碳酸盐岩差异性风化成土特征及其对石漠化形成的影响   总被引：35，自引：0，他引：35  

孙承兴  王世杰  周德全  李瑞玲  李艳丽 《矿物学报》2002,22(4):308-314

碳酸盐岩极低的酸不溶物含量使岩石风化产生的残积土壤物质数量极少，并产生巨大的体积缩小，促使早期形成的残积土在重力作用下不断向下塌陷。显著的差异性风化使基岩面强烈起伏，甚至形成大量的岩溶尘洼地、裂隙、地下管道、洞穴系统等。在重力和水的作用下，土粒沿垂直和水平方向上经微距离或短距离搬运到上述低洼或地下空间中，甚至由地下河带到更远的地方，这是碳酸盐岩地区土壤丢失的重要方式，也是形成石漠化最主要的地质因素。土壤在地表分布高度不均匀，是碳酸盐岩地区的地表少土的重要原因。对于酸不溶物含量相当的石灰岩和白云岩而言，由于白云岩的差异性风化明显弱于石灰岩，以及受各种应力作用后，白云岩形成的节理及裂隙密集而均匀，从而提高了近地表白云岩的含水能力，延长了风化过程中的水－岩反应时间，使风化作用可以相对集中于地表或近地表进行，有利于岩石的整体风化作用的进行，同时使白云岩风化壳基岩面起伏相对较小，风化残积形成的土壤分布也相对均匀。因此，白云岩区地表土层较厚，石漠化程度也稍弱于灰岩区。  相似文献   

含油玄武岩中绿泥石的形成温度   总被引：5，自引：0，他引：5  

杨献忠  杨祝良  陶奎元  王力波 《矿物学报》2002,22(4):365-370

以苏北盆地高邮凹陷闵桥地区含油玄武岩中的绿泥石为研究对象，探讨了其成因和形成温度，认为玄武岩中绿泥石有两种形成方式、五条形成途径：其一为蚀变演化，包括：火山玻璃、斜长石、辉石的蚀变，交代橄榄石斑晶，以及皂石的进一步演化；其二为沉淀结晶，包括从热液中直接沉淀生长和胶体溶液充填后的结晶。计算结果显示，蚀变演化形成的绿泥石，其形成温度为128－271℃；沉淀结晶形成的绿泥石，其形成温度为31－63℃。玄武岩中绿泥石形成温度与埋藏深度间没有明显的线性相关。进一步研究表明，本区玄武岩作为储油层，其进油时的温度为62－118℃，不超出48－137℃。  相似文献   

微波作用下化学助剂在细粉煤脱水中的应用研究   总被引：2，自引：0，他引：2  

崔平  朱静  王知彩 《矿物学报》2002,22(4):375-378

探讨了在微波加热条件下加入表面活性剂和溶剂油等有机溶剂对脱水效果的影响，力求找出其中的脱水规律。结果表明：微波脱水效果明显，同时，表面活性剂能够大大降低滤饼含湿量，而且非离子表面活性剂的效果比阳离子、阴离子好，柴油也能促进粉煤的脱水。  相似文献   

Nature, age, and tectonic setting of granitoid-hosted, orogenic gold deposits of the Jiaodong Peninsula, eastern North China craton, China   总被引：28，自引：0，他引：28  

Yumin Qiu  David I. Groves  Neal J. McNaughton  Liang-gen Wang  Taihe Zhou 《Mineralium Deposita》2002,37(3-4):283-305

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Origin of Gold—Bearing Fluid and Its Initiative Localization Mechanism in Xiadian Gold Deposit,Shandong Province     

邓军  王庆飞  孙忠实 《中国地球化学学报》2002,21(3):282-288

The composition of quartz inclusions and trace elements in ore indicate that gold-bearing fluid in the Xiadian gold deposit,Shandong Province,stemmed from both mantle and magma,belonging to a composite origin.Based on theoretical analysis and high temperature and high pressure experimental studies,gold-bearing fluid initiative localization mechanism and the forming environment of ore-host rocks are discussed in the present paper.The composite fluid extracted gold from rocks because of its expanding and injecting forces and injecting forces and flew through ore-conducive structures,leading to the breakup of rocks.The generation of ore-host faults and the precipitation of gold-bearing fluid occurred almost simultaneously.This study provides fur-ther information about the relationships between gold ore veins and basic-ultrabasic vein rocks and intermediate vein rocks,the spatial distribution of gold ore veins and the rules governing the migration of ore fluids.  相似文献   

Ordovician Graptolite Rhabdosome Complication and Its Implications on Sea Level Changes     

Wang Chuanshang  Wang Xiaofeng  Chen Xiaohong 《中国地质大学学报(英文版)》2002,13(3)

