Metallogenetic characteristics of an unique uranium-tungsten mineralization zone

A polymetallic zone dominated by U-W mineralization was found in Northeast Guangxi. Distributed along the east contact zone of a complex granite mass, it extends for about 100 km in length, with more than fifty deposits and prospects embraced. The deposits show a wide range of genetic types, related to the granite, from magmatic (including pegmatite and skarn deposits) through hydrothermal mineralizations (hypo-, meso- and epithermal) all the way to tin placers, constituting a very intact metallogenetic series of granites. The epithermal U-W deposits are considered as a new type for their unique geological and geochemical characters, such as the paragenesis of U and W and the large time gap (> 40 Ma) between ore and granite. This project was financially supported by the Open Lab. of Ore Deposit Geochemistry, Chinese Academy of Sciences.     

克拉玛依地区野外地质实习基地建设研究

野外实践教学在地学人才培养中具有重要作用,稳定的实习基地是开展实践教学的前提和基础。克拉玛依所处的准噶尔盆地西北缘地区位于哈萨克斯坦、塔里木与西伯利亚三大板块的交汇处,自晚古生代以来经历了多期次、多阶段长期而复杂的地质演化,褶皱构造、大型纵向走滑断裂构造发育,广泛发育晚古生代花岗岩侵入体和蛇绿混杂岩带,沉积地层连续、完整,沉积构造典型、特征显著,古生物化石丰富,白杨河深切峡谷、河流阶地地貌以及乌尔禾魔鬼城雅丹风蚀地貌各具特色,西北缘油砂矿、紫砂矿、金丝玉等矿藏储量丰富。区域内的地层、古生物、构造、地貌、矿产资源等为克拉玛依工程教育基地各院校的地学类相关专业的野外实践教学提供了丰富的教学资源,是一个理想的野外地质实习基地。     

基于岩石物理模型的页岩孔隙结构反演及横波速度预测

准确预测储层的等效孔隙纵横比对页岩储层岩石物理建模及横波速度预测具有重要意义。为分析页岩储层孔隙纵横比及预测横波速度,提出了基于岩石物理模型的页岩孔隙纵横比反演及横波速度预测方法。本文首先通过岩石物理模型建立岩石的纵、横波速度与孔隙纵横比、孔隙度和矿物组分等参数之间的定量关系,寻找最佳孔隙纵横比;然后通过使理论预测与实际测量的纵波速度之间误差达到最小的方式反演孔隙纵横比,并以此为约束预测横波速度。实际测井数据反演结果表明,龙马溪组页岩地层的孔隙纵横比稳定,而围岩的孔隙纵横比变化范围较大;说明与围岩相比,页岩的孔隙结构更为稳定。同时,预测得到的页岩横波速度与实测横波速度的误差较小,另外对于缺少矿物组分资料的页岩层段,用平均矿物组分预测得到的横波速度误差仍较小;说明与矿物组分相比,龙马溪组页岩的纵、横波速度对孔隙纵横比参数更敏感。综上所述,利用该方法可预测到较为准确的等效孔隙纵横比和横波速度。     

深基础护坡桩的设计与施工中的几个问题

着重介绍了间隔式钻孔灌注桩在挡土护坡技术中的应用方法，设计时的主要参考依据，计算土压力理论的应用原则以及施工中需注意的几个问题，为进行深基础挡土护坡的工程提供了部分参考依据。     

广州珠江西航道,流溪河有机污染特征与感潮作用

珠江西航道和流溪河在广州市区上游，为广州市主要水源区。由于感潮作用，受市区严重污染的水体因涨潮上溯而上游传输。严重影响上游水质。因此，弄清感潮作用对广州水源区水质的影响程度和范围，对水源保护与利用有重要意义。本研究从下游到上游，对水源区底泥中有机物特征进行了分析，结果表明：（１）从上游到上游，受感潮作用影响逐渐减小，污染程度逐渐减轻；（２）水源区有机物特征呈有规律变化。从靠近城市的下游到远离城市的     

Chemistry of alkali extraction of brown coals—I. Kinetics, characterisation and implications to coalification

