新疆罗布泊含钾地层矿物扫描电镜研究

运用扫描电子显微镜对采自ZK1200B钻孔1.12～53.00 m处岩芯的部分样品进行了分析研究。据此,较精确地划分出了4层含钾岩层,发现有钾石盐、光卤石、杂卤石、泻利盐、硫锶钾石、天青石等固体盐类矿物,其中的硫锶钾石和天青石矿物在新疆罗布泊地区属首次发现。钙芒硝岩层中含有硫锶钾石、天青石,推断其锶可能来源于深部地层水（或油田水）的补给,对罗布泊地区钾盐矿的成因研究具有重要意义。     

钾锶矾在我国的首次发现及其找钾意义

发现于四川农乐的钾锶矾,晶体发育完好,(000)解理完整,属于三方晶系,空间群R3m,一轴晶,负光性,Ne=1.549±0.001,No=1.572±0.001。钾锶矾在盐矿床中是后生矿物,其出现可以作为寻找可溶性钾盐矿床的标志。     

Distribution patterns of gypsum and kalistrontite in a dry lake basin of the southwestern Kalahari (Omongwa pan,Namibia)

The deposits of the Omongwa pan, southwestern Kalahari, Namibia, are partly gypsiferous and locally contain small amounts of kalistrontite. The distribution patterns of gypsum (CaSO₄.2H₂O) and kalistrontite (K₂Sr(SO₄)₂) are mainly determined by groundwater depth and by the lithological composition of the deposits. The latter determines the hydraulic conductivity for saturated and unsaturated flow and therefore controls the depth of the interval within the deposits where evaporation and mineral precipitation can take place. Other factors that affect the distribution of the evaporite minerals are the patterns of groundwater flow within the basin and the occurrence of a redistribution of salts during short flooding stages. Gypsum occurs as crystals of four distinct morphological types, which each developed in different conditions: prismatic crystals formed both as subaqueous precipitates and as crystals that developed within the sediment matrix of a brine-saturated surface layer; sub/euhedral tabular crystals formed within brine-filled macropores; hemi-bipyramidal crystals formed in a nearly permanently brine-saturated part of a subsurface horizon (phreatic zone), as the product of recrystallization of an older gypsum occurrence; and lenticular crystals formed by intrasediment growth in the vadose zone. The development of these morphological types of gypsum crystals is marked by differences in the differential inhibition of growth of the various crystal forms. The further growth of lenticular crystals, which are most strongly affected by differential growth inhibition, is still characterized by a difference in degree of inhibition between the {1 11} and {1 03} forms, expressed as a change in orientation of the plane of flattening. Copyright © 1999 John Wiley & Sons, Ltd.