Zircon U-Pb ages and Hf isotopic characteristics of the Dehe biotite monzonitic gneiss pluton in the North Qinling orogen and their geological significance   总被引：1，自引：0，他引：1  

LEE Ben 《中国地球化学学报》2011,30(2):204-216

The Dehe granitic pluton intruded the Xiahe Group which is in the core complex of the North Qinling Orogenic Belt(NQOB).It shows gneissic bedding and possesses typical S-type granite minerals such as muscovite and garnet.LA-ICP-MS U-Pb isotopic dating of the Dehe granite yielded a weighted average age of 925±23 Ma which represents the emplacement age of the pluton.Most of the εHf(t) values are negative,and the two-stage model ages are consistent with the age of the Qinling Group.The isotope data show that the Dehe granite was formed in the following geological setting:in the syn-collision setting of the NQOB in the Neoproterozoic,crustal thickening induced partial melting of materials derived from the Qinling complex,and then the maga upwelled and intruded into the Xiahe Group.The formation of the Dehe S-type granite implied the occurrence of a convergent event in the QOB during the Neoproterozoic.  相似文献   

Geochemical Characteristics and Geological Significance of Early Permian Baya’ertuhushuo Gabbro in South Great Xing’an Range   总被引：1，自引：0，他引：1  

LIU Jianfeng  CHI Xiaoguo  ZHAO Zhi  ZHANG Xingzhou  MA Zhihong  WANG Tiefu  HU Zhaochu 《《地质学报》英文版》2011,85(1):116-129

Field geological investigation and geochemical analysis are carried out on Baya’ertuhushuo Gabbro in South Great Xing’an Range. Field investigation reveals that the gabbro is a magmatic intrusion rather than a component of an ophiolite suite as previously thought. Zircon laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) U-Pb dating indicates the gabbro was formed in 274–275?Ma, just as the widespread volcanic rocks of Dashizhai Formation (P1d), monzogranites and miarolitic alkali-feldspar granites in the study area. The gabbro has SiO2 content between 47.23 wt% and 50.17 wt%, high MgO and FeOT contents of 6.95–11.29 wt% and 7.32–12.24wt%, respectively, and it belongs to low-K tholeiitic series in the SiO2-K2O diagram. The Chondrite-normalized rare earth element (REE) patterns and primitive mantle-normalized spider diagrams of the gabbro are similar to those of Normal Mid-Ocean Ridge Basalt (N-MORB) except for the enrichment of large ion lithophile elements (LILE), such as Rb, Ba and K. In trace element tectonic discriminative diagrams, the samples are mainly plotted in the N-MORB field, and Zircon in?situ Lu-Hf isotopic analysis also indicates the gabbro originated from depleted mantle. Through synthetic studies of the geochemical characteristics and petrogenesis of Baya’ertuhushuo gabbro, volcanic rocks of Dashizhai Formation and granitoids in the area, it is suggested that the early Permian magmatism in the Xilinhot-Xiwuqi area formed in the tectonic setting of asthenosphere upwelling, which was caused by breaking-off of the subducted Paleo-Asian Ocean slab.  相似文献   

U-Pb Dating of Volcanic Rocks and Granites along the Wuyishan Belt: Constraints on Timing of Late Mesozoic Tectonic Events in Southeast China     

XU Xianbing  ZHANG Yueqiao  JIA Dong  SHU Liangshu 《《地质学报》英文版》2011,85(1):130-144

Five volcanic rock samples and two granite samples taken from the volcanic basins in western Fujian and southern Jiangxi were dated by using the zircon laser albation-inductively coupled plasma mass spectrometry U-Pb method. Together with previously dated ages, the dates obtained provide important constraints on the timing of late Mesozoic tectonic events in SE China. The volcanic rock samples yield ages of 183.1±3.5 Ma, ca. 141 Ma to 135.8±1.1 Ma, 100.4±1.5 to 97.6±1.1 Ma, confirming three episodes of late Mesozoic volcanic activities, which peaked at 180±5 Ma, 140±5 Ma and 100±5 Ma, respectively, along the Wuyishan belt. Moreover, based on field investigations of these volcano-sedimentary basins, we have recognized two compressional tectonic events along this belt. The early one was characterized by Upper Triassic to Middle Jurassic NNE-trending folds that were intruded by late Jurassic granites; and the late one caused the Lower Cretaceous volcano-sedimentary layer to be tilted. The dated age 152.9±1.4 Ma of the granitic samples from the Hetian granitic pluton in the Changting Basin and that from the Baishiding granitic pluton, 100.2±1.8 Ma, in the Jianning Basin, give the upper boundaries of these two tectonic events respectively. Hence, the late Mesozoic tectonic evolution of SE China was alternated between extension and compression.  相似文献   

