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云南中甸地区雪鸡坪同碰撞石英闪长玢岩锆石SHRIMP U-Pb定年及其意义 总被引：17，自引：2，他引：17
对金沙江缝合带东侧雪鸡坪同碰撞石英闪长玢岩进行了岩石学、岩石化学、稀土元素、锆石SHRIMP U-Pb定年等研究,石英闪长玢岩锆石SHRIMP U-Pb年龄为215Ma.结合前人的资料,认为金沙江洋盆闭合、板块碰撞的时间应为266Ma,碰撞阶段的年龄范围为266～215Ma.对无老核的岩浆型锆石的形成条件、结构简单的典型纯岩浆型锆石定年的测试点数量等方面也进行了讨论. 相似文献
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阿拉善宗乃山岩体东南缘花岗岩LA-ICP-MS锆石U-Pb年龄与地球化学特征 总被引：2，自引：0，他引：2
阿拉善宗乃山岩体东南缘分布多种类型的花岗岩,本文主要采用岩相学、激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)锆石U-Pb定年、岩石地球化学等技术手段,对宗乃山岩体东南缘岩石类型、年代学、源岩特征以及构造背景进行了研究。结果表明:岩石类型主要为碱性-钙碱性准铝质花岗岩和闪长岩;单颗粒锆石分析获得黑云母斜长花岗岩年龄为236.8±1.9 Ma~249.7±2.6 Ma,片麻状花岗岩年龄为268.1±1.1 Ma,岩体成岩时期主要为华力西晚期和印支期早期,具有多期侵入的特征。该岩体岩石源岩为I型花岗岩,源于地壳火山弧区和同碰撞区,表明由于洋壳俯冲作用,在宗乃山东南缘形成了岛弧花岗岩侵入体。LA-ICP-MS锆石U-Pb定年技术为洋壳俯冲提供了年代学约束,确定了研究区碰撞时间为早于236.8±1.9 Ma。 相似文献
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福建紫金山矿田晚中生代英安玢岩形成时代及其成矿意义 总被引：4，自引：0，他引：4
福建紫金山Cu-Mo-Au-Ag多金属矿田是一个完整的斑岩-浅成低温热液矿床成矿体系。英安玢岩主要分布在紫金山Au-Cu矿床内火山机构及其附近,与高品位Au-Cu矿体空间上联系密切,是矿田内火山-侵入岩浆过程的一个重要环节。采自矿区的两个英安玢岩样品LA-ICP-MS锆石U-Pb定年结果分别为(105.0±0.7)Ma(MSWD=0.83)和(105.0±2.2)Ma(MSWD=1.70),其形成时代与区内Mo-Cu矿化的萝卜岭和四方岩体形成时代相近。三个岩体形成时代及地球化学特征的相似性表明它们应为同源岩浆演化的产物,它们均具有较高的锆石Ce4+/Ce3+值,即岩浆体系具有较高的氧逸度,与区内斑岩成矿体系巨量金属堆积的地质事实相一致。英安玢岩的精确定年表明,紫金山Cu-Au矿与萝卜岭Mo-Cu矿及四方岩体有关的Mo矿床为同一斑岩成矿体系的产物。 相似文献
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鹤岗北部地区黑龙江岩群的构造属性:来自岩石地球化学、锆石U-Pb定年和Hf同位素的制约 总被引：1，自引：0，他引：1
产于鹤岗北部地区的黑龙江岩群是由绿帘绿泥钠长片岩、绿帘蓝闪片岩(下部)和二云母片岩、石榴白云钠长片岩、方解白云钠长片岩、石榴白云钠长石英片岩(上部)等岩系组成。本文通过岩石地球化学、锆石U-Pb年代学和Hf同位素组成研究,厘定下岩组原岩为幔源碱性玄武岩(SiO_2=47.44%~48.38%)及岛弧钙碱性玄武岩(SiO_2=46.84%~49.22%),有3组锆石U-Pb年龄(526±44 Ma,n=3;249±11 Ma,n=6;207±4 Ma,n=8);上岩组原岩为海陆交互相碎屑岩(SiO_2=66.70%~93.00%),有4组锆石U-Pb年龄(484±13 Ma,n=3;429±24 Ma,n=3;277±4 Ma,n=11;262±3 Ma,n=6)。结合锆石的内部结构、Hf同位素和区域构造演化特征,幔源火山喷发和沉积作用发生在277±4 Ma,碰撞造山作用发生在262~249 Ma,构造折返发生在207±4 Ma。这项研究对于深入认识黑龙江岩群性质和构造属性具有重要的意义。 相似文献
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前进场岩体位于大兴安岭南段,主要岩石类型为黑云母二长花岗岩,是道伦达坝铜钨锡银矿床的赋矿围岩之一.本文对前进场岩体开展了岩石地球化学、LA-ICP-MS锆石U-Pb定年、锆石Lu-Hf同位素及矿物地球化学研究.锆石U-Pb定年结果表明前进场岩体形成于278～279 Ma,为早二叠世岩浆活动产物.岩石地球化学特征显示其S... 相似文献
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晋蒙地区西施沟复式岩体锆石U-Pb年龄、地球化学特征及岩石成因 总被引：1，自引：0，他引：1
本文对晋蒙地区的西施沟复式岩体进行了LA-ICP-MS锆石U-Pb定年、岩石地球化学特征研究,探讨了其岩石成因及其对华北克拉通北缘中生代构造岩浆演化的启示。该岩体的岩石类型从中性岩至酸性岩连续变化且以中性岩为主,内部广泛发育微粒闪长质包体,具明显的岩浆混合成因;锆石U-Pb定年结果显示其形成年龄为160.19±0.50Ma,为中晚侏罗世岩浆活动的产物;岩石地球化学数据表明,属于准铝(弱过铝)质的高钾钙碱性系列I型花岗岩;稀土总量(ΣREE)中等,轻重稀土分馏明显,无明显负铕异常;均富集轻稀土及大离子亲石元素(Ba、Rb、K),亏损高场强元素(Nb、Ta、P),具明显的陆壳成分特征;其形成可能与中晚侏罗世古太平洋板块的俯冲有关,为华北板块陆内造山作用的产物。 相似文献
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粤西圆珠顶斑岩型铜钼矿床成矿地质特征成岩成矿作用年代学研究 总被引：2，自引：0，他引：2
