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1.
大井铜-锡多金属矿床成矿作用与岩浆流体的关系 总被引：1，自引：0，他引：1
通过对大井铜锡多金属矿床硫化物的硫同位素和流体包裹体的氢同位素测定,确定了成矿期的流体以大气降水为主,但硫主要来源于深部的岩浆流体。岩浆流体对这类热液脉型矿床的形成起着重要作用, 富硫和其它挥发组分的岩浆流体携带了岩浆中的Cu、Sn等多种成矿金属元素,它与大气降水的混合是造成Sn、Cu和Zn等金属成矿物质逐步沉淀的主要原因 相似文献
2.
荷花坪锡多金属矿床是湘南地区新发现的一大型矿床, 主要由印支期矽卡岩型矿石和燕山期蚀变碎裂岩型矿石所组成, 且以前者为主体。本文在详细的野外调查和岩相学观察基础上, 将区内印支期成矿分为三个成矿阶段(I-含锡矽卡岩阶段; II-硫化物阶段; III-石英-方解石阶段), 燕山期成矿分为两个阶段(I-锡石-硫化物阶段; II-方解石阶段)。对不同期石英、绿柱石、方解石等矿物中流体包裹体的研究表明, 荷花坪矿床包裹体类型主要为H2O-NaCl型、H2O-NaCl-CO2型和少量纯CO2型。显微实验结果显示, 印支期成矿流体主要为低盐度(ω(NaCleq)=3%~10%)的H2O-NaCl和H2O-NaCl-CO2以及少量富CO2流体。三个成矿阶段的完全均一温度分别为290~390℃、190~260℃和140~180℃。成矿早阶段流体中含较多CO2, 晚阶段CO2含量减少, 主要为H2O-NaCl, 且Ca2+、Mg2+含量增高。燕山期成矿流体亦为低盐度(ω(NaCleq)=2%~10%)H2O-NaCl和H2O-NaCl-CO2, 二个成矿阶段的完全均一温度分别为190~340℃和130~170℃, 成矿早阶段流体中含较多CO2, 晚阶段CO2含量减少, 主要为NaCl-H2O。两期成矿从早到晚都呈现出盐度降低、密度增大的变化趋势。区内成矿流体主要来自岩浆和地下水热液, 成矿早阶段以岩浆流体为主, 晚阶段以地下水为主。区内锡成矿主要与含CO2的流体以及流体的沸腾作用有关, 铅锌矿化主要与盐-H2O溶液流体作用关系密切。 相似文献
3.
4.
西藏南木斑岩铜钼矿床的流体包裹体研究 总被引：15，自引：2，他引：15
南木斑岩铜钼矿床是西藏冈底斯东段铜多金属成矿带中的典型斑岩矿床。流体包裹体研究显示与成矿有关的包裹体可以分为液相包裹体、气相包裹体和含子晶多相包裹体三类，它们的均一温度为315～526℃，盐度变化大，含石盐子矿物包裹体的盐度ω(NaCleq)33．1％～52．98％。激光拉曼探针成分分析表明，黄铜矿等子矿物相存在于高盐度包裹体中，部分液相包裹体和气相包裹体含有一定量的CO2。含子矿物包裹体与液相包裹体、气相包裹体共存．且均一温度相近，盐度相差很大，表明成矿流体经历了沸腾作用。成矿流体是富含成矿金属元素的高盐度、高温岩浆流体，岩浆热液提供了主要金属物质。 相似文献
5.
抱伦金矿床的石英和方解石中的包裹体以气液包裹体为主,石英中含大量CO2包裹体.成矿流体属Na(K)-Cl型.气相成分CH4、C2H6、H2S、O2、N2和Ar的含量反映属弱还原环境.液相成分中阴、阳离子分别以Cl-、Na 为主,含少量SO42-、F-、Mg2 和Ca2 .Au在成矿流体中以AuCl2-和Au(HS)2-络合物的形式迁移.均一温度主要为160～350℃,属中温范畴.流体水的δ18O和δD值分别为-3.4‰～ 9.8‰和-61‰～-30‰,其来源主要为岩浆水与大气降水.石英的δ18O值( 10.4‰～ 15.5‰)与华南陆壳型花岗岩成因的钨、锡、稀有、稀土金属矿床一致.CO2和黄铁矿的C、S同位素反映C和S以花岗岩浆来源为主,少量来自志留系或更老的地层.综合分析认为矿床成因与印支期花岗质岩浆活动有关. 相似文献
6.
