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南秦岭西段勉略构造混杂岩带是由不同的构造岩片组成的非史密斯地层区。本文建立了勉略构造带太古宙－石炭纪的地层系统。勉略构造带及其邻区地层格架分析表明晚震旦世－－寒武纪勉略构造带及中秦岭为扬子板块北缘的一部分。奥陶纪－－志留纪大致沿勉略构造带秦岭型陷槽。泥盆纪－石炭纪该裂陷槽进一步开裂形成勉略洋。该洋盆从石炭纪开始俯冲萎缩并最缍三叠纪后期碰撞、闭合并造山。 相似文献
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南秦岭勉略构造带在研究中国大陆构造演化历史中具有重要的大地构造意义。年代学及岩石地球化学研究显示勉略蛇绿构造混杂岩的形成时代、形成原因都是非常复杂的;大量三叠纪花岗岩的分布特征及形成时代显示其成因与勉略洋盆闭合及之后发生的陆壳基底的俯冲有关,同时关于这些花岗岩形成的动力学背景,也存在多种不同的观点;区内高压基性麻粒岩的研究反映了秦岭造山带在印支期沿勉略构造带发生俯冲-碰撞-折返的造山过程。如果对勉略构造带更多高压变质岩石进行细致研究,可为恢复秦岭造山带造山过程提供更多岩石学证据。 相似文献
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南秦岭勉略缝合带北侧光头山花岗岩体由早期的石英闪长质—英云闪长质岩石和晚期的S型二长花岗岩组成。其中早期侵入相明显地经历了韧性剪切带的改造,形成于勉略构造带闭合之前。晚期的S型二长花岗岩侵位于早期的石英闪长岩、英云闪长岩和韧性剪切带中,是与勉略洋盆闭合密切相关的同碰撞—后碰撞阶段侵位的花岗岩。所以光头山岩体的形成年龄可以较好地限定西秦岭勉略洋盆闭合、扬子板块与微秦岭板块碰撞的时代。2个二长花岗岩样品的独居石电子探针U-Th-Pb定年分析,分别得到3组年龄和4组年龄。结合前人的研究成果、独居石BSE图像和表观年龄分布,确定S型花岗岩的结晶年龄为209～196Ma ,它限定了勉略构造带闭合隆升的时代为晚三叠世—早侏罗世;较老的240Ma±4Ma、318Ma±5Ma和249Ma±4Ma 记录了早期与勉略缝合带闭合洋壳俯冲相关的残留独居石的年龄,年轻的184Ma±3Ma和154Ma±3Ma反映了后期的变形作用和流体活动等的改造作用。 相似文献
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西秦岭南缘勉略构造带主要地质特征 总被引：39，自引：10，他引：29
西秦岭勉略构造带现今呈近东西－北西西向民菜布,是以自北而南多层次叠瓦状逆冲推覆构造为骨架的向南突出的巨型复合断裂弧形构造带。该带原为西秦岭微板块与扬子板块之间的古缝合带,发育有俯冲和碰撞两期变形构造,以主造山碰撞晚期的自北向南的逆冲推覆构造为显著特征。初步确定发育OIB以及N－MORB和E－MORB型玄武岩,代表了洋人舅发育的物质记录。根据已有的年代学和古生物化石研究结果,认为于泥盆纪晚期－早石炭世（D3－C1）沿勉略带发育有以蛇绿岩、洋岛玄武岩为代表的有限洋盆。在勉略带扩张打开形成有限洋盆与消减俯冲过程中,南侧发育有被动陆缘盆地沉积体系,北侧发育有深水下裂陷盆地和活动陆缘盆地沉积体系。进而确定勉略带是一条重要的东古特 提斯北侧分支洋盆俯冲消减碰撞缝合带和中国大陆印支期完成其主体拼合的主要结合带之一。 相似文献
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西秦岭勉县北部光头山二长花岗岩独居石电子探针U—Th—Pb化学法定年及其地质意义 总被引：1，自引：0，他引：1
南秦岭勉略缝合带北侧光头山花岗岩体由早期的石英闪长质-英云闪长质岩石和晚期的S型二长花岗岩组成。其中早期侵入相明显地经历了韧性剪切带的改造,形成于勉略构造带闭合之前。晚期的S型二长花岗岩侵位于早期的石英闪长岩、英云闪长岩和韧性剪切带中．是与勉略洋盆闭合密切相关的同碰撞-后碰撞阶段侵位的花岗岩。所以光头山岩体的形成年龄可以较好地限定西秦岭勉略洋盆闭合、扬子板块与微秦岭板块碰撞的时代。2个二长花岗岩样品的独居石电子探针U—Th—Pb定年分析,分别得到3组年龄和4组年龄。结合前人的研究成果、独居石BSE图像和表观年龄分布,确定S型花岗岩的结晶年龄为209-196Ma,它限定了勉略构造带闲合隆升的时代为晚三叠世-早侏罗世;较老的240Ma±4Ma、318Ma±5Ma和249Ma±4Ma记录了早期与勉略缝合带闭合洋壳俯冲相关的残留独居石的年龄,年轻的184Ma±3Ma和154Ma±3Ma反映了后期的变形作用和流体活动等的改造作用。 相似文献
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南秦岭构造带中——晚古生代伸展构造作用 总被引：16，自引：3，他引：16
华北板块与扬子板块于加里东晚期沿商丹带发生碰撞的同时，在扬子板块北缘，即现今南秦岭构造带，开始发育一条近东西向延伸的拉伸带，其中包括武当地块伸展滑脱构造、武当地块古生代大规模基性岩浆活动及其西侧紫阳－岚皋古生代碱性岩浆活动带、镇安－旬阳浅层塌陷盆地以及佛坪隆起等。该伸展构造带主体在时间上发生在秦岭两期碰撞事件之间，空间上位于南北两个缝合带之间，因此，是秦岭造山带演化过程中的一个非常重要的阶段。该伸展构造的开始很可能与南、北秦岭碰撞后的造山带重力塌陷有关，随着该伸展带南侧晚古生代勉略洋的形成，南秦岭逐渐演化为华北板块南侧的被动大陆边缘，从而使南秦岭的地壳伸展一直延续到早－中三叠世。武当地块伸展滑脱系统中顺层侵位的基性岩席群的年代学与岩石地球化学的研究表明，这些基性岩与勉略蛇绿岩组合中的变辉绿岩及变基性火山岩具有很大的相似性，因此勉略洋很可能也是南秦岭这次拉伸作用的结果。 相似文献
