论东天山觉罗塔格造山带的大地构造属性

觉罗塔格造山带位于吐哈盆地和中天山地块之间，长期以来，关于该造山带的大地构造属性争论较多，有晚古生代岛弧带、弧后盆地、裂陷槽、古生代陆缘增生带、石炭纪火山岩型被动陆缘等不同认识。基于晚古生代早期觉罗塔格地区处于板内拉张的动力学背景，而非挤压碰撞环境，结合对带内早石炭世雅满苏组火山—沉积建造较为系统的岩石学、岩石化学及岩石地球化学研究，认为觉罗塔格造山带应为一拉张型构造—岩浆岩带。     

碰撞造山带的大地构造相及研究意义

在综合介绍国内外关于大地构造相概念和大地构造相研究方法的基础上,综述了大地构造相分析在研究造山带结构和演化,非史密斯地层以及造山带沉积地质学方面的意义。     

五台山早前寒武纪碰撞造山带中的韧性剪切带及其大地构造…

在五台山早前寒武纪碰撞造山带中存在的两种类型韧性剪切带，即逆冲型和伸展型剪切带。除变质程度不同外，南部和北部构造片体中的角闪岩相逆冲型韧性剪切带与中部构造片体中的绿片岩相逆冲型韧性剪切带具有相同的变形特征，它们形成于同一变形过程，是造山作用早期地壳拼合阶段的产物。伸展型韧性剪切带在整个造山带都有分布，与造山作用晚期显著增厚的地壳发生大规模纵向伸展作用相联系。     

西南“三江”造山带大地构造相

西南“三江”造山带由多条缝合带及其间多个大小不等的中间陆块构成,其大地构造属性与划分方案历来受地学界关注与争论。本文以大地构造相理论为切入点,将西南“三江”造山带划分出11个一级及其若干二级大地构造相,包括俯冲、消减杂岩、仰冲等一级大地构造相以及与其相伴的后造山及走滑大地构造相。俯冲大地构造相类包括块体变质相、前陆褶冲相、前陆盆地相;消减杂岩大地构造相包括洋壳残片相、陆壳残片相、增生变质杂岩相、活化基底相、侵入岩相、上叠磨拉石相;仰冲板块大地构造相包括弧前盆地相、岛弧相、弧后及弧间盆地相。特提斯洋向北消减,使泛华夏大陆群各块体先拼接,其后弧后扩张、闭合、造山,从而形成了“三江”造山带“多缝合带”、“多陆体”特征。     

西昆仑北带蛇绿岩的地球化学特征及其大地构造意义

在西昆仑造山带的北侧存在着一条西起盖孜，向东经奥依塔格、库地、苏巴什至祁曼塔格的蛇绿岩带。在详实的野外考察工作和充分总结已有研究资料的基础上，通过对该蛇绿岩带岩石化学、地于化学特征的分析，认为它对西昆仑造山带大地构造演化的研究提供了重要的信息，反映了西昆仑造山带曾经历了由统一陆块在震旦纪时的破裂到喜马拉雅期的强烈推覆和走滑等过程，从而奠定了西昆仑现今的构造格架。     

造山带非史密斯地层

造山带一般都经历了多期板块裂解与拼合的复杂演化过程。造山带地层体在造山带洋盆会聚、俯冲消亡和陆内造山阶段,发生过强烈的构造搬运和构造混杂。俯冲带在消减板块下潜过程中,盆地中先前在重力机制下形成的原始浊积岩和远洋沉积(基质)、同沉积滑塌岩块,与先前在热力机制下形成的蛇绿岩和火山弧,与早先裂解的陆壳碎片等最终一并带入俯冲带内遭受剪切,发生构造混杂,由这种混杂作用形成的地层体通常由经强烈构造剪切作用的基质(浊积岩和远洋沉积)和混入的多种外来岩片(块)构成,是造山带非史密斯地层研究的主体。对造山带非史密斯地层,要针对基质和外来岩片(块)分别进行划分、对比研究。特别对基质中的外来岩片(块),要进行物态、时态,相态、位态、变形和变质历程的精细解剖与研究。通过造山带非史密斯地层研究,建立造山带地层系统理论模型,恢复造山带形成和演化历程。     

大陆造山带的大地构造特征及研究造山作用的几种学派—以秦岭—大别山造...