透岩浆流体成矿体系 总被引：45，自引：10，他引：35
根据透岩浆流体成矿理论,熔浆体系与含矿流体体系可以看作是两个相互独立的地质体系,它们因相互需要而耦合在一起形成一个复杂的混合体系。当熔浆与流体发生解耦时,可以在不同的边界条件下发生不同类型的成矿作用。因此,可以将透岩浆流体成矿体系进一步划分成正岩浆成矿体系、接触带成矿体系、远程热液成矿体系和火山热液成矿体系。如果熔浆具有很强的流体圈闭能力,所有的含矿流体都将被封存在岩浆体内,并随着岩浆的固结而析出成矿物质,形成正岩浆矿床。当岩浆具有较高的渗透率且含矿流体逸出岩浆体时,如果岩浆的直接围岩具有较强的捕获成矿物质的能力,即发生接触带成矿作用。否则,含矿流体将在岩浆热驱动下远离岩浆体,形成远程热液矿床。如果有利的流体通道直达岩浆体,含矿流体甚至可以喷出地表或其附近,形成火山热液矿床或水底喷流沉积矿床。这种理论分析似乎与许多成矿事实相吻合,可以有效地指导区域成矿预测和矿床勘探。 相似文献
7.
区域成矿流体的形成与演化 总被引：6，自引：0，他引：6
成矿流体是富含挥发份、碱金属的含矿卤水 ,其中碱金属来源于岩浆热液、变质热液、海水及通过水岩作用从岩石中萃取等 ;而挥发份来源于地幔、水岩作用与有机质分解作用。成矿流体中的硫也是多来源的 ,硫的活度与氧逸度有关 ,高温还原环境H2 S的活度降低 ;成矿流体的同位素分馏与水岩作用强度有关 ,控制同位素分馏的基本因素是温度及水岩比值。根据成矿流体的成分及物理化学性质 ,可以分类为高温硅钾卤水、中温碳酸盐卤水及低温硫酸盐型卤水。成矿流体没有固定的来源 ,在一定地质条件下 ,任何来源的热水流体都可以形成成矿流体。控制成矿流体形成的主要地质作用是岩浆作用、变质作用、地热增温作用及构造作用等。文中根据地质作用类型对区域地质流体进行划分 ,可分为岩浆作用区域成矿流体 (以高温硅钾卤水为主 ,可以有高温到中低温的流体分带 ) ,沉积作用区域成矿流体 (以中低温碳酸盐及硫酸盐型卤水为特征 ) ,大洋盆地区域成矿流体 (与岩浆岩区域成矿流体类似 ,有高温到低温的流体分带 )和变质作用区域成矿流体 (变质程度不同而有不同的流体类型混合 )。 相似文献
8.
湖南芙蓉锡多金属矿床成矿流体地球化学 总被引：9，自引：5，他引：4
湖南芙蓉锡多金属矿床是我国最近发现的与A型花岗岩具有成因联系的超大型锡多金属矿床.本文对该矿床主要的四种矿化类型(矽卡岩型、云英岩型、蚀变花岗岩型、锡石硫化物型)进行了系统的流体包裹体地球化学和稳定同位素地球化学研究.研究结果表明:该矿床中流体包裹体类型复杂,包括富含CO_2包裹体、气液包裹体、含子晶包裹体和气相包裹体.矽卡岩型矿石中流体包裹体均一温度主要集中在400～450℃,云英岩和蚀变花岗岩型矿石的均一温度相对下降,主要分布于250～350℃之间,锡石硫化物型矿石中包裹体温度进一步下降.成矿流体主要由高盐度CaCl_2-NaCl-KCl-H_2O流体(盐度多集中在32.2 wt%～50.6 wt%NaCl.eqv)和富含CO_2的CO_2-CH4-NaCl-H_2O低盐度流体(盐度多集中在32.2 wt%～50.6wt% NaCl.eqv)组成.芙蓉锡矿云英岩型矿石成矿流体中的水主要以岩浆水为主,锡石硫化物型矿石成矿流体中的水具有岩浆水和大气降水混合的特征,成矿流体中的碳为岩浆碳与沉积碳酸盐不同比例混合的结果.芙蓉锡多金属矿床的成矿流体应主要来源于骑田岭黑云母二长花岗岩岩浆结晶期后分异出的岩浆热流体.岩浆热流体沿岩体周围裂隙对围岩和原生矽卡岩进行热液交代,在造成绢云母化、白云母化、绿泥石化等热液蚀变现象的同时,导致了大规模的锡矿化.减压沸腾和低温流体与高温流体混合造成的沸腾作用是导致芙蓉锡矿锡沉淀的主要机制. 相似文献
9.
