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青海省东昆仑地区晚古生代—早中生代火山活动与区域构造演化 总被引：43，自引：1，他引：42
从沉积建造分析入手,通过对区内晚古生代—早中生代火山岩组合的构造属性识别,认为区内晚古生代—早中生代构造演化是一个连续的过程,它奠定了该区的基本构造格局,也是金与铜多金属矿产的主要成矿时期;晚古生代—早中生代发育的双岩浆弧是在同一动力学机制下不同阶段形成的造山岩浆弧：陆缘的钙碱性岩浆弧和陆内的高钾钙碱性岩浆弧。晚古生代—早中生代构造岩浆旋回可以划分为２个阶段,早期的俯冲造山阶段形成了与蛇绿岩有关的火山岩类和弧火成岩类,晚期的大洋闭合和碰撞造山阶段则形成了钾玄岩系列火山岩。 相似文献
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《International Geology Review》2012,54(11):1027-1047
New geological and petrological data on the range of magmatic complexes and formations of the Eastern Sayan show two primary magmas: basic and granitoid. These magmas were formed through melting hard deep-seated layers of the earth crust: basaltic and sialic. During the geosynclinal stage the development of magmas belonging to the Archean, Proterozoic, and Salair [Cambrian] volcanic cycles proceeded consecutively from ultrabasic and basic formations formed in a pre-orogenic or earlier-orogenic geosynclinal development stage to granitoids set up in a synorogenic or later-synorogenic development stage. During the platform stage middle Paleozoic (Lower Devonian) and Mesozoic-Cenozoic cycles of magmatism proceeded directly, without the geosynclinal preparatory stage. Their development, accompanied by faulting, proceeded in reverse order from acidic and alkalic intrusions to predominantly basic eruptives. A further development of deep-seated basic and granitoid magmas was determined first by magmatic differentiation and later by assimilation phenomena which took place during the magma's passage into upper structural layers. The granitoids of geosynclinal magmatic complexes correspond petrochemically to the intermediate types of calc-alkalic rocks of the Pacific Ocean belt. The granitoids and alkalic rocks of the Lower Devonian platform magmatic complex resemble those of the Cenozoic East-Asia alkalic province. The composition of the granitoid magma belonging to the volcanic cycle is conditioned initially chiefly by the sial environment and geosynclinal strata. Magmatic complexes and formations are characterized by definite endogenic mineralizations. Chromium, nickel, cobalt, platinum, diamond, asbestos and other deposits are genetically connected with Proterozoic basic and ultrabasic rocks; gold, muscovite and tin-rare metal pegmatite with upper Proterozoic granitoids. Copper, galenaite and gold-ore occurrences are related to the postmagmatic manifestations of Salair granitoids. Deposits of pyrochlore carbonatites, molybdenite, graphite and others belong to Lower Devonian acidic and alkalic granitoids. — Auth. English summ. 相似文献
