内蒙朱拉扎嘎金矿成矿地质条件及找矿方向初探   总被引：4，自引：0，他引：4  

孟二根  张有宽  陈旺 《矿产与地质》2002,16(3):168-173

朱拉扎嘎金矿床产于中元古界渣尔泰山群浅变质细碎屑岩中 ,矿层赋存在阿古鲁沟组一段中部层位 ,选择性的产于变质粉砂岩和变质钙质石英粉砂岩等孔隙度较好的岩性层中 ,矿区构造复杂 ,金与岩浆热液关系密切 ,且与 Ag、Cu呈正相关 ,金矿物主要是自然金和银金矿 ,围岩蚀变为中低温热液蚀变类型 ,属层控微细浸染热液交代大型金矿床。  相似文献   

Photogrammetric calibration of a C-arm X-ray system as a verification tool for orthopaedic navigation systems     

H. Broers  H. Hemken  T. Luhmann  P. Ritschl 《ISPRS Journal of Photogrammetry and Remote Sensing》2002,56(5-6)

For the total replacement of the knee joint, the precise reconstruction of the mechanical axis is significantly determined by the alignment of the cutting tool with respect to the rotation centre of the femur head. Operation techniques supported by navigation allow for the precise three-dimensional location of the hip centre by cinematic analysis.Recent results permit the reconstruction of the femur axis to be better than 0.7°. Therefore, conventional verification methods such as the post-operative recording of the complete leg are not suitable due to their limited system accuracy of about 2°.As the femur head cannot be accessed directly during the operation, an X-ray method has been used to verify alignment. The paper presents a method and the results achieved for the calibration of a C-arm system by introducing photogrammetric parameters. Since the method is used during operation, boundary conditions such as minimal invasive surgical intervention and sterility have been considered for practical applications of patients.  相似文献   

置换深度估算的一维波动方程法     

罗嗣海  龚晓南等 《地球科学》2002,27(1):115-119

强夯置换的应用已逐渐广泛，但其设计是高度经验性的。强夯置换的理论研究较为肤浅，特别是置换深度的计算尚无较好的方法。为此，提出了模拟夯击过程的一维波动方程理论模型；初步建议了模型中有关参数的取值并用工程实例进行了验证；用所提出的模型探讨了置换体形成与扩展的基本规律；给出了应用的简化形式。结果表明，一维波动方程法及其简化形式与实际吻合较好，可应用于强夯置换的置换深度估算。  相似文献   

Association of Electrum and Calcite and Its Significance to the Genesis of the Hishikari Gold Deposits, Southern Kyushu, Japan   总被引：1，自引：1，他引：1  

Akira Imai  Tadakazu Uto 《Resource Geology》2002,52(4):381-394

Abstract. Mineral assemblage, precipitation sequence and textures of the gold‐bearing veins from the Hishikari epithermal vein‐type deposits, southern Kyushu, Japan, were examined. In addition, fluid inclusion microthermometry and carbon and oxygen isotopic compositions of calcite were determined. Calcite, and that replaced by quartz, were commonly observed throughout the precipitation sequence of the veins. Thus, calcite must be a more common gangue constituent initially than observed presently. Association of calcite and electrum is observed immediately subsequent to columnar adularia in some vein samples. In addition, close association of electrum with pseudo‐acicular quartz, and electrum with truscottite were observed. The initial coprecipitation of electrum and calcite might be a common phenomenon in the gold‐bearing veins at the Hishikari deposits. The Th (homogenization temperature) data from the Honko‐Sanjin deposits are generally higher than those from the Yamada deposit. Samples that show association of calcite and electrum yielded higher Th (206–217°C, average) than the Th data from calcite associated with low‐grade Au ore or barren (180–204°C, average). The measured Tm (temperature of last melting point of ice) range from ‐0.4 to 0.0°C. The result suggests that the salinity of the hydrothermal solution was low during the precipitation both of calcite associated with Au mineralization and of barren calcite. Fluid inclusion evidence suggestive of boiling of hydrothermal solution for the precipitation of calcite was not recognized in the present work. The δ¹³C and δ¹⁸O values of calcite range from ‐10.8 to —4.7 % and from +3.2 to +15.2 %, respectively. The δ¹³C value of H₂CO₃ and the δ¹⁸O value of H₂O in the hydrothermal fluids calculated assuming isotopic equilibrium with calcite using the temperature obtained by fluid inclusion microthermometry, range from ‐14.4 to ‐9.1 %, and from ‐6.2 to +5.5 %, respectively. Thus, the calculated δ¹⁸O values of H₂O for calcite further confirm the presence of the ¹⁸O‐enriched ore fluids during the mineralization at the Hishikari deposits. The hydrothermal solution isotopically equilibrated with the sedimentary basement rocks was responsible for the gold mineralization associated with calcite.  相似文献   

