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传统意义的A型花岗岩在化学成分上可分为碱性A型花岗岩(简称AAG)和铝质A型花岗岩(简称ALAG)两类,ALAG为A型花岗岩的一个亚类。随着华南地区花岗岩研究的不断深入,印支期铝质A型花岗岩越来越被关注。本文系统阐述了ALAG岩相学、矿物学、地球化学特征及其判别方式,分析了华南印支期ALAG的物质来源、成因及形成构造环境。发现其来源于华夏地块古老变质沉积岩不同程度的部分熔融,在其形成过程中有可能混染当时的基性地幔组分;构造环境主要受控于古太平洋板块的俯冲作用,形成于后造山阶段,但应也受到了印支地块与华南陆块的后碰撞过程的影响。 相似文献
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兴凯湖花岗杂岩体的锆石U——Pb 年龄及其地质意义 总被引：3，自引：0，他引：3
佳木斯地块东南缘的兴凯湖花岗杂岩体主要由花岗闪长岩、二长花岗岩和正长花岗岩组成,其锆石的LA-ICP-MS U-Pb 测年结果显示,杨田寨南山岩体形成于257 ± 2 Ma,双子山岩体形成于215 ～212 Ma; 花岗岩的时空展布表明,两期花岗质岩浆的就位可能分别与古亚洲洋板块的俯冲作用和后造山伸展进程密切相关。结合本区和黑龙江东部其他花岗质岩石的年龄,揭示了佳木斯地块和兴凯地块在早古生代、二叠纪及三叠纪共同经历了三期大规模岩浆活动,暗示两者具有相同的构造属性,共同组成了同一陆块。 相似文献
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紫云山岩体由花岗闪长岩和黑云母花岗岩两种岩石类型组成,前者为岩体的主体,呈环状分布于岩体的周边,发育同时代的暗色微粒包体;后者为补充侵入体位于岩体的中央部位,两者呈明显的侵入接触关系,高精度LA-ICP-MS锆石U-Pb年龄分别为222.5±1Ma和222.3±1.8Ma,都为印支晚期的产物。两种岩石类型的SiO2含量存在明显间断,A/CNK变化范围分别为0.99~1.05和1.08~1.15,花岗闪长岩为准铝质-弱过铝质I型花岗岩,黑云母花岗岩为弱过铝-强过铝质S型花岗岩。两类岩石都具有高的Rb、Cs含量和Rb/Sr比值,低的Sr、Ba、Eu含量,强-中等负铕异常,以及高的(87Sr/86Sr)i值和低的εNd(t)值,显示了前寒武纪变质基底起源的花岗岩的地球化学特征。两种岩石类型形成的温压条件和成岩深度有明显差别,暗示两者的源区不同。紫云山岩体两类岩石都是在印支陆块与华南陆块碰撞挤压-松驰构造环境下形成,岩浆底侵作用形成了少量有幔源组分加入的花岗闪长岩,其后上地壳泥砂质沉积物部分熔融形成了黑云母花岗岩。华南印支期主要花岗岩体的空间分布和高精度年龄数据显示,在华南内陆带和武夷-云开山脉带,由南而北,岩体形成时代逐渐变新,是印支陆块与华南陆块碰撞拼合所引起的挤压应力由南向北传递的结果。 相似文献
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印支地块的板块构造归属不仅对特提斯演化研究有重要意义, 对探讨新生代青藏高原及周缘板块的陆内变形同样至关重要.我们近期的研究工作表明, 本区的花岗岩主要是印支期旧特提斯闭合的产物, 少数花岗岩与加里东期的构造活动有关.花岗岩内锆石Lu-Hf二阶段模式年龄主要聚集在1.8~1.6 Ga, 此外在1.4~1.2 Ga有另一峰值区.老挝北部花岗岩峰值区与印支地块内其它地区的锆石U-Pb年龄及Lu-Hf二阶段模式年龄峰值相似, 表明印支地块内部有稳定的基底组成.老挝花岗岩年龄峰值与昌都-思茅地块的年龄峰值近于一致, 同时, 由于奠边府构造带不具有缝合带的属性且两个地块有相似的古生代暖水动物群, 我们认为印支地块与昌都-思茅地块可能为同一陆块, 这个联合陆块与华南陆块在Rodinia超大陆时期可能是一体的, 因为他们的峰值区在4.0~3.5 Ga, 2.0~1.8 Ga, 1.4~1.2 Ga的3个峰值区完全重合. 相似文献
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湖南中部和广东西部3个典型花岗质岩体的LA-ICPMS锆石U-Pb定年及其成岩意义 总被引：2，自引：0，他引：2
针对湖南歇马、沩山和粤西那蓬3个印支期花岗岩体系统的LA-ICPMS锆石U-Pb年代学研究表明:湖南的歇马岩体(214.1±5.9Ma)、沩山岩体黑云母二长花岗岩(210.3±4.7Ma)和粤西那蓬岩体(206.0±1.8Ma),具有相似的印支期形成年龄。结合华南内部印支期花岗岩、及其他构造-热年代学资料认为:华南内陆形成于210Ma左右印支晚期花岗岩与形成于230～245Ma的印支早期的花岗岩具有形似的形成构造背景和成因,即华南内陆整个印支期花岗岩的形成可能与挤压构造背景下陆内地壳物质叠置加厚作用有关。这一研究为深入理解华南印支期花岗岩的时空分布及其动… 相似文献
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川西义敦岛弧碰撞造山带北段雀儿山复式花岗杂岩体的年代学和全岩地球化学研究表明,雀儿山杂岩体主要由花岗闪长岩、二长花岗岩和正长花岗岩组成。锆石LA--ICP--MS U--Pb测年结果显示,该岩体中的花岗闪长岩形成时代为晚三叠世(224±3 Ma),二长花岗岩则形成于早白垩世(102±1 Ma)。地球化学数据表明,晚三叠世花岗闪长岩为火山弧岩石序列,形成环境为碰撞前俯冲环境;早白垩世二长花岗岩和正长花岗岩为后碰撞岩石序列,形成于造山期后板内或陆内环境。结合区域地质资料,认为雀儿山杂岩体为印支期—燕山期义敦岛弧碰撞造山带经历俯冲--碰撞--隆升过程中的产物。 相似文献
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北祁连早古生代花岗质岩浆作用及构造演化 总被引：29，自引：14，他引：15
