He-Ar-S-Pb Isotopic Compositions of Pyrite: Constraints on the Source of Ore-forming Materials of the Chengchao Skarn Iron Deposit, SE Hubei Province, Eastern China

The Chengchao iron deposit,the largest high-grade skarn iron deposit in southeastern Hubei Province,contains considerable amounts of magnetite and by-product anhydrite.To obtain better understanding of the ore-formation process,this study carried out He-Ar-S-Pb multi-isotopic analyses on the pyrites formed during two stages of mineralization.The results indicate that the δ~(34)S values(ranging from 14.0‰ to 17.6‰) of pyrites formed from the two stages have no obvious differences,suggesting that they were not derived from a single magmatic sulfur source.The δ~(34)S values of anhydrite mostly range from 21.9‰ to 28.4‰,similar to that of the Middle Triassic sedimentary anhydrite in the Middle-Lower Yangtze River metallogenic belt(MLYRB).The Pb isotopic compositions of the pyrites of both stages are homogeneous,with values of ~(208)Pb/~(204)Pb,~(207)Pb/~(204)Pb,and~(206)Pb/~(204)Pb being 38.006-38.257,15.523-15.556,and 17.806-18.052,respectively,indicating a mixed crust-mantle source.The He-Ar results exhibit different compositions of the two stages:the ~3He/~4He(R/Ra) and ~(40)Ar/~(36)Ar values for the early-stage pyrite are 0.46-0.63 and 311-322,respectively,whereas the values for late-stage pyrite are 0.23-0.34 and 305-361,respectively.Both stages of pyrites indicate the multiple sources of the ore-forming fluids,with decreasing amount of magmatic water and increasing amount of modified meteoric water(MASW) during fluid evolution.The Triassic evaporites played an important role in the mineralization process.     

The crystal structure of pearls and related shellfish''s shells

In this article we explored the crystal structure of a few pearls and shellfish's shell of fresh water and sea water, and found that pearls and nacreous layer (perhaps and prismatic layer) of shells are all the same: CaCO3, orthorhombic system, aragonite structure and the value of lattice spacings are almost identical. This shows that the pearls of fresh water and sea water are all the same in nature.     

中国关键矿产现状、研究内容与资源战略分析

关键矿产是指当前和未来相当长时间内现代社会可持续发展所必须但在稳定供给方面又存在高风险的金属矿产资源,主要包括稀土、稀有、稀散金属和部分稀贵金属矿产资源。关键金属由于具有极度耐高温、耐腐蚀、光学和电磁性质优良等物理化学特性,是航空航天、电子信息、高端制造、新能源、新材料等重点领域和新兴产业发展的重要物质基础。由于高科技和新兴产业的快速发展,未来几十年全球对关键矿产的需求将迅猛增长, 供需矛盾将日益突出,可以说,未来国际矿产资源和科技的竞争在很大程度上将集中于对关键矿产资源的博弈。过去十余年来,中国一直为矿产资源第一消费大国,在未来较长时间内对关键矿产的需求量仍将持续增长。面对国内强劲需求和严峻的国际资源竞争态势, 迫切需要加大科技创新力度, 持续开展关键矿产成矿基础理论和综合利用技术研究。中国的关键矿产种类丰富,成矿过程中关键金属元素的地球化学行为和成矿机制复杂,矿化类型多样,空间分布成群成带,资源潜力大。未来要聚焦关键金属元素超常富集基础理论,重点解决好三方面的科学问题:(1)地球多圈层相互作用对关键金属元素富集的控制作用;(2)关键金属元素富集机制与成矿规律;(3)关键金属元素赋存状态与分离技术。该文立足于国际关键矿产资源形势,提出了全面提升我国对关键矿产资源的管理、勘查、开发和综合利用水平及保障关键矿产资源安全的思考和建议。     

上甸子秋冬季雾霾期间气溶胶光学特性

通过对2004年秋冬季(9—12月)4次雾霾天气过程在京、津背景地区——北京上甸子大气本底污染监测站观测的大气气溶胶光学特性的分析,发现该地区气溶胶光学特性受天气过程的影响很大。4次雾霾影响时段,平均气溶胶散射系数σ_(sca)、吸收系数σ_(abs)和单次散射反照率ω都远高于雾霾过后清洁时段的数值,其中气溶胶ω在雾霾影响时段为0.94～0.97,雾霾后为0.84～0.86,平均减小了0.1左右,表明雾霾天气有利于气溶胶的累积和生成。相比于光吸收性气溶胶,雾霾天气对光散射性气溶胶的增加更为有利,反映了二次气溶胶的产生及其对消光的贡献可能有较大增加。     

