应用ASTER数据提取矽卡岩型锡矿蚀变遥感异常信息——以滇东南马关都龙锡矿为例

运用多光谱遥感数据进行矿化蚀变信息提取,对圈定找矿预测区具有重要意义.采用ASTER数据及其矿化蚀变信息提取原理,对滇东南马关都龙锡矿含矿岩体分布区分别提取了方解石化、白云岩化、绿泥石化等3类蚀变遥感异常信息.所提取的蚀变异常与野外调查发现的矿化点吻合性好,蚀变信息可靠,对指导找矿有较好的效果,为该地区矿产资源潜力评价...     

基于城乡一体化的"现代地籍"变更研究

城乡一体化“现代地籍”建设是我国现阶段乃至今后地籍工作的一个长期目标和任务,而地籍变更是日常地籍管理工作中的重要部分.本文从城乡一体化“现代地籍”管理方式的角度,探讨了有别于传统方式的现代地籍变更模式,并详细介绍了“现代地籍”变更中的权属变更、地类变更和历史回溯.     

Tourmaline geochemistry and δ<Superscript>11</Superscript>B variations as a guide to fluid–rock interaction in the Habachtal emerald deposit,Tauern Window,Austria

Tourmalines from the Habachtal emerald deposit in the Eastern Alps formed together with emerald in a ductile shear zone during blackwall metasomatism between pelitic country rocks and a serpentinite body. Electron microprobe and secondary ion mass spectrometric (SIMS) analyses provide a record of chemical and B-isotope variations in tourmalines which represent an idealized profile from metapelites into the blackwall sequence of biotite and chlorite schists. Tourmaline is intermediate schorl-dravite in the country rock and become increasingly dravitic in the blackwall zones, while F and Cr contents increase and Al drops. Metasomatic tourmaline from blackwall zones is typically zoned optically and chemically, with rim compositions rich in Mg, Ti, Ca and F compared with the cores. The total range in δ¹¹B values is −13.8 to −5.1‰ and the within-sample variations are typically 3–5‰. Both of these ranges are beyond the reach of closed-system fractionation at the estimated 500–550°C conditions of formation, and at least two boron components with contrasting isotopic composition are indicated. A key observation from tourmaline core analyses is a systematic shift in δ¹¹B from the country rock (−14 to −10‰) to the inner blackwall zones (−9 to −5‰). We suggest that two separate fluids were channeled and partially mixed in the Habachtal shear zone during blackwall alteration and tourmaline-emerald mineralization. A regional metamorphic fluid carried isotopically light boron as observed in the metapelite country rocks. The other fluid is derived from the serpentinite association and has isotopically heavier boron typical for MORB or altered oceanic crust. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

熔融玻璃片制样-X射线荧光光谱测定页岩中主量元素

熔融片法制样,用X射线荧光光谱法测定页岩样品中硅、铝、铁、钙、钾、镁、钠7个主量元素,以页岩、岩石、水系沉积物、土壤国家一级标准物质作为校准样品,使用理论α系数和经验系数相结合的方法校正基体效应。方法精密度(RSD,n=12)≤1.50%。分析结果与化学法进行对照基本一致。     

原子荧光光谱法测定土壤和水系沉积物国家标准物质中砷

用王水浸提法和硝酸-高氯酸-氢氟酸混合酸消解法处理样品,原子荧光光度光谱法测定土壤和水系沉积物国家标准物质样品中的砷。方法检出限为0.02 mg/kg。两种前处理方法砷的测定值与标准值相符,均可以满足土壤和水系沉积物样品中砷含量的测定要求。单纯测定样品中砷含量时,王水浸提法更好;如果在测定砷同时还要测定其他元素,则可以选用混合酸消解法。     

氢化物发生-原子荧光光谱法测定三氧化二锑中锡

500℃时在锌粉、氯化铵存在下,锑以三氯化锑形式被挥发除去,锡与锌形成锌-锡合金留在残渣中,从而消除锑对锡的干扰。在10%(体积分数)的盐酸介质中,硼氢化钾将锡(Ⅱ)还原成四氢化锡,用氢化物发生-原子荧光光谱法测定锡的荧光强度。方法检出限为0.20 mg/kg,精密度(RSD,n=7)为3.73%,回收率为91.0%~104.5%。     