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《International Geology Review》2012,54(11):1279-1297
The Paleozoic tectonic evolution of Hsieh-fen-shan, western Hunan, belongs to the Caledonian and Hercynian tectonic cycles. The base of the lower Paleozoic group is defined by a geographical unconformity; the Sinian system unconformably overlies the Pan-ch'i group of the Proterozoic. The Hsieh-fen movement represented by this unconformity had not transformed this area into a platform. The lower Paleozoic group may be divided into four structural stages: Lower Sinian, Upper Sinian-Cambrian, Lower Ordovician and Middle Ordovician-Silurian. These stages are represented by the corresponding sedimentary formations: lower terrigenous elastic formation, siliceous and carbonate rocks intercalated with shale, flush formation and upper terrigenous elastic. Due to the absence of magmatic activity it is believed to be of the miogeosyncline type. In the Variscan cycle this area was already consolidated and partly covered with upper Paleozoic neoplatform sediments. Hereditary characters of the early Paleozoic tectonic evolution are obvious. According to the isopachous maps there occurred a strong tectonic differentiation at the end of the Cambrian. In Early Ordovician a northeast extended flysch geosyncline formed, and to the west of it, an uplifted denudation region. The eastern part of the uplifted region rose strongly, in parallel with the flysch geosyncline and with similar dimensions, and may be considered a geanticline. The geosyncline and geanticline have asymmetrical forms, their neighboring flanks being steeper than their opposite ones. Consequently the existence of a so-called pre-Sinian Hsieh-fen axis has not been proved and the boundaries of the Southwestern Platform with the adjoining southeastern Caledonian fold may be located approximately along T'ao-yuan, Yuan-ling Chen-chi, Hsin-Hua and Ch'ien-yang. – Authors. 相似文献
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在皖赣沿江地区分布着大量中生代侵入岩体及其岩石包体和相关的夕卡岩矿床。本文在综合整理作者研究团队近30年来所获得的区内大部分侵入岩体及其岩石包体和夕卡岩矿床研究资料的基础上,聚焦区域中生代壳幔相互作用与多成因夕卡岩成矿过程分析,为发展壳幔成矿学打下一定基础。基性侵入岩和镁铁质岩石包体的同位素年代学和岩石地球化学资料表明,皖赣沿江地区在中生代发生了碰撞后(145~135 Ma)富铜金和造山后(130~120 Ma)富铁金幔源岩浆底侵作用和相应的壳幔混源岩浆作用。壳幔混源岩浆作用主要包括结晶分异作用、同化混染作用、岩浆混合作用和岩浆熔离作用。夕卡岩矿床地质调研和镜下观察结果显示,两期壳幔混源岩浆侵入晚古生代到早中生代围岩地层后引发了多成因夕卡岩成矿作用,形成了接触交代、层控、岩浆和复合叠加等多成因夕卡岩矿床。接触交代、层控、岩浆和复合叠加夕卡岩矿床分别以热液交代、沉积+热液交代、岩浆结晶+热液交代和沉积+岩浆结晶+热液交代矿物组合和结构构造为特征。