造山前、造山和造山后花岗岩的识别

造山前、造山和造山后(或碰撞前、碰撞和碰撞后)花岗岩是花岗岩研究的热门话题。但是,目前关于造山前、造山和造山后的概念存在模糊和矛盾的认识,为此提出了关于造山前、造山和造山后的概念和新的判别方法,并结合非洲、土耳其和巴西的某些实例进行了讨论。着重讨论了青藏高原与碰撞有关的花岗岩,指出青藏高原只存在造山前和造山2个阶段,不存在造山后阶段。认为青藏高原碰撞的时间大概在55Ma左右,25～3Ma的埃达克岩和淡色花岗岩是碰撞阶段形成的。青藏高原25～3Ma的花岗岩的特征暗示青藏高原在25Ma之前已经整体抬升,25Ma之后发育的伸展构造(藏南拆离系、大规模走滑断裂和南北向裂谷)是在青藏高原挤压的大背景下出现的,属于次级的派生构造,其并不能说明青藏高原已经进入伸展减薄和垮塌的碰撞后阶段。

我国地洼型造山-造盆作用与硅藻土成矿

本文从盆-山体系演化的角度,探讨了我国地洼型造山-造盆作用与硅藻土成矿关系。研1)硅藻对成矿盆地表现出了一定的选择性,通常只有侧生或伴生型微型地洼盆地才2)地洼期盆-山耦合过程引起的气候效应对我国陆相硅藻土成矿起着积极;3)地洼期盆-山活动性直接控制着硅藻土成矿,盆-山体系的相对稳定有利于高质量硅藻;4)盆-山转换过程中,成矿期后的盆地抬升对硅藻土矿层的保存是相对有利的。

雪峰山西侧地带的地洼型造山-造盆作用

在晚三叠世前长期处于地台体制的雪峰山西侧地带,上三叠统和中-新生界的沉积相、物质成分、构造变动和地台构造层的构造变动反映,这里于地洼阶段发生了强烈的造山-造盆作用,造成了当今海拔反差达约千米的盆、山景观。这类地洼型造山-造盆作用具有多种运动方式。

东南极格罗夫山:普里兹造山带中一个典型的泛非期变质地体

距中国中山站以南约400 km的格罗夫山是普里兹造山带向南极内陆的延伸部分,其基底地体由约在920—910 Ma期间侵入的镁铁质-长英质火成岩和少量中元古代的沉积岩构成,这些岩石仅在泛非期(约570—500 Ma)经历了单相变质—构造旋回,因此是一个典型的泛非期变质地体。泛非期高峰变质作用并不像前人所认为的那样仅为中低压麻粒岩相,而是高达770—840℃、1.18—1.40 GPa,并在随后经历了近等温减压(约0.6 GPa)的P-T演化过程。大规模的A型紫苏花岗岩和花岗岩在同造山-后造山阶段侵位,并造成了麻粒岩地体近等压降温的P-T轨迹。这些花岗质岩石是由长期富集地幔的底侵物质(碱性玄武质岩石)经部分溶融而形成的。结合相邻地质体的研究资料,我们认为普里兹造山带可能发育在太古宙—格林维尔期基底地体之上,这些基底地体可能与新元古代盖层卷入到了统一的泛非期造山作用过程。在泛非期造山作用过程中,地壳曾被增厚约达40—50 km,而后又经历了厚约20 km的地壳伸展垮塌和剥蚀。所以,普里兹造山带应代表东冈瓦纳陆块内部由板块缝合作用所形成的一条泛非期碰撞造山带。

赣北庐山─鄱阳湖的造山─造盆作用

以往许多学者习惯于将造山作用与造盆作用分开来研究，且认为赣北庐山—鄱阳湖仅在第四纪形成。笔者通过对庐山及其东部鄱阳湖地区区域深部构造背景及其基本地质特征的分析，将庐山—鄱阳湖的造山—造盆作用作为一个整体来进行研究，主要论述了其造山－造盆作用的特征，即先天条件、临产条件和后天条件。在此基础上．将庐山—鄱阳湖的造山—造盆作用划分为前震旦纪基础阶段、震旦纪—早三叠世休眠阶段、晚二叠世—早第三纪雏形阶段及晚第三纪—第四纪形成阶段等四个阶段．并对各阶段造山—造盆作用的运动学与动力学特征进行了探讨。