北祁连山中段花岗岩锆石SHRIMP定年结果表明,柯柯里岩体的斜长花岗岩和石英闪长岩的年龄分别为512Ma和501 Ma,野马咀和金佛寺花岗岩的年龄分别为508Ma和424Ma。结合区内其它花岗岩体的定年资料,根据花岗岩的岩石地球化学特征及岩体产出的构造位置、区域地质资料等,我们认为,早古生代北祁连洋板块向南俯冲,至少引发了两期花岗质岩浆作用,第一次岩浆作用形成柯柯里斜长花岗岩(512Ma)、野马咀花岗岩(508Ma)和柯柯里石英闪长岩(501 Ma),第二次花岗质岩浆作用形成牛心山花岗岩(477Ma)。由于往南俯冲的板块受到柴达木板块向北俯冲的影响,俯冲受阻,继而俯冲极性发生变化,转向北俯冲,形成了民乐窑沟(463Ma)等花岗岩侵入体。大约440Ma之后,洋盆闭合,柴达木陆块和阿拉善陆块对接碰撞,形成北祁连造山带。由于造山带根部岩石圈发生折沉作用,造山带上不同的块体伸展、滑塌,形成一系列碰撞后花岗岩如金佛寺花岗岩(424Ma)及牛心山岩体的石英闪长岩(435Ma)等。 相似文献
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湘东北构造活化期花岗岩形成构造环境及成因 总被引：6，自引：1，他引：6
华南大陆从印支期进入陆内活化阶段,形成一系列沿断裂分布的印支期花岗岩。该期花岗岩代表陆内活化期的开始,在岩石地球化学和形成构造环境上以及岩石的形成方式上都与该期以后的花岗质岩石存在一定的差异。表明华南中生代陆内活化构造环境的复杂性和多阶段性。本文以湘东北印支期花岗质侵入岩为例,分析其成岩构造环境,用以反映该区陆内开始活化时的构造环境和活化方式。湘东北印支期花岗质岩石以花岗闪长岩-二长花岗岩岩石系列为主,以相对较低的SiO2、K2O和较高的TiO2、P2O5及负铕异常不明显区别于中生代其它侵入期次岩石,具有陆壳重熔型花岗岩特征,其形成为陆内俯冲导致陆壳物质在俯冲前缘重熔的结果,表明陆内俯冲作用是导致湘东北陆内开始活化的主要方式之一,其构造环境以逆冲式推覆挤压为主。 相似文献
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西秦岭舟曲峰迭和夏河桑日卡岩体锆石U-Pb年龄及其地质意义 总被引：1，自引：0，他引：1
对西秦岭疑似为燕山期花岗岩的舟曲峰迭和夏河桑日卡岩体进行岩相学研究和锆石U-Pb同位素地质年龄测定,获得锆石U-Pb年龄分别为201.3±0.9Ma和232.6±2.2Ma,表明2个岩体均属早中生代印支期造山作用岩浆活动的产物,澄清了有关地质图(1∶25万陇东幅地质图和1∶25万临夏市幅建造构造图)中2个岩体的时代归属。通过研究认为,西秦岭内部无论南带或北带基本不存在燕山期花岗岩,其花岗岩主体为出露于北带的印支期花岗岩体。因此,西秦岭可以与东秦岭的南秦岭构造单元对比,在构造带的划分上相当于南秦岭的西延。结合前人研究成果,从西秦岭与南秦岭花岗岩形成时代与同位素地球化学特征看,两者的岩浆源区相似并具有扬子地块基底属性。西秦岭缺少燕山期花岗岩的原因归咎于它的构造位置与东秦岭尤其是燕山期花岗岩极发育的小秦岭完全不同,后者燕山期岩浆作用得以盛行,可能与华北克拉通岩石圈破坏或与中生代中晚期华北地块向秦岭造山带的陆下俯冲有关。 相似文献
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莺歌海盆地周边区域构造演化 总被引：42，自引：0，他引：42
莺歌海盆地周边新生代区域构造演化综合分析表明，该舅地形成和演化构造应力场分四个阶段：第一阶段，古新世末至早渐新世印支地块快速向南东方向挤出，同时伴随着地块的顺时针旋转运动。第二阶段，晚渐新世至早中新世印支地块向南东挤出运动逐渐减弱，华南地块整体仍然相对稳定。莺歌海盆地处于左旋剪切状态。第三阶段，中、晚中新世随着印度地块逐渐楔入欧亚板块内部，印支半岛的挤出运动进一步减弱。至中中新世末，华南地块整体开始挤出。第四阶段，上新世一第四纪印支地块相对稳定，华南地块挤出运动继续进行，两地块间的相对运动呈右旋剪切运动。莺歌海盆地新生代的构造应力场演化受太平洋板块、印度与欧亚板块之间相互作用控制。其中，印度与欧亚板块碰撞作用所导致的印支地块与华南地块的相对运动，是决定莺歌海盆地新生代构造运动应力场变化的主要因素。 相似文献
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对印支地块思茅地区始新世陆相红层进行古地磁研究,获得勐伴剖面特征剩磁方向为Ds=118.2°,Is=22.1°,k=31.6,α95=10.9°;勐腊剖面特征剩磁方向为Ds=47.6°,Is=22.8°,k=20.2,α95=5.9°。其特征剩磁方向与前人研究结果基本一致。利用Hodych等的磁倾角校正方法得到校正磁倾角为28.4°±4.3°,对前人的数据重新进行E/I统计得到的校正磁倾角值为30.7°,置信区间为[25.4°,35.9°],两种不同方法得到了较一致的结果,思茅地区的古近纪磁倾角显示了一定程度的偏低。E/I磁倾角偏低检验方法在应用时存在一定的局限性,变形微弱地层的古地磁学数据适合进行E/I磁倾角偏低校正,以避免倾伏褶皱或差异性旋转变形作用对E/I磁倾角偏低校正的影响。Hodych等提出的磁倾角校正方法是现今比较可靠的磁倾角校正方法。结合前人印支地块的古地磁研究成果,本次研究结果表明印支地块思茅地区自始新世以来相对于华南板块向南滑移量约500km。 相似文献
