浅变质岩在示踪大别—苏鲁造山带大陆板块俯冲与折返过程中的意义

中国大别-苏鲁造山带为大陆板块俯冲形成的碰撞造山带,该带北缘和内部产有原岩时代为新元古代-晚古生代的浅变质岩。这些浅变质岩对应于扬子板块北缘前寒武变质基底和扬子板块北缘古生代大陆架沉积物,形成过程于印支期扬子板块向北俯冲过程中的刮削作用密切相关,与大洋板块俯冲过程中刮削形成的加积楔具有类似的动力学过程。对大别-苏鲁造山带浅变质岩的深入研究,不仅有助于揭示大陆板块俯冲过程中高压-超高压岩石形成与折返过程,而且确定了扬子板块与华北板块之间的缝合线位置位于大别造山带北淮阳带的北部和苏鲁造山带的五莲-蓬莱群的北侧。     

长江中下游成矿带深部结构层析成像图像揭示华北板块的东南向俯冲

远震层析成像结果所揭示的华北板块东南向俯冲到扬子板块之下对于重新认识长江中下游地区成矿机制具有重要意义.利用来自中国地震台网中心,包括湖北、河南、安徽、江西、浙江、江苏等省级地震台网记录的波形数据对长江中下游地区深部结构进行了远震P波层析成像反演.综合研究结果显示,三叠纪华北与扬子板块俯冲碰撞,华北板块越过郯庐断裂带,向东南俯冲到扬子板块之下.推断板块碰撞的深部缝合线在郯庐断裂带以西位于大别造山带以南,在郯庐断裂带以东位于长江一线.经历后期的中生代构造转换过程,该带发生活化,成为中生代含矿岩浆和流体上升的通道,并形成著名的大型成矿带.      

扬子板块俯冲加积杂岩的初步研究

根据大别—苏鲁造山带浅变质岩系的地质产状,本文将其与高压—超高压岩石一起作为大陆板块俯冲的加积杂岩来考虑,发现它们在岩石类型、变质时代和原岩性质等方面具有一定的可比性,因此可看作为扬子板块大陆俯冲的加积杂岩。由此根据板块俯冲的加积楔模型,对浅变质岩系的形成和演化过程进行了地球动力学解释,结果对扬子板块俯冲及其与华北板块碰撞的俯冲带和缝合带位置提供了制约。     

大别-郯庐-苏鲁造山带复合旋转拼贴作用

郯庐断裂带的成生演化与含超高压变质带(UHP)的大别及苏鲁造山带存在较密切的时空关系。郯庐断裂带所在的构造位置应是晚二叠世华北与扬子地块碰撞时的根带。UHP岩石的折返过程可能发生于华北、扬子地块的大角度旋转、拼合过程中。在华北与扬子地块的造山后期或者造山期后的构造变形中所记录的构造形迹经晚中生代以来的中国东部构造变形叠加而逐渐呈现复杂的构造组合,所谓“郯庐断裂带”的走滑平移即其中的一种运动方式。华北与扬子地块碰撞造山作用与陆内变形最终造就了大别—郯庐—苏鲁复合造山带。     

中国东部陆缘中区中-新生代区域断裂系统时空分布特征、迁移规律及成因类型

中国东部陆缘中区中-新生代深大断裂十分发育.根据断裂的时空分布规律,可划分出4个断裂系:燕山造山带断裂系、秦岭-大别-苏鲁造山带断裂系、郯庐断裂系及东海陆架盆地-冲绳海槽断裂系.4个断裂系具有各自不同的断裂迁移规律:燕山造山带印支-燕山期断裂具有从早至晚从EW→NE→NNE向偏转迁移规律;秦岭-大别造山带北麓逆冲推覆作用的强度在印支-燕山早期表现出南强北弱、东强西弱和东断西褶趋势,同时具有由东向西由早到晚穿时迁移演化特征,燕山末期-喜山早期则相反,表现出北强南弱、西强东弱的构造特征;郯庐断裂系的活动对盆地的控制作用具有由早到晚由西向东、由南向北迁移规律;东海陆架盆地-冲绳海槽断裂的形成时代具有明显的从西向东越来越新的迁移规律.4个断裂系及构造迁移规律分别是板块碰撞-陆内俯冲、陆内造山、走滑、板块俯冲后退4种不同地球动力学背景中的产物.     