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西秦岭勉略构造带现今呈近东西-北西西向展布,是以自北而南多层次叠瓦状逆冲推覆构造为骨架的向南突出的巨型复合断裂弧形构造带.该带原为西秦岭微板块与扬子板块之间的古缝合带,发育有俯冲和碰撞两期变形构造,以主造山碰撞晚期的自北向南的逆冲推覆构造为显著特征.初步确定发育OIB以及N-MORB和E-MORB型玄武岩,代表了洋盆发育的物质记录.根据已有的年代学和古生物化石研究结果,认为于泥盆纪晚期-早石炭世(D3-C1)沿勉略带发育有以蛇绿岩、洋岛玄武岩为代表的有限洋盆.在勉略带扩张打开形成有限洋盆与消减俯冲过程中,南侧发育有被动陆缘盆地沉积体系,北侧发育有深水裂陷盆地和活动陆缘盆地沉积体系.进而确定勉略带是一条重要的东古特提斯北侧分支洋盆俯冲消减碰撞缝合带和中国大陆印支期完成其主体拼合的主要结合带之一. 相似文献
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西秦岭勉略带陆内构造变形研究 总被引：12，自引：3，他引：9
秦岭造山带勉略缝合带是古特提斯洋盆向北俯冲形成的华北与华南最后拼接带。这个主缝合带俯冲-碰撞过程中以由北向南的一系列韧性逆冲推覆构造为特征,形成由前泥盆系、泥盆-石炭系和蛇绿混杂岩等不同构造岩片叠置的复杂构造带,碰撞时代从245Ma一直延续到230Ma左右。最近,作者对勉略缝合带内发育的韧性和脆性左行走滑剪切变形进行了研究,结果表明这些顺造山带的左行韧性走滑剪切变形带的变形时代为223±2Ma,与碰撞后花岗岩所确定的碰撞后构造环境的起始时间(225Ma)一致,显示这些韧性走滑剪切变形带是勉略带陆内变形初期变形产物。亦即华北、扬子大陆碰撞之后很快就转入陆内变形阶段,并且是以顺造山带的侧向走滑位移为主要变形方式。勉略带内顺造山带的脆性左行走滑断层的发育,表明这种顺造山带的侧向位移过程从深部到地壳浅层是一致的。因此,大陆碰撞在直接碰撞之后很快转变为顺造山带的侧向走滑位移为主的陆内变形,这种位移可能表现为两个大陆碰撞后的相对走滑,或是碰撞带中强烈变形部分顺造山带的侧向挤出,从而消减了正向碰撞所造成的地壳缩短和增厚。 相似文献
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SHRIMP U–Pb dating and laser ablation ICP‐MS trace element analyses of zircon from four eclogite samples from the north‐western Dabie Mountains, central China, provide evidence for two eclogite facies metamorphic events. Three samples from the Huwan shear zone yield indistinguishable late Carboniferous metamorphic ages of 312 ± 5, 307 ± 4 and 311 ± 17 Ma, with a mean age of 309 ± 3 Ma. One sample from the Hong'an Group, 1 km south of the shear zone yields a late Triassic age of 232 ± 10 Ma, similar to the age of ultra‐high pressure (UHP) metamorphism in the east Qinling–Dabie orogenic belt. REE and other trace element compositions of the zircon from two of the Huwan samples indicate metamorphic zircon growth in the presence of garnet but not plagioclase, namely in the eclogite facies, an interpretation supported by the presence of garnet, omphacite and phengite inclusions. Zircon also grew during later retrogression. Zircon cores from the Huwan shear zone have Ordovician to Devonian (440–350 Ma) ages, flat to steep heavy‐REE patterns, negative Eu anomalies, and in some cases plagioclase inclusions, indicative of