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Ailaoshan orogenic belt located at the northeastern margin of the Indochina block, southeastern Tibet, was formed by subduction and collision between the Indochina and South China blocks in Triassic and slip shearing resulted from the extrusion of the Indochina block in Cenozoic. The high‐pressure pelitic granulite is located at the southeastern margin of the Ailaoshan metamorphic belt, occurs as a slice of about 500～700m in thickness, consists of garnet, sillimanite, feldspar, biotite and quartz with accessory of kyanite, sapphirine, spinel, rutile, ilmenite, zircon and apatite. The petrography and mineral chemistry show that the high‐pressure pelitic granulite had suffered three stages of metamorphism: 1) the prograde metamorphism recorded by the mineral assemblage of garnet, kyanite, feldspar, biotite and rutile; 2) the peak metamorphism shown by the mineral assemblage of garnet, sillimanite, sapphirine, ternary feldspar, K‐feldspar, plagioclase, biotite, spinel, quartz, rutile and zircon mantle; 3) the retrograde metamorphism recorded by the mineral assemblage of biotite, muscovite, plagioclase, quartz and zircon rim. Zircon SHRIMP U‐Pb dating indicates that the protolith of the pelite granulite was deposited before 336 Ma, the prograde to peak metamorphism occurred at P‐T conditions of ≥10.4 kbar at 850～919 °C in 235 Ma, and the retrograde metamorphism occurred at the P‐T condition of 3.5～3.9 kbar at 572～576 °C until to 33 Ma. They are consistent with the times of Indochina separated from Gondwanaland during late Paleozoic, the amalgamation of the south China and Indochina blocks during the Triassic, and the sinistral slip‐shearing since the Early Cenozoic respectively. It is inferred that that the sedimentary rock was subducted to the lower continental crust (30 km) and suffered granulite‐facies metamorphism due to the collision during Indosinian, then exhumed quickly to middle‐upper crust (10–12km) and superimposed retrograde metamorphism since the Cenozoic. 相似文献
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Experimental evidence for the dynamics of the formation of the Yinggehai basin, NW South China Sea 总被引：1，自引：0，他引：1
The Yinggehai basin is located on the northwestern shelf of the South China Sea. It is the seaward elongation of the Red River Fault Zone (RRFZ). The orientation and rift shape of the Yinggehai basin are mainly controlled by NW-, NNW- and nearly NS-trending basal faults. The depocenter migrated southeastward when the basin developed. The depocenter trended northwest before about 36 Ma, then jumped southward and became nearly N–S trending and migrated toward the southeast up to 21 Ma; thereafter, the