Self-consistent field method and non-self-consistent field method for calculating the positron lifetime

Many methods are used to calculate the positron lifetime, these methods could be divided into two main types. The first method is atomic superposition approximation method and the second one is the so called energy band calculation method. They are also known as the non-self-consistent field method and self-consistent field method respectively. In this paper, we first introduce the two basic methods and then, we take Si as an example and give our calculation results, these results coincide with our latest experimental results, finally, we discuss the advantages and disadvantages of the two methods.     

鄂尔多斯盆地大牛地气田上古生界沉积演化特征

鄂尔多斯盆地上古生界海陆变迁过程中其沉积演化特征决定了气田内储层成因类型,分布特征和分类评价。通过对大牛地地区太原组-山西组-下石盒子组岩芯观察,结合测井,地震等资料分析,综合确定太原组为滨浅海环境,下部发育碳酸盐岩斜坡体系,上部为障壁-潮坪-潟湖沉积体系;受北部物源区抬升影响,陆源推进和尚未完全褪去的海水影响,山西组为海陆过渡环境,发育潮控辫状三角洲沉积体系;伴随北部物源区逐渐抬升,陆相碎屑显著推进至研究区,下石盒子组底部形成陆相河流环境,发育辫状-曲流河沉积体系;大牛地上古生界整体呈陆进海退特征。由海向陆变迁过程中,太原组和山西组发育的煤层是研究区重要烃源岩;太原组上部障壁砂坝和潮道等砂体,山西组下部辫状河道,潮道和潮砂坝砂体和下石盒子组底部厚层叠置辫状-曲流河道砂体是研究区内上古生界重要的产气储层。     

与煎茶岭金矿有关超基性岩体地球化学特征

煎茶岭金矿与煎茶岭超基性岩体有密切的成因联系.岩体的主量元素分析成果表明:SiO2含量为27.38%～41.88%,MgO含量为25.16%～39.27%,(Na2O K2O)含量为0.02%～1.67%,m/f比值为(5.35～9.75).煎茶岭岩体属镁质、超镁铁质岩石.全碱-硅投影显示煎茶岭岩体原岩岩性为纯橄榄岩、斜方辉橄岩;微量元素分析成果显示成矿元素Au、Pb、As含量较高;稀土元素球粒陨石标准化曲线显示轻稀土富集而重稀土亏损;δEu值介于0.43～1.48之间,说明岩体有一定的分异演化,但程度不均匀.结合矿床地质特征,推测煎茶岭金矿成矿流体和成矿物质主要来自岩浆,在热液充填交代和氧化淋滤复合作用下,促使热液流体中的金沉淀成矿.