文章以秦岭－大别山造山带的研究为例，介绍了运用“开合律”总结的五种造山带类型。运用抽拉－逆冲岩片构造观点研究大陆造山运动发展，演化的新观点以及运用多旋回造山运动观点对造山带的解释。认为秦岭－大别山造山带是多旋回构造运动的场地，但缺少威尔逊旋回。     

洋底凸起地质体及其对造山带中蛇绿岩组分的贡献

蛇绿岩作为造山带中保存的曾经存在过的大洋或与大洋有关地质体的残留,除了部分的露头出露有完整的岩石组分之外,研究发现许多露头只出露部分的岩石组分,如只出露第1层的深海/远洋沉积物和第2层的玄武岩或绿岩,且其基性岩以MORB和OIB的地球化学特征为主,而不是SSZ型岩浆的地球化学特征。审视以前的蛇绿岩就位模型,学者们认为俯冲洋壳的洋底是平坦的;该假设与现状大洋洋底地形探测资料不吻合。大洋洋底测绘资料显示洋底可以在洋中脊处和海山/洋底高原的位置发育凸起地貌。本文根据岩石破裂的力学性质,分析了它们的破裂过程;结合中国新疆西准噶尔玛依勒地区、日本造山带和美国加州海岸山脉增生楔和蛇绿岩中岩石组合和构造属性,以及它们的就位时代和形成时代年龄差可达几十个百万年到上百个百万年,认为洋底表面的凸起地质体上段部位的岩石容易被滑脱断层错断并卷入到造山带中,而且它们比构造叠置的围岩-海沟沉积物更老。     

Evidence for Palaeozoic magmatism recorded in the Late Neoproterozoic Marlborough ophiolite,New England Fold Belt,central Queensland

The ultramafic‐mafic complex in the Marlborough terrane of the northern New England Fold Belt is dominated by members of a Neoproterozoic (ca 560 Ma) ophiolite (V1). The ophiolite has been intruded by the products of three Palaeozoic tectonomagmatic episodes (V2, V3 and V4). The V2 magmatic episode is represented by tholeiitic and calc‐alkaline basalts and gabbros of island‐arc affinities. Sm/Nd isotopes give a whole‐rock isochron age of 380 ± 19 Ma (2σ) to this episode, some 180 million years younger than the V1 ophiolitic rocks. The V3 magmatic episode includes tholeiitic and alkali basalts with enriched geochemical signatures characteristic of intraplate volcanism. A whole‐rock Sm/Nd isochron age of 293 ± 35 Ma is obtained for this event. A fourth magmatic event (V4) is represented by basaltic andesites and siliceous intrusives with geochemical features similar to modern adakites. This event has its type locality in the Percy Isles. These data provide tectonic and geochronological constraints for the previously enigmatic Marlborough terrane and as such contribute to the ever‐evolving understanding of New England Fold Belt development.     

Geochemistry of the ophiolite and island-Arc volcanic rocks in the Mianxian-Lueyang suture zone, southern Qinling and their tectonic significance

Ultrabasic rocks in the Mianxian-Lueyang ophiolitic melange zone include harzburgite and dunite which exhibit LREE depletion with remarkable positive Eu anomaly.The diabase dike swarm shows LREE enrichment but slightly negative Eu anomaly.Metamorphosed volcanic rocks can be divided into two groups in terms of their REE geochemistry and trace element ratios of Ti/V,Th/Ta,Th/Yb and Ta/Yb.One is ths MORB-type basalt with LREE depletion,representing the fragments of oceanic crust and implying an association of the MORB-type ophiolite and an ancient ocean basin between the Qinling and Yangtze plates during the Middle Paleozoic-Early Mesozoic era.The oter comprises the island-arc volcanic rocks including tholeiitic basalt and a large amount of calc-alkaline intermediate-acic volcanic rock,which could not be the component of the ancient oceanic crust but the result of magmatism at the continental margin.This indicates that the Mianxian-Lueyang limited ocean basin had undergone a whole process of development,evolution and vanishing from Devonian-Cretaceous to Permian.And the Qinling area had becone an independent lithospheric microplate,on the southern side of which there were exhibited the tectonic characteristics of active continental margins during the Late Paleozoic-Early Mesozoic.That is to say.the Qinling cannot be simply considered as a result of collision between the Yangtze and North China plates.     

板块构造与幔柱构造的相互关系——以中国东部中、新生代控矿因素为例

侏罗纪以来,太平洋板块与欧亚板块俯冲碰撞,促成了中国东部以NNE-NE向断裂为主体的断裂构造格局。从地震面波层析成像反演资料及东北和华北地质剖面得知,该地区应属东亚巨型宽裂谷体系的东部地区,系亚幔柱活动所致。全区P波速度、岩石圈不连续和减薄转型、软流圈物质呈蘑菇云状上升以及大火成岩省等特征证明中国东部中、新生代为亚幔柱构造控制成矿成藏,从而证实板块构造与幔柱构造相辅相成的关系。幔柱构造可划分3级,金属矿床常受幔枝构造的控制,多成群成带分布。由于成矿物质来自深部地核或软流圈,金属元素呈垂直分带的规律成为"攻深找盲"的理论依据;而油气田深部常受深部热源影响,若有海相烃源层分布,是寻找"无机"和海相油气田的主攻目标。     