[摘要]马厂箐铜钼金多金属矿床是西南三江地区的重要矿床之一,对其成因迄今存在争议。本
文报道了新的观测资料,结合前人的研究结果,试图以透岩浆流体成矿理论为指导解释马厂箐矿床的成
因。透岩浆流体成矿作用是罗照华等(2009)提出的一种与国内外矿床学界内生矿床成矿理论主流见解
不同的新理念和新见解。马厂箐铜、钼、金成矿与马厂箐小岩体空间上紧密相伴,时间上相近或稍晚。
马厂箐矿区岩体和矿脉S、C、Pb、H、O、Si 和He、Ar 同位素数据表明:铜、钼矿的成矿物质主要来源于深
部地幔流体(透岩浆流体),金矿成矿物质由深部地幔流体(透岩浆流体)和围岩地层共同提供。马厂箐
的小岩体既有幔源岩石(如煌斑岩),又有壳源岩石(如花岗斑岩),而原生流体则均来自地幔,流体与岩
浆来源的不一致性暗示了透岩浆流体的性质;马厂箐矿床的时空展布特征与透岩浆流体成矿理论的预
测相一致,比传统岩浆热液成矿理论更好地解释了矿床成因;马厂箐矿床是透岩浆流体成矿作用的产
物,主要与区农小岩体群有关,斑状花岗岩体仅仅起着含矿流体的屏蔽作用。马厂箐铜、钼、金多金属矿
是在同一能量驱动机制下,岩浆热压力和地幔流体内压力可能驱动含矿流体在不同的位置上堆积不同
种类的金属,从而在含矿流体通过的路径上发生不同性质的成矿作用,并形成一系列不同类型的矿床,
其铜、钼、金多金属成矿过程可以全部归属为透岩浆流体成矿体系。 相似文献
10.
内蒙古维拉斯托铜多金属矿床流体包裹体研究 总被引：4，自引：2，他引：2
对内蒙古维拉斯托铜多金属矿床地质特征、流体包裹体和氢、氧同位素的研究表明,成矿具有多阶段性,根据矿脉穿插关系和矿石结构构造特征可以分为4个阶段:石英-黄铁矿阶段、多金属硫化物阶段、黄铜矿-磁黄铁矿-石英阶段和石英-碳酸盐阶段。流体包裹体类型以富液相包裹体为主,含有少量富气相包裹体和含子矿物包裹体以及含CO2三相包裹体。包裹体形态多为椭圆形、负晶形或近圆形,数量较多,呈不规则分布。均一温度变化区间为106~389℃,盐度为1.23%~9.86%NaCl eqv.,显示成矿流体具有中温、低盐度和低密度的特点。激光拉曼光谱分析包裹体成分主要为CO2、CH4和H2O。氢、氧同位素分析结果表明成矿热液是岩浆水和大气降水的混合作用来源。综合对比研究认为,维拉斯托铜多金属矿床与该区燕山期中酸性岩浆活动密切相关,为深部岩浆在上升过程中与下渗的大气降水发生混合,矿质在构造有利部位沉淀富集的结果。矿床为与燕山期岩浆活动有关的中温热液矿床。 相似文献
11.
WANG Chengyang LIU Guanghu SUN Zhenjun LIU Jie LI Jianfeng LIANG Xinyang 《《地质学报》英文版》2019,93(5):1522-1543
The Southern Great Xing'an Range(SGXR) hosts a number of Early Cretaceous Sn and associated metal deposits, which can be divided into three principal types according to their geological characteristics: skarn type deposits, porphyry type deposits and hydrothermal vein type deposits. Fluid inclusion assemblages of different types of deposits are quite different, which represent the complexities of metallogenic process and formation mechanism. CH_4 and CO_2 have been detected in fluid inclusions from some of deposits, indicating that the ore-forming fluids are affected by materials of Permian strata. Hydrogen and oxygen isotope data from ore minerals and associated gangue minerals indicate that the initial ore fluids were dominated by magmatic waters, some of which had clearly exchanged oxygen with wall rocks during their passage through the strata. The narrow range for the δ~(34)S values presumably reflects the corresponding uniformity of the ore forming fluids, and these δ~(34)S values have been interpreted to reflect magmatic sources for the sulfur. The comparation between lead isotope ratios of ore minerals and different geological units' also reveals that deeply seated magma has been a significant source of lead in the ores. 相似文献
12.