在碰撞后酸性-中酸性侵入岩体中产有富Cu和Zn等成矿物质的元古宙变质岩包体,表明碰撞后富铜金的底侵玄武岩浆或其演化岩浆在浅位岩浆房中同化了元古宙变质基底成矿物质(铜锌等)储库导致铜进一步富集,从而形成更富铜的酸性-中酸性岩浆。在碰撞后中基性-基性侵入岩体中产有含大量Cu-Fe硫化物(黄铜矿和磁黄铁矿)和氧化物包裹体的深位和浅位堆积岩,表明碰撞后富铜金的底侵玄武岩浆在深位岩浆房中和其演化岩浆在浅位岩浆房中发生了强烈的结晶分异作用导致铜铁亏损,形成更富金的中基性-基性岩浆。酸性-中酸性侵入岩体中夕卡岩包体和夕卡岩中辉长岩-夕卡岩过渡包体的存在表明,碰撞后富铜金的底侵玄武岩浆在侵位处同化晚古生代含铜铁矿源层的碳酸盐地层导致铜进一步富集,形成更富铜的夕卡岩岩浆。更富铜的酸性-中酸性岩浆、更富金的中基性-基性岩浆和更富铜的夕卡岩岩浆是形成碰撞后时期接触交代和层控夕卡岩铜矿、接触交代夕卡岩金矿和岩浆夕卡岩铜矿的最重要控制因素。在造山后中基性-基性侵入岩体中产有含大量Cu-Fe硫化物(黄铜矿和磁黄铁矿)和氧化物包裹体的堆积岩,表明造山后富铁金的底侵玄武岩浆在深位岩浆房中发生了强烈的结晶分异作用导致铜铁亏损,从而形成更富金的中基性-基性岩浆。造山后富铁金的底侵玄武岩浆在侵位处同化晚古生代含铜铁矿源层的碳酸盐地层、早中生代铁矿源层或者早中生代铁硅矿源层,导致铁、铁和铁硅的进一步富集,分别形成更富铁的夕卡岩岩浆、基性岩浆和中基性岩浆。更富金的中基性-基性岩浆及更富铁的夕卡岩岩浆、基性岩浆和中基性岩浆是形成造山后时期接触交代夕卡岩金矿、岩浆夕卡岩铁矿、矿浆型铁矿和接触交代夕卡岩铁矿的关键控制因素。 相似文献
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地层中常见到多种矿产富集的现象,特别是有岩浆侵入的地区,更有利于多种矿产的生成和保存,大大提升了矿产资源的勘探效益与开发价值。以山东黄河北煤田为例,开展中生代岩浆侵入与古生代多矿产(煤炭、煤层气、煤系页岩气、富铁矿)成因机制研究。结果表明:黄河北煤田石炭–二叠系构造条件和沉积环境利于煤层的发育,平面上煤层分布具有东多西少、东薄西厚、北薄南厚的特征,纵向上具有下厚上薄的特征;煤层气藏具有煤层厚度中等、煤级分布广、含气量中等、吸附性好、特低欠饱和、低孔较高渗、欠压、埋深适中的特点;煤系页岩气藏具有泥页岩累积厚度大、有机质丰度较高、生烃能力中等、Ⅱ型干酪根为主、成熟度中等、低孔特低渗的特点;中生代岩浆侵入奥陶系马家沟组灰岩地层中,含矿热液与围岩发生接触交代作用和磁铁矿化,形成了接触交代型富铁矿床;中生代岩浆的侵入与岩浆热变质作用,使得研究区上覆煤系中出现了以岩浆侵入体为中心的煤类分带和局部地区煤层气与煤系页岩气的大量产生与成藏。煤层和泥页岩含气量、孔隙率/孔径、有机质的热演化程度和生烃能力与距离侵入体的距离成负相关关系,且煤层距离侵入体越近,气体的吸附性能越弱,以游离态为主。综上,中生代的岩浆侵入作用控制了古生代多种矿产的形成与共存。 相似文献
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塔里木盆地古生代构造格架与沉积特征 总被引：25，自引：3，他引：25
本文以板块构造理论为主线，应用最新的物探成果和钻井资料，分析了前古生代塔里木盆地地球动力学背景和寒武－奥陶纪、志留－泥盆纪、石炭－二叠纪板块构造演化所形成的盆内隆坳构造格架与沉积特征，认为古生代克拉通原型盆地的发育、各时期的沉积相带分布与沉积建造以及下古生界东厚西薄、上古生界东薄西厚的厚度特征，都是不同地质时代构造演化控制的结果。 相似文献
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武当地块基性侵入岩群的地质特征与构造意义 总被引：13，自引：0，他引：13
南秦岭构造带武当地块中发育密集侵位的基性侵入岩群，由于武当地区构造变形复杂，这些基性侵入岩体的侵位特征一直没有明确的研究结果。而查明它们的侵位特征，对认识其侵位机制、判断岩浆侵位的大地构造背景以及开展进一步的岩石地球化学和岩浆动力学的研究都具有重要意义。本文通过在武当地块不同构造部位所做的一些详细的1：5万地质填图以及相应的构造学研究表明，这些侵入岩体是顺层侵位到武当山岩群和耀岭河组中的，少数直接侵位到震旦系陡山沱组和邓影组中，侵入体密集发育的部位受武当地块古生代顺层伸展拆离构造的主拆离面控制。作者同时获得了402Ma的单颗粒锆石U—Pb年龄，表明这些基性侵入岩群形成于中古生代。因此无论这些基性侵入岩群的地质特征，还是其同位素年代学测试结果，都表明与前人所说的元古代超大陆的裂解很可能没有直接的成因联系。考虑到这个时期南秦岭构造带中发生的紫阳-岚皋碱性岩浆活动、镇安-旬阳浅层塌陷盆地、武当地块伸展滑脱构造及随枣地区基性侵入岩群的侵位等地质构造事件，作者认为武当地块基性侵入岩群很可能是古生代时期南秦岭岩石圈拉伸所导致的深部基性岩浆上侵的结果。 相似文献
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姚家岭特大型Cu-Pb-Zn多金属矿床的发现,是铜陵地区近年来找矿勘探上的一项重大突破,成矿母岩为姚家岭岩体。然而,目前对该岩体的形成年龄和岩石成因尚无系统研究。本次工作表明岩体的锆石LA-ICPMS定年结果指示其形成年龄为140.7±1.3 Ma,处于长江中下游地区中生代岩浆活动3个阶段中的第一阶段,姚家岭岩体具有富集的Sr-Nd同位素组成和类似大陆岛弧的微量元素特征,和铜陵地区其它中生代侵入岩体是一致的,成岩岩浆由被俯冲板片流体/熔体交代的富集岩石圈地幔和太古代下地壳分别部分熔融产生的岩浆混合形成,并经历了角闪石和榍石等矿物的结晶分异。岩石的形成处在本地区由挤压转为拉张的过渡时期。 相似文献
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《International Geology Review》2012,54(9):1562-1568