X射线荧光光谱法同时测定钛精矿中主次量组分

采用铁矿标准样品和高纯二氧化钛混合配制钛精矿的校准样品,X射线荧光光谱法同时测定钛精矿中氧化镁、三氧化二铝、二氧化硅、磷、硫、氧化钙、二氧化钛、五氧化二钒、锰、铁等主次量成分,并对熔剂选择、熔融条件、钒Kα峰位确定及基体效应校正等进行了探讨。测定结果与标准样品标称值吻合,相对标准偏差(RSD,n=7)除低含量的磷、硫外均在5%以下,能满足钛精矿的检测需要。     

氢化物发生-原子荧光光谱法测定铜矿石中的砷锑铋

样品经王水溶矿分解,在氨水存在下,以Fe3+作共沉淀剂分离铜后,用氢化物发生-原子荧光光谱法测定铜矿石中的砷、锑、铋。方法检出限为砷0.19μg/g、锑0.052μg/g、铋0.049μg/g;精密度(RSD,n=10)为砷5.87%、锑7.58%、铋2.42%。     

黑龙江东宁县金厂金矿围岩蚀变和成矿年代学特征

金厂金矿床位于黑龙江省东宁县境内,构造上位于显生宙兴蒙造山带东端,隶属松辽地块.由于缺乏精确可靠的成矿时代和深入的热液蚀变研究,导致前人对该矿床的类型存在不同认识.为深入认识该矿床的类型和形成时代,文章对矿区18#矿体的7个钻孔岩心进行了详细的热液蚀变矿物组合分带和成矿时代研究.结果表明,该矿体在水平方向上和垂向上均存在较为明显的蚀变分带现象;从底部到顶部分别发育钾长石化带、绢英岩化带和青磐岩化带.该分带现象与典型的斑岩型矿床的垂向蚀变分带特征一致,暗示该矿床应为斑岩型;黄铁绢英岩化花岗岩和花岗斑岩脉中的绢云母单颗粒Rb-Sr同位素测年结果分别为(107±5) Ma和(110±3 )Ma,表明成矿时代发生在110 Ma左右.这与花岗斑岩脉中锆石获得的(113±2)Ma 的U-Pb年龄一致,进一步支持该矿床类型为斑岩型金矿的结论.根据目前矿区矿体剥蚀情况来看,斑岩体尚未出露,深部仍有很大的找矿前景.     

Neoproterozoic hydrothermally altered basaltic rocks from Rajasthan, northwest India: Implications for late Precambrian tectonic evolution of the Aravalli Craton

The isolated volcano-sedimentary sequences of the Punagarh and Sindreth Groups occur along the western flank of the Delhi Fold Belt in northwest India, and include mafic rocks (pillow basalts and dolerite dykes) that are dominantly olivine tholeiites with minor quartz-normative and alkali basalts. Sindreth samples appear to have higher primary TiO₂ and P₂O₅ abundances relative to those from Punagarh. Both suites of mafic rocks show variable, but profound hydrothermal alteration effects, with loss on ignition (LOI) values up to 10.3 wt.%, and extensive secondary minerals including albite, sericite, chlorite and calcite. Despite this, there is excellent preservation of magmatic textures, but there has been extensive albitization of plagioclase phenocrysts, a hallmark of hydrothermal alteration processes in oceanic crust. Supporting evidence for such hydrothermal alteration comes from correlations of LOI abundances with CaO/Na₂O, and evidence for U mobility is apparent on diagrams of Nb/Th vs. Nb/U. Felsic volcanic rocks (rhyolite, dacite) interlayered with the Sindreth basalts yield U–Pb zircon ages (TIMS method) between 761 ± 16 and 767 ± 3 Ma, which we interpret as representing the time of primary magmatic activity. We infer that the volcano-sedimentary rocks of the Punagarh also formed at this time, on the basis of similarities in lithology, stratigraphy, field relations and geochemistry. Intermediate granitoid rocks yield older U–Pb ages of 800 ± 2 and 873 ± 3 Ma, which we correlate with the post-Delhi Supergroup Erinpura Granites. Taken together, the features of the Punagarh and Sindreth Groups are consistent with their formation in a back-arc basin setting. Their coevality with other magmatic systems in NW India (Malani Igneous Suite), the Seychelles and Madagascar, for which a continental arc setting has also been proposed, supports the notion of an extensive convergent margin in western Rodinia at 750–770 Ma.