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1.
The Huangsha-Tieshanlong quartz-vein tungsten polymetallic ore deposit, located in the northern Pangushan-Tieshanlong tungsten ore field in eastern Ganxian-Yudu prospecting areas of the Yushan metallogenic belt, is a well-known tungsten deposit in southern Jiangxi province, China. SHRIMP-determined dating of zircons from the Tieshanlong granite yields ages of 168.1±2.1 Ma (n=11, MSWD=1.3). Rhenium and osmium isotopic dating of molybdenite from the Huangsha quartz-vein tungsten deposit determined by ICP-MS yields a weighted average ages of 153±3 Ma and model ages of 150.2±2.1 Ma – 155.4±2.3 Ma. The age of the Huangsha tungsten deposit is 10 to 15 Ma later than the Tieshanlong granite, which shows that there might have been another early Late Jurassic magmatic activity between 150 and 160 Ma, a process which is closely related with tungsten mineralization in this area. The Tieshanlong granite, the Huangsha tungsten deposit and the Pangushan-Tieshanlong ore field were all formed around 150–170 Ma, belonging to products of a Mesozoic second large-scale mineralization. According to the collected molybdenite Re-Os dating results in southern Jiangxi province, the timescale of the associated molybdenum mineralization is 2–6 Ma in the tungsten deposit and the timescale of independent molybdenum mineralization is 1–4 Ma, implying the complexity of tungsten mineralization. Times of molybdenum mineralization are mainly concentrated in the Yanshanian, which includes three stages of 133~135 Ma, 150–162 Ma, and 166–170 Ma, respectively. The 150–162 Ma-stage is in accordance with ages of large-scale W-Sn mineralization, which is mainly molybdenum mineralization characterized by associated molybdenum mineralization with development of an even greater-intensity independent molybdenum mineralization. Independent molybdenum mineralization occurred before and after large-scale W-Sn mineralization, which indicates that favorable prospecting period for molybdenum may be in Cretaceous and early late Jurassic.  相似文献   

2.
Xihuashan tungsten deposit is one of the earliest explored tungsten deposits in southeastern China. It is a vein type deposit genetically associated with the Xihuashan granite pluton. Here we report new dating and zircon geochemistry results. Re–Os isotopic dating for molybdenite intergrowth with wolframite in the oldest generation of the Xihuashan pluton yielded an isochron age of 157.0 ± 2.5 Ma (2σ). Zircon U–Pb laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) dating shows that the pluton crystallized at 155.7 ± 2.2 Ma (2σ). This age is similar to the molybdenite Re–Os age for the ore deposit within error. This, together with published data, suggests that the major W(Mo)‐Sn mineralization occurred between 160–150 Ma in southeastern China. These deposits constitute a major part of the magmatic‐metallogenic belt of eastern Nanlin. The lower Re content in molybdenite of the Xihuashan tungsten deposit shows crustal origin for the ore‐forming material. The limited direct contributions from the subducting slab for the tungsten mineralization in the Nanling region suggest a change of the style of the paleo‐Pacific plate beneath southeastern China.  相似文献   

3.
矽卡岩型钨矿是赣南地区的一种重要钨矿床类型。本文以焦里和宝山两个典型的矽卡岩型钨多金属矿床为例,开展了系统的成岩成矿年代学和岩石地球化学研究,结合区域钨锡矿床最新年代学研究成果,探讨了赣南地区钨矿的成岩成矿时代及形成构造环境。结果表明,焦里矽卡岩型钨多金属矿区斑状花岗闪长岩SHRIMP锆石U-Pb年龄为164.4±1.1Ma,辉钼矿Re-Os等时线年龄为170.6±4.6Ma;宝山矽卡岩型钨矿区花岗岩SHRIMP锆石U-Pb年龄为156.6±3.9Ma,辉钼矿Re-Os模式年龄加权平均值为161.0±1.9Ma,厘定了它们的成岩成矿年龄为中-晚侏罗世,同一矿区的成岩和成矿年龄在误差范围内基本一致。结合赣南崇(义)-(大)余-(上)犹钨锡矿集区已有的年代学资料,指出本区的成岩成矿年龄介于170～150Ma,集中在160～150Ma,认为赣南钨矿形成于华南中生代岩石圈伸展-减薄时期的侏罗纪板内拉张的地球动力学背景,系同一成岩成矿系统的产物。  相似文献   

