粤西庞西垌-桂东南金山银金成矿带晚燕山期花岗岩的性质与成矿作用   总被引：7，自引：0，他引：7  

王祖伟  周永章  张海华  吴家勇  李春武 《岩石矿物学杂志》1998,(2)

分析了云开地区粤西庞西垌－桂东南金山银金成矿带晚燕山花岗岩的特征与成矿作用的关系。认为晚燕山期英桥花岗岩体属于铝过饱和富钾质的钙碱性花岗岩系列,是同熔型花岗岩。晚燕山期岩浆活动与银金矿床在空间和时间上密切相关,在微量元素、稀土元素、稳定同位素和包体成分等地球化学特征上具有相似性,晚燕山期岩浆活动对银金矿床的形成起着重要的作用。  相似文献   

Thermal model for the Zanskar Himalaya   总被引：8，自引：0，他引：8  

M. P. SEARLE  A. J. REX 《Journal of Metamorphic Geology》1989,7(1):127-134

ABSTRACT Crustal thickening along the northern margin of the Indian plate, following the 50 Ma collision along the Indus Suture Zone in Ladakh, caused widespread high-temperature, medium-pressure Barrovian facies series metamorphism and anatexis. In the Zanskar Himalaya metamorphic isograds are inverted and structurally telescoped along the Main Central Thrust (MCT) Zone at the base of the High Himalayan slab. Along the Zanskar valley at the top of the slab, isograds are the right way-up and are also telescoped along northeast-dipping normal faults of the Zanskar Shear Zone (ZSZ), which are related to culmination collapse behind the Miocene Himalayan thrust front. Between the MCT and the ZSZ a metamorphic-anatectic core within sillimanite grade rocks contains abundant leucogranite-granite crustal melts of probable Himalayan age. A thermal model based on a crustal-scale cross-section across the Zanskar Himalaya suggests that M₁ isograds, developed during early Himalayan Barrovian metamorphism, were overprinted during high-grade MCT-related anatexis and folded around a large-scale recumbent fold developed in the hanging wall of the MCT.  相似文献   

胶东昆嵛山杂岩中高锶花岗岩地球化学成因及其意义   总被引：15，自引：12，他引：15  

张华锋翟明国  何中甫彭澎　许保良 《岩石学报》2004,20(3):369-380

华北克拉通性质的胶东陆块之间.本文主要对其中具定向构造的垛崮山与瓦善高锶花岗岩体的地球化学成因及其地质意义的研究.垛崮山岩体岩性主要为花岗闪长岩,瓦善岩体主要为二长花岗岩.岩石化学特征表明两岩体为亚碱性岩石,属钙碱性系列和高钾钙碱性系列.SiO2=69～71%,高Al(Al2O3＞15%,SiO2=70%),富碱Na2O=3.54～4.88%,K2O=2.11～4.44%,K2O+Na2O=5.65～9.02%.Na2O/K2O=0.9～1.9,表明属Na质花岗岩.富集大离子亲石元素,如Ba、Sr(Ba＞1440μg/g,Sr＞650μg/g),而亏损高场强元素(如Nb、P、Ti以及Y＜18μg/g、＜2μg/g),具右倾陡斜的稀土配分模式(Lan/Ybn＞12),无Eu异常或Eu异常不明显.上述地球化学特点与Adakite、太古宙TTG、秘鲁科迪勒拉布兰卡钠质花岗岩以及中国东部大量中生代花岗质岩石类似.然而,本文中的花岗岩石化学显示与钠质花岗岩最为相近,其钙碱性演化趋势不同于TTG、埃达克岩通常所显示的奥长花岗岩演化趋势.前人报道的同位素特征(Sr87/Sr86i=0.7097～0.7098,εNd(t)=-19.6～-20.0)和700～800Ma的继承锆石特征以及胶东区域地质上没有与之同期甚至早期的基性岩浆伴生共同表明,昆嵛山高锶花岗岩不可能来自幔源岩浆混合或基性岩浆的结晶分异,也不可能是新生玄武质下地壳和太古宙胶东陆块的熔融产物,而是以晚元古扬子陆块的基性下地壳(＞40km)部分熔融为主.尽管均表现出高锶花岗岩的地球化学特征,但两岩体岩石、地化特征存在一定的差异.造成这种差异性的原因可能是晚期瓦善岩体源区有少量富集地幔特征的物质加入以及部分熔融程度相对早期垛崮山岩体低或源区较深所至.形成它们的动力学机制可能是岩石圈减薄作用引起的玄武质岩浆底侵导致基性下地壳的部分熔融.高锶花岗岩的低Y、Yb含量和高S∥Y、hn/¨n比值暗示源区残留固相以石榴石+角闪石为特征,而无斜长石的残留.源区深度在石榴石麻粒岩相至榴辉岩相,熔融后的残余固相(高压麻粒岩至榴辉岩相岩石)因密度大而可能引发下地壳沉入地幔,加速地壳的减薄.昆嵛山高锶花岗岩的成因暗示胶东地区140～160Ma加厚的铁镁质下地壳依然存在以及中国东部高锶花岗岩物质来源的多样性.  相似文献   