derivation from North China Block igneous and low pressure metamorphic source rocks. Cores from Hong'an Group zircon are Neoproterozoic (780–610 Ma), consistent with derivation from the South China Block. In the western Dabie Mountains, the first stage of the collision between the North and South China Blocks took place in the Carboniferous along a suture north of the Huwan shear zone. The major Triassic continent–continent collision occurred along a suture at the southern boundary of the shear zone. The first collision produced local eclogite facies metamorphism in the Huwan shear zone. The second produced widespread eclogite facies metamorphism throughout the Dabie Mountains–Sulu terrane and a lower grade overprint in the shear zone. 相似文献
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The Anzishan ophiolite, a typical ophiolitic block of early Carboniferous age in the Mian-Lue suture zone of the Qinling Mountains, central China, consists of amphibolites/metabasalts, gabbros and gabbroic cumulates. All of these rocks, as well as those in the Hunshuiguan-Zhuangke (HZ) block, have compositions similar to normal MORB and back-arc basin basalts (BABB) with high εNd(t) values, indicating that they were derived from a depleted mantle source. The Mian-Lue suture zone also contains blocks of other lithologies, e.g., rift volcanic rocks in the Heigouxia block and arc volcanic rocks in the Sanchazi block. Although they are in fault contact with each other, the presence of these different blocks in the Mian-Lue suture zone may represent a complete Wilson cycle, from initial rifting to open ocean basin to final subduction and continent-continent collision, during the late Paleozoic-early Triassic. In this region, the North and South China Cratons were separated by Paleo-Tethys at least until the early Carboniferous, and final amalgamation of both cratons along the Qinling orogenic belt took place in the Triassic. 相似文献
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INTRODUCTION Anew ultrahigh pressure ( UHP) metamorphicbelt ,the South Altun-North Qaidam-North QinlingUHP metamorphic belt ,has been recently discoveredand widely discussed by different workers (Yang J Set al .,2003 ,2002 ,2001 ,2000 ,1998 ;Zhang J Xetal .,2002 ,1999 ; Zhang G et al .,2001 ; Hu et al .,1996 ,1995 ,1994) . Detailed studies have also beencarried out onthe Dabie-Sulu UHP/ HP metamorphicbelt inthe central orogenic belt (COB) of China (Gaoet al .,2002 ;Sun et al … 相似文献
