云南镇康芦子园铅-锌矿的成矿年龄

芦子园铅锌矿为保山-镇康地块中一个重要的热液矿床。矿床赋存于早古生代碳酸盐岩中,经人工分选出矿石中的闪锌矿、黄铜矿、与矿石硫化物密切共生的热液石英及石英钾长石脉中的钾长石等共10件单矿物样品,采用Rb-Sr同位素定年分析,获得等时线年龄141.9±2.6 Ma,初始锶同位素组成为87Sr/86Sr(t=141.9 Ma)=0.714 497。揭示成矿作用时代与中特提斯怒江洋闭合时期大致相当,矿石初始锶同位素组成也与保山-镇康地块中燕山期花岗岩初始Sr同位素组成基本一致,指示矿床的成因可能与燕山期岩浆活动有关,是中特提斯怒江洋闭合过程中碰撞造山作用的响应。     

中国云南哀牢山含海蓝宝石伟晶岩的起源和成岩模拟实验研究

The Ailaoshan aquamarine-bearing pegmatites are associated with Proterozoic metamorphic rocks in the southern portion of the Ailaoshan fault-folded complex.The gem-bearing pegmatite mineralization zones of the region occur in areas generally consistent with the regional tectonic trend.The pegmatites are found in metamorphic rocks,migmatites and in the inner/outer contact zones of gneissoid granites. The Rb-Sr isochron drawn for the pegmatites is 26～31 Ma,(i.e.in Himalayan).The homogenization temperatures of melt and liquid inclusions in minerals vary from 185 to 920℃,which are comparable to the inclusions observed in banded migmatites and ptygmatic quartz veins in the surrounding metamorphic rocks. The mineralization fluids of the pegmatite were rich in HCO_3 and CO_2,and their compositional assemblages are comparable to metamorphic fluids.Results of H,O,C,Si etc.isotopic analyses and REE,and Be analyses indicates that the sources of mineralization components that formed the pegmatites are closely associated with metamorphic fluids and the enclosing metamorphic rocks. A pegmatite structure simulation experiment was conducted at high temperature and pressure(840℃and 1,500×105Pa.),with various metamorphic rock samples in a water-rich and volatile-rich environment.When the liquidus was reached,the temperature was gradually decreased at the rate of 5～10℃/day over a time period of three months.SEM energy-dispersive spectrum analyses were performed on the experimental products.A series of pegmatoid textures were observed including zonal texture,megacryst texture,drusy cavities,crystal druses,and vesicular texture along with more than ten types of minerals including plagioclase,microcline,quartz and biotite.Different metamorphic rock melts generated different mineral assemblages.Experiment results revealed that the partial melting of metamorphic rocks could form melts similar to pegmatite magmas. Based upon the geological characteristics,geochemistry,and pegmatite texture simulation experimental results,it is concluded that the mineralization components of Ailaoshan aquamarine-bearing pegmatites came from metamorphic rocks.The petrogenetic model for the origin of pegmatites is related to ultrametamorphism and metamorphic anatexis.     

山西铝土矿Rb-Sr同位素定年

采用Rb Sr全岩与粘土矿物等时线年龄方法测得山西五台剖面 (RS0 1) ,临县剖面 (RS0 2 )和孝义剖面 (RS0 3)的 3个含矿粘土岩的Rb Sr同位素年龄分别为 :316 .9± 1.2Ma ,87Sr/86Sr为 0 .710 5 4± 14 ;315 .5± 1.3Ma ,87Sr/86Sr为 0 .710 86±18;317.3± 1.1Ma ,87Sr/86Sr为 0 .710 5 0± 14。它们代表了铝土矿和含矿系列成矿的同位素年龄 ,相当于晚石炭世早期     

苏北榴辉岩Sm-Nd等时线同位素年龄及地质意义

采用Sm-Nd同位素定年方法，测得江苏北部新沂地区踢球山榴辉岩岩体时代为221.6±8.4 Ma,Sm-Nd年龄被看作为踢球山超高压变质之后板块折返过程中的高压榴辉岩相重结晶阶段年龄。中朝板块与扬子板块碰撞时代主要发生在晚三叠世。     