4.
福建行洛坑大型钨矿的地质特征、成矿时代及其找矿意义   总被引：24，自引：2，他引：22  
行洛坑钨矿是目前福建最大也是武夷山成矿带最大的钨矿,已知储量主要分布于岩体内部,宜归属于斑岩型钨矿范畴。本文通过Re-Os法和Rb-Sr等时线法测定花岗岩体中辉钼矿的Re-Os等时线年龄为156.3±4.8Ma,石英脉中流体包裹体的Rb-Sr等时线年龄为147.5±2.9Ma,表明成矿作用与岩浆岩的形成基本同步,并延续了大约10Ma。因此,行洛坑钨矿虽然属于斑岩型钨钼矿但岩体以外的空间也可能找到石英脉钨矿,而整个武夷山成矿带中生代持续而复杂的成矿历史预示了其良好的找矿前景。  相似文献   

5.
Previous studies have obtained some petrogenetic and metallogenic chronological data with SHRIMP (sensitive high-resolution ion microprobe) zircon U-Pb, zircon LA-ICPMS (laser-ablation–inductively coupled plasma mass spectroscopy) U-Pb, molybdenite Re-Os isochron and muscovite Ar-Ar methods in southern Jiangxi Province and its adjacent areas. Based on these, the purpose of this paper is to study the petrogenetic and metallogenic ages and their time gap for different genetic types of W-Sn deposits, and thus to research their numerous episodes, zonal arrangement and their geodynamic background. The result shows that the large-scale W-Sn mineralization in southern Jiangxi Province occurred in the middle to late Jurassic (170–150 Ma), the skarn W-Sn-polymetallic deposits formed much earlier (170–161 Ma), and all of the wolframite – quartz vein type, greisen type, altered granite type and fractured zone type tungsten deposits formed in the late Jurassic (160–150 Ma). In one ore field or ore district, greisen type tungsten deposits formed earlier than quartz vein type ones hosted in the endo- or exo-contact zone; and quartz vein type hosted in the endocontact zone formed earlier than that of exocontact zone. There is no significant time difference between tungsten-tin mineralization and its intimately associated parent granite emplacement (1–6 Ma). They all formed in the same rock-forming and ore-forming system and under the same geodynamic setting. Regionally, rock-forming and ore-forming processes of the W-Sn deposits in the Nanling region (include southern Jiangxi Province, southern Hunan Province, northern Guangdong Province and eastern Guangxi Zhuang Autonomous Region) exhibit numerous episodes. The mineralization in the Nanling region mainly occurred at (240–210) Ma, (170–150) Ma and (130–90) Ma. The tungsten-tin deposits in this region are centered by the largest scale in southern Jiangxi Province and southern Hunan Province, and become small in the east, west, south and north directions. This displays a zonal arrangement and temporal and spatial distribution regularity. Integrated with the latest research results, it is concluded that the W-Sn mineralization in southern Jiangxi Province and its adjacent areas corresponds to the second large-scale mineralization in South China. The Indosinian W-Sn mineralization formed under the extensional tectonic regime between collisional compressional stages, while the Yanshanian large-scale petrogenetic and metallogenic processes occurred in the Jurassic intraplate extensional geodynamic setting of lithosphere extension.  相似文献   

