纳米比亚欢乐谷地区斑状花岗岩成因及构造背景   总被引：1，自引：0，他引：1  

王生云  范洪海  陈金勇  顾大钊  陈东欢  高阳  聂江涛 《世界地质》2013,32(4):773-782

对纳米比亚欢乐谷地区斑状花岗岩进行系统的地球化学及 Sr--Nd 同位素研究,并对其岩石成因及构造意义进行了讨论。结果表明,该斑状花岗岩为高钾钙碱性-钾玄岩系列的准铝质花岗岩; 岩石富碱、轻稀土和 Ｒb、Th、U、K、Pb 等大离子亲石元素,贫 Nb、Ta、Ti、Zr、Hf 等高场强元素,具有中等铕负异常。岩石锶初始值为 0. 715 61 ～0. 722 07,εNd( t) 为 －13. 9 ～ －12. 7,Nd 同位素模式年龄为2 025 ～2 153 Ma。揭示欢乐谷地区斑状花岗岩为同碰撞 S 型花岗岩,主要来源于古老地壳物质的重熔,是 Kalahari 克拉通和 Congo 克拉通碰撞造山的产物。  相似文献   

哈密头苏泉哈尔欣巴A型花岗岩厘定   总被引：1，自引：0，他引：1  

何峻岭  廖群安  刘跃飞  董文钦 《新疆地质》2013,(2)

初步研究表明新疆哈密头苏泉地区哈尔欣巴花岗岩为A型花岗岩.该岩体富硅(SiO2=71.87%~76.80%)和碱(K2O+N2O=7.39%~8.94%),贫铁、锰、镁(FeOt 0.67%~2.04%;MnO 0.03%~0.06%;MgO 0.10%~0.61%),具较高FeOt/MgO比值,A/NKC=0.78~1.02,属准铝质花岗岩石.在微量元素和稀土元素组成上,岩石富Zr,Rb,Ce等不相容元素,亏损Ni,Co,Cr等元素.10000×Ga/Al为3.12~4.1,大于A型花岗岩下限值(2.6).在Zr,Ce,Nb,Y与10000×Ga/Al,及(Nb+Zr+Ce+Y)/(FeOt/MgO)、SiO2/( FeOt/MgO)图解中大多数点都落在A型花岗岩区域.在A1-A2构造环境判别图上显示后造山花岗岩特征.对头苏泉地区哈尔欣巴A型花岗岩的厘定,为研究该区地壳物质组成及构造演化具重要意义.  相似文献   

南岭地区钨矿床共（伴）生金属特征及其地质意义初探   总被引：8，自引：0，他引：8  

华仁民  张文兰  李光来  胡东泉  王旭东 《高校地质学报》2008,14(4):527-538

南岭是世界上最重要的钨矿产地,南岭钨矿床中与钨共（伴）生的有色、稀有及贵金属种类很多,数量可观,也是我国重要的矿产资源。论述了南岭及其邻近地区众多钨矿床中与钨共生或伴生的锡、钼、铋、铌钽、铜、铅锌、金银、稀土等元素的不同状况和特征,其中锡、钼、铋是南岭钨矿床中最普遍最重要的共（伴）生元素,铌钽只在演化程度较高的花岗岩相关的钨矿床中伴生产出,铜、金作为钨矿床伴生金属的意义较小,而钨矿床中伴生的银、铅锌具有相当重要的意义。从元素地球化学性质、南岭的区域地背景、花岗岩演化、多期多阶段成矿作用等方面出发,分析和解释了它们之间相互共（伴）生的原因及差异性,探讨了其地质意义。  相似文献   

Deformation features of garnet-bearing granites from Huwan,western Dabie Mountains   总被引：1，自引：0，他引：1  

KunGuang Yang  Qiang Liu  JianLei Xie  Wei Dan  ZhenBing She  ChangQian Ma 《中国科学D辑(英文版)》2009,52(1):55-65

Foliated garnet-bearing granite, usually associated with high pressure and ultrahigh -pressure (UHP) metamophic rocks, is a particular rock-type extensively exposed in the Mesozoic Dabie-Sulu orogenic belt of China. This study focuses on deformation features and SHRIMP zircon dating of foliated garnet granite in a high-pressure metamorphic unit from Huwan, western Dabie Mountains in order to resolve discrepancies in current versions of its petrogenesis and structural evolution. SHRIMP dating reveals a zircon age of 762 ± 15 Ma (MSWD=1.7) for Huwan granites, representing the Middle to Late Neoproterozoic age of intrusion and crystallization. Field and microstructural studies show that the Huwan granite body underwent multiple-stage deformation. The deformation was manifested by an early stage of rootless folding and imposition of relict foliation (S₁); an Indosinian main stage marked by imposition of north-dipping penetrative gneissosity (S₂) and development of ductile shear zones under NNE-SSW directed compression; and a final Indosinian stage of southward thrusting of the Huwan high-pressure unit. Shallow level extension prevailed after the Late Triassic, giving rise to south-dipping thrust faults and north-dipping normal faults. Supported by the National Natural Science Foundation of China (Grant Nos. 40802046 and 40334037) and the Project of Science & Technology Research and Development from Sinopec (Grant No. P02009)  相似文献   