Classic porphyry Cu–Mo deposits are mostly characterized by close temporal and spatial relationships between Cu and Mo mineralization. The northern Dabate Cu–Mo deposit is a newly discovered porphyry Cu–Mo polymetallic deposit in western Tianshan, northwest China. The Cu mineralization postdates the Mo mineralization and is located in shallower levels in the deposit, which is different from most classic porphyry Cu–Mo deposits. Detailed field investigations, together with microthermometry, laser Raman spectroscopy, and O‐isotope studies of fluid inclusions, were conducted to investigate the origin and evolution of ore‐forming fluids from the main Mo to main Cu stage of mineralization in the deposit. The results show that the ore‐forming fluids of the main Mo stage belonged to an NaCl + H2O system of medium to high temperatures (280–310°C) and low salinities (2–4 wt% NaCl equivalent (eq.)), whereas that of the main Cu stage belonged to an F‐rich NaCl + CO2 + H2O system of medium to high temperatures (230–260°C) and medium to low salinities (4–10 wt% NaCl eq.). The δ18O values of the ore‐forming fluids decrease from 3.7–7.8‰ in the main Mo stage to ?7.5 to ?2.9‰ in the main Cu stage. These data indicate that the separation of Cu and Mo was closely related to a large‐scale vapor–brine separation of the early ore‐forming fluids, which produced the Mo‐bearing and Cu‐bearing fluids. Subsequently, the relatively reducing (CH4‐rich) Mo‐bearing, ore‐forming fluids, dominantly of magmatic origin, caused mineralization in the rhyolite porphyry due to fluid boiling, whereas the relatively oxidizing (CO2‐rich) Cu‐bearing, ore‐forming fluids mixed with meteoric water and precipitated chalcopyrite within the crushed zone at the contact between rhyolite porphyry and wall rock. We suggest that the separation of Cu and Mo in the deposit may be attributed to differences in the chemical properties of Cu and Mo, large‐scale vapor–brine separation of early ore‐forming fluids, and changes in oxygen fugacity. 相似文献
13.
《Resource Geology》2018,68(3):227-243
As a newly discovered medium‐sized deposit (proven Pb + Zn resources of 0.23 Mt, 9.43% Pb and 8.73% Zn), the Dongzhongla skarn Pb–Zn deposit is located in the northern margin of the eastern Gangdese, central Lhasa block. Based on the geological conditions in this deposit of ore‐forming fluids, H, O, C, S, Pb, Sr, and noble gas isotopic compositions were analyzed. Results show that δ18OSMOW of quartz and calcite ranged from −9.85 to 4.17‰, and δDSMOW ranged from −124.7 to −99.6‰ (where SMOW is the standard mean ocean water), indicating magma fluids mixed with meteoric water in ore‐forming fluids. The δ13CPDB and δ18OSMOW values of calcite range from −1.4 to −1.1‰ and from 5.3 to 15.90‰, respectively, show compositions consistent with the carbonate limestone in the surrounding rocks, implying that the carbon was primarily sourced from the dissolution of carbonate strata in the Luobadui Formation. The ore δ34S composition varied in a narrow range of 2.8 to 5.7‰, mostly between 4‰ and 5‰. The total sulfur isotopic value δ34S was 4.7‰ with characteristics of magmatic sulfur. The 3He/4He values of pyrite and galena ranged from 0.101 to 5.7 Ra, lower than those of mantle‐derived fluids (6 ± 1 Ra), but higher than those of the crust (0.01–0.05 Ra), and therefore classified as a crust–mantle mixed source. The Pb isotopic composition for 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values of the ores were in the ranges of 18.628–18.746, 15.698–15.802, and 39.077–39.430, respectively, consistent with the Pb isotopic composition of magmatic rocks in the deposit, classified as upper‐crust lead. The ore lead was likely sourced partially from the crustal basement of the Lhasa Terrane. The initial (87Sr/86Sr)i value from five sulfide samples ranged from 0.71732 to 0.72767, and associated ore‐forming fluids were mainly sourced from the partial melting of the upper‐crust materials. Pb isotopic compositions of ore sulfides from the Dongzhongla deposit are similar to that of the Yuiguila and Mengya'a deposit, indicating that they have similar sources of metal‐rich ore‐forming solution. According to basic skarn mineralogy, the economic metals, and the origin of the ore‐forming fluids, the Dongzhongla deposit was classified as a skarn‐type Pb–Zn deposit. 相似文献
14.