苏鲁造山带地壳上地幔结构层析成像研究

扬子与华北板块在三叠纪的俯冲碰撞形成了著名的苏鲁超高压造山带,其板块碰撞接触关系一直是热点问题.利用国家台网中心64个省台记录的1 079个近震事件的10 922个P波到时和251个远震事件的11 931个P波到时数据,采用远近震联合反演的层析成像方法对苏鲁地区进行了地壳上地幔速度结构反演.结果显示,研究区内两个低速异常区分别对应山东半岛西部的华北板块地幔上隆区和壳幔相互作用强烈的长江中下游成矿带地区.在地幔300 km深度之下出现的高速异常体可能代表了早中生代扬子与华北板块碰撞之前俯冲拆沉的古特提斯洋板块.传统观点的扬子板块岩石圈向北俯冲不明显,华北板块表现为向东南俯冲的高速特征.华北板块俯冲以苏鲁造山带中部的北纬35°为界,分为南北两种俯冲样式.北部俯冲不明显,华北板块停滞在郯庐断裂带以西;南部则表现华北板块向东南陡倾俯冲到苏鲁造山带之下.      

大别-苏鲁造山带在朝鲜半岛可能的构造表现

在晚二叠世—早三叠世期间,中国的华北与扬子板块俯冲碰撞形成了大别-苏鲁造山带。针对这次碰撞作用向东在朝鲜半岛的延伸方式,近些年来不同学者提出了多种模式,但都有其局限性。通过比较临津江带、沃川带与大别造山带之间的构造活动关系,结合已有的变质地质学和地质年代学数据,建立了大别-苏鲁造山带在朝鲜半岛的东延模式。推测自临津江带至沃川带构成了一条较完整的中生代造山带,即大别-苏鲁造山带在朝鲜的东部延伸,原来意义上的“京畿地块”已不复存在。而岭南地块上与华北板块相似的信息可能是造山作用后期伸展拆离作用下来自朝鲜半岛北部的外来构造岩片所致。     

苏鲁造山带东北端超高压变质花岗岩中低δ18O值锆石的发现

大别-苏鲁造山带是扬子陆块与华北陆块之间在三叠纪时期俯冲碰撞所形成的超高压变质带.     

郯庐断裂带起源与大陆斜向汇聚

郯庐断裂带起源于华北克拉通与扬子板块的汇聚过程中已被多数学者所认同。该断裂带的起源机制，涉及到这两个大陆板块的汇聚方式。可是，对于这一重要问题却长期存在着不同的认识。本文依据郯庐断裂带内部及其两侧前陆上构造与年代学研究成果，综合分析该断裂带的起源机制。郯庐断裂带内部残留的起源期构造为左行走滑韧性剪切带，所获得的白云母40Ar/39Ar同位素年龄为239~217 Ma。华北克拉通边缘的徐淮弧形逆冲-推覆构造，及九江地区扬子板块上的弧形褶皱带，分别为苏鲁造山带、大别造山带点碰撞的产物。郯庐断裂带西侧的华北克拉通边缘，在汇聚过程中呈现为刚性陆块的特征，没有出现大规模的牵引弯曲现象。而东侧的扬子板块前陆构造，在汇聚过程中却明显出现了大规模的牵引弯曲现象。断裂带东侧的张八岭隆起北段，出露了扬子板块上中地壳韧性拆离带，其中所获得的白云母40Ar/39Ar同位素年龄为245~218 Ma，其滑动方向受控于郯庐断裂带起源期的左行走滑运动。这一系列构造与年代学信息，表明郯庐断裂带起源于华北克拉通与扬子板块的汇聚过程中，代表了这两个大陆的斜向汇聚边界。该断裂带起源期的活动时限，与大别、苏鲁造山带内大陆深俯冲时间相吻合。在大别造山带北部的华北克拉通，原始应存在着向南的突出体(嵌入体)，从而导致嵌入式碰撞与嵌入体边界的大陆斜向汇聚(起源期郯庐断裂带)，符合嵌入式碰撞导致板片撕裂模式。     

