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敞开酸溶和偏硼酸锂碱熔ICP-MS法测定多金属矿中的稀土元素及铌钽锆铪 总被引：2，自引：2，他引：0
用电感耦合等离子体质谱法(ICP-MS)测定地质样品中的稀土及难熔元素,混合酸敞开酸溶法和碱熔融法是两种主要的溶样方法。但地质样品组分复杂,元素之间存在相互共生的现象,对于特殊元素、特殊样品用传统酸溶法会造成部分元素消解不完全,使测定结果不准确;而碱熔法的操作过程繁琐,且溶液盐度高,易产生基体干扰和堵塞仪器进样系统。本文改进了传统四酸和五酸体系,采用氢氟酸-硝酸-硫酸敞开酸溶体系,用国家一级标准物质制作标准曲线测定15种稀土元素,方法准确度(ΔlgC)为0.001～0.027。同时改进了偏硼酸锂碱熔法,样品用偏硼酸锂碱熔提取,加入氢氧化钠调节溶液至碱性条件,所测元素与偏硼酸锂共沉淀后过滤分离熔剂,再用硝酸复溶测定15种稀土元素及铌钽锆铪。两种溶样方法的测定值与认定值的相对误差为1.09%～9.30%。将混合酸敞开酸溶法测定稀土元素、偏硼酸锂碱熔法测定铌钽锆铪的结果与其他实验室密闭酸溶法相比,两组数据的相对偏差为0.13%～15.32%。本实验表明,混合酸敞开酸溶法适用于测定地质样品中的稀土元素,偏硼酸锂碱熔法不仅适用于测定地质样品中的稀土元素及铌钽锆铪,也适用于测定如古老高压变质岩石及铝含量高的样品中的铌钽锆铪。 相似文献
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安溪南坑矿区铅锌矿已圈定4个矿体和1个矿化体,受断裂构造控制,呈北东向脉状产于石英斑岩脉外侧的下元古界麻源群变质岩中。近矿围岩蚀变有碳酸盐化、硅化、黄铁矿化,属热液交代-充填型矿床。 相似文献
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The ultramafic massifs of the Serranía de Ronda (namely Ronda, Ojén and Carratraca) are portions of Proterozoic (∼1.2–1.8 Ga) subcontinental lithospheric mantle (SCLM) affected by partial melting and infiltration of melts. The latter of these events was broadly coeval with the tectonic emplacement of the peridotites into the continental crust in the Early Miocene. This resulted in the formation of chromite and Ni-arsenide ores (Cr-Ni) associated with orthopyroxenites and cordieritites. Six zircons recovered from a massive chromitite sample from the Ronda massif yield both concordant and discordant ages between 2309 ± 37 Ma and 109 ± 15 Ma, and δ18O between 8.3‰ and 9.4‰. Two Proterozoic ages obtained for zircons of this population (1815 ± 9 Ma and 1794 ± 17 Ma) are identical, within error, to those of zircons reported previously in the garnet pyroxenites of Ronda (1783 ± 37 Ma). Similarly, concordant Early Jurassic (192 ± 13 Ma) and Cretaceous ages (109 ± 15 Ma) obtained from the core and rim, respectively, of a single zircon from the chromitite are also consistent with the ages (180 ± 5 Ma, 178 ± 6 Ma, and 131 ± 3 Ma) already reported for magmatic zircons from corunudum-bearing garnet pyroxenites in the Ronda massif. The observation that chromitites and garnet-pyroxenites contain similar populations of zircons suggests that the parental melts of chromitites inherited zircons from their protolithic garnet pyroxenites, representing relics of oceanic/arc crust recycled in the mantle. Eleven zircons recovered from a massive cordieritite associated with chromitite in the Ronda massif yield scattered concordant and discordant ages between 568 Ma and 21 Ma, with correspondingly variable δ18O (4.8–13.5‰) and unradiogenic Hf-isotope ratios (εHf(t) from −12.36 to −4.43). The youngest age is concordant at 21.18 ± 0.4 Ma and matches the ages of zircons from the chromitite (weighted average age of 20.4 ± 0.87 Ma, n = 4) and a plagioclasite dyke (scattering between 20.1 ± 0.2 Ma and 17.9 ± 0.1 Ma; n = 11) associated with the Cr-Ni mineralization in the Ojén massif. These zircons show similar unradiogenic Hf-(εHf(t) between −14.5 and −7.6) and heavy O-isotope compositions (δ18O = 11.3–12.4‰). A sample of the massive cordieritite hosting the chromitites contains abundant zircons that yield scattered concordant, sub-concordant and discordant U-Pb ages varying from 33.8 ± 1 Ma to 781 ± 10 Ma; these zircons (n = 21) have variable U-contents (105–13900 ppm) and Th/U ratios (0.003–0.8). On the basis of O- and Hf-isotope compositions, these zircons define three populations independently of their ages: (1) grains with consistent high δ18O (6.1–12.7‰) and negative εHf(t) (from −14.42 to −6.88); (2) grains with high δ18O (7.6–11.1‰) and positive εHf(t) (3.10–4.84); and (3) grains with δ18O < 5.5‰ typical of mantle values. We