6.
Feng  Yuannan  Lan  Tingguang  Pan  Lichuan  Liu  Tingting  Dong  Shaohua 《中国地球化学学报》2019,38(4):530-540

The Nanling Range in South China is well known for its rich granite-related W–Sn deposits. To elucidate the controls of different granite-related W–Sn metallogenesis in the region, we chose five representative ore-related granites (Yanbei, Mikengshan, Tieshanlong, Qianlishan, and Yaogangxian intrusions) in the Hunan–Jiangxi region, and studied their magmatic zircon ages and trace element geochemistry. Our new zircon data showed the differences in ages, temperatures and oxygen fugacity of the ore-forming magmas. Zircon U–Pb ages of the Yanbei and Mikengshan intrusions are characterized by 142.4 ± 2.4 and 143.0 ± 2.3 Ma, respectively, whereas the Tieshanlong and Qianlishan intrusions are 159.5 ± 2.3 and 153.2 ± 3.3 Ma, respectively. The Sn-related intrusions were younger than the W-related intrusions. The Ti-in-zircon thermometry showed that there was no systematic difference between the Sn-related Yanbei (680–744 °C) and Mikengshan (697–763 °C) intrusions and the W-related Tieshanlong (730–800 °C), Qianlishan (690–755 °C) and Yaogangxian (686–751 °C) intrusions. However, the zircon Ce4+/Ce3+ ratios of the Yanbei (averaged at 18.3) and Mikengshan (averaged at 18.8) intrusions are lower than those of the Tieshanlong (averaged at 36.9), Qianlishan (averaged at 38.4) and Yaogangxian (averaged at 37) intrusions, indicating that the Sn-related granitic magmas might have lower oxygen fugacities than those of the W-related. This can be explained by that, in more reduced magmas, Sn is more soluble than W and thus is more enriched in the residual melt to form Sn mineralization. The difference in source materials between the Sn-related and the W-related granites seems to have contributed to the different redox conditions of the melts.

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7.
The large Huamei'ao tungsten deposit, with total WO3 reserves of 67,400 tons at an average grade of 1.334% WO3, is located in the convergent zone of the eastern Nanling E–W-trending tectono-magmatic belt and the western Wuyishan NNE–SSW-trending tectono-magmatic belt in southern Jiangxi Province, China. The tungsten mineralization in this deposit is mainly found in quartz–wolframite veins, with most orebodies distributed at the outer contact zone between concealed Late Jurassic granitic stocks and Sinian weakly metamorphosed sandstones and phyllites. Zircons collected from medium- to fine-grained biotite granite in a diamond drill hole at a sea level of ca. − 10 m yield a crystallization age of 159.9 (± 1.2) Ma through laser ablation–multicollector–inductively coupled plasma–mass spectrometry (LA–MC–ICP–MS) U–Pb dating. Molybdenite and muscovite that were both separated from quartz–wolframite veins yield a Re–Os isochron age of 158.5 (± 3.3) Ma and an 40Ar–39Ar weighted plateau age of 157.9 (± 1.1) Ma, respectively. These dates, obtained via three independent geochronological techniques, constrain the ore-forming age of the Huamei'ao deposit and link the genesis of the ore and the underlying granite. Analyses of available high-precision zircon U–Pb, molybdenite Re–Os and muscovite 40Ar–39Ar radiometric ages of major W–Sn deposits in southern Jiangxi Province indicate that there is no significant time interval between W–Sn mineralization and its intimately associated parent granite emplacement (interval of 0–6 Ma). These deposits formed over three intervals during the Mesozoic (240–210, 170–150, and 130–90 Ma), with large-scale W–Sn mineralization occurring mainly between 160 and 150 Ma. The majority of W–Sn deposits in this region are located in southern Jiangxi and southern Hunan provinces.  相似文献   

8.
Mesozoic granitic intrusions are widely distributed in the Nanling region,South China.Yanshanian granites are closely connected with the formation of tungsten deposits.The Xihuashan granite is a typica...  相似文献   

