西安东部黄土断层活动性与显微结构的相关性

本文研究了西安东部包括临潼—长安断裂在内的三条活动断裂的黄土样品,运用扫描电子显微镜(SEM)分析了其微结构类型。根据微结构的组合特征讨论了断裂的粘滑(快速滑动)和稳滑(蠕滑)作用。断裂的粘滑作用与地震的关系密切,其微结构的组合标志为:结构定向性、随机性新生矿物和非粘结型滑面。     

Types and Ore-forming Conditions of Gold Deposits in the Jinsha River-Lancang River-Nujiang River Area

The Jinsha River-Lancang River-Nujiang River area is one of the important prospect areas for noble metal and nonferous metal deposits of China. Of a great variety of gold deposits present in this area, the following types seem to be economically most valuable and promising: tectonic alteration type in ophiolitic melange; polymetallic quartz vein type related to intermediate-acid intrusions; finely disseminated type in fracture zones; mixed hydrothermal type in tectonic fractures of carbonate rocks; hydrothermal type related to subvolcanic rocks; volcanic-hot spring type; submarine volcano exhalation-sedimentary-hydrothermal reformation type. Metallogenic epochs are exclusively Mesozoic and Cenozoic, and ore deposits and orebodies are controlled by linear structures. Magmatic activity has affected gold mineralization in varying degrees, and gold deposits are basically of mesothermal-epithermal type with ubiquitous and intense alterations. Ore-forming materials and hydrothermal solutions show multi-source character.     

Experimental Study on the Leaching of Gold from Greenstone1

Abstract Experiments were conducted on the leaching of gold from greenstone by chloride solution under the temperature of 200-550°C and the pressure of 60 MPa. During part of the experiments, the oxygen fugacity was controlled. The results show that the leaching rate of gold is related to temperature, composition of the solution, pH and oxygen fugacity. In the experiment with oxidative acidic solution, the leaching rate was up to 50% or more. It is known that the leaching of gold is restricted by the reaction in which the gold is dissolved from the rock to form gold chloride complex. Therefore, the authors hold that the acidic chloride solution derived from granite magma has caused the remobilization-migration of gold from greenstone and its enrichment into ore.     

夏季华北地区高空槽前有无暴雨的对比分析

本文通过两个个例的对比分析,研究夏季华北在什么条件下高空槽过境时会引起暴雨。发现有暴雨出现的高空槽,处于继续发展阶段,水汽充沛,在大尺度上升运动区域内,有中间尺度系统存在。而没有暴雨的高空槽,则转向衰减阶段,水源不足,没有中间尺度系统、 文中还给出高空槽暴雨的各种参数,这对预报有参考意义。     

我国东部几个中新生代盆地泥质岩中的氨基酸

从现代沉积物到前寒武纪的沉积岩中都发现有氨基酸的存在。关于它们的组成、含量及其地质意义在许多文献中都曾涉及到,特别是对近代各种环境沉积中的氨基酸及其在成岩作用过程中的变化,已经积累了相当多的分析资料。本文对以渤海第三纪沉积盆地为主的我国东部地区中新生代泥质岩样品进行了氨基酸的分析,并初步讨论了这些分析结果与沉积环境的关系。     

Sequence stratigraphy of Jurassic-Cretaceous boundary strata in Luanping,Northern Hebei,China

Division and correlation of terrestrial J-K bound are a knotty-argued problem. The key to solving the problem is to find a deposition-continuous section. Owing to stratigraphic hiatus and organism-phylogeny break, we have been discussing the problem without any unitary criterion for several decades. Tectonic ac-tivities occurring strongly in the J-K transitional pe-riod caused commonly sedimentary omissions and frequently volcanic eruptions in northern Hebei Prov-ince, western Liaoning Prov…     

安徽铜陵朝山金矿床稳定同位素、稀土元素地球化学研究

朝山金矿床位于安徽铜陵狮子山矿田，属于矽卡岩型金矿床，侵入岩体为白芒山辉石二长闪长岩体。成矿过程包括矽卡岩阶段、石英-硫化物阶段和碳酸盐阶段3个主要成矿阶段。文章通过对朝山金矿床的氢、氧、碳、硫、硅同位素组成和稀土元素地球化学特征的研究，探讨成矿溶液中水、碳、硅和硫的来源以及成矿溶液的演化问题。研究表明，成矿热液早期以岩浆热液为主，随着成矿过程的进行，加入的大气降水比重越来越大，到晚期可能主要以大气降水为主。该矿床矿石中方解石的碳、氧同位素组成与矿区大理岩的碳、氧同位素组成明显不同，其δ^13 Cv-PDB、δ^18OV-SMOW值分别为-4．5～-5．3‰、13．9～14．0‰，与岩浆作用形成的CO2的碳、氧同位素组成一致，表明矿石中方解石的碳、氧来源于岩浆作用。硅和硫具深部岩浆或岩浆热液来源的特点。     

Variations of δ^18 O in Precipitation along Vapor Transport Paths

Three sampling cross sections along the south path starting from the Tropics through the vapor passage in the Yunnan-Guizhou Plateau to the middle-low reaches of the Yangtze River, the north path from West China, via North China, to Japan under the westerlies, and the plateau path from South Asia over the Himalayas to the northern Tibetan Plateau, are set up, based on the IAEA (International Atomic Energy Agency)/WMO global survey network and sampling sites on the Tibetan Plateau. The variations, and the relationship with precipitation and temperature, of the δ^18 O in precipitation along the three cross sections are analyzed and compared. Along the south path, the seasonal differences of mean δ^18 O in precipitation are small at the stations located in the Tropics, but increase markedly from Bangkok towards the north, with the 51so in the rainy season smaller than inthe dry season. The δ^18 O sovalues in precipitation fluctuate on the whole, which shows that there are different vapor sources. Along the north path, the seasonal differences of the mean δ^18 O in precipitation for the stations in the west of Zhengzhou are all greater than in the east of Zhengzhou. During the cold half of the year, the mean δ^18 O in precipitation reaches its minimum at Uriimqi with the lowest temperature due to the wide, cold high pressure over Mongolia, then increases gradually with longitude, and remains at roughly the same level at the stations eastward from Zhengzhou. During the warm half of the year, the δ^18 O values in precipitation are lower in the east than in the west, markedly influenced by the summer monsoon over East Asia. Along the plateau path, the mean δ^18 O values in precipitation in the rainy season are correspondingly high in the southern parts of the Indian subcontinent, and then decrease gradually with latitude. A sharp depletion of the stable isotopic compositions in precipitation takes place due to the very strong rainout of the stable isotopic compositions in vapor in the process of lifting over the southern slope of the Himalayas. The low level of the δ^18 O in precipitation is from Nyalam to the Tanggula Mountains during the rainy season,but δ^18 O increases persistently with increasing latitude from the Tanggula Mountains to the northern Tibetan Plateau because of the replenishment of vapor with relatively heavy stable isotopic compositions originating from the inner plateau. During the dry season, the mean δ^18 O values in precipitation basically decrease along the path from the south to the north. Generally, the mean δ^18 O in precipitation during the rainy season is lower than in the dry season for the regions controlled by the monsoons over South Asia or the plateau, and opposite for the regions without a monsoon or with a weak monsoon.