LA-ICP-MS Zircon U-Pb Geochronology of the Fine-grained Granite and Molybdenite?Re-Os?Dating in the Wurinitu Molybdenum Deposit, Inner Mongolia, China   总被引：3，自引：0，他引：3  

LIU Cui  DENG Jinfu  KONG Weiqiong  XU Liquan  ZHAO Guochun  LUO Zhaohu  LI Ning 《《地质学报》英文版》2011,85(5):1057-1066

The Wurinitu molybdenum deposit, located in Honggor, Sonid Left Banner of Inner Mongolia, China, is recently discovered and is considered to be associated with a concealed fine-grained granite impregnated with molybdenite.?The wall rocks are composed of Variscan porphyritic-like biotite granite and the Lower Ordovician Wubin’aobao Formation.?LA-ICP-MS zircon U-Pb dating of the fine-grained granite reveals two stages of zircons,?one were formed at 181.7±7.?4 Ma and?the other at 133.6±3.3 Ma. The latter age is believed to be the formation age of the fine-grained granite, while the former may reflect the age of inherited zircons, based on the morphological study of the zircon and regional geological setting. The Re-Os model age of molybdenite is 142.2±2.5?Ma, which is older than the diagenetic age of the fine-grained granite.?Therefore the authors believe that the metallogenic age of the Wurinitu molybdenum deposit should be?nearly 133.6±3.3 Ma or slightly later, i.e., Early Cretaceous.?Combined with regional geological background research, it is speculated that the molybdenum deposits were formed at the late Yanshanian orogenic cycle in the Hingganling-Mongolian orogenic belt, belonging to the relaxation epoch posterior to the compression and was associated with the closure of the Mongolia-Okhotsk?Sea.  相似文献   

Re–Os and U–Pb Geochronology of the Erlihe Pb–Zn Deposit, Qinling Orogenic Belt, Central China, and Constraints on Its Deposit Genesis     

ZHANG Fan  LIU Shuwen  LI Qiugen  SUN Yali  WANG Zongqi  YAN Quanren  YAN Zhen 《《地质学报》英文版》2011,85(3):673-682

The Erlihe Pb–Zn deposit is an important mine of the Pb–Zn metallogenic zone in the South Qinling Orogen. It has been considered a sedimentary exhalative deposit in previous investigations because the ore body occurs concordantly at the transitional location of an upright fold. Re and Os isotopic analyses for paragenetic pyrites with sphalerite and galena from the ore body have been used to determine the timing of mineralization and to trace the source of metallogenic materials. The Re–Os isotopic data of four pyrite samples construct an isochron, yielding a weighted average age of 226±17 Ma (mean square weighted deviation=1.7), which is considered the main mineralization age. A dioritic porphyrite vein sample, showing weaker mineralization, was also dated using the SHRIMP zircon U–Pb isotopic method to constrain the youngest metallogenic age of the ore deposit, because it distributes along a group of tensional joints cutting not only the upright fold in the deposit field, but also the main ore bodies. The dioritic porphyrite sample yields a weighted mean 206Pb/238U age of 221±3 Ma, which is slightly younger than the Re–Os isotopic isochron age of the pyrites, considered as the upper age limit of the mineralization, namely the ending age of the mineralization. The Os isotopic compositions of sulfide minerals distribute within a range between Os isotopic compositions of the crust and the mantle, indicating that the ore deposit can be derived from magma-related fluid, and the metallogenic materials are most likely derived from the mixing source of the crust and the mantle. The Erlihe Pb–Zn deposit and associated dioritic porphyrite vein, important records of Qinling tectonic–magmatism–mineralization activities, were formed during the Triassic collisional orogeny processes.  相似文献   

Geochronology and Petrogenesis for the Protolith of Biotite Plagioclase Gneiss at Lianghe, Western Yunnan   总被引：5，自引：0，他引：5  