9.
The recently discovered Baizhangyan skarn‐porphyry type W–Mo deposit in southern Anhui Province in SE China occurs near the Middle–Lower Yangtze Valley polymetallic metallogenic belt. The deposit is closely temporally‐spatially associated with the Mesozoic Qingyang granitic complex composed of g ranodiorite, monzonitic g ranite, and alkaline g ranite. Orebodies of the deposit occur as horizons, veins, and lenses within the limestones of Sinian Lantian Formation contacting with buried fine‐grained granite, and diorite dykes. There are two types of W mineralization: major skarn W–Mo mineralization and minor granite‐hosted disseminated Mo mineralization. Among skarn mineralization, mineral assemblages and cross‐cutting relationships within both skarn ores and intrusions reveal two distinct periods of mineralization, i.e. the first W–Au period related to the intrusion of diorite dykes, and the subsequent W–Mo period related to the intrusion of the fine‐grained granite. In this paper, we report new zircon U–Pb and molybdenite Re–Os ages with the aim of constraining the relationships among the monzonitic granite, fine‐grained granite, diorite dykes, and W mineralization. Zircons of the monzonitic granite, the fine‐grained granite, and diorite dykes yield weighted mean U–Pb ages of 129.0 ± 1.2 Ma, 135.34 ± 0.92 Ma and 145.3 ± 1.7 Ma, respectively. Ten molybdenite Re–Os age determinations yield an isochron age of 136.9 ± 4.5 Ma and a weighted mean age of 135.0 ± 1.2 Ma. The molybdenites have δ34S values of 3.6‰–6.6‰ and their Re contents ranging from 7.23 ppm to 15.23 ppm. A second group of two molybdenite samples yield ages of 143.8 ± 2.1 and 146.3 ± 2.0 Ma, containing Re concentrations of 50.5–50.9 ppm, and with δ34S values of 1.6‰–4.8‰. The molybdenites from these two distinct groups of samples contain moderate concentrations of Re (7.23–50.48 ppm), suggesting that metals within the deposit have a mixed crust–mantle provenance. Field observation and new age and isotope data obtained in this study indicate that the first diorite dyke‐related skarn W–Au mineralization took place in the Early Cretaceous peaking at 143.0–146.3 Ma, and was associated with a mixed crust–mantle system. The second fine‐grained granite‐related skarn W–Mo mineralization took place a little later at 135.0–136.9 Ma, and was crust‐dominated. The fine‐grained granite was not formed by fractionation of the Qingyang monzonitic granite. This finding suggests that the first period of skarn W–Au mineralization in the Baizhangyan deposit resulted from interaction between basaltic magmas derived from the upper lithospheric mantle and crustal material at 143.0–146.3 and the subsequent period of W–Mo mineralization derived from the crust at 135.0–136.9 Ma.  相似文献   

10.
Limu W–Sn–Nb–Ta mining district is located in the Nanling Range W–Sn poly‐metallic mineralization belt in south China. The district includes a number of Sn–Nb–Ta and W–Sn ore occurrences; all of them are spatially associated with granite stocks of a largely‐unexposed pluton, the Limu granitic pluton. A granite sample collected from the Sn–Nb–Ta‐bearing Jinzhuyuan granite stock yields a zircon SHRIMP U–Pb age of 218.3 ± 2.4 Ma, a muscovite 40Ar/39Ar plateau age of 212.4 ± 1.4 Ma, and a muscovite 40Ar/39Ar isochron age of 213.2 ± 2.2 Ma. Another granite sample collected from the W–Sn‐bearing Sangehuangniu granite stock yields a zircon SHRIMP U–Pb age of 214 ± 5 Ma. The geochronological data provide new constraints on the age of the Limu granite pluton and the timing of the associated W–Sn–Nb–Ta mineralization—at least it sets a reasonable upper age limit for the mineralization of the W–Sn–Nb–Ta ores. The reported ages suggest an active Late Triassic granitic magmatism in Limu area which is part of a regional magmatic event near the end of the Indosinian orogeny in south China.  相似文献   

11.
江西朱溪铜钨矿床是近年来在赣北地区发现的又一超大型矽卡岩型钨矿,矿床的形成与花岗岩类侵入体密切相关,矿区处于钦—杭结合带江西段塔前—赋春成矿带中部。该矿床的发现进一步证明了研究区建立的"南钨北扩"格局,然而前人对其成矿岩浆岩地球化学特征及侵入时代缺少必要的研究,直接制约了对这一格局的深入认识。本文选择朱溪铜钨矿区与成矿有关的细粒白云母花岗岩作为研究对象,结合详细野外地质工作和前人研究成果,首次采用LA-ICP-MS锆石U-Pb定年方法获得了该岩体中锆石206Pb/238U加权平均年龄为146.90±0.97 Ma(MSWD=0.55);并利用X射线荧光光谱和ICP-MS技术进行岩石地球化学分析,结果显示该岩体具有高硅、高碱、富钾、强过铝质的地球化学特征,属于典型的S型花岗岩,说明晚侏罗世早期在江南隆起一带存在一期与成矿作用有关的岩浆侵位事件,为研究朱溪超大型铜钨矿和区域上塔前—赋春成矿带成矿规律研究提供了新证据。  相似文献   