华北东部地区中生代盆地格局及演化过程探讨

华北东部中生代盆地演化受控于欧亚构造域的板块挤压拼接和滨太平洋构造域"洋-陆"俯冲碰撞两大动力学背景,与兴蒙造山带、秦岭-大别造山带、太行山隆起及郯庐断裂带等陆内及周边造山带的形成、深大断裂发育演化以及深部动力等因素有着密切的联系。早-中三叠世华北地区基本继承了晚海西期以来的构造格局和沉积特点,地势北西高、东南低,为一南陡北缓、呈NWW向展布的大型内陆沉积盆地;晚三叠世扬子板块与华北板块剪刀式碰撞拼接,华北地区全面抬升,且西部抬升小,东部抬升幅度大,盆地范围向西部退缩,沉积范围缩小,东部地区地势较高,地貌复杂,以隆升剥蚀为主;早-中侏罗世华北东部处于由古亚洲构造域向滨太平洋构造域演化的过渡阶段,该时期太行山的形成将华北地区分割成东、西两个大盆,西部鄂尔多斯盆地依然为一个大型沉积盆地,东部渤海湾盆地区在早-中侏罗世的早期为一些小的山间沉积盆地群,主要表现为对印支期造成的大量NWW或近EW向逆冲断层及阔缓褶皱所产生的低洼地区的充填,晚期则表现为披覆式沉积;晚侏罗世-早白垩世太平洋板块活动取代了扬子板块、西伯利亚板块活动对华北地区构造演化的控制地位,中国东部进入大规模的裂陷或断陷盆地发育阶段,且出现了明显的分区性:在盐山-歧口-新港-兰考-聊城断裂系以东,由于受郯庐断裂带左旋走滑构造应力场的控制,主要发育NW或NWW向断陷盆地,而在该断裂系以西至太行山以东的地区,受左旋走滑影响较弱,主要发育NE和NNE向断陷盆地,在张家口-蓬莱走滑断裂带以北的下辽河坳陷区,盆地的长轴方向为NNE,属郯庐断裂带内部的走滑拉张盆地;晚白垩世郯庐断裂带以西的华北广大地区整体处于隆升剥蚀状态,仅在河南信阳盆地及冀中、临清、黄骅坳陷的少数低洼地区接受沉积,多以红色河湖相粗碎屑为主。研究华北东部中生代盆地演化对于该地区前第三系油气勘探具有指导意义。     

大别造山带浅变质岩的地质-地球化学特征及成因机制

大别造山带超高压变质带内部及其北缘,出露仅经过绿片岩相变质作用的浅变质岩系。通过对部分浅变质岩的区域分布、地质特征及地球化学的综合研究表明,这些浅变质岩系形成于新元古代扬子板块北缘的裂陷盆地中,并遭受新元古代岩浆侵位和以寒冷气候位特征的大气降水热液蚀变,共同经历了与扬子大陆板块俯冲-碰撞过程中有关的构造热事件;因此认为这些浅变质为扬子板块俯冲过程中被“刮”下来的构造残片,为大陆板块俯冲过程中形成的加积杂岩,并为扬子板块与华北板块的俯冲和碰撞的动力学过程提供有力的科学佐证。在此基础上,厘定了大别造山带浅变质岩的形成及其与扬子大陆板块俯冲的构造模型。     

A new concept on tectonic correlation between Korea, China and Japan: Histories from the late Proterozoic to Cretaceous