CONG Feng  LIN Shiliang  ZOU Guangfu  XIE Tao  LI Zaihui  TANG Fawei  PENG Zhimin 《《地质学报》英文版》2011,85(4):870-880

In this paper,we report an integrated study of U-Pb age and Hf isotope compositions of zircons from biotite plagioclase gneiss at Lianghe in western Yunnan.The zircons preserved inherited core and rim texture.Igneous zircon grains and rims yielded a weighted mean ~(206)Pb/~(238)U age of 120.4±1.7 Ma,theirε_(Hf)(120 Ma)values were mainly negative ranging from-13.9 to-10.7,with Hf model ages between 1.9 Ga and 2.0 Ga,some zircons had positiveε_(Hf)(120 Ma)values ranging from 0.2 to 2.1.The inherited cores ...  相似文献   

江南隆起带中段新元古代花岗岩锆石U-Pb年代学和Hf同位素组成研究   总被引：5，自引：1，他引：4  

张菲菲  王岳军  范蔚茗  张爱梅  张玉芝 《大地构造与成矿学》2011,35(1):73-84

对江南隆起带中段湘东西园坑岩体和赣西九岭岩体的LA-ICPMS锆石U-Pb年代学测定和LA-MC-ICPMS锆石Hf同位素原位分析测试表明:西园坑岩体形成于(804±3)Ma,赣西九岭岩体的年龄为(813±4)Ma和(823±2)Ma,均为新元古代花岗岩.上述三个样品的εHf(t)的加权平均值分别为0.68±0.71,...  相似文献   

内蒙古乌拉特中旗乌兰地区石炭纪花岗闪长岩年代学及地球化学研究   总被引：1，自引：0，他引：1  

张青伟  刘正宏  柴社立  徐仲元  赵庆英  徐学纯 《矿物岩石》2011,31(2)

利用锆石SHRIMP U-Pb法对乌拉特中旗乌兰地区花岗闪长岩进行年龄测试,得到的两个花岗闪长岩样品中锆石的加权平均年龄分别为(322.1±3.4)Ma和(323.4±3.4)Ma,为早石炭世。岩石地球化学及同位素地质年代学研究显示该花岗闪长岩为具有埃达克岩性质的I型花岗岩类,属准铝质-过铝质高钾钙碱性系列;富集Rb,Ba,Sr等大离子亲石元素和Th,U,Nd,Zr等高场强元素;为轻稀土富集型,轻、重稀土高度分异,轻稀土发生明显的分馏作用,铕异常不明显。岩体形成于活动大陆边缘同碰撞构造环境,是残留洋壳部分熔融所形成的基性岩浆与由古老片麻岩基底部分熔融所形成的中酸性岩浆发生混合作用的产物。  相似文献   

贵州梵净山白云母花岗岩锆石年代、铪同位素及对华南地壳生长的制约   总被引：7，自引：0，他引：7       下载免费PDF全文

王敏  戴传固  王雪华  陈建书  马会珍 《地学前缘》2011,18(5):213-223

贵州梵净山地区位于＂江南造山带＂西南段,出露地层为中新元古界梵净山群、青白口系板溪群、南华系及古生界地层。梵净山群已强烈褶皱,被青白口系板溪群角度不整合覆盖。浅色白云母花岗岩侵位于褶皱的梵净山群中;锆石原位LA-ICP-MS分析结果显示,其形成时代为（838.5±1.5）Ma。地球化学分析结果表明,其A/CNK值〉1....  相似文献   

大别山鲁家寨花岗岩地球化学、锆石年代学和Hf同位素特征:扬子克拉通北东缘新元古代岩浆活动证据          下载免费PDF全文

孙洋  马昌前  张超 《地学前缘》2011,18(2):85-99

对大别山造山带的鲁家寨花岗岩进行了锆石U-Pb年代学、锆石Hf同位素和岩石地球化学研究.锆石LA-ICP-MS U-Pb定年结果表明鲁家寨花岗岩形成于新元古代((816±17)Ma).鲁家寨花岗岩总体具有高硅(SiO2 69.13%～75.47%)、准铝-弱过铝(A/CNK=0.98～1.01)的化学组成特征.稀土元素...  相似文献