suggest that zircons from this cordieritite with U-Pb ages older than Miocene are inherited, and were incorporated physically into the SCLM by fluids or melts produced during dehydration-melting of the crustal rocks wrapping the peridotite massifs. The population of Early Miocene zircons found in the chromitites and associated cordieritites and the plagioclasite dyke in the mineralization of the Ojén massif date the crustal emplacement of the peridotites and, therefore, the formation of the Cr-Ni ores. We propose a model in which the unique Cr-Ni mineralizations found in the ultramafic rocks of the Serranía de Ronda were formed as a result of contamination of the SCLM with crustal components. 相似文献
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Polymetallic vein-type Zn-Pb deposits are located in the Xiangxi–Qiandong zinc-lead metallogenic belt (XQMB) of the northwestern margin of the Jiangnan Orogen, South China. Ores are mainly found in fault-bounded quartz veins hosted in the upper part of the Banxi Group that consists of low-grade metamorphic sandstone, siltstone with minor tuff interbeds. The Zn-Pb deposits primarily contain sphalerite, galena, chalcopyrite and pyrite, accompanied by quartz and minor calcite. Zinc, lead, copper, indium and gallium are enriched in these ores. Investigation of the ore fluid reveals low temperature (87–262 °C) with scattered salinity (range from 2.73 to 26.64 wt% NaCleqv.). Hydrogen and oxygen isotopic compositions of fluid inclusions in quartz indicate mixing of magmatic hydrothermal fluid and meteoric water (δ18OH2O SMOW = 0.2‰ to 4.2‰; δDH2O SMOW = −126‰ to −80‰). Carbon and oxygen isotopic composition of carbonate samples indicate the magmatic hydrothermal origin of CO32− or CO2 in ore-forming fluid (δ13CPDB = −6.9‰ to −5.7‰, δ18OSMOW = 11.3‰ to 12.7‰). Sulfur and lead isotopic compositions (δ34SVCDT = 8.8–14.2‰ and 206Pb/204Pb = 17.156–17.209, 207Pb/204Pb = 15.532–15.508, 208Pb/204Pb = 37.282–37.546) demonstrate that sulfur sources were relatively uniform, and low radiogenic lead isotopic compositions indicate that ore metals were derived from a relatively unradiogenic source, probably by mixing of mantle with crust. Therefore, polymetallic vein-type Zn-Pb mineralization in this area probably arose from a magmatic-related hydrothermal system, and the deposition of sulfides occurred in response to cooling and boiling of magmatic hydrothermal fluids (high salinity, high δ18OH2O and δDH2O and metal-bearing), and is mainly the result of emplacement into open space and mixing with meteoric water (low salinity, low δ18OH2O and δDH2O). This study provides direct evidence that magmatism was involved in the ore-forming processes of the low temperature metallogenic district, South China, and it raises awareness about the presence of polymetallic vein-type Zn-Pb deposits in the northwest margin of Jiangnan Orogen and their potential as a source of zinc, copper, indium and gallium. 相似文献
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四川甲基卡矿田是中国乃至于世界上锂矿资源最集中的地区之一,目前运用遥感技术开展甲基卡型锂矿的研究工作尚较为薄弱,文章运用遥感技术在甲基卡特殊地貌区开展找矿填图应用研究,建立了研究区典型岩石及矿物的波谱数据库,总结了研究区黑云母片岩、十字石片岩、十字石堇青石片岩、角岩、二云母花岗岩、含锂辉石伟晶岩、无矿伟晶岩、石英脉、长石斑晶、锂辉石单晶、云母、绿柱石的波谱特征;之后分别基于中等分辨率遥感数据Landsat 8和高空间分辨率遥感数据Geoeye-1进行图像处理和信息提取,开展了地质填图应用初步研究。研究结果表明遥感技术作为一种新兴的技术手段,对甲基卡型锂矿的填图及找矿具有重要的指导意义,可以作为今后地质找矿工作的"先头兵"。 相似文献
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滇东南中三叠统法郎组是重要的含锰地层,前人对其沉积环境的认识却存在着深水浊流沉积和浅水潮坪沉积的争议。本文通过对建水-开远地区典型剖面的研究,认为法郎组为浊积扇沉积。法郎组底部为碳酸盐滑塌沉积、碎眉流沉积与泥岩粉砂岩互层,中上部逐渐由外扇渐变为中扇辫状水道和辫状水道间沉积,顶部为内扇补给水道和溢岸沉积。相对海水深度总体表现为在拉丁早期逐渐加深,到拉丁中晚期有逐渐变浅。锰矿层主要发育在底部的碎屑流沉积中,其彤成可能与拉丁早期相对水深的增高有关。 相似文献
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