depocenter trended northwest again. Based on above and structural evolution in neighbor areas, it is believed that the Yinggehai basin formation was mainly controlled by the extrusion accompanied by clockwise rotation of Indochina. We set up analogue models (thin basal plate model and thick basal plate model) to investigate the evolution of Yinggehai basin. From the experiments, we consider that the basin evolution was related to the extrusion and clockwise rotation of the Indochina block, which was caused by the collision of the Indian plate and Tibet. This process took place in four main stages: (1) Slow rifting stage (before 36 Ma) with a NW-trending depocenter; (2) rifting stage formed by sinistral slip of the Indochina block accompanied by rapid clockwise rotation between 36 and 21 Ma; (3) rifting-thermal subsidence stage affected by sinistral slip of the Indochina (21–5 Ma) block and (4) dextral strike–slip (5–0 Ma). 相似文献
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莺歌海盆地构造演化与强烈沉降机制的分析和模拟 总被引：12，自引：3，他引：9
莺歌海盆地新生代发生了快速沉降, 盆内充填了最厚达17 km的沉积, 根据模拟实验, 印支地块或之上刚性地块的存在对莺歌海盆地的强烈沉降具有重要的贡献, 可能是造成莺歌海盆地裂陷期强烈沉降的重要原因之一.结合地质分析和物理模拟实验, 莺歌海盆地的演化大致可以分为以下4个主要阶段: 早期(42 Ma以前) 主要受到南海北部陆缘(主要是北部湾盆地) 裂解造成的右旋转换伸展作用的影响, 但影响范围较小, 主要为莺歌海盆地西北部和东部边界.42~21 Ma期间, 主要受控于印支地块左行走滑和顺时针旋转作用的影响, 莺歌海盆地在此期间发育了主体裂陷体系, 东侧受到右旋转换伸展应力场的叠加影响而导致沉降加强; 21~10.4 Ma期间, 受印支地块逐渐减弱直至停止的左行走滑作用的影响, 盆地西北部在21~15.5 Ma期间发生局部反转褶皱, 但盆地整体进入以热沉降为主的时期; 10.4 Ma以后, 盆地受华南地块沿红河断裂右旋走滑作用和5 Ma以后新一期热事件的影响. 相似文献
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Tectonic framework and Phanerozoic evolution of Sundaland 总被引：1，自引：0，他引：1
Ian Metcalfe 《Gondwana Research》2011,19(1):3-21
Sundaland comprises a heterogeneous collage of continental blocks derived from the India–Australian margin of eastern Gondwana and assembled by the closure of multiple Tethyan and back-arc ocean basins now represented by suture zones. The continental core of Sundaland comprises a western Sibumasu block and an eastern Indochina–East Malaya block with an island arc terrane, the Sukhothai Island Arc System, comprising the Linchang, Sukhothai and Chanthaburi blocks sandwiched between. This island arc formed on the margin of Indochina–East Malaya, and then separated by back-arc spreading in the Permian. The Jinghong, Nan–Uttaradit and Sra Kaeo Sutures represent this closed back-arc basin. The Palaeo-Tethys is represented to the west by the Changning–Menglian, Chiang Mai/Inthanon and Bentong–Raub Suture Zones. The West Sumatra block, and possibly the West Burma block, rifted and separated from