12.
The southern Jiangxi Province is a major part of the Nanling W–Sn metallogenic province of southern China, where all W–Sn ore deposits are temporally and spatially related to Mesozoic granitic intrusions. The Tianmenshan–Hongtaoling orefield is a recently explored territory endowed by several styles of W–Sn mineralization. The orefield comprises three composite granitic plutons: Tianmenshan, Hongtaoling and Zhangtiantang associated with several tens of W–Sn-polymetallic ore deposits (Maoping, Baxiannao, Niuling, Zhangdou, Yaolanzhai and others) along their contacts. In this study, four new SHRIMP zircon U–Pb ages were determined for three composite granitic plutons, and 33 molybdenite samples from five W–Sn deposits were analysed by ICP-MS Re–Os isotopic method. SHRIMP zircon U–Pb ages for both medium to coarse-gained biotite granite and porphyritic biotite monzogranite from the Tianmenshan composite pluton are 157.2 ± 2.2 Ma and 151.8 ± 2.9 Ma, respectively. Molybdenite Re–Os isochron ages for the related Baxiannao fracture-controlled tungsten deposits are 157.9 ± 1.5 Ma. Maoping greisens-type tungsten deposits were emplaced at 155.3 ± 2.8 Ma and the Maoping wolframite–quartz veins at 150.2 ± 2.8 Ma, respectively. The SHRIMP U–Pb age of zircons from the Hongtaoling biotite granite is 151.4 ± 3.1 Ma whereas the molybdenite Re–Os isochron ages of the genetically related Niuling endocontact tungsten quartz veins and Zhangdou exocontact tungsten quartz veins are 154.9 ± 4.1 to 154.6 ± 9.7 Ma and 149.1 ± 7.1 Ma, respectively. The SHRIMP zircon U–Pb age of the Zhangtiantang fine-grained muscovite granite is 156.9 ± 1.7 Ma, whereas the molybdenite Re–Os isochron age for the related Yaolanzhai greisens-type tungsten deposit is 155.8 ± 2.8 Ma. These new age data, combined with those available from the literature, indicate that the ages of W–Sn ores and related granites are Late Jurassic with a peak at 150 to 160 Ma, which corresponds to the widespread Mesozoic metallogenic event in southern China. Molybdenites from this group of tungsten deposits have quite low Re contents (29.1 to 2608 ppb), suggesting continental crustal provenance of the ore metals.  相似文献   

13.
The Xianghualing Sn-polymetallic orefield in Hunan Province, southern China, is a large-size tin orefield. Although numerous studies have been undertaken on this orefield, its genesis, mineralization age, and tectonic setting are still controversial, mainly because of the lack of reliable geochronological data on tin mineralization. The 40Ar/39Ar stepwise heating dating method was first employed on muscovite from different deposits in this orefield. The muscovite sample from the Xianghualing Sn-polymetallic deposit defines a plateau age of 154.4±1.1 Ma and an isochron age of 151.9±3.0 Ma; muscovite from the Xianghuapu W-polymetallic deposit yields a plateau age of 161.3±1.1 Ma and an isochron age of 160.0±3.2 Ma; muscovite from the Jianfengling greisen-type Sn-polymetallic deposit gives a plateau age of 158.7±1.2 Ma and an isochron age of 160.3±3.2 Ma. The tungsten-tin mineralization ages in the Xianghualing area are therefore restricted within 150-160 Ma. The tungsten -tin mineralization in Xianghualing occurred at the same time as the regional tin-tungsten mineralization including the Furong tin orefield, Shizhuyuan tungsten-tin polymetallic deposit and Yaogangxian tungsten-polymetallic deposit. Thus, the large-scale tungsten-tin metallogenesis in South China occurring at 160-150 Ma. probably is closely related to asthenospheric upwelling and crust-mantle interaction under a geodynamic setting of crustal extension and lithosphere thinning during the transformation of tectonic regimes during the Mid-Late Jurassic.  相似文献   