Hydrothermal Fluid Sources of the Fengjia Barite–fluorite Deposit in Southeast Sichuan,China: Evidence from Fluid Inclusions and Hydrogen and Oxygen Isotopes 
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下载免费PDF全文 The Fengjia barite–fluorite deposit in southeast Sichuan is a stratabound ore deposit which occurs mainly in Lower Ordovician carbonate rocks. Here we present results from fluid inclusion and oxygen and hydrogen isotope studies to determine the nature and origin of the hydrothermal fluids that generated the deposit. The temperature of the ore‐forming fluid shows a range of 86 to 302 °C. Our detailed microthermometric data show that the temperature during mineralization of the fluorite and barite in the early ore‐forming stage was higher than that during the formation of the calcite in the late ore‐forming stage. The salinity varied substantially from 0.18% to 21.19% NaCl eqv., whereas the density was around 1.00 g/cm3. The fluid composition was mainly H2O (>91.33%), followed by CO2, CH4 and traces of C2H6, CO, Ar, and H2S. The dominant cation was Na+ and the dominant anion Cl‐, followed by Ca2+, SO42‐, K+, and Mg2+, indicating a mid–low‐temperature, mid‐low‐salinity, low‐density NaCl–H2O system. Our results demonstrate that the temperature decreased during the ore‐forming process and the fluid system changed from a closed reducing environment to an open oxidizing environment. The hydrogen and oxygen isotope data demonstrate that the hydrothermal fluids in the study area had multiple sources, primarily formation water, as well as meteoric water and metamorphic water. Combined with the geological setting and mineralization features we infer that the stratabound barite–fluorite deposits originated from mid–low‐temperature hydrothermal fluids and formed vein filling in the fault zone. 相似文献
15.
Zhenjun Sun Zongqi Wang Henan Yu Chengyang Wang Guanghu Liu Xaingdong Bai 《Resource Geology》2019,69(1):1-21
The Zhuanshanzi gold deposit lies in the eastern section of the Xingmeng orogenic belt and the northern section of the Chifeng‐Chaoyang gold belt. The gold veins are strictly controlled by a NW‐oriented shear fault zone. Quartz veins and altered tectonic rock‐type gold veins are the main vein types. The deposits can be divided into four mineralization stages, and the second and third metallogenic stages are the main metallogenic stages. In this paper, based on the detailed field geological surveys, an analysis of the orebody and ore characteristics, microtemperature measurement of fluid inclusions, the Laser Raman spectrum of the inclusions, determination of C? H? O? S? Pb isotopic geochemical characteristics, and so on were carried out to explore the origin of the ore‐forming fluids, ore‐forming materials, and the genesis of the deposits. The results show that the fluid inclusions can be divided into four types: type I – gas–liquid two‐phase inclusions; type II – gas‐rich inclusions; type III– liquid inclusions; and type IV – CO2‐containing three‐phase inclusions. However, they are dominated by type Ib – gas liquid inclusions and type IV – three‐phase inclusions containing CO2. The gas compositions are mainly H2O and CO2, indicating that the metallogenic system is a CO2? H2O? NaCl system. The homogenization temperature of the ore‐forming fluid evolved from a middle temperature to a low temperature, and the temperature of the fluid was further reduced due to meteoric water mixing during the late stage, as well as a lack of CO2 components, and eventually evolved into a simple NaCl? H2O hydrothermal system. C? H? O? S? Pb isotope research proved that the ore‐forming fluids are mainly magmatic water during the early stage, with abundant meteoric water mixed in during the late stage. Ore‐forming materials originated mostly from hypomagma and were possibly influenced by the surrounding rocks, suggesting that the ore‐forming materials were mainly magmatic hydrothermal deposits, with a small amount of crustal component. The fluid immiscibility and the CO2 and CH4 gases in the fluids played an active and important role in the precipitation and enrichment of Au during different metallogenic stages. The deposit is considered a magmatic hydrothermal deposit of middle–low temperature. 相似文献
16.