青藏高原东缘新构造与活动构造研究新进展及展望

新构造运动与活动构造对人类的出现、演化、生存和发展都产生着深刻影响。近年来在青藏高原东缘部署开展的活动断裂调查与活动构造体系研究、川滇地块旋扭变形的古地磁学研究、西秦岭地区新构造与活动构造研究、滇西盆谷区的新构造幕划分、腾冲火山活动特征及其新构造背景调查等都取得了一系列重要进展与成果。这些成果对于深入认识和理解青藏高原东部地区现今地壳变形特征及其动力学机制和探索活动构造体系控震作用都具有重要意义,并可为该区的重大工程规划建设与国土规划利用的科学决策和城镇化发展等提供重要的地质依据。     

青藏高原东缘新构造与活动构造研究新进展及展望

新构造运动与活动构造对人类的出现、演化、生存和发展都产生着深刻影响。近年来在青藏高原东缘部署开展的活动断裂调查与活动构造体系研究、川滇地块旋扭变形的古地磁学研究、西秦岭地区新构造与活动构造研究、滇西盆谷区的新构造幕划分、腾冲火山活动特征及其新构造背景调查等都取得了一系列重要进展与成果。这些成果对于深入认识和理解青藏高原东部地区现今地壳变形特征及其动力学机制和探索活动构造体系控震作用都具有重要意义,并可为该区的重大工程规划建设与国土规划利用的科学决策和城镇化发展等提供重要的地质依据。     

青藏高原北羌塘盆地多彩地区蛇绿岩地球化学特征及构造环境

多彩蛇绿岩是通天河蛇绿混杂岩的组成部分,区域上隶属西金乌兰—金沙江缝合带北延部分。多彩蛇绿岩各岩石组分呈构造岩块、岩片产出,出露零星,面积小,但岩石组分较齐全,主要由异剥橄榄岩、单斜辉石岩、辉长岩、玄武岩、辉绿岩及硅质岩等组成,缺乏地幔橄榄岩,蛇绿岩组分均与围岩呈构造接触关系。异剥橄榄岩以富MgO、贫TiO2、贫P2O5为特征,Eu不显异常或显弱负异常,是具有SSZ型蛇绿岩的重要岩石组分;辉长岩具高TiO2、Al2O3;玄武岩与辉绿岩具相似的特性,玄武岩Th/Ta平均为1.78,Ta/Hf0.15,而Ta/Hf=0.15～0.2,与大洋板内玄武岩相似;硅质岩Al2O3/(Al2O3+Fe2O3)比值为0.9,(La/Ce)N值为1.81,可能具有陆源海特性。由上述特征并结合蛇绿岩形成时代及构造环境判别图解,推测多彩蛇绿岩形成于俯冲带构造环境。     

蛇绿岩研究的最新进展

关于蛇绿岩的形成、定义和分类争论了近200年。早期蛇绿岩被认为是有成因联系的几种岩石的组合,发育在优地槽的核部。在板块构造中它被看作形成于洋脊的古洋壳残片。经过几十年的研究,发现导致蛇绿岩多样性的因素很多,一个新的定义和分类方案被提出。新定义强调了蛇绿岩形成的构造环境,认为在威尔逊旋回的各个阶段都会形成性质不同的蛇绿岩,并根据生成环境将蛇绿岩分为两大类,即与俯冲作用无关和与俯冲作用相关的蛇绿岩,两大类型还可以划分出不同的亚类。这些类型的蛇绿岩有其特有的地球化学、岩石学指标和内部结构。最近的研究还发现蛇绿岩产生的主要时段与全球超大陆的形成、裂解,以及巨型地幔柱活动的时间吻合。根据新分类方案,一部分前寒武纪绿岩应属于蛇绿岩,表明在太古宙时期地球已进入板块构造体制。新的定义和分类为蛇绿岩研究指出了新的方向。     

蛇绿岩研究的最新进展

关于蛇绿岩的形成、定义和分类争论了近200年。早期蛇绿岩被认为是有成因联系的几种岩石的组合,发育在优地槽的核部。在板块构造中它被看作形成于洋脊的古洋壳残片。经过几十年的研究,发现导致蛇绿岩多样性的因素很多,一个新的定义和分类方案被提出。新定义强调了蛇绿岩形成的构造环境,认为在威尔逊旋回的各个阶段都会形成性质不同的蛇绿岩,并根据生成环境将蛇绿岩分为两大类,即与俯冲作用无关和与俯冲作用相关的蛇绿岩,两大类型还可以划分出不同的亚类。这些类型的蛇绿岩有其特有的地球化学、岩石学指标和内部结构。最近的研究还发现蛇绿岩产生的主要时段与全球超大陆的形成、裂解,以及巨型地幔柱活动的时间吻合。根据新分类方案,一部分前寒武纪绿岩应属于蛇绿岩,表明在太古宙时期地球已进入板块构造体制。新的定义和分类为蛇绿岩研究指出了新的方向。     

