我国钾盐找矿规律新认识和进展

本文通过对比研究国内外钾盐矿床成钾特征,总结出了我国海、陆相成盐盆地和成盐成钾特性:成盐具有多期性、成盐时代差异性、成盐作用迁聚性、物质成分多样性、后期盐盆地的变动性和多液态矿的特点;厘定了3个盐类成矿域和1个成矿带;提出了我国找钾策略——以海相蒸发盐盆地为主攻方向、兼探陆相盐湖及含钾地下卤水;提出了我国主要的古代盐盆地多产于“准克拉通(陆块)”,特别是海相盐盆地均发育于前寒武纪为基底的陆块中,以及钾盐沉积于构造稳定区中相对活动的亚稳定区和在构造亚稳定区中聚集于相对稳定区的新认识;发展了适合中国地质特点的找钾理论认识,有效地推动了油钾兼探工作.发现滇西南—羌北中上侏罗统若干钾盐显示,特别是指导和部署滇西南深部侏罗纪找钾,并取得超常规的进展;进一步缩小陕北奥陶系找钾包围圈;引领“油钾兼探”实施,实现了塔里木盆地库车凹陷古近系找钾的重大实质性进展;在柴达木盆地西部发现新的早第四纪富钾层位;指导和取得青藏高原特种盐湖综合找锂、钾和评价的重要进展,新发现一批大中型锂、钾特种盐湖(特别是多格错仁大型锂、硼(钾)盐湖)和取得综合利用工艺新进展.     

用磁化率各向异性研究构造变形的几个问题

本文讨论了用磁化率各向异性研究构造变形时应注意的几个问题。介绍用磁化率各向异性研究岩石变形的限制条件,待解决的问题及应用前景。同时提出了地质历史时期岩石脆性破裂前的塑性变形可能会引起磁化率各向异性的变化及岩石中不同期,不同种类的磁性矿物的共存可能是影响磁化率椭球与应变椭球对应关系的是一个重要因素的观点。     

锂能源金属矿产基地深部探测技术示范项目进展

锂作为21世纪的能源金属,已经并仍将在未来的能源结构中占有重要地位.中国锂资源对外依存度将近75％,采矿深度普遍不超过300 m,深部探矿势在必行.为提高中国锂矿深部探测能力,储备一批深部探测技术方法,2017年国家重点研发计划设立锂能源金属矿产基地深部探测技术示范项目.项目由中国地质科学院矿产资源研究所牵头,共十余家...     

西藏北羌塘盆地多格错仁地区盐泉水化学特征及其物质来源

西藏北羌塘盆地是我国侏罗系海相找钾的主要远景区之一,在多格错仁地区发育有一系列具有明显的含钾异常的现代盐泉,研究这些盐泉水的物质来源具有重要的找钾意义和科学价值。野外采集了40个盐泉水的样品,并在室内测定了其化学组分、δ34 S和87 Sr/86 Sr。分析结果显示,盐泉水具有富Na+、Ca2+、K+、Cl-,贫Mg2+、SO2-4、HCO-3的特征,其Cl-含量约占矿化度的50%以上,并与矿化度呈正相关关系,Na+、Ca2+、K+浓度也与矿化度呈正相关关系。根据盐泉水的钠氯系数和溴氯系数判断,盐泉水属于地层溶滤水;源泉河、东温泉、多格错仁湖南岸3处的盐泉水具有与侏罗纪海水相一致的硫同位素特征,表明其在地下运移时,很可能溶解了地层中的石膏沉积;盐泉水的1000/Sr-87Sr/86Sr投点图说明各处盐泉水在地下的运移路径和形成过程明显不同;盐泉水的87Sr/86Sr值与其区域背景值对比显示,盐泉水在形成过程中可能溶滤了夏里组二段和索瓦组一段中的蒸发岩,区内夏里组和索瓦组最有可能蕴含有成盐成钾层系。     

H2O-H2SO4 system in Venus' clouds and OCS, CO, and H2SO4 profiles in Venus' troposphere

A coupled problem of diffusion and condensation is solved for the H2SO4-H2O system in Venus' cloud layer. The position of the lower cloud boundary and profiles of the H2O and H2SO4 vapor mixing ratios and of the H2O/H2SO4 ratio of sulfuric acid aerosol and its flux are calculated as functions of the column photochemical production rate of sulfuric acid, phi H2SO4. Variations of the lower cloud boundary are considered. Our basic model, which is constrained to yield fH2O (30 km) = 30 ppm (Pollack et al. 1993), predicts the position of the lower cloud boundary at 48.4 km coinciding with the mean Pioneer Venus value, the peak H2SO4 mixing ratio of 5.4 ppm, and the H2SO4 production rate phi H2SO4 = 2.2 x 10(12) cm-2 sec-1. The sulfur to sulfuric acid mass flux ratio in the clouds is 1 : 27 in this model, and the mass loading ratio may be larger than this value if sulfur particles are smaller than those of sulfuric acid. The model suggests that the extinction coefficient of sulfuric acid particles with radius 3.7 micrometers (mode 3) is equal to 0.3 km-1 in the middle cloud layer. The downward flux of CO is equal to 1.7 x 10(12) cm-2 sec-1 in this model. Our second model, which is constrained to yield fH2SO4 = 10 ppm at the lower cloud boundary, close to the value measured by the Magellan radiooccultations, predicts the position of this boundary to be at 46.5 km, which agrees with the Magellan data; fH2O(30 km) = 90 ppm, close to the data of Moroz et al. (1983) at this altitude; phi H2SO4 = 6.4 x 10(12) cm-2 sec-1; and phi co = 4.2 x 10(12) cm-2 sec-1. The S/H2SO4 flux mass ratio is 1 : 18, and the extinction coefficient of the mode 3 sulfuric acid particles is equal to 0.9 km-1 in the middle cloud layer. A strong gradient of the H2SO4 vapor mixing ratio near the bottom of the cloud layer drives a large upward flux of H2SO4, which condenses and forms the excessive downward flux of liquid sulfuric acid, which is larger by a factor of 4-7 than the flux in the middle cloud layer. This is the mechanism of formation of the lower cloud layer. Variations of the lower cloud layer are discussed. Our modeling of the OCS and CO profiles in the lower atmosphere measured by Pollack et al. (1993) provides a reasonable explanation of these data and shows that the rate coefficient of the reaction SO3 + CO --> CO2 + SO2 is equal to 10(-11) exp(-(13,100 +/- 1000)/T) cm3/s. The main channel of the reaction between SO3 and OCS is CO2 + (SO)2, and its rate coefficient is equal to 10(-11) exp(-(8900 +/- 500)T)cm3/s. In the conditions of Venus' lower atmosphere, (SO)2 is removed by the reaction (SO)2 + OCS --> CO + S2 + SO2. The model predicts an OCS mixing ratio of 28 ppm near the surface.     