新疆造山-造盆作用与砂岩型铀成矿

盆山体系演化,尤其是盆山耦合过程与成矿的研究已成为当代地质科学研究的热点之一.我国陆相沉积盆地砂岩型铀矿床（点）分布广泛,成因类型多样.但对矿床的成因分析研究似乎缺乏总体的认识和深化.由于可地浸砂岩型铀成矿明显受到盆山体系的形成演化机制制约,尤其是盆地基底形成之后的盆山演化起着关键的作用.作者结合新疆10多年来的找矿实践,试图通过对区域大地构造演化及其对盆地形成演化的分析,初步分析新疆可地浸砂岩型铀成矿作用与区域造山、造盆作用的关系.通过个别盆地砂岩型铀矿找矿实例分析,进一步探讨盆山耦合过程中可地浸砂岩型铀成矿规律,并提出今后工作意见.

全新世以来区域构造及气候因素对鄱阳湖盆地沉积特征的影响

以全新世以来鄱阳湖盆地沉积体系为基础,发现在鄱阳湖盆地边缘沉积体系呈现不对称性,垂向系列上呈现旋回性。经研究认为,盆地的造盆作用及区域构造决定了盆地的不对称性,从而造成沉积体系的不同;第四纪以来四次大的气候旋回对应着湖平面的四次扩张与萎缩,从而造成沉积物在垂向序列上呈现旋回性。

论浙江山麓快速粗碎屑建造及其作用

本文系统地论述了发育在浙江地质历史时期内，各个不同大地构造阶段中，各山麓快速粗碎屑建造（PFMF）的特征。运用历史—动力学方法，综合分析研究了它们与造山—造盆作用及其大地构造学意义。指出PFMF是具有严格时空概念的构造—沉积相，为造山—造盆作用的重要组成部分；是研究造山带沉积地质学及造山—造盆作用关键的沉积纪录；认为浙江东南部PFMF的时空演变从地洼造山—造盆作用由早期至晚期，其演变自西向东迁移，其力学性质由任性向张性转变的过程，具有重要的大地构造学意义。

中国东北地区主要地质特征和地壳构造格架

中国东北地区位于亚洲大陆东缘,发育中国乃至地球上最古老的地质记录、多个时代的古洋岩石圈残片和活动陆缘及陆间碰撞岩浆岩带,具有独特的盆山-山脉相间地貌特征,蕴藏着丰富的自然资源。迄今为止,对于该区古生代构造单元如何划分,一直存在截然不同的认识;对于该区中生代以来的构造格架,缺乏系统的论述。本文在简要介绍现今不同山脉和盆地等地理单元地质特征的基础上,基于断裂构造和地貌特征等方面的资料,把该区新生代构造单元划分为大兴安岭、小兴安岭、阴山-燕山和长白山等4个隆起带,海拉尔-锡林浩特、松辽、三江-兴凯湖和下辽河等4个断陷带。基于岩浆活动和沉积盆地分布,结合区域地球动力学背景,提出了该区晚三叠世至中侏罗世、晚侏罗世、早白垩世早期和早白垩世晚期至古新世等不同阶段构造单元划分的初步方案。基于对已有资料的综合研究,对该区古生代构造单元的特征、松辽盆地的基底组成、早古生代和晚古生代华北克拉通北部边界的位置以及古生代洋盆演化及结束时间等重大地质构造问题,进行了初步探讨,提出了阴山-燕山地区在古生代晚期由克拉通转化为陆缘活化造山带;松辽盆地基底具有与周缘造山系相同的地质组成;该区古生代构造单元是陆缘造山带与碰撞造山带的复合而不是地块拼贴;该区在二叠纪晚期遭受了碰撞造山并在华北北缘形成了高耸的近东西走向的碰撞造山带等新认识。根据洋岩石圈残片和古陆缘岩浆岩的分布,把该区古生代构造单元划分为大兴安岭、阴山-燕山、小兴安岭、张广才岭和老爷岭等5个造山系及华北克拉通,简要介绍了不同造山系的地质特征。

