Single zircon ages from high-grade rocks of the Jianping Complex, Liaoning Province, NE China

The high-grade rocks of the Jianping Complex in Liaoning Provi nce, NE China, belong to the late Archaean to earliest Proterozoic granulite belt of the North China craton. Single zircon ages obtained by the Pb–Pb evaporation method and SHRIMP analyses document an evolutionary history that began with deposition of a cratonic supracrustal sequence some 2522–2551 Ma ago, followed by intrusion of granitoid rocks beginning at 2522 Ma and reaching a peak at about 2500 Ma. This was followed by high-grade metamorphism, transforming the existing rocks into granulites, charnockites and enderbites some 2485–2490 Ma ago. The intrusion of post-tectonic granites at 2472 Ma is associated with widespread metamorphic retrogression and ends the tectono–metamorphic evolution of this terrain. A similar evolutionary sequence has also been recorded in the granulite belt of Eastern Hebei Province. We speculate that the Jianping Complex was part of an active continental margin in the late Archaean that became involved in continental collision and crustal thickening shortly after its formation. There is a remarkable similarity between the 2500 Ma North China granulite belt and the equally old granulite belt of Southern India, suggesting that the two crustal domains could have been part of the same active plate margin in latest Archaean times.     

煤层气储层钻井过程中的地层损害及保护

钻井施工是造成煤层气储层损害的一个重要环节,针对煤层气储层的特点,分析了煤层损害的机理及特殊性,并简要介绍了保护煤层免受损害的钻井技术。     

矿井粘土岩特性及其对巷道稳定性的影响

在分析龙口矿区2号煤层顶底板粘土岩的物质组成、微结构和物化特性的基础上,讨论了粘土岩的膨胀特性对巷道稳定性的影响,进而指出了本研究在巷道工程应用中的意义。     

Preliminary studies on methane fluxes in Hainan mangrove communities

INTRODUCTIONChrbondioxideandInehanearethetwomostabundantabosphericcarbonspedes.Methane'sconcenhati0nintheboposphereinonsesO.7-l.l%peryearraasmussenandKhaili,l98l,BlakeandRowand,l988,Scheeetal.,l989).Ihauseofmethne'sforpaCtontheearth'sclirnateandthechernistryoftheatInosphere,thebudgetofabosphericmethanehasmivedconsiderableattchti0n.Wetlandsareestirnataltobeoneofthelamptsoimofabosphericmethane,aocountingforab0ut4O%to5O%0ftheglobalInehanesoonannually(Cforneand0reInland,l988,WhitingandC…     

河南省吉家洼金矿床地球化学特征

吉家洼金矿是熊耳山地区一个构造蚀变岩型金矿床。Ａｕ的丰度由区域—矿区—构造岩—矿体呈几何级数递增。矿体中Ａｕ与ＳｉＯ２相关,与亲硫元素和重矿化剂元素强相关,元素具明显的轴向分带。矿体不同部位的元素组合和元素对比值具指示意义。矿体头部中低温和高温元素共存,显示多期次叠加矿化特征,指示矿体有大的延深。     

中国大陆上空水汽资源

根据１９８１～１９８６年计算结果，指出我国大陆上空拥有水汽资源年总量＋３３１８４．４亿ｍ＾３暖季（４～１０月）＋３０４９４．１２亿ｍ＾３寒季（１１～次年３月）＋２６９０．２８亿ｍ＾３，全年唯有气温最低的隆冬（１２～次年２月），是水汽资源亏耗（－７７３．６３亿ｍ＾３）季节，而夏季（６～８月）则是我国大陆上空水汽资源最关键的汇聚时期，资源量＋１８１９７．５６亿ｍ＾３，１６号，１４份边界分别为１１～５月     

内蒙古兴安盟旅游资源评价

沿边地区的开放和东北地区经济技术协作的推进，为兴安盟开发旅游资源，发展旅游业提供了机遇。把旅游业作为先导产业，是振兴兴安盟经济的理想选择。综合评价了兴安盟旅游资源，提出了兴发盟旅游资源的开发设想。     

昆仑山垭口小南川末次冰期早期成层坡积的沉积特征和气候意义

成层坡积结构构造特征、粒度、化学、电镜扫发描分析和测年资料揭示其形在于末次冰期间冰段（６００００ａＢＰ～４４０００ａＢＰ）。存在由湿冷向干冷的气候变化。成层坡积上覆的坡积黄土则代表末次冰期全盛及全新世环境以显著干冷为特征。此剖面突出表明昆仑山垭口地区末次冰期早期不是干冷，而是湿冷，与季风模式不吻合。故只能认为当时该区受西风带影响。     

应用人工神经网络解释煤层厚度

本文介绍了人工神经网络解释煤层厚度的方法，为直接利用煤田地震资料确定煤层厚度提供了一种新的途径。利用煤层厚度与煤层反射波动力学特征参数之间的非线性关系，用人工神经网络进行定量描述，便可根据地震资料求出煤层厚度。     

节理化块体边坡失稳机理数值分析

针对三峡库区移民新址的工程地质问题，用改进的岩土工程软件系统FINAL，研究了节理化块体岩坡的失稳机理，指出除了节理的C，值控制岩块的滑移、倾覆变形，倾倒等破坏形式外，岩块的模量E也对倾覆变形破坏起重要作用，从而不仅说明了保护坡脚，防止岩块浸水软化的必要性，也说明了应用传统离散元法分析这类问题的局限性。