This article discusses the historical tectonic development of the portion of Siberia lying within the Arctic Circle. The exposed rocks are referred to seven tectonic or geotectonic stages: Archean, Proterozoic, Sinian, lower to middle Paleozoic, upper Paleozoic to lower Mesozoic, and Mesozoic-Cenozoic. Locally on the Shorikka and Kamennaya, the nearly horizontal Lower Cambrian beds overlie the Sinian with angular unconformity. In contrast, isolated areas on the west side of the Yenisey show a gradational relationship between the Late Sinian and Early Cambrian beds in a dominantly carbonate succession. The present tectonic elements of the Siberian platform were developed in Mesozoic-Cenozoic time, and differential movements in the basement have continued into Neogene time. The sedimentary platform cover was enlarged by sedimentary overlap from Sinian to mid-Paleozoic time. The sediment came from the older fold systems. The major structures are measured in terms of variations in stratigraphic thickness, but details are unfortunately omitted. The main features are delineated on a geotectonic map embracing 42 map units and symbols. The map lacks basic reference data, geographic designations, scale, and other essential information. — B. N. Cooper. 相似文献
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秦岭造山带主要大地构造单元的新划分 总被引：48，自引：6，他引：42
根据近年来的地层、沉积、岩浆-火山和构造变形及岩石地球化学等方面研究新进展,结合前人的成果,按照大地构造相单元划分原则,将秦岭造山带分为13个主要构造单元: ①华北南缘陆坡带,包括第一层序的青白口系大庄组、震旦系罗圈组和寒武系,与之对应的豫西栾川群;第二层序的奥陶纪陶湾群;②北秦岭弧后杂岩带,以宽坪群和部分二郎坪群中的基性火山岩与碳酸盐岩的构造块体与变质的古生代深海碎屑岩混杂为特征;③秦岭岛弧杂岩带,由丹凤群不同的古洋隆块体、富水幔源岛弧基性岩浆杂岩、云架山群、斜峪关群和草滩沟群的岛弧钙碱性岩浆岩和火山岩及深海沉积物及秦岭群弧基底杂岩等构成,时间跨度为奥陶纪-石炭纪;④秦岭弧前盆地系,泥盆系及其它晚古生代地层是其主要充填物,同沉积断裂控制了一系列的次级盆地;⑤秦岭增生混杂带,由泥、砂岩组成的基质和基性、超基性岩、火山岩、灰岩、硅质岩等岩块构成,最终形成于二叠纪末-三叠纪初;⑥南秦岭岛弧杂岩带,碧口群的基性-中酸性火山岩和岩浆岩组成,称碧口弧;由三花石群的中基性火山岩以及西乡群的中酸性火山岩共同构成,称西乡弧;由耀岭河群和郧西群中基性熔岩和中酸性火山岩组成,称安康弧;⑦南秦岭弧前盆地系,碧口弧前盆地充填物是以碎屑岩为主的横丹群和关家沟群;西乡弧前沉积主要由三花岩群包括王家坝组砂岩以及由泥岩、砂岩和中酸性火山岩变质而成的片岩、片麻岩和石英岩组成.安康弧前盆地具有明显的深海扇沉积特征梅子垭群和大贵坪组;⑧南秦岭弧后盆地系,包括后龙门山的茂县群和上古生界及三叠系,大巴山的洞河群和部分耀岭河群的火山岩;⑨南秦岭弧后陆坡带,只保留大巴山弧后陆缘,是高川-毛坝以南的下古生界;⑩南秦岭前陆褶冲带,包括龙门山北段、米仓山和大巴山前陆褶冲带.三带形成于印支-燕山期,但构造线不同,且在出现的时间上,由西到东由早到晚;(11)三叠纪残余海盆;(12)中-新生代走滑拉分和断陷盆地;(13)基底断块. 相似文献
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近几年来,为配合寻找富铁矿及其他科研任务,对冀东、辽东、豫西、川西等地的前寒武系,及庐枞、宁芜、繁昌和浙西等地的中生代火山岩地层进行了同位素年龄测定和研究。在所内外的大力支持协助下,进行了野外观察和采样,同时接受了所内外兄弟单位送来的样品及有关地层资料。我们对这些样品进行了同位素年龄测定。冀东、辽东、豫西和川西前寒武纪地层的样品,主要用Rb-Sr全岩等时线法,其中对川西的样品并用了少数K-Ar法。对庐枞、宁芜、繁昌和浙西的中生代地层样品,主要用K-Ar法。对浙西的个别样品并用了Rb-Sr全岩等时线法。对测定得到的部分年龄数据,以前曾以不同方式报道。 相似文献
14.
