山西阳高堡子湾金矿地质特征及找矿标志   总被引：1，自引：0，他引：1  

张北廷  邢福林 《华北地质矿产杂志》1997,12(1):75-84

堡子湾金矿位于华北地台北缘天镇断拱东部阳高凸起区，是与印支未－－海西期火山一次火岩有关的隐爆角砾岩型金矿床。成矿物质主要来自重熔型岩源－－石英二长（斑）岩，隐爆角砾岩为容矿岩石，与隐爆带总体走向平行的张扭性断裂为导矿构造，隐爆角砾岩的内部裂隙及角砾间隙，是良好的储矿构造。  相似文献   

季节性冻结滞水促滑效应——滑坡发育的一种新因素   总被引：12，自引：4，他引：12  

吴玮江 《冰川冻土》1997,19(4):359-365

在综合分析西北季节性冻土地区滑坡发生时间规律和危险斜坡变形动态规律的基础上，提出季节性冻融作用产生的冻结滞水效应可使斜坡区地下水富集，土体软化范围扩大瞌 水压力增大，是本区滑坡发育的一种重要外动力因素，并对其作用机理和发生条件进行了论述。  相似文献   

胶东涧里金矿床地质特征及找矿方向     

郝凤泉 《黄金地质》1997,3(3):55-58

论述了涧里金矿区地质概况及矿床地质特征，对矿床成因进行了探讨，并在此基础一进行了臧放预测，提出了今后找矿方向  相似文献   

扬子地台北缘裂谷系金与多金属成矿特征   总被引：3，自引：0，他引：3  

涂怀奎 《黄金地质》1997,3(4):36-42

扬子地台北缘大多数金矿床集中集中在裂谷系古陆隆起内外接触处，经历了复杂的地壳结构演化，形成新的金矿类型和矿化组合，具多源性，以深源为主，浅源次之，再次是陆源，控矿构造含同生构造与封闭聚矿盆地等多种成矿作用的叠加。  相似文献   

STUDY ON THE VARIATION IN THE CONFIGURATION OF SUBTROPICAL ANTICYCLONE AND ITS MECHANISM DURING SEASONAL TRANSITION-PART Ⅱ:SEASONAL TRANSITION INDICES OVER THE ASIAN MONSOON REGION          下载免费PDF全文

MAO Jiangyu  WU Guoxiong  LIU Yimin 《Acta Meteorologica Sinica》2004,18(1):17-32

Based on the studies in Part Ⅰ (see Mao et al.2003),this paper further examines the relationship between the Asian summer monsoon onset and variation in meridional position of the warm temperature ridge with a zonal orientation in mid-upper troposphere.During the Asian monsoon bursting consequentially over the Bay of Bengal,South China Sea,and South Asia,in addition to the reversal of winds in the lower and upper troposphere and deep convection before and after the onset,the atmospheric meridional temperature gradient (MTG) in the vicinity of the ridge-surface of subtropical high (WEB defined in Part Ⅰ) exhibits a significant reversal.Since the establishment of temperature structure with higher over north than over south of the WEB in the mid-upper troposphere (200-500 hPa) characterizes the collective essential that the Asian summer monsoon bursts over different areas,the MTG in mid-upper troposphere,based on the thermodynamics associated with the seasonal transition,should be a reasonable index to measure the Asian monsoon onset.The definition for onset date is proposed,and the time series of onset date for different sections are determined.As compared with the onset dates determined by other indices such as 850-hPa zonal wind and OLR.correlation analyses indicate that the 850-hPa zonal wind is only regional index,but the MTG index is applicable universally to the Asian monsoon regime.  相似文献   

巴林左旗-阿鲁科尔沁旗5.9级地震前地震活动异常特征     

曹井泉  刘芳  朱学健  腾喜林 《东北地震研究》2004,20(4):1-7

对2003年8月16日巴林左旗阿鲁科尔沁旗间5．9级地震前震源区附近地震活动图像和地震学参数研究结果表明，震前5～1年震源区附近地震活动异常平静，而外围(150km≤△≤300km)区地震活动显著增强；震前2年左右，震源区附近地震学参数异常比较明显，异常项数比40％；震前1．0～0．5年地震学参数异常明显减弱，异常项数比仅10％。可见，地震学短期异常不明显。  相似文献   

Seasonal and Diurnal Variation of Surface Ozone and a Preliminary Analysis of Exceedance of its Critical Levels at a Semi-arid Site in India   总被引：1，自引：0，他引：1  

Gur Sumiran Satsangi  A. Lakhani  P. R. Kulshrestha  A. Taneja 《Journal of Atmospheric Chemistry》2004,47(3):271-286

The mixing ratios of surface O₃ were measured at St. John's College, Agra, an urban and traffic influenced area for the period of 2000–2002. The monthly averaged O₃ mixing ratios ranged between 8 to 40 ppb with an annual average of 21 ppb. Strong diurnal and seasonal variations in O₃ mixing ratios were observed throughout the year except for monsoon season. The mixing ratios of O₃ follow the surface temperature cycle and solar radiation (r = 0.72 and r = 0.65 with temperature and solar radiation, respectively). Concentrations were higher with winds associated with NE and NW direction indicating the impact of pollution sources on surface O₃ concentration. Exceedance of ozone critical level was calculated using the AOT 40 index and found to be 840 ppb.h and 2430 ppb.h for summer and winter seasons, respectively. The present O₃ exposures are lower than the critical level of O₃ and suggest that the present level of O₃ does not have any impact on reduction in crop yields.  相似文献   

福建黄地金-多金属矿床地质特征     

戴建斌  龚贵伦 《黄金地质》2004,10(4):37-40

黄地金-多金属矿床严格受黄地逆冲推覆断层控制,矿脉(体)赋存于由推覆体构造带上下盘岩石所形成的碎裂岩化、糜棱岩化带中,并且金、铅、锌在空间上具有分段富集的特点.矿石为动力变质多金属硫化物蚀变岩型,主要有自形-半自形、他形粒状,包含、碎裂等结构,块状、浸染状、角砾状等构造.金属矿物主要有黄铁矿、磁黄铁矿、方铅矿、闪锌矿以及银金矿和自然金,非金属矿物主要为石英和绢云母.自然金主要产于黄铁矿的晶洞中,少部分包裹于非金属矿物中.成矿作用可分为岩浆接触交代期、气-水热液矿化期和氧化期,其中气-水热液矿化期的早期石英-硫化物阶段为主成矿阶段,成矿物质主要来源于动力变质作用所形成的深部矿化热液,为沿推覆构造充填交代所形成.  相似文献   

中国南水北调工程进展综述     

盛海洋 《地球科学进展》2004,(Z1)

论述南水北调工程的调水背景、工程规划、工程特征、环境影响与生态环境保护及其工程综合效益。  相似文献   

紫色土丘陵区典型小流域水体N、P含量及其环境特征   总被引：8，自引：0，他引：8  

高美荣  朱波  陈克亮  李庆召 《地球科学进展》2004,(Z1)

N、P各形态浓度在川中丘陵区小流域的水体中显示出明显的时空特征,在地表水中,以旱地为主的小流域上部的硝态氮、氨态氮、全氮要低于小流域下部水田的,而以流域人口密度较大的群英池和小流域下部的沟道水中氨态氮浓度较高,说明人为活动对其影响较大。在地下水中以小流域上部为最高,明显高于该流域的中下部;它们的季节变化与流域降水的季节变化基本是一致的。紫色土丘陵区水体富N,地下水NO_3~--N超标率达60％,;地表水和地下水均尚未出现P的富营养,但潜在的污染不可忽视。  相似文献