14.
Abstract This paper discusses the relationships between granitic magmatism and gold mineralization and the exhumation history of the Dapinggou gold deposit in northern Altun, NW China based on the geochronological data, including zircon U‐Pb ages, Rb‐Sr isochron age and 40Ar‐39Ar dating and MDD modeling data. The main granitic magmatism age in this area is attained from the ID TIMS U‐Pb geochronology of zircons from the Kuoshibulak granite, the biggest granite in the northern Altun area, which gives a concordant age of 443±5 Ma in the Late Ordovician. Zircon ID TIMS U‐Pb geochronology of the West Dapinggou biotite granite west of the Dapinggou gold deposit gives concordant ages around 485±10 Ma, representing the early stage of Ordovician magmatism. The Rb‐Sr isochron age (487±21 Ma) of 6 quartz inclusion samples from quartz veins in this gold deposit is very close to that of the West Dapinggou granite. MDD modeling of step heating 40Ar‐39Ar data of K‐feldspar from the same West Dapinggou biotite granite gives a rapid cooling history from 300°C to 150°C during 200–185 Ma. According to the age data and the geological setting of this area, we conclude that the Dapinggou gold deposit was formed at the early stage of the Early Paleozoic granitic magmatism in northern Altun, and exhumed in the Early Jurassic due to the normal faulting of the Lapeiquan detachment. The Early Paleozoic magmatism may provide heat source and produce geological fluids, which are very important for gold mineralization. Exhumation in the Mesozoic caused the uplift of the deposit towards the ground surface.  相似文献   

15.
The general classification of intermediate-acid intrusive rocks in the metamorphic zone of Gaoligong Mountains as one of the metamorphic terranes of Proterozoic Gaoligong Mountains is problematic regarding the intrusion stage and age, as well as the subsequent metamorphism and deformation. In this study, we investigated granitic gneiss in the metamorphic zone of Gaoligong Mountains based on the 1:50,000 regional geological survey of Qushi Street (2011-2013) and SHRIMP U-Pb zircon geochronology. Results showed that the SHRIMP U-Pb zircon dating of granitic gneiss ranged from 163.5±5.7 Ma to 74.0±2.0 Ma. Thus, the granitic gneiss was grouped into orthometamorphic rocks (metamorphic intrusions). The dating data of granite rocks associated with intense metamorphism and deformation were divided into three groups, 163.5±5.7 to 162.3±3.1 Ma, 132.2-101.0 Ma and 99.4±3.5-74.0±2.0 Ma, which respectively represented three independent geologic events including an important magma intrusion with superimposed metamorphic effects in the late Middle Jurassic, regional dynamic metamorphism and superimposed reformation of fluid action in the early Cretaceous, and dynamic metamorphism dominated by ductile shear and metamorphism starting from the late Cretaceous.  相似文献   

16.
The Tieshanlong tungsten‐polymetallic deposit is a large wolframite deposit of quartz vein type located in southern Jiangxi, South China. It is genetically related to a high‐K S‐type granite. Seven pyrite and two wolframite samples, selected for He and Ar isotope analyses, yielded 3He/4He values of 0.04–0.98 Ra, 40Ar/36Ar ratios of 293.5–368.0, and 38Ar/36Ar ratios of 0.176–0.193. These data indicate that the ore‐forming fluids associated with the deposit did not result from a simple mixing of the crustal‐ and mantle‐derived end‐member fluids, but that primeval meteoric fluids were also involved in the generation of the associated granitic magma by partial melting of crustal metasedimentary rocks. Further investigations show that only minimal He from the mantle was added during generation of the associated granitic magma. It is postulated that boiling and second mixing with “new” meteoric fluids took place during migration of magmatic‐hydrothermal fluids into wall‐rock fractures, resulting in a drastic decrease of their metal transport capacity, which triggered the tungsten‐polymetallic mineralization.  相似文献   

