Magma type and genesis of the basic-ultrabasic layered intrusions in Panzhihua-Xichang area,Southwest China

The layered intrusions in the Panzhihua-Xichang area may be grouped into two types: basic rock masses represented by the Panzhihua rockbody and basic-ultrabasic rock masses represented by the Hongge rockbody. Their major difference lies in that the former has poorly developed ultramafic facies, while the latter is characterized by well developed mafic facies and ultramafic facies. There exists apparent rhythmic stratification in the rock masses, which can be basically divided into four grades in terms of superimposition relationship and multicycle characters. Both direct and indirect evidence suggest that the magma responsible for the layered intrusions in this area should be a transition-type alkaline olivine basalt magma derived directly from partial melting of the upper mantle. In rhythmic cycles of various grades, the magmatic evolution is characterized obviously by periodicity and early enrichment of Fe and Ti, which is evidently different from the evolution of the Skaergaard magma in which Fe and Ti are enriched at the late stage. The FCA diagram can be used to describe the unique evolutionary trend of magma in this area. It is demonstrated in this diagram that the enrichment of Fe and Ti is consistent with the increase of basicity. In the upper magmatic chamber, the evolutionary trend of magma is conditioned by the difference in pressure, and this enables magma to form different types of rock assemblage. In the Fo-Di-An system, when the pressure exceeds 5 x 18⁸ Pa, forsterite is incompatible with anorthite, and the rock facies sequence of Hongge type might form; when the pressure is lower than 5 x 10⁸ Pa, forsterite can coexist with anorthite, and the rock facies sequence of Panzhihua type is likely to form if the magma is relatively rich in Mg and Fe components.     

Preparation and After-Treatment of BaMgAl10 O17 ：Mn^2＋

INTRODUCTION The properties of phosphor usedin a plasma dis-play panel (PDP) affect the performance of the PDP(Okazaki et al .,2000 ; Rao and Devine ,2000) . Theluminescent properties of the phosphor are decided bythe morphology ,particle size and size distribution ofthe powder ,sothe requirements for the powder mor-phology are high in a color PDP which belongs to ahigh resolution display apparatus (I m et al .,2005 ;Yang et al ., 2005) . Studies have shown that withsmall particle si…     

Study on the geochemical characteristics of arc-volcanic rocks in the Chiang Rai-Lampang belt of northern Thailand

On the basis of the petrographic characteristics, rock assemblages, petrochemistry, REEs, trace elements and geotectonic settings, the authors described the characteristics of continental marginal arc-volcanic rocks in the Late Permian-Early Triassic (P2-T1) volcanic rocks distributed on the eastern side of the ocean-ridge/oceanic island basalts in the Chiang Mai belt. The volcanic rock assemblage is basaltic andesite-andesite-rhyolite. The volcanic series is dominated by the calc-alkaline series, with the tholeitic series coming next. The chemical composition of the volcanic rocks is characterized by high Al2O3; the REE distribution patterns are of the LREE-enrichment rightward incline type; the large cation elements are highly enriched, and the volcanic rocks are generally enriched in U and Th and depleted in Ti, Cr and P. The petrochemical plot falls within the field of island-arc volcanic rocks, in consistency with the projected points of continental marginal arc-volcanic rocks in the Lancangjiang belt. These continental mar-ginal arc-volcanic rocks, together with ocean-ridge/oceanic island-type volcanic rocks in the Chiang Mai belt, con-stitute the ocean-ridge volcanic rock-arc magmatic rock belts distributed in pairs, indicative of eastward subduction of the oceanic crust in the Chiang Mai belt. This result is of great importance in exploring the evolution of the pa-leo-Tethys in the Chiang Mai belt.     

库车坳陷下侏罗统沉积特征及砂体展布

库车坳陷位于塔里木盆地北部，北缘是南天山山前断裂带，南缘是塔北隆起，呈NEE向展布，东西长250km，南北宽20－60km，面积约21170km^2。下侏罗统自下而上发育阿合组、阳霞组。对吐格尔明、克孜勒努尔、库车河剖面及依南2井岩芯观察发现，阿合组和阳霞组按其岩性特征均可以划分为5个岩性段，各个岩性段在全具有对比性。还可分出4类和17个亚类岩相。阿合组细砂岩以上的粗碎屑岩含量为80％以上；阳霞组细砂岩以上的碎屑岩含量为50％－60％。砂岩厚度占总地层厚度的50％－60％以上，是油气勘探的重要目的层系。以吐格尔明剖面为代表的依南2井以东地区的阿合组和阳霞组岩矿特征基本相似，以克孜勒努尔地区为代表的依南2井以西地区有较大差异，即阳霞组长石含量几乎为零。两区共同点是以岩屑砂岩为主，成分成熟度低，结构成熟度中等，岩屑含量较高。从岩性组合、沉积构造、微观岩石成分、结构和砂体形态等方面的综合分析认为，辫状三角洲沉积体系是该区阿合组和阳霞组的主要沉积体系。阿合组砂体纵向上以多个辫状三角洲平原上的辫状分流河道砂岩加积复合为主，横向上指状镶嵌叠置呈东西向展布。阳霞组第3岩性段砂体纵向上以多个辫状三角洲前缘上的水下辫状分流河道砂岩加积复合为主，横向上指状镶嵌叠置也呈东西向展布。第2、4、5岩性段砂体以河道滞流砂岩侧砂为主，横向叠瓦状叠置呈东西向展布。     