Isotope and Trace Element Geochemistry of Fuchuan Ophiolite Suite,Anhui,China

The Fuchuan ophiolite suite in Shexian County, Anhui Province, was formed in the Middle-Late Proterozoic. It is characterized by varying Nd [∈_Nd (T) =0.7−3.8], Sr [∈_Sr(T) = 30.7−53.9] and O(δ¹⁸O=3.2−11.0%.) and low ratios of Nd/La (<0.8), Ti/Y (<350) and Ti/V (<30). These characteristics, in combination with geological features, indicate that the ophiolite suite was formed in the axial part of the back-arc basin of the Jiangnan ancient island arc at the southeastern margin of the Yangtze Plate. The varying ∈_Nd (T) was caused by the contamination of the underlying inmature sialic crust during the formation of the ophiolite and variations in ∈_Sr(T) and δ¹⁸ O may have resulted from hydrothermal alteration by seawater during or shortly after its formation.     

Propagating rift tectonics of a Caledonian marginal basin: Multi-stage seafloor spreading history of the Solund-Stavfjord ophiolite in western Norway

The Late Ordovician Solund-Stavfjord ophiolite in western Norway represents a remnant of the Iapetus oceanic lithosphere that developed in a Caledonian marginal basin. The ophiolite contains three structural domains that display distinctively different crustal architecture that reflects the mode and nature of magmatic and tectonic processes operated during the multi-stage seafloor spreading evolution of this marginal basin. Domain I includes, from top to bottom, an extensive extrusive sequence, a transition zone consisting of dike swarms with screens of pillow breccias, a sheeted dike complex, and plutonic rocks composed mainly of isotropic gabbro and microgabbro. Extrusive rocks include pillow lavas, pillow breccias, and massive sheet flows and are locally sheared and mineralized, containing epidosites, sulfide-sulfate deposits, Fe-oxides, and anhydrite veins, reminiscent of hydrothermal alteration zones on the seafloor along modern mid-ocean ridges. A fossil lava lake in the northern part of the ophiolite consists of a >65-m-thick volcanic sequence composed of a number of separate massive lava units interlayered with pillow lavas and pillow breccia horizons. The NE-trending sheeted dike complex contains multiple intrusions of metabasaltic dikes with one- and two-sided chilled margins and displays a network of both dike-parallel normal and dike-perpendicular oblique-slip faults of oceanic origin. The dike-gabbro boundary is mutually intrusive and represents the root zone of the sheeted dike complex. The internal architecture and rock types of Domain I are analogous to those of intermediate-spreading oceanic crust at modern mid-ocean ridge environments. The ophiolitic units in Domain II include mainly sheeted dikes and plutonic rocks with a general NW structural grain and are commonly faulted against each other, although primary intrusive relations between the sheeted dikes and the gabbros are locally well preserved. The exposures of this domain occur only in the northern and southern parts of the ophiolite complex and are separated by the ENE-trending Domain III, in which isotropic to pegmatitic gabbros and dike swarms are plastically deformed along ENE-striking sinistral shear zones. These shear zones, which locally include fault slivers of serpentinite intrusions, are crosscut by N20°E-striking undeformed basaltic dike swarms that contain xenoliths of gabbroic material. The NW-trending sheeted dike complex in the northern part of Domain II curves into an ENE orientation approaching Domain III in the south. The anomalous nature of deformed crust in Domain III is interpreted to have developed within an oceanic fracture zone or transform fault boundary.REE chemistry of representative extrusive and dike rocks from all three domains indicates N- to E-MORB affinities of their magmas with high Th/Ta ratios that are characteristic of subduction zone environments. The magmatic evolution of Domain I encompasses closed-system fractional crystallization of high-Mg basaltic magmas in small ephemeral chambers, which gradually interconnected to form large chambers in which mixing of primary magmas with more evolved and fractionated magma caused resetting of magma compositions through time. The compositional range from high-Mg basalts to ferrobasalts within Domain I is reminiscent of modern propagating rift basalts. We interpret the NE-trending Domain I as a remnant of an intermediate-spread rift system that propagated northeastwards (in present coordinate system) into a pre-existing oceanic crust, which was developed along the NW-trending doomed rift (Domain II) in the marginal basin. The N20°E dikes laterally intruding into the anomalous oceanic crust in Domain III represent the tip of the rift propagator. The inferred propagating rift tectonics of the Solund-Stavfjord ophiolite is similar to the evolutionary history of the modern Lau back-arc basin in the SW Pacific and suggests a complex magmatic evolution of the Caledonian marginal basin via multi-stage seafloor spreading tectonics.