The Dabie–Sulu collision belt in China extends to the Hongseong–Odesan belt in Korea while the Okcheon metamorphic belt in Korea is considered as an extension of the Nanhua rift within the South China block. The Hongseong–Odesan belt divides Korea's Gyeonggi massif into northern and southern portions. The southern Gyeonggi massif and the Yeongnam massif are correlated with China's Yangtze and Cathaysia blocks, respectively, while the northern Gyeonggi massif is part of the southern margin of the North China block. The southern and northern Gyeonggi massifs rifted from the Rodinia supercontinent during the Neoproterozoic, to form the borders of the South China and North China blocks, respectively. Subduction commenced along the southern and eastern borders of the North China block in the Ordovician and continued until a Triassic collision between the North China and South China blocks. While subduction was occurring on the margin of the North China block, high-P/T metamorphic belts and accretionary complexes developed along the inner zone of southwest Japan from the Ordovician to the Permian. During the subduction, the Hida belt in Japan grew as a continental margin or continental arc. Collision between the North and South China blocks began in Korea during the Permian (290–260 Ma), and propagated westwards until the Late Triassic (230–210 Ma) creating the sinistral TanLu fault in China and the dextral fault in the Hida and Hida marginal belt in Japan. Phanerozoic subduction and collision along the southern and western borders of the North China block led to formation of the Qinling–Dabie–Sulu–Hongseong–Hida–Yanji belt.     

吉林-黑龙江高压变质带的初步厘定:证据和意义

本文定义的吉林-黑龙江高压变质带是指我国东北地区佳木斯-兴凯地块西缘和南缘共同发育的呈弧形展布的高压变质带,具体包括佳木斯-兴凯地块西缘增生杂岩带(黑龙江蓝片岩带和张广才-小兴安岭增生杂岩带)和佳木斯-兴凯地块南缘的长春-延吉增生杂岩带.其中佳木斯-兴凯地块西缘增生杂岩带形成于晚三叠-早侏罗世(180 ～ 210Ma),为佳木斯-兴凯地块向西冲增生而形成的高压变质带;而长春-延吉增生杂岩带由一系列特征性俯冲-增生杂岩组成,包括石头口门-烟筒山红帘石片岩带、呼兰群变质杂岩、色洛河群变质杂岩、青龙村群变质杂岩和开山屯变质杂岩等,形成时代为187～230Ma,峰期为220～230Ma.长春-延吉增生杂岩带曾被认为是西拉木伦河断裂带的东延部分,但是区域构造分析表明,它们形成的动力学背景与佳木斯-兴凯地块西缘增生杂岩带相同,均为太平洋板块三叠纪-早侏罗世的西向俯冲导致佳木斯-兴凯地块自东向西的“剪刀式”闭合过程.我们将佳木斯-兴凯地块西缘和南缘发育的三叠纪-早侏罗世增生杂岩带作为统一的构造单元来考虑,结合该区发育有典型的高压变质带,因此命名为“吉林-黑龙江高压变质带,简称吉黑高压带”.吉黑高压带形成于太平洋板块三叠纪-早侏罗世的西向俯冲导致佳木斯-兴凯地块自东向西的“剪刀式”闭合的过程,同时该带记录了古亚洲构造域的结束和太平洋俯冲开始的关键时期,为两大构造域叠加与转换的关键性地质证据.     

苏鲁造山带浅变质岩的成因及其大地构造意义

苏鲁造山带超高压变质带内部及其北缘,出露仅经过绿片岩相变质作用的浅变质岩系。通过对该浅变质岩的区域分布、地质特征及地球化学的综合研究,表明这些浅变质岩系与大别-苏鲁造山带大陆板块俯冲存在密切的成因关系,为扬子板块俯冲过程中被刮削下来的构造残片,构成大陆板块俯冲过程中形成的构造加积杂岩。在此基础上,厘定了苏鲁造山带的构造成因模型,并对苏鲁造山带的东延问题进行了讨论。     

Tectonic evolution of a composite collision orogen: An overview on the Qinling–Tongbai–Hong'an–Dabie–Sulu orogenic belt in central China