内蒙古东部二连浩特-乌兰浩特地区金矿化特征的初步研究 总被引：2，自引：0，他引：2
研究区属含古老地块并经中生代改造的中古生代造山带,存在金、锡等丰度较高的锡林浩特元古宙杂岩、古生代蛇绿岩及板块缝合带、二叠系火山岩、中生代伸展构造背景下的大规模火山-侵入活动及锡多金属成矿作用.本区金矿化类型主要有:韧性剪切带中的石英脉型、蚀变岩型金矿,产于幔源中基性侵入岩中的铜金矿,燕山晚期斑岩型铜金矿,与燕山期次火山岩浆活动有关的脉状铜矿床中的伴生金矿化,微细浸染型金矿化,浅成低温热液型金矿化等.研究区金矿成矿时代可分为242~229Ma、169~161.8Ma、132~159Ma (可能以130~140Ma为主)、127~109.2Ma四个区间.认识到存在印支期成矿、燕山期多阶段成矿等特点对于区内金矿勘查有重要意义.新发现7个矿床(点)的伴生金矿化.毛登、大井等多金属矿床的伴生金矿化具有重要的潜在工业意义. 相似文献
15.
秦岭造山带构造-成矿旋回与演化 总被引：5，自引：0，他引：5
构造与成矿活动是否具有旋回性是地质界长期争论的一个命题。本文根据矿床成矿系列理论和方法,论述了秦岭造山带构造-成矿活动,划分出新太古代-古元古代早期、古元古代晚期、中-新元古代、早古生代、晚古生代和中、新生代6个构造-成矿旋回,探讨了每个旋回的矿床成矿系列特征和成矿演化历史。指出该造山带的成矿作用既有长期性和连续性,也有间断性和旋回性;中、新元古代至早古生代和中、新生代两个时期是秦岭造山带中两个主要的成矿高峰期;构造-成矿作用可分为开裂、拼合及相对稳定三个阶段;成矿作用早期以幔源岩浆侵入及海相火山活动为主,晚期以壳幔混源-壳源的陆相中酸性岩浆侵入及火山活动为主;与火成活动及开裂作用有关的成矿活动在南、北两个成矿域之间具有振荡性演化的特征. 相似文献
16.
《International Geology Review》2012,54(3):405-419
A complex of variously metamorphosed sedimentary and volcanic rocks, migmatites, and plutonic intrusives are exposed in long fault blocks at different structural and metamorphic levels in the Main Range Region of the West Caucasus. A Proterozoic and lower Paleozoic suite is largely comprised of amphibolite foliates and biotite schist and gneiss. A middle Paleozoic suite consists of metasedimentary and metavolcanic rocks mostly in the green schist facies. Intrusive and extrusive magmatic products are classified as middle Paleozoic, upper Paleozoic, and Mesozoic. Petrography and mineralogy of the major metamorphic and igneous units are described in detail. Complex isoclinal to open folds occur in long blocks bounded by subvertical longitudinal faults. Major deformation is Hercynian. Modern strike-slip faulting is briefly described. The region is subdivided tectonically and described in detail. — L.T. Grose. 相似文献
17.