Tectonic framework of Qilian orogen: reveal from an aeromagnetic anomaly feature

The Qilian Orogenic belt is one of the typical orogenic belts globally and a natural laboratory for studying plate tectonics.Many researchers have studied the ophiolite and high pressure and ultra-high pressure metamorphic rocks in the Qilian orogen and obtained valuable achievements.However,a hot debate exists on the basement property,the distribution of ophiolite,and the boundaries of tectonic units.Large-scale high-precision aeromagnetic surveys have recently been conducted in the Qilian Orogenic belt and adjacent areas.In this study,we are trying to analysis the tectonic framework of the Qilian Orogen using 1:500,000 aeromagnetic data.The results provide geophysical perspectives for studying the structural framework and deformation of this area.According to the aeromagnetic∆T anomaly map,the central and Southern Qilian have the same magnetic anomaly feature that noticeably differs from the North Qilian Orogenic belt and the Qaidam Block.This result indicates that the central and Southern Qilian have a unified magnetic basement and differ from the North Qilian orogenic belt and Qaidam Block.The map shows the distribution of ophiolite in the North Qilian orogenic belt.Linear magnetic anomalies represent the ophiolites because the mafic–ultramafic rocks usually have high magnetic susceptibility.The ophiolite belts are continuously distributed in the western part of North Qilian orogenic belt and have a large scale.However,the scale of the ophiolite belt and the outcropping of mafic–ultramafic rocks reduces when they pass through Qilian County to the east.The results indicate differences in the evolution process between the eastern and western parts of North Qilian,with Qilian County as the transition zone.This study also systematically defines the geophysical boundaries of the Qaidam Block,Qilian Block,North Qilian Orogenic belt,and Alxa block.It is proposed that the sinistral displacement of the Altun Fault is adjusted and absorbed by the series of NE-trending faults in the Qilian orogen and merge into the Longshoushan–Gushi Fault.The extension of the North Qilian Orogenic belt is strengthened by the neotectonics movement along the shearing direction,which separated the North Qilian Orogenic belt into several segments and formed a series of northeast-trending faults.

滇西昌宁-孟连带海西-印支期成因地层学分析

地层层序和地层分区研究是造山带地质研究的关键之一。过去通常以古生物及其古地理资料为主要依据划分对比地层 ,对哑地层则采用岩石地层方法。由于昌宁 -孟连带构造地层状况复杂 ,利用单一方法进行以上工作有困难 ,故采用了沉积环境分析、大地构造背景分析、阴极发光分析、古生物地理分析和物源分析相结合的方法对昌宁 -孟连带的地层成因及地层格架进行了探讨 ,按地层在沉积盆地中的原始位置 ,把昌宁 -孟连带地层分为东区、中区、西区。东区为大陆边缘地层区 ,包括南段群 (组 ) (D3- C1 )和拉巴群(C2 - P2 ) ;中区为洋盆地层带 ,包括准洋脊玄武岩及相应的硅质岩 (D3- P2 ) ,也可能包括部分腊垒群的硅质岩 ;西区地层区包括火山岩—碳酸盐台地地层序列 (C1 - P)、大陆边缘沉积的南皮河群 (D3- T1 )和腊垒群 (D1 - T2 )

西藏羌塘地块西北部银利沟早白垩世钾玄质侵入岩的发现——来自地球化学和锆石U-Pb年龄的证据

银利沟二长岩分布于西藏羌塘西北部,岩石具有高碱、低Ti的特征,在SiO2-K2O图解中位于钾玄岩区。二长岩的锆石U-Pb同位素年龄为121.3Ma±0.6Ma,具有富集LIL、LIEE及显著的Ta-Nb-Ti负异常的地球化学特征,表现出与俯冲有关的钾玄岩的地球化学特征,形成于晚造山—后造山构造背景。这种背景很可能与冈底斯和羌塘地块在晚侏罗世—早白垩世发生的碰撞作用有关。

Structure of different types of coal metamorphism by HTEM

In order to discuss the effect of tectonic stress on the structural evolution of coal, given the importance attached to High-resolution Transmission Electron Microscopy (HTEM), we investigated several aspects of material structures of high-rank Carboniferous period coal, located in the northern foreland basin of the Dabie orogenic belt in eastern China. High powered crystal lattice images of Bright Fields (BF) and Selected Area Diffraction patterns (SAD) of different types of metamorphism in coal were obtained. The results show that the Basic Structural Units (BSU) become increasingly more compact as a function of rising tem-perature and pressure. Under pressure, the local orientation of molecules is strengthened, the arrangement of BSU speeds up and the degree of order is clearly enhanced.

Relation between structural evolution of the Longmenshan orogenic zone and sedimentation of its foreland basin

In order to determine the area for oil and gas exploration in China’s north Sichuan basin,we have divided the time during which the Longmenshan foreland basin was formed into five periods,based on the sedimentary response relationship of the foreland basin to structural evolution: 1) a late Triassic Noric period;2) an early-Middle Jurassic period;3) a late Jurassic to early Cretaceous period;4) a late Cretaceous to Paleogene-Neogene period and 5) the Quaternary period. As well,we analyzed the sedimentary environment and lithologic features of every basin-forming period. The results show that there are several favorable source-reservoir-cap assemblages in our study area,making it a major region for future oil and gas exploration in China’s northern Sichuan basin.