Three Australian brown coals have been separated into humin and humic acid fractions and studied by high resolution solid state ¹³C NMR spectroscopy and Fourier transform IR spectroscopy. The aromatic rings of the humic acids are highly substituted showing that extensive cross linking must have occurred during formation from wood lignin and tannin. However, the humins contain more aliphatic carbon and hydrogen than the corresponding humic acids. This shows that little cross linking has occurred with other components of the brown coal such as resins, waxes cutin and algal detritus, and cross linking has not rendered the aromatics alkali insoluble. The kinetics of extraction are complex and not simple first order. This is reflected in the chemical composition of the humic acid which is extraction temperature dependent. We also observed that there is a conversion of aromatic carbon to aliphatic carbon and gas during extraction, probably by alkaline oxidation, resulting in ring opening. A range of suitable model compounds have been studied to confirm this finding. Such a mechanism may account for the modification of lignin in oxidising environments such as those occurring in the initial stages of coalification (lignite or brown coal formation) and in soils.     

漳州热田地下热水的循环深度

漳州热田是我国东南沿海地区目前所见温度(121.5℃)最高的一个。热田地热地质、地球化学以及地温场的研究结果表明,漳州热田属于深循环对流型热田。为了计算热田的热水循环深度,本文采用管道模型的方法,利用热田中心钻孔的测温资料计算地下热水上涌的流速,利用热田内水化学资料计算热储温度,然后用图解法求出漳州热田热水的循环深度为3.4—4.0 km,为漳州热田的成因分析和热水资源的评价提供了依据。     

扬中金源时代购物中心基坑降水数值模拟分析

基坑降水的成功与否,将对基坑开挖和周边环境产生重要影响,因此有必要对基坑降水方案进行评估。针对扬中金源时代购物中心基坑降水问题,采用MIDAS/GTS对基坑降水效果进行研究。首先,依据地勘报告中提供的土体渗透系数,结合单井、双井抽水试验结果,反演出MIDAS/GTS中需要的土层渗流系数和边界函数;然后利用反演得到的参数,建立了考虑回灌井补水效应的三维基坑降水效果分析模型,模拟基坑内水位降深与时间的变化关系,并对基坑降水效果进行分析和评估,以期指导土方开挖工程的施工。     

乾安县浅层高氟地下水的分布规律及成因的初步探讨

本文主要阐述了乾安县浅层高氟地下水的分布规律;探讨了浅层高氟地下水的成因与构造、地貌、古气候、地层岩性和水文地质条件的关系,从而闸明了广泛分布的湖沼相松散沉积物的组成和水文地质条件是本区浅层高氟地下水的主要原因。     

Environmental significance of snowpit chemistry in the typical monsoonal temperate glacier region,Baishui glacier no. 1, Mt Yulong,China

Samples were collected from two snowpits in Baishui glacier no. 1, Mt Yulong, China, in May 2006. Snowpit chemistry was studied, using ion tracer techniques, HYSPLIT model, factor analysis, correlation and trend analysis. It indicated that total cation concentration is higher in 4,900-m snowpit than in 4,750-m snowpit, whereas total anion concentration is higher in 4,750-m snowpit. Cations, especially Ca²⁺, dominate ionic concentrations in Baishui glacier no. 1. According to correlation analysis and factor analysis, ions can be categorized as follows: Cl⁻ and NO₃ ⁻ as Group 1, SO₄ ²⁻ as Group 2, Mg²⁺ and Ca²⁺ as Group 3, Na⁺ as Group 4, K⁺ as Group 5. Contribution made by terrestrial dust to ionic concentration accounts for 52.27, 100, 99.36, 98.91, 96.16 and 99.97% of Cl⁻, NO₃ ⁻, SO₄ ²⁻, K⁺, Mg²⁺ and Ca²⁺, respectively, in 4,900-m snowpit, and for 64.00, 100, 99.57, 98.63, 96.25 and 99.97% in 4,750-m snowpit. Local dust is the principal source of snowpit chemical components. Pollutants brought from industrial areas of South Asia, Southeast Asia and South China by monsoonal circulation also makes some contribution to anion concentrations, but pollution associated with human activities makes a very slight contribution in study area. The chemical characteristics of two snowpits are different owing to the difference of deposition mechanism and local environment in different altitudes.