园珠顶大型铜钼矿床位于大瑶山隆起北缘、粤桂交界的广东省封开县境内。铜钼矿化普遍发育于斑岩体及其外接触带中,岩体内部见星点状黄铁矿、黄铜矿、辉钼矿分布,但铜钼工业矿体主要产于岩体外接触带中,并围绕着岩体具椭圆形环状矿化分带特征,由内向外依次为钼矿化带→铜钼矿化带→铜矿化带,成矿作用与二长花岗斑岩有关。运用高分辨率和高灵敏度离子探针和Re-Os分析技术,作者分别对矿区二长花岗斑岩和矿体进行了年代学研究,获得二长花岗斑岩的锆石U-Pb SHRIMP年龄为154±2Ma(95%可信度,MSWD=0.75,N=11),铜钼矿体辉钼矿Re-Os等时线年龄为155±5Ma(95%可信度,MSWD=0.31,N=8),表明圆珠顶斑岩型铜钼区的成岩成矿作用都发生于中侏罗世晚期,成矿作用发生于华南拉张大地构造背景下。 相似文献
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Whole‐rock geochemistry, zircon U–Pb and molybdenite Re–Os geochronology, and Sr–Nd–Hf isotopes analyses were performed on ore‐related dacite porphyry and quartz porphyry at the Yongping Cu–Mo deposit in Southeast China. The geochemical results show that these porphyry stocks have similar REE patterns, and primitive mantle‐normalized spectra show LILE‐enrichment (Ba, Rb, K) and HFSE (Th, Nb, Ta, Ti) depletion. The zircon SHRIMP U–Pb geochronologic results show that the ore‐related porphyries were emplaced at 162–156 Ma. Hydrothermal muscovite of the quartz porphyry yields a plateau age of 162.1 ± 1.4 Ma (2σ). Two hydrothermal biotite samples of the dacite porphyry show plateau ages of 164 ± 1.3 and 163.8 ± 1.3 Ma. Two molybdenite samples from quartz+molybdenite veins contained in the quartz porphyry yield Re–Os ages of 156.7 ± 2.8 Ma and 155.7 ± 3.6 Ma. The ages of molybdenite coeval to zircon and biotite and muscovite ages of the porphyries within the errors suggest that the Mo mineralization was genetically related to the magmatic emplacement. The whole rocks Nd–Sr isotopic data obtained from both the dacite and quartz porphyries suggest partial melting of the Meso‐Proterozoic crust in contribution to the magma process. The zircon Hf isotopic data also indicate the crustal component is the dominated during the magma generation. 相似文献
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Laimin Zhu Guowei Zhang Bo Guo Ben Lee Hujun Gong Fei Wang 《Chemie der Erde / Geochemistry》2010,70(2):159-174
Simultaneous determinations of U–Pb dating and Hf isotopes on single zircon grains by excimer laser-ablation quadrupole and multiple-collector ICP-MS and petrologic and ore geochemical studies have been applied to the ore-bearing porphyry of the Jinduicheng porphyritic molybdenum deposit in East Qinling. Lithogeochemical data show that the porphyry is characteristic of high K2O, K-feldspar porphyritic calc-alkaline granitoids with 176Hf/177Hf=0.282020–0.282436 and εHf(t)=?23.7 to ?8.9, which indicates its mixed origin involving a crustal and a mantle component. The weighted average U–Pb age from single zircon grains of the porphyry is 141.5±1.5 Ma. This age coincides with the oldest molybdenite Re-Os model age as dated by others, suggesting that the period of mineralization was almost simultaneous with the porphyry emplacement, or slightly later. The porphyry intrusion and the molybdenum mineralization