THE THRUST AND NAPPE TECTONIC ZONE ALONG THE SOUTHERN MARGIN OF THE COAL-FORMING REGION OF NORTH CHINA

A thrust and nappe tectonic zone with imbricate branch thrusts is developed along the southern margin of the coal-forming region of North China. This tectonic zone is tightly related to the Qinling-Dabie collision orogen in genesis and belongs to the frontal zone of a huge thrust system developed during Yanshanian episode at the northern foot of the orogen. It is pointed out that thrusting had distorted the original depositional margin of the coal-forming region and some new coal-bearing blocks would be found out in the frontal sheets and under the undulate sole thrust.

Diagenesis tectonic setting and U-Pb dating for zircon from Tanjianshan Group in northern margin of Qaidam Basin

The shape,texture,content and REE characteristics of zircons from the O2tnd-1,O3tnd-2,O3tnd-3pyroclastic rock of Tanjianshan Group on the north margin of Qaidam Basin indicate that the O2-3tndis the product of volcanism during the transitional period from ocean-land interim crust to oceanic crust.The U-Pb surface ages obtained from O3tnd-2and O3tnd-3can be divided into 9 groups,every age group coincides with the period when significant tectonic-heat event took place at Oulongbuluke micro-continental base of northern Qaidam,suggesting that the base rocks have provided materials for the formation of sedimentary and volcanic rock in O2-3tnd.The volcanic rocks of O3tnd-3formed at 440 Ma,with time gap 46 Ma to those of O1tna-1and O3tnd-3may represent the minor period that Xitieshan back-arc extension have lasted,the scale of back-arc basin that formed in Xitieshan extension may approach to 1 400 km.Based on the test of ithochemistry data for major elements and analysis of Sr isotope geochemistry for the clastic sedimentary rock in O1tna-2and O3tnd-2,the authors get the conclusion that the O1tna-2and O3tnd-2of Tanjianshan Group may form in back-arc basin environment,while the lithology difference between these two formations may reflect the changes of geodynamic processes as the diagenesis tectonic environment transformed from continental margin depression to adjacent sea basin.

Tectonic evolution of the Tongbai-Hong'an orogen in central China: From oceanic subduction/accretion to continent-continent collision

The Tongbai-Hong'an orogen is located in a key tectonic position linking the Qinling orogen to the west and the Dabie-Sulu orogen to the east. Because the orogen preserves a Paleozoic accretionary orogenic system in the north and a latest PaleozoicMesozoic collisional orogenic system in the south, it may serve as an ideal place to study the tectonic evolution between the North and South China Blocks. The available literature data in the past 20 years indicate that the tectonic processes of the Tongbai-Hong'an orogen involved four stages during the Phanerozoic:(1) Early Paleozoic(490–420 Ma) oceanic subduction, arc magmatism and arc-continent collision created a new Andean-type active continental margin on the North China Block;(2) Late Paleozoic(340–310 Ma) oceanic subduction and accretion generated separated paired metamorphic belts: a medium P/T Wuguan-Guishan complex belt in the south of the Shandan-Songpa fault and a high P/T Xiongdian eclogite belt in the northern edge of the Mesozoic HP metamorphic terrane;(3) Latest Paleozoic-Early Mesozoic(255–200 Ma) continental subduction and collision formed the Tongbai HP terrane in the west and the Hong'an HP/UHP terrane in the east as a consequence of deep subduction towards the east and syn-subduction detachment/exhumation of the down-going slab;(4) Late Mesozoic(140–120 Ma) extension, voluminous magma intrusion and tectonic extrusion led to the final exhumation of the Tongbai-Hong'an-Dabie HP/UHP terrane and the wedge-shaped architecture of the terrane narrowing towards the west. However, many open questions still remain about the details of each evolutionary stage and earlier history of the orogen. Besides an extensive study directly on the Tongbai-Hong'an orogen in the future, integrated investigation on the "soft-collisional" Qinling orogen in the west and the "hard-collisional" Dabie-Sulu orogen in the east is required to establish a general tectonic model for the whole Qinling-TongbaiHong'an-Dabie-Sulu orogenic belt.