自动磁力分离仪提纯沥青铀矿

在开展对铀矿床物质成分及矿床成因的研究工作中,需提取一定数量的纯沥青轴矿,供单矿物化学全分析、X 光衍射分析同位素年龄测定、差热分析、热重分析等使用,但分离单矿物费工费时,尤其对小于0.10毫米粒级,常因不易提纯而被丟弃。我们在工作中采用 WCF-2型多用磁性分析仪(北京地质仪器厂制)分离、提纯沥青铀矿取得较好的效果。沥青铀矿单矿物纯度达99%以上,每小时平均可提取纯单矿物0.5—1.0     

水－岩反应的铀系不平衡判别

天然体系中水－岩反应的铀系不平衡判别,是基于水－岩反应使岩石中天然铀衰变系子体核素＾２３４Ｕ,＾２２６Ｒｂ和六价铀的选择性溶失,造成原始放射性平衡遭到不同程度破坏,因而可利用现今测得的岩石中３组核素放射性活度比值Ａ（＾２３４Ｕ）／Ａ（＾２３８Ｕ）,Ａ（＾２３０Ｔｈ）／Ａ（＾２３４Ｕ）和Ａ（＾２２６Ｒａ）／Ａ（＾２３０Ｔｈ）反演判别该岩石曾经历了近代水－岩反应的大致强度和出现,持续时间,这是近十余年     

某古岩溶铀矿床中铀,钼,铼的赋存状态

本文采用电子探针、透射电镜和化学物相法,查明某古岩溶铀矿床中铀主要呈显微和超显微状沥青铀矿、铀石,其次呈分散吸附状和铀酰（次生）矿物形态存在;钼主要呈蓝钼矿、钼钙矿、钼华、钼铅矿等氧化物,其次呈胶硫钼矿等形态存在;铼主要呈吸附状,其次可能在黄铁矿中呈二硫化物包裹体形态产出。最后讨论了该三个元素赋存状态与该铀矿床形成地球化学环境之间的关系。     

我国最大古岩溶型铀矿床成因的同位素地球化学研究

据对某大型古岩溶型铀矿床中铀－铅同位素体系及硫、碳、氧、氢同位素组成的研究结果，表明该矿床成矿物质源自矿区众多地层，成矿流体的变质水和古岩溶水（古大气降水）的混合水；成矿经历了古岩溶铀淋积富集，燕山早、晚期构造运动促使两次含铀热水溶液改造、叠加成矿（１３５～１１９。６５Ｍａ），成矿作用与古岩溶和区域地质构造演化密切相关，属古岩溶型热造铀矿床。     

两花岗岩体接触带铀系核素迁移的初步模拟

随着世界各国大力发展核电，放射性废料的安全处置已成为当今研究热点和前沿学科。高放废物深地质处置的安全性主要取决于处置库内放射性核素向生物圈的迁移程度。在侵入岩中，放射性核素主要是通过地下水沿岩石孔隙从处置库向生物圈迁移的。为了理解放射性核素在花岗岩体接触带的迁移行为，本文根据两花岗岩体接触带中样品的铀系核素放射性活度比值（^234U/^238U,^230Th/^234U,^226Ra/^230Th,^230Th/^238U)，利用 α-反冲（弹射）作用引起的放射性不平衡理论，计算了铀系核素子体^234U,^230Th,^226Ra在后期地下水的作用下在花岗岩体接触带及其裂隙内的迁出率、迁入率、并进行了质量平衡的计算。结果表明，经α-反冲作用进入流体的核素的迁出率要远大于因核素自然衰变的消亡率；裂隙充填物及裂隙能阻滞大量核素的迁移，其沉淀核素来自接触带花岗岩；花岗岩能强烈阻滞核素的迁移，可作为阻止放射性核素从核废料地下处置库向外迁移的有利天然屏障。     

我国再次发现硒铅矿

本文报道了我国再次在华南6217花岗岩型铀矿床中发现硒铅矿，测定了该矿物的化学成分，结合该铀矿床的矿物组合和成矿物理化学条件，讨论了硒铅矿的生成环境。