的碰撞和摩擦是导致颗粒动能减小的主要原因;而三种不同导引结构对颗粒动能的耗散效果无显著差异。导引结构的作用对于颗粒堆积体积分布有显著的影响,主要影响区是靠近坡脚处,对导引结构之后的堆积区域的颗粒体积分布影响不显著。通过对冲击效应和堆积特性的研究,得到凹型圆弧结构形式最优,可以为碎屑流的防护工程抗冲击设计提供参考。 相似文献
10.
Arc–continent collision is a key process of continental growth through accretion of newly grown magmatic arc crust to older continental margin. We present 2D petrological–thermo-mechanical models of arc–continent collision and investigate geodynamic regimes of this process. The model includes spontaneous slab bending, dehydration of subducted crust, aqueous fluid transport, partial melting of the crustal and mantle rocks and magmatic crustal growth stemming from melt extraction processes. Results point to two end-member types of subsequent arc–continent collisional orogens: (I) orogens with remnants of accretion prism, detached fragments of the overriding plate and magmatic rocks formed from molten subducted sediments; and (II) orogens mainly consisting of the closed back-arc basin suture, detached fragments of the overriding plate with leftovers of the accretion prism and quasi insignificant amount of sediment-derived magmatic rocks. Transitional orogens between these two endmembers include both the suture of the collapsed back-arc basin and variable amounts of magmatic production. The orogenic variability mainly reflects the age of the subducting oceanic plate. Older, therefore colder and denser oceanic plates trigger subduction retreat, which in turn triggers necking of the overriding plate and opening of a backarc basin in which new oceanic lithosphere is formed from voluminous decompression melting of the rising hot asthenosphere. In this case, subducted sediments are not heated enough to melt and generate magmatic plumes. On the other hand, young and less dense slabs do not retreat, which hampers opening of a backarc basin in the overriding plate while subducted sediments may reach their melting temperature and develop trans-lithospheric plumes. We have also investigated the influences of convergence rate and volcanic/plutonic rocks' ratio in newly forming lithosphere. The predicted gross-scale orogenic structures find similarities with some natural orogens, in particular with deeply eroded orogens such as the Variscides in the Bohemian Massif. 相似文献
11.
徐宿弧形构造对袁庄矿矿井构造的影响机制 总被引：1，自引：0，他引：1
以徐宿弧形构造西部外缘带中段闸河复式向斜北部的袁庄矿地质构造为主要研究对象,探讨了徐宿弧形构造对闸河向斜和袁庄矿矿井构造形成的影响机制,并分析了各级构造对煤层、瓦斯及岩浆岩的控制作用。研究表明:在徐宿弧形构造背景下,闸河向斜构造虽处于应力集中区,但因石炭-二叠纪地层软弱,故闸河向斜褶皱发育,逆冲断裂却很少,这与向斜两侧的逆冲断裂系形成鲜明对比;袁庄矿矿井构造秉承了闸河向斜构造特征,以褶皱为主要构造形式;煤层赋存、瓦斯含量及岩浆岩等开采地质条件的特征明显受各级构造形式的影响。研究认为,不同尺度下的各级构造有一定的相似性,但又有各自独有的特征,因此在多级次构造研究中,在考虑区域构造背景的同时还应重视次级构造自身条件的研究。 相似文献
12.
鄂尔多斯盆地侏罗纪西界分析 总被引：1，自引：0，他引：1
鄂尔多斯盆地西界,特别是其早—中侏罗世盆地西界,由于不同期次、不同性质的构造相互叠加而模糊不清,究竟是在贺兰山以西还是现在银川盆地以东的问题,至今尚无共识,极大地影响着矿产资源的评价和找矿战略的部署。本文在前人工作的基础上,通过针对性的野外工作,分析和筛分了不同时期的古构造,探讨了晚侏罗世和早—中侏罗世盆地的西界。文章认为,鄂尔多斯盆地西部巨大的近南北向挤压构造形成于晚侏罗世,而东西向的挤压构造则出现于晚三叠世。两期方向截然不同的挤压构造相互叠加,构成了鄂尔多斯盆地西部复杂的叠加构造和不规则的盆地西界。晚期挤压构造较为清晰,表现为近南北向的逆冲推覆构造带和纵贯盆地南北的"古脊梁",使盆地西界退缩到桌子山东麓断裂、横山堡—磁窑堡断褶带以及马儿庄冲断裂和崆峒山断裂以东。早期挤压构造受后期构造的叠加改造,断断续续,时隐时现。近东西向挤压构造受古亚洲域的影响,是印支运动的产物,近南北向挤压构造转受滨太平洋域的作用,是燕山运动的表现。在古亚洲域向太平洋域转换过程中的早—中侏罗世,鄂尔多斯盆地西部出现了近东西向的拉张伸展,在盆地内部表现为近东西向隆起凹陷的古地形,使盆地西缘波状弯曲,而非平直,"银川古隆起"和"汝箕沟—鄂... 相似文献
13.
