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在野外地质研究的基础上,借助流体包裹体和地球化学热力学方法研究了九嶷山锡矿田W,Sn的迁移形式。研究结果表明,钨在热液中主要以WO3CI^-,WO2Cl4^2-,HWO4^-和WO4^2-等氯-氧离子团的形式迁移;锡在热液中主要以SnCl2^o,SnCl3^-和SnCl4^2-形式迁移。钨锡矿床是在含矿热液由于温度、压力、pH,fO2和fS3降低等综合作用,W,Sn配合物发生化学解析作用形成。 相似文献
104.
The Yinyan Sn deposit, one of the three typical porphyry Sn deposits in China, is located in the western Guangdong province of the Cathaysia Block. Rhenium and osmium isotopes of molybdenites from the Yinyan deposit were first used to constrain the age of mineralization. Rhenium concentrations in molybdenite samples range from 0.13 to 1.3 µg g?1, indicating a crustal source for the ore‐forming materials. The Re–Os dating yield model ages ranging from 78.1 to 79.52 Ma, with an average of 78.65 ± 0.98 Ma, and give an isochron age of 78.8 ± 2.6 Ma. Evidently, isochron age is consistent with model ages in the error within the allowable range, so we can constrain the precise age of Yinyan Sn deposit at the Late Cretaceous. Based on the geological history and spatial‐temporal distribution of the Sn deposits, it is proposed that the formation of Sn deposits in the Cathaysia Block were related to lithospheric extension that are associated with a change in the polarity of the subduction of the Paleo‐Pacific Plate from oblique subduction to parallel the eastern margin of the Eurasian Plate after 135 Ma. 相似文献
105.
内蒙古维拉斯托斑岩型锡矿床成岩、成矿时代及其地质意义 总被引:7,自引:3,他引:4
维拉斯托Sn矿床为内蒙古中南段地区新发现的大型斑岩型矿床,矿床的形成与石英斑岩有密切的成因联系。该斑岩型Sn矿床的发现与该区已发现的维拉斯托和拜仁达坝大型脉状Cu_Pb_Zn_Ag多金属矿床可能属于同一岩浆_热液成矿体系。虽然前人已对热液脉状Zn_Cu矿床和Ag_Pb_Zn矿床有了较多研究,但对新发现的斑岩型锡矿床开展的研究还十分欠缺。文章首次报道了新发现斑岩型矿床的成岩和成矿年龄。利用LA_ICP_MS方法对石英斑岩中的锆石进行U_Pb同位素定年,获得的年龄为(135.7±0.9)Ma(MSWD=1.4,n=24),表明石英斑岩的侵位时代为早白垩世。对与Sn矿化密切相关的辉钼矿进行了Re_Os同位素定年,结果显示辉钼矿的Re_Os同位素等时线年龄为(125.7±3.8)Ma(MSWD=1.7,n=4),可代表斑岩型矿床中Sn发生矿化的时间。本次获得的年代学数据表明,该斑岩型矿床成矿年龄稍晚于成岩年龄,与国内外众多典型斑岩型矿床具有类似特征。新发现的维拉斯托斑岩型Sn矿床形成于燕山晚期,与该区众多岩浆_热液多金属矿床的形成时代一致,推测矿床的成岩、成矿过程很可能与中生代岩石圈的伸展构造有关。 相似文献
106.
Tin (Sn) isotope geochemistry has great potential in tracing geological processes. However, lack of equilibrium Sn isotope fractionation factors of various Sn species limits the development of Sn isotope geochemistry. Equilibrium Sn isotope fractionation factors (124Sn/116Sn and 122Sn/116Sn) among various Sn(II, IV) complexes in aqueous solution were calculated using first-principles calculations. The results show that the oxidation states and the change of Sn(II, IV) species in hydrothermal fluids are the main factors leading to tin isotope fractionation in hydrothermal systems. For the Sn(IV) complexes, Sn isotope fractionation factors depend on the number of H2O molecules. For the Sn(II) complexes, the Sn isotope fractionation between Sn(II)?F, Sn(II)?Cl and Sn(II)?OH complexes is mainly affected by the bond length and the coordination number of anion, whereas the difference in 1000lnβ values of Sn(II)?SO4 and Sn(II)?CO3 complexes is insignificant with the change of anion coordination number. By comparing the 1000lnβ values of all Sn(II, IV) complexes, the enrichment trend in heavy Sn isotopes is Sn(IV) complexes > Sn(II) complexes. The equilibrium Sn isotopic fractionation factors enhance our understanding of the tin transportation and enrichment processes in hydrothermal systems. 相似文献
107.