Spectroscopy of Mars from 2.04 to 2.44 micrometers during the 1993 opposition: absolute calibration and atmospheric vs mineralogic origin of narrow absorption features

We present moderate-resolution (lambda/delta lambda = 300 to 370) reflectance spectra of Mars from 2.04 to 2.44 micrometers that were obtained at UKIRT during the 1993 opposition. Seven narrow absorption features were detected and found to have a Mars origin. By comparison with solar and Mars atmospheric spectra, five of these features were attributed all or in part to Mars atmospheric CO2 or CO(2.052 +/- 0.003, 2.114 +/- 0.002, 2.150 +/- 0.003, 2.331 +/- 0.001, and 2.357 +/- 0.002 micrometers). Two of the bands (2.331 +/- 0.001 and 2.357 +/- 0.002 micrometers) appear to have widths and depths that are consistent with additional, nonatmospheric absorptions, although a solar contribution cannot be entirely ruled out. Two other weak bands centered at 2.278 +/- 0.002 and 2.296 +/- 0.002 micrometers may be at least partially mineralogic in origin. The data provide no conclusive identification of the mineralogy responsible for these absorption features. However, examination of terrestrial spectral libraries and previous moderate spectral resolution mineral studies indicates that the most likely origin of these features is either (bi)carbonate or (bi)sulfate anions in framework silicates or (Fe, Mg)-OH bonds in sheet silicates. If the bands are caused by phyllosilicate minerals, then an explanation must be found for the extremely narrow widths of the cation-OH features in the Mars spectra as compared to terrestrial minerals.     

白铁矿转变和黄铁矿前身物的岩相学鉴定

利用综合的关于由白铁矿合成的黄铁矿，以及由白铁矿和磁黄铁矿形成的黄铁矿的天然样品的特征，就能识别薄片中由白铁矿转变和由磁黄铁矿氧化淋滤而形成的黄铁矿。由白铁矿转变而形成的黄铁矿的特征有：其孔隙空间约为实际矿物的２％，孔隙内无副产物充填，光学各向异性（暗绿至暗红色）和呈相对于白铁矿母晶具两个取向的他形子体黄铁矿晶畴。由磁黄铁矿氧化溶解（与淋滤作用相反）形成的黄铁矿或白铁矿的特征有：孔隙空间达实际矿物     

西藏高原盐湖的构造地球化学和生物学研究

按盐湖的盐类组分和地质构造背景差别,将其概分为普通盐湖和特种盐湖。前者产于克拉通、地台等稳定构造区;后者分布于活动构造区,包括大陆边缘火山弧后盆地或陆-陆碰撞带,板块转换带后盆地。西藏高原盐湖产于陆-陆碰撞带;盐湖硼和稀碱元素主要来自高原深部壳层重熔岩浆,热水成为输入盐湖中的重要载体;盐湖水化学类型和组分特征控制了不同的成矿专属性。笔者等对藏北高原作了大范围盐湖生物概查,在调查的125个湖泊中,确定30个盐湖有卤虫繁衍。在羌塘北部21个湖泊中,已鉴定出浮游植物95种,主要种类有Gloeothece linearis,Doctylococcopsis rhaphichoidesHansg,Chroococcus minor,Naviculasp.,Cymbella pusilla,Dunaliellasalina,Chlorella rulgaris,Diatoma elongatum。浮游动物共鉴定出原生动物16种,主要种类有Voriticellaspp.,Epistylisspp.,Keratella quadrata,Daphniopsis tibetana,Artemiasp.等。     

夏威夷玄武岩源区深海沉积物的铪（Hf）同位素证据

全球比例尺上表面固定的热点位置和火山对应于地下软流圈的恒定漂移速率表明它们产生于地幔深处。大洋岛玄武岩（ＯＩＢｓ）的３Ｈｅ／４Ｈｅ比值高于洋中脊玄武岩（ＭＯ＿ＲＢｓ）的３Ｈｅ／４Ｈｅ比值,反映ＯＩＢ地幔中（Ｕ Ｔｈ）／３Ｈｅ比值相对较低,这有可能表明下地幔比上地幔去气少。这种诠释为地幔对流模式提供了一重要限制,与ＯＩＢｓ源区是次生海洋岩石圈（其上物质在很大程度上被预料是去气）的证据相抵触。痕量元素丰度与Ｐｂ、Ｎｄ、Ｈｆ同位素比值都表明原始地幔并不是ＯＩＢｓ的主要源区。锇同位素的测量表明,一旦一种成分…