Gondwana, along with Indochina and East Malaya in the Devonian and were accreted to the Sundaland core in the Triassic. West Burma is now considered to be probably Cathaysian in nature and similar to West Sumatra, from which it was separated by opening of the Andaman Sea basin. South West Borneo and/or East Java-West Sulawesi are now tentatively identified as the missing “Argoland” which must have separated from NW Australia in the Jurassic and these were accreted to SE Sundaland in the Cretaceous. Revised palaeogeographic reconstructions illustrating the tectonic and palaeogeographic evolution of Sundaland and adjacent regions are presented. 相似文献
17.
《Tectonophysics》1999,301(1-2):133-144
We report the Cretaceous palaeomagnetic results from Hainan Island, south China. In Hainan island we collected the Early Cretaceous redbeds of the Lumuwan Formation at eleven sites. We also describe the tectonic kinematics for and around Hainan Island since the Cretaceous, deduced from our and previous palaeomagnetic results. The palaeolatitude of Hainan Island is 25.9°N (+3.4°/−3.2°), implying that Hainan island was situated about 7° north from the present position during the Cretaceous. The palaeopole of Hainan Island (latitude = 77.7°N, longitude = 162.1°E, k=65.6, and A95=4.4°) suggests 4.0±5.8° counterclockwise rotation and 14.1±5.5° southward translation relative to the suspected coherent part of the south China block (SCB) since the Cretaceous. The rotation and translation of similar sense (18.8±7.4° and 7.8±6.9°, respectively) are detected in the existing palaeomagnetic result from the Xinlong Formation in Guangxi, which is situated approximately 400 km north-northwest from Hainan Island. The southward translation of both areas seems to have been due to the southeastward extrusion of dissected zones within the southwestern part of the SCB in a similar pattern to the Indochina block, which had resulted from the indentation of India into Asia. This SW part seems to have slightly rotated counterclockwise, because its extrusion was probably smaller in scale than the Indochina block and therefore it was dragged out by the Indochina block. This hypothesis is supported by the existence of a northwest–southeast-trending fault system parallel to the Red River Fault. 相似文献
18.
通过在红河两侧（大姚、景谷、江城、勐腊剖面）的早第三纪古地磁样品的研究，进一步证实了红河两侧由白垩纪古地磁研究所揭示的印支地块相对于华南地块存在的左旋相对运动。这一结果说明了印度支那地块在印度板块的挤压下，于早第三纪至中新世沿红河大断裂发生向南侧向滑移达1000km左右，它不仅使青藏高原的巨大构造缩短得到调整，而且在北部湾地区形成伸展构造，并引起南中国海的张开。印度支那地块北部各地区的差异性旋转和红河断裂共轭的剪切断裂系的发育，以及红河大断裂早第三纪至中新世左旋剪切作用密切相关。 相似文献