松潘造山带马尔康强过铝质花岗岩的成因及其构造意义   总被引：2，自引：0，他引：2  

时章亮  张宏飞  蔡宏明 《地球科学》2009,34(4):569-584

松潘造山带广泛出露印支期后碰撞型花岗岩类, 其中包括埃达克质花岗岩类、A型花岗岩和I型花岗岩, 但目前人们对该区印支期强过铝质花岗岩尚未有深入的研究.松潘造山带马尔康花岗岩属于强过铝质花岗岩(A/CNK=1.10~1.20), 其岩石类型主要为中粒二云母花岗岩和中细粒二云母花岗岩.利用LA-ICP-MS锆石U-Pb定年方法, 获得中粒二云母花岗岩的岩浆结晶年龄为208±2Ma, 中细粒二云母花岗岩的岩浆结晶年龄为200±2Ma.马尔康强过铝质花岗岩K₂O/Na₂O=1.13~1.75, 富Rb、Th和U, 贫Sr、Ba、Co和Ni等元素; 稀土元素组成上显示存在强到中等的负Eu异常(Eu/Eu*=0.15~0.65);全岩初始87Sr/86Sr比值(ISr) 为0.70712~0.71137, εNd (t) =-10.36~-8.43, 锆石εHf (t) =-11.8~-1.1.地球化学和Sr-Nd-Hf同位素组成一致表明, 它们的岩浆来自于地壳物质的部分熔融, 其中中粒二云母花岗岩的源岩类型主要为地壳中的泥质岩类, 而中细粒二云母花岗岩的源岩主要为地壳中的杂砂岩类.结合松潘带的地质背景、区域构造-岩浆事件及其岩浆岩的组合分析, 印支期岩石圈拆沉作用可以用来解释马尔康强过铝质花岗岩的形成机制.在松潘带, 印支期岩石圈拆沉作用导致软流圈物质上涌, 这不仅促使了加厚下地壳物质发生部分熔融, 如松潘带印支期埃达克质和I型花岗岩浆的形成, 而且还诱发了中地壳物质的部分熔融, 如马尔康强过铝质花岗岩的形成.这表明松潘带印支期岩石圈拆沉作用已使地壳不同层次发生部分熔融作用.   相似文献   

Tonian rift-related, A-type continental plutonism in the Araçuaí Orogen, eastern Brazil: New evidence for the breakup stage of the São Francisco–Congo Paleocontinent     

L.C. da Silva  A.C. Pedrosa-Soares  L.R.  Teixeira  R. Armstrong 《Gondwana Research》2008,13(4):527-537

Zircon U–Pb SHRIMP, petrographical and geochemical data lead to the first characterization of the Tonian plutonism (Salto da Divisa Granite Suite), ascribed to the continental rift stage of the precursor basin of the Araçuaí Orogen (Eastern Brazil). The suite includes batholitic plutons and comprises mainly fluorite-bearing, dominantly mesoperthitic hornblende–biotite leucogranites. The presence of mafic (tholeiitic) gabbroic enclaves and syn-plutonic dykes confers to the suite a bimodal character. The plutons were locally deformed and foliated under amphibolite facies conditions, in response to the Neoproterozoic collage of the Araçuaí Orogen against the São Francisco Cratonic margin. However, undeformed magmatic facies are well preserved at inner portions of the plutons. The granitoids are metaluminous, with high SiO₂ and HFSE: Nb, Zr, Y, Ta and REE (except Eu); low CaO, Al₂O₃, Sc, Ba, Sr; high FeOt/MgO ratios, characterizing a chemical signature akin to the subalkaline, A-2 type granites. U–Pb SHRIMP data obtained on zircons from the main pluton yielded a magmatic crystallization age of 875 ± 9 Ma. Some inherited xenocrysts revealed ages of ca. 2080 Ma, corresponding to ages of the host rocks, a Paleoproterozoic basement. Nd isotopic evolution studies confirm the Paleoproterozoic influence on magma genesis with a T_DM model age of ca. 1.6 Ga and ε_Nd of − 5.58 at 880 Ma. The African counterpart, the West Congo Belt, encompasses thick rift-related alkaline volcanic-sedimentary basin (Zadinian and Mayumbian groups, and associated anorogenic granites), dated in the interval of ca. 1000–900 Ma. The age differences between the Salto da Divisa Suite intrusion and the anorogenic magmatic episode at the West Congo Belt suggests a westward migration (i.e. to the Brazilian side) of the thermal axis of the rift, ca. 30 Ma after the ending of the extensional process in Africa.  相似文献   