17.
土地庙沟铅锌矿床是豫西南铅锌银多金属成矿区域的重要组成部分。本文以与土地庙沟铅锌矿床成矿关系密切的栗扎树岩体为研究对象,利用LA-ICP-MS锆石U-Pb测年和Hf同位素分析方法,探讨岩体成岩时代及其与矿床成矿时空相关性。岩体测得的LA-ICP-MS锆石U-Pb年龄加权平均值分别为141.6±1.3Ma（样品YZY-G07）、135.5±1.6Ma（样品YZY-G08）、116.2±1.2Ma（样品YZY-G01）,Hf同位素分析二阶段模式年龄为1724Ma~2244 Ma,表明成岩物质主要来源于地壳,并结合矿床特征,与栾川-维摩寺断裂北侧的合峪、伏牛山、太山庙相比,从早到晚,140Ma、135Ma、117Ma均有较好的对应关系。根据形成于140Ma左右的花岗岩浆活动,结合岩石地球化学、矿床地质特征、同位素特征等资料,并与华北克拉通南缘南泥湖矿田的成矿构造热事件对比,可推断出矿床为早白垩世早期同一构造-岩浆-流体成矿事件的产物,为矿山企业勘查找矿提供了科学依据。  相似文献   

18.
Thin layers and lenses of granitic leucosome are widely distributed within amphibolites, paragneisses and orthogneisses of the Sulu UHP terrane. They are parallel to, or cross‐cut, foliations in the host rocks at different scales and show evidence of coalescence and migration to form centimetre‐ to decimetre‐scale segregations. Variously migmatized rocks extend at least 350 km from SW Sulu (Maobei) to NE Sulu (Weihai), in a band at least 50 km wide. A combined study of mineral inclusions, cathoduluminescence (CL) images, U–Pb LA‐ICP‐MS dates, and in‐situ trace element compositions of zircon provide clear evidence on the nature and timing of partial melting in these UHP rocks. Most zircon from the granitic leucosomes occurs as distinct overgrowths around inherited (igneous or metamorphic) cores or as new, euhedral crystals. The overgrowths and new crystals commonly show perfectly euhedral shapes, have pronounced oscillatory zoning and contain felsic mineral inclusions, such as Kfs + Pl + Qtz ± Ilm ± monazite (Mon). In contrast, the inherited igneous or metamorphic cores are rounded or irregular, contain low‐P or UHP mineral inclusions and show clear dissolution textures. These data suggest that the new zircon is anatectic in origin and that it grew during partial melting of the UHP rocks. The REE patterns of the anatectic zircon show steep slopes from the HREE to LREE with strongly to moderately negative Eu anomalies (Eu/Eu* = 0.31–0.72) and pronounced positive Ce anomalies (Ce/Ce* = 6.8–26.5). Abundant U–Pb spot analyses of the anatectic zircon reveal two discrete and meaningful ages of partial melting within the Sulu UHP terrane. Anatectic zircon from 12 granitic leucosomes within amphibolites, paragneisses, and orthogneisses from Sulu UHP slices II and III yields consistent mean U–Pb ages of 219.0 ± 1.2 to 218.3 ± 1.6 Ma, 218.8 ± 2.0 to 217.3 ± 1.7 Ma and 218.2 ± 1.4 to 215.0 ± 1.5 Ma, respectively. In contrast, anatectic zircon from six granitic leucosomes within paragneisses and orthogneisses from Sulu UHP slice III records younger mean U–Pb ages of 151.9 ± 1.3 to 151.1 ± 1.8 Ma and 155.9 ± 1.8 to 153.7 ± 1.7 Ma, respectively. These data imply that the Sulu UHP terrane experienced two Mesozoic partial melting events. The first partial melting event (219–215 Ma) was probably associated with a Late Triassic granulite facies stage of ‘hot’ exhumation, whereas the second (156–151 Ma) is interpreted as the result of Middle‐Late Jurassic extension and thinning of the previously thickened crust of the Sulu UHP terrane. Both partial melting events induced extensive retrograde metamorphism of the eclogites and their country rocks.  相似文献   