Geochemical evidence for contribution of ore-forming materials from peraluminous granite basement —— Taking Fucheng pluton and No. 6722 uranium deposit in southern Jiangxi Province as examples   总被引：2，自引：0，他引：2  

章邦桐  陈培荣  杨东生  孔兴功 《中国科学D辑(英文版)》2003,46(3)

Source of ore-forming material is always one of the fundamental subjects in the study of mineral deposits. Recently, in order to probe deep sources of ore-forming materials, many interna-tional and Chinese investigators have paid much attention to the rel…  相似文献   

中国东部燕山期强过铝质花岗岩的地球动力学意义——以冀晋辽地区和广东吴川-四会地区为例     

汪洋 《城市地质》2002,(3)

强过铝质花岗岩的岩石化学特征可以提供地壳发生部分熔融时的温压条件的信息。在冀晋辽地区和广东省吴川 -四会地区均有燕山期强过铝质花岗岩出露。它们的岩石化学成分表现出高钾质的特征。冀晋辽地区燕山期强过铝质花岗岩的Al2 O3/ Ti O2 比值变化于 5 0到 2 5 0之间 ,暗示其熔融温度在 80 0到 90 0℃之间 ;而燕山期强过铝质花岗岩 ,其大多数的 Al2 O3/ Ti O2 比值较低 ,暗示其源区熔融温度在 875℃以上。它们的稀土元素配分形式指示其熔融源区的残留矿物组合中含有斜长石、单斜辉石、石榴子石和角闪石 ,表明这些强过铝质岩浆形成于 0 .9～ 1.7GPa的压力条件下。这表明中国大陆东部地区燕山期深部热背景存在南北差异。在造山作用特征方面 ,华南在燕山期表现出“热”造山带的特点 ,华北则表现出过渡型的特点。  相似文献   

Geochemical and Nd, Sr Isotopic Study of the Post-Orogenic Granites in the Yidun Arc Belt of Northern Sanjiang Region, Southwestern China   总被引：7，自引：0，他引：7  

Xiaoming QU  Zengqian HOU  Shugui ZHOU 《Resource Geology》2002,52(2):163-172

Abstract: In the arc (basin)–back area of the Yidun arc belt in the north segment of the Sanjiang tectonic zone, southwestern China, there occurs a post‐orogenic granite belt extending for more than 300 km in NNW direction. It strides across two different tectonic units of the arc (basin)–back area and the subduction area, and is accompanied by extensive Ag‐Sn polymetal–lic mineralizations. More than ten granite bodies have very similar geochemical characteristics: high SiO₂ (73.8–76.3 wt%) and K₂O+Na₂O (7.16‐8.41 %), and low Al₂O₃ (11.9–13.6 %), CaO (0.46‐1.54 %) and MgO (0.16‐0.61 %), as well as high enrichment of Nb, Ta, Ga and Y, and strong depletion of Sr and Eu. Most of these features are peculiar to A‐type granite. Rb‐Sr and ⁴⁰Ar/³⁹Ar isotopic dating results indicate that the formation ages of the granites decrease from 103.7 Ma of the north end to 75.2 Ma near the south end, and that the magmatism became younger from north to south. The tectonic environment analysis clearly reveals that they were formed in post‐orogenic within–plate extension settings. The magma genesis was controlled by a united crustal extension regime after the arc‐continent collision. The granites have low _Nd values ranging from –4.96 to –8.40, whereas the _Sr values vary greatly ranging from –31.7 to 296, reflecting that the source composition transited from mantle – differentiated igneous rocks in the north to basement – dominated metamorphosed sedimentary rocks in the south. Under high temperature and water‐absent conditions, the anatexes of the crustal rocks made a great amount of plagioclase separated from melts and left in magma sources. Through this mechanism, the post‐orogenic granites took geo‐chemical characteristics such as low Al₂O₃ and CaO, and strong depletion of Sr and Eu.  相似文献   