Generation of Late Cretaceous silicic rocks in SE China: Age, major element and numerical simulation constraints   总被引：2，自引：0，他引：2  

Cheng-Hong Chen  Chi-Yu Lee  Hsueh-Yu Lu  Pei-Shan Hsieh 《Journal of Asian Earth Sciences》2008,31(4-6):479-498

Rhyolite-dominating bimodal volcanic suites (rhyolite/basalt), mafic dikes and A-type granites distribute from N Zhejiang to S Fujian over 800 km in the Southeast Coast Magmatic Belt (SCMB) – the Late Yanshanian (LY) orogenic belt in SE China. Data of ⁴⁰Ar/³⁹Ar and K–Ar whole-rock ages and LA-ICPMS U–Pb zircon ages indicate that rhyolitic volcanism (101–72 Ma) is contemporaneous with the A-type granitic intrusions (100–90 Ma) and mafic dike injections (94–77 Ma). This time span is used to define the upper volcanic series in Zhejiang–Fujian areas. One striking feature of rhyolites in the SCMB is that many are strongly peraluminous (SP) and others, mostly restrict in Fujian, are peralkaline to mildly peraluminous (P-MP) and chemically resemble A-type granites. The SP character is unique among well-known large rhyolite provinces worldwide. Based on experimental works for a common thermal regime and inherited zircon age information, we suggest that SP and P-MP rhyolites represent low pressure melting of the felsic (quartzofeldspathic) granite (±metapelite) and the accompanied granodioritic, tonalitic and trondhjemitic member of the core complex assemblage, respectively, to account for the decreasing aluminosity. They could have also been contaminated by young igneous rocks, and ancient crust to a lesser degree, during ascent to the surface. Plate subduction and lithosphere extension processes, respectively, are numerically simulated for the magma generation of these rhyolites using the mafic underplating model. Results suggest that the most effective controlling factor to generate SP and associated P-MP (A-type) magmas during 95–80 Ma is thinning of the lithosphere thickness with a high exhumation rate. Under this circumstance, the core complex assemblage can be uplifted to lower level of the crust and match the constraint of experimental works.  相似文献   

江西省武功山地区浒坑花岗岩的锆石U-Pb定年及元素地球化学特征   总被引：11，自引：5，他引：6  

刘珺  毛景文  叶会寿  谢桂青  杨国强  章伟 《岩石学报》2008,24(8)

浒坑花岗岩侵入体位于武功山复式背斜东南翼,发育有大型的浒坑石英脉型钨矿床,其是武功山钨、铜、铋、钼多金属成矿带的重要组成部分.本文通过对浒坑白云母花岗岩精确的锆石LA-ICPMS U-Pb测年,测得其成岩时代为151.6±2.6Ma,属晚侏罗世,对应于华南中生代第一次花岗岩侵位事件(164～153Ma);其花岗岩岩浆的形成温度为676～695℃.通过浒坑花岗岩主微量元素结果的分析,认为浒坑白云母花岗岩属于高钾钙碱性系列,为准铝质-弱过铝质的分异S型花岗岩,其源岩为富粘土的泥质来源,形成于岩石圈伸展减薄环境.  相似文献   

福建北东沿海高分异I型花岗岩的成因: 锆石U-Pb年代学、地球化学和Nd-Hf同位素制约   总被引：26，自引：12，他引：14  

邱检生  肖娥  胡建  徐夕生  蒋少涌  李真 《岩石学报》2008,24(11):2468-2484

  相似文献   

新疆北部花岗岩类的稀土特征     

周汝洪 《新疆地质》1991,(2)

新疆北部的改造系列花岗岩演化由斜长花岗岩阶段、钾长花岗岩阶段至碱长花岗岩阶段,其稀土配分组成递降曲线簇.新疆北部的同熔型花岗岩类稀土配分基本为轻稀土富集型,具Eu负异常,有递增曲线簇和递降曲线簇两种情况.深源碱性系列轻重稀土比值大、Eu负异常一般不显著.文中还叙述了新疆北部的幔分异系列花岗岩类及一些古老花岗岩的稀土特征.  相似文献