四国海盆是位于菲律宾海板块内由岛弧张裂形成的弧后盆地,其深部地壳结构对认识伊豆小笠原岛弧的裂解和弧后盆地的扩张过程有重要的意义.在反射多道地震剖面和深部海底地震（OBS）探测剖面的约束下,结合磁异常条带数据,利用两条横穿四国海盆的重力测线数据对海盆的地壳物性结构反演,对比重力反演剖面与深部探测剖面地壳厚度和密度特征,得到更加精细的四国海盆地壳结构.研究结果显示,四国海盆洋壳厚度自西向东逐渐增厚,在残留扩张脊处莫霍面深度迅速增加.根据地壳密度和厚度将四国海盆分为:洋壳减薄区、洋壳增厚区、后扩张洋壳增生区,分别对应初始慢速张裂、单翼快速扩张、对称慢速扩张3期扩张活动.南北测线不同构造分区得到的扩张速率与由磁异常条带得到扩张速率相同;洋壳减薄区下地壳均有高密度体,与OBS剖面中下地壳高速体相对应,可能是由于洋壳慢速扩张过程中强烈拆离作用,地幔蛇纹石化导致. 相似文献
14.
西南“三江”格咱岛弧斑岩成矿系统 总被引：15，自引：10，他引：5
西南“三江”格咱岛弧是“三江”古特提斯演化形成的重要地质构造单元,该单元从晚三叠世洋壳俯冲、洋盆关闭转入碰撞及走滑剪切阶段都产生酸性岩体,形成斑岩Cu-Mo-Au矿床,并构成独立的成矿系统.笔者将格咱岛弧成矿作用以三大岩浆活动期次为基础划分为三套成矿系统,即印支期斑岩Cu多金属成矿系统、燕山期斑岩Mo-Cu多金属成矿系统和喜马拉雅期富碱斑岩Au-Mo-Cu多金属成矿系统.本文从成矿时间、成矿物质来源、成矿流体系统和成矿动力学背景等方面详细总结论述了格咱岛弧的三套斑岩成矿系统.同一地区三大成矿系统反映三次地质构造事件,这种构造演化的连续性和成矿对应性使得该带的研究具有重要意义. 相似文献
15.
《Tectonophysics》1987,144(4):337-352
Halmahera is situated in eastern Indonesia at the southwest corner of the Philippine Sea Plate. Active arc-arc collision is in process in the Molucca Sea to the west of Halmahera. New stratigraphic observations from Halmahera link this island and the east Philippines and record the history of subduction of the Molucca Sea lithosphere. The Halmahera Basement Complex and the basement of east Mindanao were part of an arc and forearc of Late Cretaceous-Early Tertiary age and have formed part of a single plate since the Late Eocene-Early Oligocene. There is no evidence that Halmahera formed part of an Oligo-Miocene arc but arc volcanism, associated with eastwards subduction of the Molucca Sea beneath Halmahera, began in the Pliocene and the Pliocene arc is built on a basement of the early Tertiary arc. Arc volcanism ceased briefly during the Pleistocene and the arc shifted westwards after an episode of deformation. The present active arc is built upon deformed rocks of the Pliocene arc. The combination of new stratigraphic information from the Halmahera islands and models of the present-day tectonic structure of the region deduced from seismic and other geophysical studies is used to constrain the tectonic evolution of the region since the Miocene. Diachronous collision at the western edge of the Philippine Sea Plate which began in Mindanao in the Late Miocene impeded the movement of the Philippine Sea Plate and further motion has been achieved by a combination of strike-slip motion along the Philippine Fault, subduction at the Philippine Trench and subduction of the Molucca Sea lithosphere beneath Halmahera. 相似文献
16.
智利铁氧化物-铜-金矿床区域定位构造-矿田构造类型与特征 总被引：2，自引：0，他引：2
智利铁氧化物铜金矿床形成于安第斯型活动大陆边缘中生代岩浆弧及弧后盆地,区域构造特征主要为岩浆侵入构造岩相带和阿塔卡玛断裂系统(AFZ),岩浆侵入构造及岩相分带控制矿田形成,AFZ断裂系统控制了矿化带和大型矿体产出.矿田构造主要有五种类型:火山构造;岩浆侵入构造+复式背斜;NS向平行韧性断裂带+岩浆侵入构造;走滑断裂弯曲... 相似文献
17.