Petrogenesis and tectonic implications of Late-Triassic high εNd(t)-εHf(t) granites in the Ailaoshan tectonic zone(SW China)

High εNd（t）-εHf（t） granites are robust evidence for crustal growth. In this paper we report results of petrologic, geochronological and geochemical investigations on the Huashiban granites from the Ailaoshan tectonic zone in western Yunnan （SW China）. Zircon grains separated from the two samples （10HH-119A and 10HH-120A） yield the weighted mean 206pb/238u ages of 229.9 ± 2.0 Ma and 229.3 ± 2.3 Ma, respectively, interpreted as the crystallization ages of the granites. Based on our results, in combination with the existing U-Pb geochronological data for the Ailaoshan metamorphic rocks, we propose that the Ai- laoshan Group might be a rock complex composed of the Mesoproterozoic, Neoproterozoic, Hercynian, Indosinian and Hima- layan components, rather than a part of the crystalline basement of the Yangtze block. The zircon grains show highly depleted Lu-Hf isotope compositions, with positive eHf（t） values ranging from 8.4 to 13.1. The Huashiban granites have high SiO2 （72.66 wt%-73.70 wt%）, low Mg# （0.28-0.34） with A/CNK=1.01-1.05, and can be classified as peralumious high-K calc-alkaline I-type granites. A synthesis of these data indicates that the Ailaoshan tectonic zone had evolved into a post-collisional setting by the Late-Triassic （229 Ma）. Genesis of the Huashiban high εNd（t）-εHf（t） granites involved into two processes： （1） underplating of the sub-arc mantle into the lower crust, and （2） remelting of the juvenile crustal materials in re- sponse to the upwelling of the asthenospheric mantle in the post-collisional setting.

Developing plate tectonics theory from oceanic subduction zones to collisional orogens

Crustal subduction and continental collision is the core of plate tectonics theory. Understanding the formation and evolution of continental collision orogens is a key to develop the theory of plate tectonics. Different types of subduction zones have been categorized based on the nature of subducted crust. Two types of collisional orogens, i.e. arc-continent and continent-continent collisional orogens, have been recognized based on the nature of collisional blocks and the composition of derivative rocks. Arc-continent collisional orogens contain both ancient and juvenile crustal rocks, and reworking of those rocks at the post-collisional stage generates magmatic rocks with different geochemical compositions. If an orogen is built by collision between two relatively old continental blocks, post-collisional magmatic rocks are only derived from reworking of the old crustal rocks. Collisional orogens undergo reactivation and reworking at action of lithosphere extension, with inheritance not only in the tectonic regime but also in the geochemical compositions of reworked products(i.e., magmatic rocks). In order to unravel basic principles for the evolution of continental tectonics at the post-collisional stages, it is necessary to investigate the reworking of orogenic belts in the post-collisional regime, to recognize physicochemical differences in deep continental collision zones, and to understand petrogenetic links between the nature of subducted crust and post-collisional magmatic rocks. Afterwards we are in a position to build the systematics of continental tectonics and thus to develop the plate tectonics theory.

Carboniferous slab-retreating subduction of backarc oceans:the final large-scale lateral accretion of the southern Central Asian Orogenic Belt

During Carboniferous time,tremendous juvenile arc crust was formed in the southern Central Asian Orogenic Belt(CAOB),although its origin remains unclear.Herein,we presented zircon U-Pb-Hf and whole-rock geochemical and Sr-Nd isotopic data for a suite of volcanic and pyroclastic rocks from the Khan-Bogd area in southern Mongolia.These Carboniferous pyroclastic rocks generally have some early Paleozoic zircons,probably derived from the granitic and sedimentary rocks of the Lake Zone and the Gobi-Altai Zone to the north,indicative of a continental arc nature.In addition,they have a main zircon U-Pb age of ca.370–330 Ma,positive Hf and Nd isotopes,and mafic-intermediate arc affinity,similar to the coeval arc magmatism.Moreover,the pyroclastic rocks of the northern area have more mafic and older volcanic components with depositional time(ca.350–370 Ma;Visean and Bashkirian stages)earlier than that in the southern area(mainly ca.350–315 Ma;Serpukhovian and Bashkirian stages).Combining a preexisting northward subduction supported by the available magnetotelluric data with a slab rollback model of the main oceanic basin of the Paleo-Asian Ocean(PAO)during Carboniferous and Triassic times,we infer that the Carboniferous arc magmatism was probably derived from a backarc ocean triggered by slab rollback.Thus,the juvenile arc volcanism of Mongolia,together with other areas(e.g.,Junggar)in the southern CAOB,represented a significant lateral accretion that terminated after the Carboniferous due to a significant contraction of the PAO.