A total of four times of rhabdosome complication events, i.e., the lateral branching of graptolite stipes during the Late Middle Ordovician, the secondary branching of graptolite stipes at the earliest Upper Ordovician, the early Qiantangjiangian of Upper Ordovician and the middle Qiantangjiangian, respectively, is discussed in this paper. These events and other adaptation events demonstrate close relationships between a diverse graptolite fauna and sea level changes, and consequently can be employed to study sea level fluctuations. It is safe to conclude that the complication of rhabdosome started at the maximum flooding surface (MFS) and terminated at the beginning of regression.  相似文献   

Heat flow and thermal modeling of the Yinggehai Basin, South China Sea   总被引：9，自引：0，他引：9  

Lijuan He  Liangping Xiong  Jiyang Wang 《Tectonophysics》2002,351(3)

Geothermal gradients are estimated to vary from 31 to 43 °C/km in the Yinggehai Basin based on 99 temperature data sets compiled from oil well data. Thirty-seven thermal conductivity measurements on core samples were made and the effects of porosity and water saturation were corrected. Thermal conductivities of mudstone and sandstone range from 1.2 to 2.7 W/m K, with a mean of 2.0±0.5 W/m K after approximate correction. Heat flow at six sites in the Yinggehai Basin range from 69 to 86 mW/m², with a mean value of 79±7 mW/m². Thick sediments and high sedimentation rates resulted in a considerable radiogenic contribution, but also depressed the heat flow. Measurements indicate the radiogenic heat production in the sediment is 1.28 μW/m³, which contributes 20% to the surface heat flow. After subtracting radiogenic heat contribution of the sediment, and sedimentation correction, the average basal heat flow from basement is about 86 mW/m².Three stages of extension are recognized in the subsidence history, and a kinematic model is used to study the thermal evolution of the basin since the Cenozoic era. Model results show that the peak value of basal heat flow was getting higher and higher through the Cenozoic. The maximum basal heat flow increased from 65 mW/m² in the first stage to 75 mW/m² in the second stage, and then 90 mW/m² in the third stage. The present temperature field of the lithosphere of the Yinggehai Basin, which is still transient, is the result of the multistage extension, but was primarily associated with the Pliocene extension.  相似文献   

Fluid permeability of sedimentary rocks in a complete stress–strain process     

J. -A. Wang  H. D. Park   《Engineering Geology》2002,63(3-4):291-300

The permeability of sedimentary rocks during triaxial compression tests was investigated to relate it to the complete strain–stress process. It was found that the permeability was not constant, but varied with the stress and strain states in the rocks. Prior to the peak strength, the permeability decreases with increasing load. A dramatic increase in permeability occurs during the strain softening period. In the present study, in situ measurements of fluid flow and pressure in floor strata was carried out in a double longwall mining face in the Yangzhuang colliery. These measurements show that both the strata pressure and the position with respect to the mining face influence the hydrogeologic properties. The permeability increased in the floor strata behind the mining face because those mining induced fractures opened as the strata pressure decreased. To better understand this change in hydraulic behavior around the mining faces, 3-D numerical modeling was carried out. The model provides the general picture of the stress distribution and failure zone both in the floor and roof strata. The field and model results demonstrate the importance of changes in the stress and strain states on the hydrogeology of a site.  相似文献   

Gold Occurrence and Ore Genesis,Yata Micro—Disseminated Gold Deposit,Guizhou,Southwest China     

朱笑青  王中刚 《中国地球化学学报》2002,21(4):370-373

The mode of occurrence of gold in the Yata micro-disseminated gold deposit is ap-proached through chemical phase studies coupled with ore-dressing monitoring and micro-beam analysis.The results showed that gold occurred for the most part as ultra-microscopic particles adsorbed on the surfaces or fracture planes of pyrite and other sulphides.The proportions of gold of different occurrences were estimated solutions containing nanometer-sized gold particles were prepared following the hydrolysis-reduction procedure and the adsorption of nanometer-sized gold on ordinary sulphides and rocks was experimentally determined.It is evident that sulphides are good adsorbents of gold and this is consistent with geological observations.  相似文献   

Image analysis applied to quantitative evaluation of chromatic impact generated by open-pit quarries and mines     

Victor Pinto  Xavier Font  Miquel Salgot  Jose Tapias  Tomas Mañá 《Environmental Geology》2002,41(5):495-503

One of the most important environmental impacts resulting from opencast mining, and especially quarries, is the visual impact. Evaluation of this impact considers two aspects: first, the area occupied by the quarry as seen by an observer from a specific place, and, second, the chromatic contrast existing between landscape and exploitation. In this study we develop a methodology to assess the chromatic impact in an objective and comparable form. To assess this impact we developed a method based on image analysis that allows us to obtain from a picture or image its equivalent as a function of chromatic impact, according to the sensibility of the human eye to different wavelengths. The methodology was applied to the Martinenca limestone quarry (Alcanar, Tarragona) and to Cerro Kori Kollo mine, La Joya district (Bolivia).  相似文献