Geology and D-O-C Isotope Systematics of the Tieluping Silver Deposit,Henan, China: Implications for Ore Genesis 总被引：22，自引：0，他引：22
Franco PIRAJNO 《《地质学报》英文版》2005,79(1):106-119
The Tieluping silver deposit, which is sited along NE-trending faults within the high-grade metamorphic basement of the Xiong‘er terrane, is part of an important Mesozoic orogenic-type Ag-Pb and Au belt recently discovered. Ore formation includes three stages: Early (E), Middle (M) and Late (L), which include quartz-pyrite (E),polymetallic sulfides (M) and carbonates (L), respectively. The E-stage fluids are characterized by δD=-90%c,δ^13CCO2=2.0‰ and δ^18O=9‰ at 373℃, and are deeply sourced; the L-stage fluids, with δD=-70‰, δ^13C CO2=-1.3%c and δ^18O=-2‰, are shallow-sourced meteoric water; whereas the M-stage fluids, with δD=-109‰, δ^13C CO2=0.1%c and δ^18O2‰, are a mix of deep-sourced and shallow-sourced fluids. Comparisons of the D-O-C isotopic systematics of the Estage ore-forming fluids with the fluids derived from Mesozoic granites, Archean-Paleoproterozoic metamorphic basement and Paleo-Mesoproterozoic Xiong‘er Group, show that these units cannot generate fluids with the measured isotopic composition (high δ^180 and δ^13C ratios and low δD ratios) characteristic of the ore-forming fluids. This suggests that the E-stage ore-forming fluids originated from metamorphic devolatilization of a carbonate-shale-chert lithological association, locally rich in organic matter, which could correspond to the Meso-Neoproterozoic Guandaokou and Luanchuan Groups, rather than to geologic units in the Xiong‘er terrane, the lower crust and the mantle. This supports the view that the rocks of the Guandaokou and Luanchuan Groups south of the Machaoying fault might be the favorable sources. A tectonic model that combines collisional orogeny, metallogeny and hydrothermal fluid flow is proposed to explain the formation of the Tieluping silver deposit. During the Mesozoic collision between the South and North China paleocontinents, a crustal slab containing a lithological association consisting of carbonate-shale-chert, locally rich in organic matter (carbonaceous shale) was thrust northwards beneath the Xiong‘er terrane along the Machaoying fault.Metamorphic devolatilization of this underthrust slab provided the ore-forming fluids to develop the Au-Ag-(Pb-Zn) ore belt, which includes the Tieluping silver deposit. 相似文献
17.
The Kendekeke polymetallic deposit, located in the middle part of the magmatic arc belt of Qimantag on the southwestern margin of the Qaidam Basin, is a polygenetic compound deposit in the Qimantag metallogenic belt of Qinghai Province. Multi-periodic ore-forming processes occurred in this deposit, including early-stage iron mineralization and lead-zinc-gold-polymetallic mineralization which was controlled by later hydrothermal process. The characteristics of the ore-forming fluids and mineralization were discussed by using the fluid inclusion petrography, Laser Raman Spectrum and micro-thermometry methods. Three stages, namely, S1-stage(copper-iron-sulfide stage), S2-stage(lead-zinc-sulfide stage) and C-stage(carbonate stage) were included in the hydrothermal process as indicated by the results of this study. The fluid inclusions are in three types: aqueous inclusion(type I), CO2-aqueous inclusion(type II) and pure CO2 inclusion(type III). Type I inclusions were observed in the S1-stage, having homogenization temperature at 240–320oC, and salinities ranging from 19.8% to 25.0%(wt % NaCl equiv.). All three types of inclusions, existing as immiscible inclusion assemblages, were presented in the S2-stage, with the lowest homogenization temperature ranging from 175 oC to 295oC, which represents the metallogenic temperature of the S2-stage. The salinities of these inclusions are in the range of 1.5% to 16%. The fluid inclusions in the C-stage belong to types I, II and III, having homogenization temperatures at 120–210oC, and salinities ranging from 0.9% to 14.5%. These observations indicate that the ore-forming fluids evolved from high-temperature to lowtemperature, from high-salinity to low-salinity, from homogenization to immiscible separation. Results of Laser Raman Spectroscopy show that high density of CO2 and CH4 were found as gas compositions in the inclusions. CO2, worked as the pH buffer of ore-forming fluids, together with reduction of organic gases(i.e. CH4, etc), affected the transport and sediment of the minerals. The fluid system alternated between open and close systems, namely, between lithostatic pressure and hydrostatic pressure systems. The calculated metallogenic pressures are in the range of 30 to 87 Mpa corresponding to 3 km mineralization depth. Under the influence of tectonic movements, immiscible separation occurred in the original ore-forming fluids, which were derived from the previous highsalinity, high-temperature magmatic fluids. The separation of CO2 changed the physicochemical properties and composition of the original fluids, and then diluted by mixing with extraneous fluids such as meteoric water and groundwater, and metallogenic materials in the fluids such as lead, zinc and gold were precipitated. 相似文献
18.