雅鲁藏布蛇绿混杂岩带位于藏东南南迦巴瓦峰地区(喜马拉雅东构造结),呈弧形大致沿雅鲁藏布江分布,出露宽度2～10km。带内岩石变质、变形强烈,按产状可分为两大类:基质和岩块(片)。岩块(片)包括蛇绿岩套中的超镁铁岩、辉绿岩墙和辉长岩,石英(片)岩,大理岩和两侧老基底片麻岩等。岩块(片)大小不一,大的延伸可>50km,小的仅约0.5m;基质是塑性变形十分强烈的绢云母石英片岩、二云母石英片岩、绿片岩等岩石组合。变质玄武岩岩石地球化学特征表明,该蛇绿混杂岩带可能由形成环境不同的“碎片”组成,包括弧前扩张带、岛弧、弧后盆地及洋岛等环境,是典型的消减带环境的蛇绿岩(SSZ)。初步的同位素年代学测试结果,说明蛇绿岩可能在200Ma前形成,比原认为距今110～120Ma要早得多,这一结果与该带其它地段的研究成果相似。 相似文献
18.
《International Geology Review》2012,54(11):1235-1251
Data on peculiarities of configuration and positional interrelations of folded structure belonging to the Middle Paleozoic structural stage of the Bolshoy Karatau Ridge are given in the paper. On the basis of both the geological-structural map of this region compiled by the author and an abundance of other materials conclusions are made as to the most important morphological features of the geosynclinal folds; considerations regarding the modes of their formation are suggested. Within the above-mentioned structural stage three most important genetic fold types are isolated: stamped folds, warping folds, flow folds. The former originated under the effect of vertically directed forces normally applied to the stratum. The second are the results of a tangential compression of stratified beds. And the formation of the last was caused by the flow of the most plastic constituents of the section. The author is of the opinion the above fold types are generally most widespread among the folded structures of the geosynclinal regions. The stamped folds are a direct result of local uplifts and subsidences of the Earth crust and thus their origin is quite clear from the mechanical standpoint. The warping folds might have formed in the course of uplifting of previously formed downwarpings when the filling rock beds had to pass through the chord of their original arc. Moreover they might have originated as a result of broad gravitational bed sliding. And finally, the flow folds most frequently formed evidently also under the effect of gravitational forces (when the latter are great enough to provoke plastic rock deformation) or under the effect of a difference of confining pressures.—Auth. English summ. 相似文献
19.
宁夏中部牛首山地区构造特征及其地质意义 总被引：2，自引：4，他引：2
宁夏中部牛首山地区的古生代地层发育了许多具有逆冲构造特征的的变形构造,断层相关褶皱非常发育。通过分析这些构造及其相互关系,恢复了该地区中奥陶统米钵山组的变形过程,表明该套地层经历了(1)岩层受到水平挤压,顺层缩短阶段,(2)褶皱变形阶段,(3)逆冲变形阶段等三个阶段;这些构造是逆冲推覆构造发育不同阶段的产物。牛首山以及宁夏南部的大、小罗山是古逆冲构造带的前缘部分,宁夏中南部地区在中奥陶世至泥盆纪是作为北祁连造山带北侧的弧后前陆盆地靠大陆一侧而存在随着该弧后盆地的关闭,牛首山前缘构造带形成。而现今的牛首山以及宁夏中南部的奥陶系很可能都是无根的。 相似文献
20.
昆仑多岛弧盆系及泛华夏大陆的增生 总被引：9，自引：1，他引：9
自从Rodinia超大陆在晚元古代解体之后,冈瓦纳大陆群与泛华夏大陆群间从晚元古代至中生代始终存在一大洋-特提斯洋。从早古生代至中生代,特提斯洋分三个阶段向泛华夏陆块群俯冲,形成了弧后扩张、弧陆碰撞和弧前增生。弧后盆地扩张到达小洋盆,出现蛇绿混杂岩。由于早期大陆边缘已向南发生了增生,继后的弧后扩张和前锋弧的位置也就相应地向南迁移了。因而蛇绿岩带、岩浆岩带会出现多条,且从北向南时代有从老变新的趋势。由于陆缘向南裂离,并到达高纬度位置,或者如洋岛的生成,随着洋壳的消减速、俯冲,高纬度的沉积体向低纬度的不断增生,这样就出现了生物的冷暖型混生。且从泛华夏陆块群或从冈瓦纳大陆群裂离的块体不能越过大洋中脊拼合在另一大陆块体上。因此,泛华夏大陆的西南缘-昆仑带只是在弧后海底扩张、弧-弧碰撞、弧-陆碰撞的多岛弧造山作用、向南不断增生过程中形成的。 相似文献