occurred during the transition from compression to extension in the Jurassic – Cretaceous periods. The corresponding tectonic setting was the intracontinental orogenic and extension stage after collision and orogenesis between the Southern China plate and the Northern China plate. The Jinduicheng porphyry and the deposit's geochemical data indicate that the ore-forming material originated from a mixing of lower crust and upper mantle. When the molybdenum-enriched magma intruded into the upper crust along zones of structural weakness, ore-forming fluid generated by magma crystallization of the porphyry interacted with wall rock or mingled with meteoric water to form the deposit. 相似文献
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鸭子沟多金属矿是近年来青海省地质调查院在东昆仑祁漫塔格地区发现的一个具有斑岩型成矿特点的矿床。本文利用SHRIMP 锆石UPb和辉钼矿ReOs同位素对含矿斑岩体和矿石进行了精细成岩成矿时代测定,获得钾长花岗斑岩的SHRIMP锆石UPb年龄为224.0±1.6 Ma（n=15,MSWD=1.2）,矿石的辉钼矿ReOs等时线年龄为224.7±3.4Ma（n=11,MSWD=2.7）,成岩与成矿的时间一致,正好属于印支晚期东昆仑地区发生强烈壳幔相互作用并导致产生大量岩浆热液活动和成矿作用的时期。钾长花岗斑岩与矿床具有密切的时空和成因联系,斑岩体在时空分布上与矿区内的闪长岩、辉绿玢岩及辉长岩等幔源脉体紧密相伴,推测同属壳幔相互作用的产物。成岩、成矿的年代学研究表明,矿床形成的地球动力学背景与东昆仑地区印支晚期的区域动力学背景相一致,同时区内具有较大的寻找斑岩型矿床的潜力。 相似文献
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相山铀矿田是中国迄今为止发现的最大的火山岩型铀矿床,其北部主要铀矿类型为花岗斑岩型铀矿床,铀成矿在时空和成因上与超淺成侵入相的花岗斑岩有关。前人多针对某一具体矿床含矿主岩开展工作,获得的花岗斑岩成岩年龄数据相差较大,影响了对相山花岗斑岩型铀矿的深入研究。选择相山北部横涧、游坊、沙洲、云际等铀矿床的含矿主岩——花岗斑岩系统开展野外地质调查、地球化学特征和LA-ICP-MS锆石U-Pb定年研究,以期厘定相山花岗斑岩型铀矿床含矿主岩的成岩时代和成因类型。花岗斑岩LA-ICP-MS锆石U-Pb定年结果显示,横涧、游坊、沙洲、云际的花岗斑岩206Pb/238U年龄加权平均值分别为135.6±1.3Ma(MSWD=0.45,n=26)、136.2±1.3Ma(MSWD=1.2,n=21)、133.4±11Ma(MSWD=0.67,n=24)及134.3±1.1Ma(MSWD=0.88,n=25),集中在132~137Ma之间,属于早白垩世。研究认为,相山北部花岗斑岩成因类型界于A型花岗岩与S型花岗岩之间的过渡型,为A-S型花岗岩。花岗斑岩岩浆起源于中元古代地壳,地壳物质作为主要成分参与了花岗斑岩的形成,同时有少量地幔物质的加入。花岗斑岩为板内构造界境下伸展体制的产物,可能是由于太平洋板块俯冲后,因板块后撤导致岩浆侵入作用的结果。 相似文献
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粤北大宝山矿区次英安斑岩与铜多金属矿之间关系研究 总被引：1，自引：0，他引：1
大宝山是粤北独具特色的铜多金属矿区,其矿床成因一直争议不休。本文在野外工作的基础上,通过对大宝山矿区次英安斑岩的岩石学、地球化学、同位素年代学、锆石微量和矿质迁移定量分析,认为大宝山矿区次英安斑岩是早侏罗世晚期(～175 Ma)沿逆冲推覆构造侵位的次火山岩,并捕获了大量志留纪岩浆锆石。铜多金属矿化具有斑岩型矿床特征,次英安斑岩与灰岩接触时外接触带形成的矽卡岩中赋存块状、层状、似层状矿体;与泥质、长英质岩石接触时,由于外接触带角岩的流体圈闭作用,在岩体内形成了细脉状铜多金属矿化和绢英岩化。大宝山和九曲岭次英安斑岩既是成矿母岩又是有利的赋矿围岩,铜多金属矿的成矿流体是次英安斑岩深部岩浆房晚期去气作用排出的含矿热液,其中富含SiO_2、Fe_2O_3、K_2O、Mo、W、Cu、Rb、Th、U、Bi、Tl、Cs、In、Cd、Be和挥发分等,具有强氧化(Fe3+/Fe2+平均值为8.55)、高交代参数(K^+/Na^+平均值为56.62)的特征,并于围岩交代过程中,萃取其中的TiO_2、FeO、MnO、CaO、Na_2O、P_2O_5、REE及Sc、Pb、Ba、Sr、Ni、Mn、Zr等。 相似文献
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Qing-Bin Guan Bin Wang Xiong Wang Xing-An Wang Qiang Shi 《International Geology Review》2018,60(15):1883-1905