GONG Xiaodong YAN Guangsheng YE Tianzhu ZHU Xinyou LI Yongsheng ZHANG Zhihui JIA Wenbin YAO Xiaofeng 《《地质学报》英文版》2015,89(3):822-835
The Dahutang tungsten polymetallic ore field is located north of the Nanling W-Sn polymetallic metallogenic belt and south of the Middle—Lower Yangtze River Valley Cu-Mo-Au-Fe porphyry-skarn belt.It is a newly discovered ore field,and probably represents the largest tungsten mineralization district in the world.The Shimensi deposit is one of the mineral deposits in the Dahutang ore field,and is associated with Yanshanian granites intruding into a Neoproterozoic granodiorite batholith.On the basis of geologic studies,this paper presents new petrographic,microthermometric,laser Raman spectroscopic and hydrogen and oxygen isotopic studies of fluid inclusions from the Shimensi deposit.The results show that there are three types of fluid inclusions in quartz from various mineralization stages:liquid-rich two-phase fluid inclusions,vapor-rich two-phase fluid inclusions,and three-phase fluid inclusions containing a solid crystal,with the vast majority being liquid-rich two-phase fluid inclusions.In addition,melt and melt-fluid inclusions were also found in quartz from pegmatoid bodies in the margin of the Yanshanian intrusion.The homogenization temperatures of liquid-rich two-phase fluid inclusions in quartz range from 162 to 363℃ and salinities are 0.5wt%-9.5wt%NaCI equivalent.From the early to late mineralization stages,with the decreasing of the homogenization temperature,the salinity also shows a decreasing trend.The ore-forming fluids can be approximated by a NaCl-H_2O fluid system,with small amounts of volatile components including CO_2,CH_4 and N_2,as suggested by Laser Raman spectroscopic analyses.The hydrogen and oxygen isotope data show that δ5D_(V-smow) values of bulk fluid inclusions in quartz from various mineralization stages vary from-63.8‰ to-108.4‰,and the δ~(18)O_(H2O) values calculated from the δ~(18)O_(V-)smow values of quartz vary from-2.28‰ to 7.21‰.These H-O isotopic data are interpreted to indicate that the ore-forming fluids are mainly composed of magmatic water in the early stage,and meteoric water was added and participated in mineralization in the late stage.Integrating the geological characteristics and analytical data,we propose that the ore-forming fluids of the Shimensi deposit were mainly derived from Yanshanian granitic magma,the evolution of which resulted in highly differentiated melt,as recorded by melt and melt-fluid inclusions in pegmatoid quartz,and high concentrations of metals in the fluids.Cooling of the ore-forming fluids and mixing with meteoric water may be the key factors that led to mineralization in the Dahutang tungsten polymetallic ore field. 相似文献
19.