19.
The large low-grade Piaotang W–Sn deposit in the southern Jiangxi tungsten district of the eastern Nanling Range, South China, is related to a hidden granite pluton of Jurassic age. The magmatic-hydrothermal system displays a zonation from an inner greisen zone to quartz veins and to peripheral veinlets/stringers (Five-floor zonation model). Most mineralization is in quartz veins with wolframite > cassiterite. The hidden granite pluton in underground exposures comprises three intrusive units, i.e. biotite granite, two-mica granite and muscovite granite. The latter unit is spatially associated with the W–Sn deposit.Combined LA-MC-ICP-MS U–Pb dating of igneous zircon and LA-ICP-MS U–Pb dating of hydrothermal cassiterite are used to constrain the timing of granitic magmatism and hydrothermal mineralization. Zircon from the three granite units has a weighted average 206Pb/238U age of 159.8 ± 0.3 Ma (2 σ, MSWD = 0.3). The cathodoluminescence (CL) textures indicate that some of the cassiterite crystals from the wolframite-cassiterite quartz vein system have growth zonations, i.e. zone I in the core and zone II in the rim. Dating on cassiterite (zone II) yields a weighted average 206Pb/238U age of 159.5 ± 1.5 Ma (2 σ, MSWD = 0.4), i.e. the magmatic and hydrothermal systems are synchronous. This confirms the classical model of granite-related tin–tungsten mineralization, and is against the view of a broader time gap of >6 Myr between granite magmatism and W–Sn mineralization which has been previously proposed for the southern Jiangxi tungsten district. The elevated trace element concentrations of Zr, U, Nb, Ta, W and Ti suggest that cassiterite (zone II) formed in a high-temperature quartz vein system related to the Piaotang granite pluton.  相似文献   

20.
The Lakange porphyry Cu–Mo deposit within the Gangdese metallogenic belt of Tibet is located in the southern–central part of the eastern Lhasa block, in the Tibetan Tethyan tectonic domain. This deposit is one of the largest identified by a joint Qinghai–Tibetan Plateau geological survey project undertaken in recent years. Here, we present the results of the systematic logging of drillholes and provide new petrological, zircon U–Pb age, and molybdenite Re–Os age data for the deposit. The ore‐bearing porphyritic granodiorite contains elevated concentrations of silica and alkali elements but low concentrations of MgO and CaO. It is metaluminous to weakly peraluminous and has A/CNK values of 0.90–1.01. The samples contain low total REE concentrations and show light REE/heavy REE (LREE/HREE) ratios of 17.51–19.77 and (La/Yb)N values of 29.65–41.05. The intrusion is enriched in the large‐ion lithophile elements (LILE) and depleted in the HREE and high field‐strength elements (HFSE). The ore‐bearing porphyritic granodiorite yielded a Miocene zircon U–Pb crystallization age of 13.58 ± 0.42 Ma, whereas the mineralization within the Lakange deposit yielded Miocene molybdenite Re–Os ages of 13.20 ± 0.20 and 13.64 ± 0.21, with a weighted mean of 13.38 ± 0.15 Ma and an isochron age of 13.12 ± 0.44 Ma. This indicates that the crystallization and mineralization of the Lakange porphyry were contemporaneous. The ore‐bearing porphyritic granodiorite yielded zircon εHf(t) values between ?3.99 and 4.49 (mean, ?0.14) and two‐stage model ages between 1349 and 808 Myr (mean, 1103 Myr). The molybdenite within the deposit contains 343.6–835.7 ppm Re (mean, 557.8 ppm). These data indicate that the mineralized porphyritic granodiorite within the Lakange deposit is adakitic and formed from parental magmas derived mainly from juvenile crustal material that partly mixed with older continental crust during the evolution of the magmas. The Lakange porphyry Cu–Mo deposit and numerous associated porphyry–skarn deposits in the eastern Gangdese porphyry copper belt (17–13 Ma) formed in an extensional tectonic setting during the India–Asia continental collision.  相似文献   

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