This study presents new zircon U–Pb geochronology, geochemistry, and zircon Hf isotopic data of volcanic and subvolcanic rocks that crop out in the Bayanhushuo area of the southern Great Xing’an Range (GXR) of NE China. These data provide insights into the tectonic evolution of this area during the late Mesozoic and constrain the evolution of the Mongol–Okhotsk Ocean. Combining these new ages with previously published data suggests that the late Mesozoic volcanism occurred in two distinct episodes: Early–Middle Jurassic (176–173 Ma) and Late Jurassic–Early Cretaceous (151–138 Ma). The Early–Middle Jurassic dacite porphyry belongs to high-K calc-alkaline series, showing the features of I-type igneous rock. This unit has zircon εHf(t) values from +4.06 to +11.62 that yield two-stage model ages (TDM2) from 959 to 481 Ma. The geochemistry of the dacite porphyry is indicative of formation in a volcanic arc tectonic setting, and it is derived from a primary magma generated by the partial melting of juvenile mafic crustal material. The Late Jurassic–Early Cretaceous volcanic rocks belong to high-K calc-alkaline or shoshonite series and have A2-type affinities. These volcanics have εHf(t) and TDM2 values from +5.00 to +8.93 and from 879 to 627 Ma, respectively. The geochemistry of these Late Jurassic–Early Cretaceous volcanic rocks is indicative of formation in a post-collisional extensional environment, and they formed from primary magmas generated by the partial melting of juvenile mafic lower crust. The discovery of late Mesozoic volcanic and subvolcanic rocks within the southern GXR indicates that this region was in volcanic arc and extensional tectonic settings during the Early–Middle Jurassic and the Late Jurassic–Early Cretaceous, respectively. This indicates that the Mongol–Okhotsk oceanic plate was undergoing subduction during the Early–Middle Jurassic, and this ocean adjacent to the GXR may have closed by the Late Middle Jurassic–Early Late Jurassic. 相似文献
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长江铀矿田深部赋矿辉长闪长岩的岩石成因制约着对铀成矿作用认识的深入.通过对辉长闪长岩开展锆石U-Pb定年、Lu-Hf同位素、矿物学和地球化学分析,探讨其岩石成因、成岩构造背景及其与铀成矿的关系.辉长闪长岩LA-ICP-MS锆石U-Pb年龄为150 Ma,形成于晚侏罗世,具板内玄武岩地球化学特征.环带斜长石与黑云母主量元素变化记录了岩浆由基性到中性的演化过程.锆石（~150 Ma）εHf（t）为-14.1~-8.6,tDM2为1.7~2.1 Ga.辉长闪长岩源区为遭受俯冲带流体交代改造的相对富集地幔,岩浆上升侵位过程与中元古代-古元古代壳源物质发生了不同程度的地壳混染,形成于地壳伸展拉张和岩石圈大规模减薄的构造背景.辉长闪长岩为铀成矿提供了更为有利的还原性环境,促使热液中U6+的还原沉淀. 相似文献
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相山铀矿田钾玄质岩石与铀成矿 总被引：4，自引：2，他引：2
岩石学、元素地球化学研究表明,相山铀矿田的英安斑岩属于板内型钾玄质岩类,为钾玄质英安斑岩。其主要地球化学特征是:SiO2含量变化小(66.73%～69.88%),高碱(K2O+Na2O=6.06%～8.41%),高K2O/Na2O比值(1.53～3.49),高Al2O3(13.24%～15.96%),强烈富集大离子亲石元素(LILE)和轻稀土元素(LREE),P、Sr、Ti显著负异常,无明显的Nb和Ta负异常,Th/Yb>5,U和Th异常偏高。相山钾玄质英安斑岩的形成是源于地幔玄武岩浆的底侵作用,其中较基性的包体应为地幔岩浆残留产物。相山铀矿化在时空上与钾玄质英安斑岩关系密切,其形成应该与钾玄质岩有关,幔源流体在铀成矿过程中扮演了重要角色。 相似文献