The formation of collisional orogens is a prominent feature in convergent plate margins. It is generally a complex process involving multistage tectonism of compression and extension due to continental subduction and collision. The Paleozoic convergence between the South China Block (SCB) and the North China Block (NCB) is associated with a series of tectonic processes such as oceanic subduction, terrane accretion and continental collision, resulting in the Qinling–Tongbai–Hong'an–Dabie–Sulu orogenic belt. While the arc–continent collision orogeny is significant during the Paleozoic in the Qinling–Tongbai–Hong'an orogens of central China, the continent–continent collision orogeny is prominent during the early Mesozoic in the Dabie–Sulu orogens of east-central China. This article presents an overview of regional geology, geochronology and geochemistry for the composite orogenic belt. The Qinling–Tongbai–Hong'an orogens exhibit the early Paleozoic HP–UHP metamorphism, the Carboniferous HP metamorphism and the Paleozoic arc-type magmatism, but the three tectonothermal events are absent in the Dabie–Sulu orogens. The Triassic UHP metamorphism is prominent in the Dabie–Sulu orogens, but it is absent in the Qinling–Tongbai orogens. The Hong'an orogen records both the HP and UHP metamorphism of Triassic age, and collided continental margins contain both the juvenile and ancient crustal rocks. So do in the Qinling and Tongbai orogens. In contrast, only ancient crustal rocks were involved in the UHP metamorphism in the Dabie–Sulu orogenic belt, without involvement of the juvenile arc crust. On the other hand, the deformed and low-grade metamorphosed accretionary wedge was developed on the passive continental margin during subduction in the late Permian to early Triassic along the northern margin of the Dabie–Sulu orogenic belt, and it was developed on the passive oceanic margin during subduction in the early Paleozoic along the northern margin of the Qinling orogen.Three episodes of arc–continent collision are suggested to occur during the Paleozoic continental convergence between the SCB and NCB. The first episode of arc–continent collision is caused by northward subduction of the North Qinling unit beneath the Erlangping unit, resulting in UHP metamorphism at ca. 480–490 Ma and the accretion of the North Qinling unit to the NCB. The second episode of arc–continent collision is caused by northward subduction of the Prototethyan oceanic crust beneath an Andes-type continental arc, leading to granulite-facies metamorphism at ca. 420–430 Ma and the accretion of the Shangdan arc terrane to the NCB and reworking of the North Qinling, Erlangping and Kuanping units. The third episode of arc–continent collision is caused by northward subduction of the Paleotethyan oceanic crust, resulting in the HP eclogite-facies metamorphism at ca. 310 Ma in the Hong'an orogen and low-P metamorphism in the Qinling–Tongbai orogens as well as crustal accretion to the NCB. The closure of backarc basins is also associated with the arc–continent collision processes, with the possible cause for granulite-facies metamorphism. The massive continental subduction of the SCB beneath the NCB took place in the Triassic with the final continent–continent collision and UHP metamorphism at ca. 225–240 Ma. Therefore, the Qinling–Tongbai–Hong'an–Dabie–Sulu orogenic belt records the development of plate tectonics from oceanic subduction and arc-type magmatism to arc–continent and continent–continent collision.     

南秦岭花岗岩锆石U-Pb定年及其地质意义

锆石Ｕ－Ｐｂ定年结果表明,南秦岭勉、略构造带以北迷坝、光头山和东江口等花岗岩体形成于三叠纪（２０６￣２２０Ｍａ）,与南秦岭勉－略构造带洋盆的闭合时代及大别山超高压变质时代基本一致显示了它们的形成与勉－略古生代洋盆闭合后及华南陆块与华北陆块碰撞之间的内在联系。它支持华南和华北两大陆块最终在印支期碰撞的观点。     

Kanfenggou UHP Metamorphic Fragment in Eastern Qinling Orogen and Its Relationship to Dabie-Sulu UHP and HP Metamorphic Belts, Central China