南岭地区钨锡铌钽花岗岩及其成矿作用   总被引：26，自引：1，他引：25  

陈骏  陆建军  陈卫锋  王汝成  马东升  朱金初  张文兰  季峻峰 《高校地质学报》2008,14(4):459-473

在晚侏罗世时,南岭地区发生了与花岗岩有关的钨锡铌钽大规模成矿作用。依据花岗岩的岩石学、地球化学及其矿化特征,可将南岭地区含钨锡铌钽花岗岩划分为三个主要类型：含钨花岗岩、含锡钨花岗岩和含钽铌花岗岩。含钨花岗岩的地球化学特征可归纳为铝过饱和,低Ba+Sr 和TiO2,轻重稀土比值低,铕亏损强烈,富Y 和Rb,Rb/Sr 比值高,分异强烈。含锡钨花岗岩总体特征表现为TiO2 含量高,准铝质—弱过铝质,轻重稀土比值和CaO/(K2O+Na2O)比值高,富高场强元素、稀土、Ba+Sr 和Rb,低Rb/Sr 比值,分异演化程度较低。含钽铌花岗岩的地球化学特征主要为TiO2 含量和CaO/(K2O+Na2O)比值低,Al2O3/TiO2 和Rb/Sr 比值明显偏高,强过铝质,贫Ba+Sr、稀土和高场强元素,铕亏损强烈,明显富Rb 和Nb,高度分异演化。三类含矿花岗岩具有明显不同的演化特征,成矿作用与它们的演化密切相关。黑云母花岗岩主要与锡成矿作用有关,二云母花岗岩和白云母花岗岩主要产生钨矿化或锡钨共生矿化,钠长石花岗岩主要与钽铌或锡（钨）钽铌矿化有关。总结了南岭锡钨钽铌矿床的重要类型,提出了绿泥石化花岗岩型锡矿新类型,指出南岭地区要特别注意在含锡钨花岗岩中寻找此类锡矿和云英岩- 石英脉型锡钨矿。  相似文献   

大兴安岭锡多金属成矿带花岗岩地球化学特征   总被引：5，自引：0，他引：5  

郝立波  段国正 《世界地质》1999,18(2):66-72

大兴安岭中南段华力西褶皱带是我国北方重要的锡多金属成矿带。已发现了许多大中型锡矿床、锡多金属矿床、铅锌矿床、铜矿床等。这些矿床形成与花岗岩有密切成因联系。本文较详细地阐述了花岗岩产出的地质背景,各期次花岗岩的地球化学特征,提出与成矿有关的花岗岩体地质地球化学判别标志。  相似文献   

新疆乌伦古富碱花岗岩带碱性花岗岩成因及其形成构造环境   总被引：20，自引：1，他引：19  

刘家远  袁奎荣 《高校地质学报》1996,2(3):257-272

新疆东准噶尔西北部乌伦古河南岸,受乌伦古深断裂控制、沿扎河坝－萨尔铁列克－塔斯嗄克－线,发育着一系列碱性花岗和偏碱性花岗岩侵入体,构成了东准噶尔境内一条颇具物色的富碱花岗岩带,与乌伦古蛇绿岩带相伴产出,显示其重要的构造意义。花岗岩地质学、岩石学矿物学和地球化学研究表明,同国内外已知Ａ型花岗岩相对比,乌伦古富碱花岗岩、属典型的Ａ型花岗岩;同时又具有不同于其碱性花岗岩的某些特性,如岩石化学成分上相对较高的Fe2O3和MnO含量,Na2O>K2O 等,通过乌伦古带碱性花岗岩的系统研究,并参考前人研究成果,笔者提出了“地幔物质活动+脱水的硅铝质源岩部分熔融+花岗质岩浆分异作用+张性地质环境”这一A 型花岗岩的复合成因模式,可以较好地解释A 型花岗岩的成因机理。通过一系列地球化学图解的判别,结合区域构造演化的分析,得出了乌伦古带碱性花岗岩形成于中、晚石炭世碰撞造山之后的拉张构造环境的结论。乌伦古带碱性花岗岩重要的构造意义,在于不仅它的形成代表着东准噶尔造山作用的结束,而且它的空间分布,同其南侧卡拉麦里带碱性花岗岩一道,标志着西伯利亚和哈萨克斯坦两大板块之间巨型缝合带的客观存在,从而揭示了花岗岩类的研究 探讨和解决大地构造问题上的重要作用。  相似文献   

Permian felsic magmatism in the Neoproterozoic Nagar Parkar Igneous Complex of the Malani Igneous Suite: Evidence from zircon U–Pb age     

Hafiz U. Rehman  Tahseenullah Khan  Hao‐Yang Lee  Sun‐Lin Chung  Mamoru Murata  M. Qasim Jan 《Island Arc》2019,28(6)

We report Permian (ca. 272 Ma ±5.4 Ma) felsic dykes that intrude into the Neoproterozoic (ca. 750 Ma) magmatic suite of the Nagar Parkar Igneous Complex (NPIC), the western extension of the Malani Igneous Suite (MIS). The NPIC consists of Neoproterozoic basement amphibolites and granites (riebeckite–aegirine gray granites and the biotite–hornblende pink granites), all of which are intruded by several generations of mafic and felsic dykes. Granitic magmatism occurred in the Late Neoproterozoic (ca. 750 Ma) due to the subduction‐, followed by the rift‐related tectonic regime during the breakup of the Rodinia supercontinent. U–Th–Pb zircon and monazite CHIME age data of 700–800 Ma from the earlier generation porphyritic felsic dykes suggest the dyke intrusion was coeval or soon after the emplacement of the host granites. Our findings of Permian age orthophyric felsic dykes provide new insights for the prevalence of active tectonics in the MIS during late Paleozoic. Textural features and geochemistry also make the orthophyric dykes distinct from the early‐formed porphyritic dykes and the host granites. Our newly obtained age data combined with geochemistry, suggest the existence of magmatism along the western margin of India (peri‐Gondwana margin) during Permian. Like elsewhere in the region, the Permian magmatism in the NPIC could be associated with the rifting of the Cimmerian micro‐continents from the Gondwana.  相似文献