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The Zijinshan ore district occurs as one of the largest porphyry-epithermal Cu–Au–Mo ore systems in South China, including the giant Zijinshan epithermal Cu–Au deposit and the large Luoboling porphyry Cu–Mo deposit. The mineralization is intimately related to Late Mesozoic large-scale tectono-magmatic and hydrothermal events. The Cu–Au–Mo mineralization occurs around intermediate-felsic volcanic rocks and hypabyssal porphyry intrusions. In this study, we summarize previously available Re–Os isotopes, zircon U–Pb age and trace elements, and Sr–Nd–Pb isotope data, and present new Pb–S and Re–Os isotope data and zircon trace elements data for ore-related granitoids from the Zijinshan high-sulfidation epithermal Cu–Au deposit and the Luoboling porphyry Cu–Mo deposit, in an attempt to explore the relationship between the two ore systems for a better understanding of their geneses. The ore-bearing porphyritic dacite from the Zijinshan deposit shows a zircon U-Pb age of 108–106 Ma and has higher zircon Ce4+/Ce3+ ratios (92–1568, average 609) but lower Ti-in-zircon temperatures (588–753 °C, average 666 °C) when compared with the barren intrusions in the Zijinshan ore district. Relative to the Zijinshan porphyritic dacite, the ore-bearing granodiorite porphyry from the Luoboling deposit show a slightly younger zircon U–Pb age of 103 Ma, but has similar or even higher zircon Ce4+/Ce3+ ratios (213–2621, average 786) and similar Ti-in-zircon temperatures (595–752 °C, average 675 °C). These data suggest that the ore-bearing magmatic rocks crystallized from relatively oxidized and hydrous magmas. Combined with the high rhenium contents (78.6–451 ppm) of molybdenites, the Pb and S isotopic compositions of magmatic feldspars and sulfides suggest that the porphyry and ore-forming materials in the Luoboling Cu–Mo deposit mainly originated from an enriched mantle source. In contrast, the ore-bearing porphyritic dacite in the Zijinshan Cu–Au deposit might be derived from crustal materials mixing with the Cathaysia enriched mantle. The fact that the Zijinshan Cu–Au deposit and the Luoboling Cu–Mo deposit show different origin of ore-forming materials and slightly different metallogenic timing indicates that these two deposits may have been formed from two separate magmatic-hydrothermal systems. Crustal materials might provide the dominant Cu and Au in the Zijinshan epithermal deposit. Cu and Au show vertical zoning and different fertility because the gold transports at low oxygen fugacity and precipitates during the decreasing of temperature, pressure and changing of pH conditions. It is suggested that there is a large Cu–Mo potential for the deeper part of the Zijinshan epithermal Cu–Au deposit, where further deep drilling and exploration are encouraged. 相似文献