In the Central Orogenic Belt, China, two UHP metamorphic belts are discriminated mainly based on a detailed structural analysis of the Kanfenggou UHP metamorphic fragment exposed in the eastern Qinling orogen, and together with previous regional structural, petrological and geochronological data at the scale of the orogenic domain. The first one corresponds to the South Altun-North QaidamNorth Qinling UHP metarnorphic belt. The other is the Dabie-Sulu UHP and HP metamorphic belts. The two UHP metamorphic belts are separated by a series of tectonic slices composed by the Qiniing rock group, Danfeng rock group and Liuling or Foziling rock group etc. respectively, and are different in age of the peak UHP metamorphism and geodynamic implications for continental deep subduction and collision. Regional field and petrological relationships suggest that the Kanfenggou UHP metamorphic fragment that contains a large volume of the coesite- and microdiamond-bearing eclogite lenses is compatible with the structures recognized in the South Altun and North Qaidam UHP metamorphic fragments exposed in the western part of China, thereby forming a large UHP metamorphic belt up to 1000 km long along the orogen strike. This UHP metamorphic belt represents an intercontinental deep subduction and collision belt between the Yangtze and Sino-Korean cratons, occurred during the Paleozoic. On the other hand, the well-constrained Dabie-Sulu UHP and HP metamorphic belts occurred mainly during Triassic time (250-220 Ma), and were produced by the intracontinental deep subduction and collision within the Yangtze craton. The Kanfenggou UHP metamorphic fragment does not appear to link with the DabieSulu UHP and HP metamorphic belts along the orogen. There is no reason to assume the two UHP metamorphic belts as a single giant deep subduction and collision zone in the Central Orogenic Belt situated between the Yangtze and Sino-Korean cratons. Therefore, any dynamic model for the orogen must ac-count for the development of UHP metarnorphic rocks belonging to the separate two tectonic belts of different age and tectono-metamorphic history.     

Geochronology and geochemistry of metamorphic rocks in the Jiaobei terrane: Constraints on its tectonic affinity in the Sulu orogen

Tectonic affinity of tectono-lithological units close to ultrahigh-pressure metamorphic belt is a key issue for understanding the geodynamics of continental collision. This is particularly so for the Jiaobei terrane northeast of the Dabie-Sulu orogenic belt in China. New data from LA-ICPMS zircon U–Pb dating, whole-rock elements and Nd–Sr isotopes, and mineral O isotopes are presented for metamorphic rocks from this terrane. The results place geochronological and geochemical constraints on their protolith nature and metamorphic timing and thus on its tectonic affinity to one of the two Triassic collided continents, the North and the South China Blocks. Protolith ages for TTG gneiss, amphibolite and mafic granulite are ∼2.7, ∼2.5 and ∼2.4 Ga, respectively; regional metamorphism took place extensively at ∼1.76 Ga. Protolith of the TTG gneiss was generated by partial melting of mantle-derived rocks at the root of a thickened crust. Protolith of the amphibolite was probably a product of arc-like magmatism; protolith of the mafic granulite was derived from a depleted mantle source. Both of them were locally contaminated by supracrustal materials. Protoliths of paragneiss and schist in the Fenzishan Group were mostly derived from supracrustal sources, but protolith of amphibolite in the Fenzishan Group is of mantle-derived signature. Unlike the UHP metaigneous rocks in the Dabie-Sulu orogenic belt that show unusual ¹⁸O-depletion, the Jiaobei metamorphic rocks have basically preserved their original mantle-like O isotope compositions. In general, the nature and timing of geological events recorded in the metamorphic rocks from the Jiaobei terrane are comparable with those from the North China Block rather than the South China Block. Thus, the Jiaobei terrane is concluded to have tectonic affinity to the former, but behave like a micro-continent during the Triassic continental collision. The ∼1.76 Ga regional metamorphism in the Jiaobei terrane is likely related to reworking of the arc-continent collisional orogen in the periphery of the North China Block rather than the ∼1.85 Ga collision event between the eastern and western North China Blocks. The present study lends support to the common assumption that the suture boundary between the North and South China Blocks in the Sulu orogen is located along the Wulian-Yantai fault. Tectonic mingling along the Wulian-Yantai fault is probably related to subduction erosion during the continental collision.