Shao-Cong Chen Jin-Jie Yu Min-Feng Bi Bernd Lehmann 《Chemie der Erde / Geochemistry》2022,82(1):125856
It remains poorly constrained whether remobilization of Sn from granites and prograde skarns plays an essential role in forming economic (skarn-type) tin mineralization. Using both electron probe microanalysis and laser ablation–inductively coupled plasma–mass spectrometry methods, in-situ Sn contents, as well as major elements, were analyzed for numerous silicates and magnetite from fresh granite, altered granite, and skarn at the large Furong Sn deposit (530,000 t Sn @ 0.8% Sn) in the Nanling Range, South China. Hornblende and biotite in fresh granite are the main Sn-bearing phases (Sn = 44–321 ppm), while plagioclase and K-feldspar are poor in Sn (< 5 ppm). In altered granite, tin is hosted mainly by hydrothermal muscovite (299–583 ppm) replacing plagioclase, but rarely by chlorite (mostly <10 ppm) replacing hornblende and biotite. In contrast, most silicates (garnet, diopside, vesuvianite, pargasite and epidote) and magnetite from tin skarn are Sn-rich (47–44,241 ppm), except for Sn-poor phlogopite and scapolite (< 10 ppm). In particular, garnet, pargasite, and epidote reach tin concentrations in the percent range. Tin generally enters the stannous silicates and magnetite through substitutions for octahedral Alvi and Fe3+. Comparisons of Sn contents between magmatic and hydrothermal minerals in granite, prograde and retrograde minerals related to tin skarn indicate that remobilization of Sn from granite and prograde skarn is not a pre-requisite to form tin mineralization. 相似文献
108.
来利山锡矿床与小龙河锡矿床是滇西地区典型的云英岩型锡矿床。为揭示它们在成因上深层次的差异性,对来利山锡矿和小龙河锡矿的锡石进行了电子探针成分分析、镜下观察以及成矿环境对比分析。结果表明,锡石中的铁多以Fe~(3+)的形式与Sn~(4+)发生类质同象,氧逸度越高,锡石中Fe~(3+)越多,宏观上表现为锡石的颜色越深。来利山矿区锡石中Fe含量明显低于小龙河矿区,且锡石颜色明显比小龙河矿区颜色浅,反映了来利山锡矿成矿环境相对开放,成矿流体氧逸度偏低,流体中Sn络合物迁移能力较强,在花岗岩体外接触带的围岩裂隙中形成外云英岩型锡矿床;而小龙河锡矿成矿环境相对封闭,成矿流体氧逸度偏高,流体中Sn络合物迁移能力较弱,多在花岗岩体顶部的构造裂隙中形成内云英岩型锡矿床。 相似文献
109.
Comparative Studies of the Petrochemistry of Sn–W‐Mineralized Granitoids: Continent vs. Island Arc 下载免费PDF全文
Shunso Ishihara 《Resource Geology》2015,65(3):285-295
Granitic rocks obtained during field excursions of the famed mineralized regions of the Erzgebirge, Germany (mainly tin‐bearing), and South China (mainly tungsten‐bearing) have been geochemically analyzed and their results are compared with similar (mainly tungsten‐bearing) granites in the island‐arc setting of Southwest Japan. The studied granitoids all belong to the ilmenite‐series. The collision‐related Erzgebirge granitoids are rich in K2O and P2O5, have high A/CNK ratios (1.11–1.24, i.e. S type), but are also high in Ga/Al ratio (i.e., having some A‐type characteristics). In South China, the Xihuashan granites, in contrast, are very low in P2O5, and have A/CNK slightly above 1.0 (1.01–1.05), indicative of I type granites. The (Sn‐) W‐related granites of southwest Japan have similarly low P2O5 and A/CNK ratios, indicative also of I‐type. Both in the Xihuashan and southwest Japan, the tungsten‐related granites have high whole‐rock δ18O values implying involvement of W‐rich crustal rocks. Sn and W contents of the unaltered granites are lowest in the island‐arc setting where the related Sn–W deposits are smallest in size relative to the collision and continental margin settings of the Erzgebirge and South China. 相似文献
110.
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