吉林露水河硅藻土在煅烧中的结构及性能的变化

应用X射线衍射、红外光谱分析、扫描电镜及化学分析方法对吉林露水河硅藻土在煅烧中的结构及性能的变化进行研究，结果表明：高温时蛋白石转变成方英石，激烈的相变温度为1160℃左右；当温度在1100℃～1200℃时，硅藻的微孔开始阻塞或消失，并出现开裂现象，硅藻的结构变得模糊，但硅藻仍保持其外形；室温～600℃，比表面积逐渐增加，600℃～1200℃比表面积则减少；室温～700℃时，pH值逐渐减小，700℃～1200℃时，pH值则逐渐增加。     

单道扫描电感耦合等离子体发射光谱法测定地质样品中的微量稀土元素

采用Na_2O_2熔融矿样,水提取,加三乙醇胺、EGTA做掩蔽剂。经氢型阳离子交换树脂交换分离富集稀土元素,由于选择了合适的仪器条件及测定波长,有效地消除了电感耦合等离子体发射光谱法(ICP-AES)测定过程中的基体干扰和光谱干扰。应用于地质样品中的稀土元素分析,获得了满意的准确度、精密度及检出限。     

Experimental simulation of dolomite dissolution under burial diagenesis conditions and thermodynamic interpretation

Simulating experiments on dolomite dissolution by acetic acid were made under burial diagenesis conditions,at temperatures ranging from 75℃to 130℃ and pressures from 20 MPA to 30MPa,The results show that the dissolution rate of dolomite increased rapidly with increasing temperature and prssure,From 75℃/Mpa to 130℃/30 MPa,the total amount of released ca and Mg increased from 32.98mg/L to 337.9mg/L,over one order of magnitude in difference,Thermodynamic calculation indicates that the increment of Gibbs free energy (ΔG） of the chemical reaction decreases with increasing temperature and pressure.This thermodynamic result is consistent with the experimental result.Based on the Experimental results.it is suggested that secondary prosities formed by dolomite dissolution under conditions of deep burial diagenesis should be more common than those under epigenesis and shallow burial conditions,and therefore dolomite reservoires in the formations that have been deeply buried should be more abundant than in the formations that have only been shallowly buried.     

Lead isotope geochemical characteristics of Pb-Zn-Cu deposits on the southwestern margin of Tarim, and their significance

The polymetallic(Pb,Zn,Cu,etc) ore belt on the southwestern margin of Tarim is one of the major regions with the greatest prospecting potential in Xinjiang.Reported in this paper are the lead isotope data for 66 sulfide samples(including 50 galena samples,15 chalcopyrite samples and 1 pyrite sample) collected from such representative deposits as Tamu,Tiekelike,Kalangu,Abalieke,etc.in this ore belt.The Pb isotopic ratios of 206 Pb/204 Pb,207 Pb/204 Pb and 208 Pb/204 Pb in the galena samples range from 17.931 to 18.176,15.609 to 15.818 and 38.197 to 38.944,with the average values of 18.017,15.684 and 38.462,respectively.Those in the chalcopyrite samples range from 17.926 to 18.144,15.598 to 15.628 and 38.171 to 38.583,with the average values of 18.020,15.606 and 38.262,respectively.The pyrite sample has the Pb isotopic ratios of 206 Pb/204 Pb,207 Pb/204 Pb and 208 Pb/204 Pb to be 17.980,15.604 and 38.145,respectively.In combination with the previous Pb isotope data for sulfides,it is found that there is only a slight variation in the Pb isotopic composition of galena,chalcopyrite,sphalerite and pyrite in the ore belt.However,there is some difference in Pb isotopic characteristics between galena and chalcopyrite,especially the Pb isotopic composition of galena shows an obvious linear correlation with some other relevant parameters(e.g.β and γ).The comprehensive analysis suggested that lead in galena(maybe including sphalerite and pyrite) was derived principally from wall rocks and underlying basement,and that in chalcopyrite only originated from the basement.The single-stage model ages of these sulfides couldn’t indicate the time limit of metallogenesis(Pb,Zn,Cu,etc.),and the positive linear correlations for the Pb isotopic composition of galena are of no single-stage and two-stage Pb-Pb isochron significance.Furthermore,there are significant differences in Pb isotopic composition characteristics between the genetic type of deposits in this polymetallic ore belt and the Mississippi Valley type(MVT).In addition,the authors also pointed out that there is a phenomenon of differentiation(not paragenesis) for lead and copper elements during the process of metallogenesis in this ore belt.     

Magnetic properties,characteristic spectra and colors of turquoise

The unique bright bluish-green color of turquoise as a high-grade jade has long received wide attention. The relationship between the color of turquoise and its composition and structure is described in this paper on the basis of chemical data, EPR, magnetic susceptibility, absorption and Mössbauer spectra. The results show that the basic color of turquoise (bright blue) is related to the existence of octahedrally on the amount of iron. EPR, magnetic susceblue through green to earth-yellow is dependentcoordinated Cu²⁺ and the shade variation from ptibility, and crystal-field spectra of Cu²⁺ have been analyzed and compared with the theoretical calculations. A preliminary discussion is also made of the color change as a function of temperature.     

Geochemical Features of Ophiolite in Mianxian Lueyang Suture Zone，Qinling Orogenic Belt

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