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大别造山带的汇聚演化历史一直存在不同的认识,来自扬子陆块和华北陆块显生宙以来的地层记录以及北淮阳地区的地层记录可能为两个陆块的汇聚模式提供制约。通过对扬子陆块与华北陆块显生宙以来岩相古地理进行比较,其中3个阶段相似, 2个阶段差别很大。以浊积岩发育作为俯冲阶段的标志,磨拉石建造出现作为闭合的标志,显生宙以来,大别造山带曾经历了两次俯冲和两次汇聚,俯冲时间分别是晚奥陶世—早志留世和早三叠世,汇聚的时间分别为中 晚泥盆世和中三叠世,早期的汇聚具有软碰撞特征,以上认知得到了北淮阳地区地层、古生物和沉积记录的支持,同时也与大别山造山带榴辉岩的同位素年龄数据基本吻合。高压 超高压变质岩在晚三叠世处于快速折返阶段,早侏罗世以前到达地表,其平均折返隆升速率为39～66mm/a。 相似文献
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桐柏-大别山区高压变质相的构造配置 总被引：18，自引：3，他引：15
作为华北和扬子陆块间的碰撞造山带桐柏大别山区以发育高压、超高压变质带为特征,从南到北变质相从低级到高级,代表俯冲带深度不同的变质产物,整体形成高压变质相系列。不过现今各变质相岩石的分布极受后期地壳规模的伸展构造控制,大别杂岩的穹隆作用更使高压变质相带的空间分布复杂化。超高压变质岩今日多呈大小不等的块体嵌布于相对低压的大别杂岩之内,造山带根部物质的热软化,使许多深层地幔物质得以像挤牙膏一样挤出于大别杂岩内。它们之中广泛发育着减压退变质的显微结构,与大别杂岩内一些麻粒岩相表壳岩所保存的减压退变质证迹一样,同是挤出作用和碰撞后隆升的构造证迹。高压相系的发育使南桐柏山和大别山迥然不同于桐商（ 商丹） 断裂以北的北秦岭北淮阳变质带。新近发表的同位素年代学（４０Ａｒ ３９ Ａｒ） 资料：３１６ ～４３４ Ｍａ ,已证明北秦岭是古生代变质带,它与桐柏－ 大别印支期碰撞造山带差异甚大。这两个变质地温梯度差异甚大的变质地体的拼合,说明华北和扬子陆块碰撞的主缝合带是商丹－ 桐商断裂带 相似文献
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大别-苏鲁造山带的东延及板块缝合线:郯庐-鸭绿江-延吉断裂的厘定 总被引：9，自引：0，他引：9
根据大别-苏鲁造山带北缘和吉林-黑龙江东部的三叠纪浅变质加积杂岩特征标志,认为大别地区的板块缝合线为信阳-舒城断裂,苏鲁地区的为郯庐-鸭绿江断裂,且苏鲁造山带向北延入东北的吉林-黑龙江东部地区,而华北与扬子板块之间构造缝合线的东延部分则为郯庐-鸭绿江-图们江-延吉断裂。在此基础上,提出了亚洲东部三叠纪以来连续的俯冲-加积模型：(1)三叠纪扬子板块在华北板块向南突出部位(大别-苏鲁一带)发生点碰撞形成超高压变质岩,之后扬子板块由点碰撞逐渐向两侧旋转拼贴形成加积杂岩;(2)侏罗纪-新生代在三叠纪碰撞基础上,太平洋板块向欧亚大陆连续俯冲和加积,进而形成由三叠纪-新生代杂岩组成的欧亚大陆东部地区的巨大加积杂岩带。 相似文献
17.
《Precambrian Research》2007,152(1-2):48-82
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. 相似文献
18.
大别造山带超高压变质岩折返隆升的地层学证据—毛坦厂组榴辉岩砾石的启示 总被引：23，自引：0，他引：23
大别山北缘地区发育厚达近万米的中新生代碎屑岩，它们记录着大别山造山带和在株罗纪以来的演化历史。在安徽省六安地区毛坦厂组中，发现多块榴辉岩砾石。砾石新鲜，质地坚硬，表明属于第一旋回砾石。榴辉岩由石榴子石、多硅白云母、绿帘石、石英、金红石等组成。具有明显的退变质作用，发育以钠长石和闪石类组成的后合成晶、以及石榴子石周边的次为边。石榴子石以铁铝榴石和钙铝榴石为主，恪地C类榴辉岩。根据其特征应该属于大别山南部和北部超高压榴辉岩。毛坦厂组层位确切，古生物化石和同位素年龄都表明以晚株罗世为主，这一发现表明，在晚株罗世，以榴辉岩为代表的造山带根部物质，即：超高压变质岩已经出露地表，并作为毛坦厂组的物源。因此，大别造山带超高压为质岩折返到地表，最迟在晚株罗世。 相似文献
19.
Kanfenggou UHP Metamorphic Fragment in Eastern Qinling Orogen and Its Relationship to Dabie-Sulu UHP and HP Metamorphic Belts, Central China 总被引：3，自引：0，他引：3
SuoShutian ZhongZengqiu ZhouHanwen YouZhendong 《中国地质大学学报(英文版)》2003,14(2):95-102
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. 相似文献