白云鄂博矿床成因——矿体内霓长岩化成矿作用与赋矿白云岩的联系 总被引：1，自引：0，他引：1
通过对组成赋矿白云岩的白云石矿物系统的显微结构和化学成分的研究表明,赋矿白云岩是碳酸岩质次火山岩,因此白云鄂博矿床是与火成碳酸岩有关的矿床。赋矿白云岩属于镁质碳酸岩(MgOFeO+MnO)和铁质碳酸岩(MgOFeO+MnO)系列,FeO、MnO和SrO含量高,这与FeO、MnO和SrO含量很低的沉积碳酸岩完全不同。赋矿白云岩的这一特点还表明它来自经历过分异结晶后的白云质碳酸岩浆而不是初始白云质碳酸岩浆。赋矿白云岩复杂的矿物组合表明,其母岩浆是富含F、Cl、P和S这些挥发分以及REE,Na、K和Fe这些元素的。在碳酸岩浆上升和侵位的过程中由于温度压力的降低,碳酸岩浆释放的含上述组分的流体会向上部地壳集中并对其接触的围岩进行交代,这就形成了矿体内呈不对称带状分布的霓长岩化矿石带。在大量的萤石和稀土氟碳酸盐矿物形成以后(其对应于萤石-稀土条带状矿石),流体的成分仍相对富钠和CO_2,钠可以和围岩中的硅结合形成钠辉石,流体较高的比值,有利于稀土的富集,此时形成的钠辉石型矿石的稀土含量是相当高的,仅次于条带状矿石。随着流体继续迁移和交代,流体中CO_2浓度下降而H_2O含量增加,温度也有所下降,但是流体中的钠依然活跃,所以出现了含有结构水的钠闪石,形成了钠闪石型矿石。流体中H_2O的增加,比值的下降,不利于稀土的大量富集,因此,钠闪石型矿石的稀土含量明显低于钠辉石型矿石。这说明,从碳酸岩浆中外逸的流体,在迁移交代围岩的过程中其成分、温度和氧逸度都是有变化的。从初期富CO_2,温度和氧逸度较高,到后期富H_2O,温度和氧逸度都有所降低。不同矿石类型的形成与这种变化有直接的关系。不同矿石类型中的磁铁矿的生成方式虽然不同于白云岩中的磁铁矿,但前者的氧同位素继承了后者的特点,表明了它们的亲缘关系和成因上的联系。稀土分布型式表明,不同矿石类型的稀土分布型式与赋矿白云岩的大体一致,有明显的LREE富集和明显的HREE亏损,且总稀土含量越高,轻重稀土分离程度越高。但是,不同矿石类型在轻稀土含量上有一定程度的差别,表明在霓长岩化过程中轻稀土活动性更强。总之,氟、钠和铁的交代作用在主东矿最强,稀土、铌和铁资源也最为富集,这里的白云岩厚度也最大,表明白云鄂博矿的霓长岩化成矿作用与赋矿白云岩衍生的流体的大量聚集以及流体对围岩广泛强烈的交代作用直接相关。 相似文献
20.
Feng Yang Wei Zhai Xiaoming Sun Reiner Klemd Yanyan Sun Yunshan Wu Renmin Hua Siqi Zheng 《Resource Geology》2019,69(1):107-122
The Yaoling tungsten deposit is a typical wolframite quartz vein‐type tungsten deposit in the South China metallogenic province. The wolframite‐bearing quartz veins mainly occur in Cambrian to Ordovician host rocks or in Mesozoic granitic rocks and are controlled by the west‐north‐west trending extensional faults. The ore mineralization mainly comprises wolframite and variable amounts of molybdenite, chalcopyrite, pyrite, fluorite, and tourmaline. Hydrothermal alteration is well developed at the Yaoling tungsten deposit, including greisenization, silicification, fluoritization, and tourmalinization. Three types of primary/pseudosecondary fluid inclusions have been identified in vein quartz, which is intimately intergrown with wolframite. These include two‐phase liquid‐rich aqueous inclusions (type I), two‐ or three‐phase CO2‐rich inclusions (type II), and type III daughter mineral‐bearing multiphase high‐salinity aqueous inclusions. Microthermometric measurements reveal consistent moderate homogenization temperatures (peak values from 200 to 280°C), and low to high salinities (1.3–39 wt % NaCl equiv.) for the type I, type II, and type III inclusions, where the CO2‐rich type II inclusions display trace amounts of CH4 and N2. The ore‐forming fluids are far more saline than those of other tungsten deposits reported in South China. The estimated maximum trapping pressure of the ore‐forming fluids is about 1230–1760 bar, corresponding to a lithostatic depth of 4.0–5.8 km. The δDH2O isotopic compositions of the inclusion fluid ranges from ?66.7 to ?47.8‰, with δ18OH2O values between 1.63 and 4.17‰, δ13C values of ?6.5–0.8‰, and δ34S values between ?1.98 and 1.92‰, with an average of ?0.07‰. The stable isotope data imply that the ore‐forming fluids of the Yaoling tungsten deposit were mainly derived from crustal magmatic fluids with some involvement of meteoric water. Fluid immiscibility and fluid–rock interaction are thought to have been the main mechanisms for tungsten precipitation at Yaoling. 相似文献