云南墨江金矿床含金石英脉中流体包裹体的地球化学特征及其意义

本文对含金石英脉中流体包裹体进行了研究 ,结果表明主阶段石英中流体包裹体均一温度为 1 2 2～ 30 6℃ ,存在两个区间分别为 1 30～ 2 2 0℃、2 5 0～ 2 70℃ ,均一温度在水平和垂直方向存在规律性变化 ,盐度主要集中在3%～8%NaCl范围内 ,密度为 0 .80～ 0 .95g/cm3 ,流体包裹体具有相对稳定的气液比 ,流体包裹体气液相成分与典型的岩浆水和大气降水不同。结合氢氧锶和稀有气体同位素研究 ,认为墨江金矿成矿流体曾发生过部分地幔流体、大气降水等多种类型水不充分的混合 ,水岩反应和多种流体混合可能为墨江金矿矿质迁移沉淀主要机制。结合哀牢山金矿带成矿流体类似性和流体包裹体特征分析认为墨江金矿深部可能存在有含金石英脉型矿体。     

南昆线南那段红土类型划分及微观特征研究

本文在野外调查的基础上,根据母岩岩性和红土化作用程度对南那段红土作了初步分类,并对几种主要的红土的物质成分和微观结构特征进行了研究。     

Characteristics of the mantle source region of sodium lamprophyres and petrogenetic tectonic setting in northeastern Hunan,China

~~Characteristics of the mantle source region of sodium lamprophyres and petrogenetic tectonic setting in northeastern Hunan,China~~     

云南省墨江金矿床成矿时代探讨

在系统研究墨江金矿床地质事件的基础上 ,以富金石英脉中的石英流体包裹体为测定对象 ,获得Rb_Sr等时线年龄为 (1 35± 3)Ma。上三叠统地层中含金石英脉旁侧发育的铬水云母脉K_Ar法年龄为 (1 0 9.5± 1 .7)Ma。结合前人的研究资料 ,认为墨江金矿床经历了多期次成矿作用 ,其中构成本矿床的主体———富金石英脉的形成时代可能为 1 35～ 90Ma,相当于燕山晚期     

Geological and Geochemical Characteristics of Early Cretaceous Mafic Dikes in Northern Jiangxi Province, SE China and Their Geodynamic Implications

The development of Early Cretaceous mafic dikes in northern and southern Jiangxi allows an understanding of the geodynamic setting and characteristics of the mantle in southeast China in the Cretaceous. Geological and geochemical characteristics for the mafic dikes from the Wushan copper deposit and No. 640 uranium deposit are given in order to constrain the nature of source mantle, genesis and tectonic implications. According to the mineral composition,the mafic dikes in northern Jiangxi can be divided into spessartite and olive odinite types, which belong to slightly potassium-rich calc-alkaline lamprophyre characterized by enrichment in large ion lithophile elements (LILE) and light rare earth elements (LREE), large depletion in high strength field elements (HSFE) and with negative Nb, Ta and Ti anomalies, as well as 87Sr/86Sr ratios varying from 0.7055 to 0.7095 and 143Nd/r44Nd ratios varying from 0.5119 to 0.5122.All features indicate that the magma responsible for the mafic dikes was derived mainly from metasomatic lithosphere mantle related to dehydration and/or upper crust melting during subduction. Differences in geochemical characteristics between the mafic dikes in northern Jiangxi and the Dajishan area, southern Jiangxi were also studied and they are attributed to differences in regional lithospheric mantle components and/or magma emplacement depth. Combining geological and geochemical characteristics with regional geological history, we argue that southeast China was dominated by an extensional tectonic setting in the Early Cretaceous, and the nature of the mantle source area was related to enrichment induced by asthenosphere upwelling and infiltration of upper crust-derived fluids responding to Pacific Plate subduction.     

卫星热红外观测进行地震预报的可能性分析

阐述了低空大气卫星热红外增温的理论基础，及与其他异常的关系。简述了地震前低空大气卫星热红外增温的普遍性，卫星热红外观测技术的特点和问题，及利用低空大气卫星热红外增温预报地震的可能性。