Tracking the birth and growth of Cimmeria: Geochronology and origins of intrusive rocks from NW Iran
New geochronological and geochemical data for Late Neoproterozoic to Mesozoic intrusive rocks from NW Iran define major regional magmatic episodes and track the birth and growth of one of the Cimmerian microcontinents: the Persian block.After the final accretion of the Gondwanan terranes, the subduction of the Prototethyan Ocean beneath NW Gondwana during the Late Neoproterozoic was the trigger for high magmatic fluxes and the emplacement of isotopically diverse arc-related intrusions in NW Gondwana. The Late Neoproterozoic rocks of NW Iran belong to this magmatic event which includes intrusions with highly variable εHf(t) values. This magmatism continued until a magmatic lull during the Ordovician, which led to the erosion of the Neoproterozoic arc, and then was followed by a rifting event which controlled the opening of Paleotethys. In addition, it is supposed that a prolonged pulse of rift magmatism in Persia lasted from Devonian-Carboniferous to Early Permian time. These magmatic events are geographically restricted and are mostly recorded from NW Iran, although there is some evidence for these magmatic events in other segments of Iran. The Jurassic rocks of NW Iran are interpreted to be the along-strike equivalents of a Mesozoic magmatic belt (the Sanandaj-Sirjan Zone; SaSZ) toward the NW. Magmatic rocks from the SaSZ show pulsed magmatism, with high-flux events at both ~176–160 Ma and ~130 Ma. The SaSZ magmatic rocks are suggested to be formed along a continental arc but a rift setting is also considered for the formation of the SaSZ rocks based on the plume-related geochemical signatures. The arc signatures are represented by Nb-Ta depletion in the highly contaminated (by upper continental crust) plutonic rocks whereas the plume-related signature of less-contaminated melts is manifested by enrichment in Nb-Ta and high εHf(t) values, with peaks at +0.6 and +11.2. All these magmatic pulses led to pre-Cimmerian continental growth and reworking during the Late Neoproterozoic, rifting and detachment of the Cimmerian blocks from Gondwana in Mid-Late Paleozoic time and further crustal growth and reworking of Cimmeria during the Mesozoic. 相似文献
18.
《International Geology Review》2012,54(8):1009-1015
Accumulations of tin, tungsten, molybdenum and other ores in the territory, generally associated with Mesozoic intrusions into Paleozoic and Proterozoic sedimentary and metamorphic rocks and into Hercynian granitoids, are shown to be structurally-tectonically controlled and are classified according to type of control and origin, with attention to their economic potential. -- IGR Staff. 相似文献
19.
拉鸡山断裂带位于祁连山褶皱带内,呈北西-南东向延伸.后者构成青藏高原的东北边缘,由三个主要构造单元组成:北部是一条早古生代的板块缝合带,中部是一个元古代的结晶地块,南部由一套晚古生代到三叠纪的被动大陆边缘沉积物组成.对拉鸡山及其邻区的构造研究结果表明,祁连山褶皱带在古生代加里东期发生过大规模的缩短,北祁连的早古生代蛇绿岩和岛弧火山岩沿祁连山中央冲断层向南,陆内俯冲到中祁连元古界变质杂岩之下.由于发生在晚古生代和晚中生代的陆内变形,位于中祁连之下的北祁连的蛇绿岩和岛弧火山岩发生褶皱,并被抬升到地表.到新生代,由于印度板块和欧亚大陆之间的碰撞和陆内汇聚作用,拉鸡山断裂带再次活动,这些下古生界蛇绿岩和岛弧火山岩通过冲断作用快速抬升,将中祁连地块一分为二.因此,拉鸡山是一个抬升的构造窗,不是一个中祁连结晶地块中的早古生代大陆裂谷. 相似文献
20.
安徽的地壳演化:Sr,Nd同位素证据 总被引：13，自引：0，他引：13
在地壳(幔)演化和板块构遣的框架内，评述了有关安徽南部(扬子地块东部，包括大别遣山带和江南遣山带)的同位素地质年代学和Nd，Sr同位素地球化学示踪研究的成果。该地区出露地表的中元古界溪口群浅变质岩代表皖南的基底，沿江地区和大别山区的基底包舍太古宇或／和古元古界古老岩石。此格局还影响到从震旦纪到古生代沉积岩的物源区，江南深断裂以北的沉积岩中有古老岩石的贡献，而以南的物源主要来自出露的中元古界岩石。扬子陆块南北缘(大别和江南遣山带)的晋宁期演化可能与罗迪尼亚超大陆演化有密切关系，但有关研究开展很少。三叠纪大陆深俯冲和超高压变质作用研究已成为国际地球科学的热点。晚中生代(120-140Ma)本区发生强烈的岩浆活动，并伴有重要矿床的形成。中酸性岩的形成是一种壳幔物质混合的过程。沿江地区陆下地幔具有富集特征，为扬子型岩石圈地幔与软流圈地幔混合的产物。从晚中生代到第四纪，基性岩指示其源区的地球化学性质有随时间变得越来越亏损的趋势。 相似文献