定向钻进泥浆后处理     

刘珍 《岩土钻凿工程》2008,(4):14-16

本文介绍了废弃泥浆的成分及其对环境的影响,探讨了处理废弃泥浆的一般方法和技术及定向钻进环空泥浆替换技术。  相似文献   

湖南东山钨矿地质特征及成矿预测          下载免费PDF全文

宋宏邦  黄满湘  樊钟衡 《地质找矿论丛》2004,19(1):13-16

东山钨矿床产于尖峰岭花岗岩体与泥盆系和石炭系石灰岩的接触带中,钨矿体的形成与接触带构造及古岩溶的发育程度密切相关,矿床成因为夕卡岩-热液充填交代型白钨矿床.采用地质与物化探结合的方法,进行了成矿预测,圈定了找矿远景区.  相似文献   

强度折减有限元法在昆明新机场高填方边坡稳定分析中的应用   总被引：1，自引：0，他引：1  

陈金锋  宋二祥  徐明 《岩土力学》2011,32(Z1):636-0641

介绍了碎石桩、强夯置换两种工程常用的山区高填方地基的处理方式。为了解不同地基处理方式下,山区机场高填方边坡的稳定性,采用强度折减有限元法及对比研究的手段对昆明新机场79-79?工程地质剖面处边坡的稳定性进行分析,而且将强度折减有限元与简化Bishop方法的计算结果进行对比。另外,对土体强度参数未折减时,不同地基处理方式下的边坡位移及剪应变也进行比较。结果表明：用碎石桩或强夯置换处理坡脚内地基的相对软弱土层,不仅能有效提高边坡安全系数,还能大幅度减小边坡的最大剪应变与最大位移;当边坡的最危险滑移面接近圆弧形时,强度折减有限元法与简化Bishop法计算所得安全系数与最危险滑移面均接近,且强度折减有限元法计算的安全系数略偏小,偏于安全;当中风化基岩上方覆盖土层深度大于强夯置换的有效处理深度时,用碎石桩处理原地基效果更优  相似文献   

华南地区某地表层土壤重金属污染农田情况研究     

施玉娇  杨芳芳  刘雯婷  林小龙  陈青云  王建超  唐艳萍 《地质论评》2024,70(S1):211-214

<正>研究区农田表层土壤重金属污染主要来源于其上游20世纪50年代开采的铅锌矿,该矿于1958年在采矿坑口附近建立了小型浮选厂进行选矿生产,由于在生产期间未对废水进行有效处理,并且由于强降雨造成尾矿砂坝坍塌,致使携带Pb、Cd、As等重金属的尾矿渣和废水流入下游河流,致使研究区农田表层土壤大面积受到污染（李强,2014,  相似文献   

Dolomite dissolution: An alternative diagenetic pathway for the formation of palygorskite clay     

Brooks H. Ryan  Stephen E. Kaczmarek  John M. Rivers 《Sedimentology》2019,66(5):1803-1824

Palygorskite is a fibrous, magnesium‐bearing clay mineral commonly associated with Late Mesozoic and Early Cenozoic dolomites. The presence of palygorskite is thought to be indicative of warm, alkaline fluids rich in Si, Al and Mg. Palygorskite has been interpreted to form in peritidal diagenetic environments, either as a replacement of detrital smectite clay during a dissolution–precipitation reaction or solid‐state transformation, or as a direct precipitate from solution. Despite a lack of evidence, most diagenetic studies involving these two minerals posit that dolomite and palygorskite form concurrently. Here, petrological evidence is presented from the Umm er Radhuma Formation (Palaeocene–Eocene) in the subsurface of central Qatar for an alternative pathway for palygorskite formation. The Umm er Radhuma is comprised of dolomitized subtidal to peritidal carbonate cycles that are commonly capped by centimetre‐scale beds rich in palygorskite. Thin section, scanning electron microscopy and elemental analyses demonstrate that palygorskite fibres formed on both the outermost surfaces of dissolved euhedral dolomite crystals and within partially to completely dissolved dolomite crystal cores. These observations suggest that dolomite and palygorskite formed sequentially, and support a model by which the release of Mg²⁺ ions and the buffering of solution pH during dolomite dissolution promote the formation of palygorskite. This new diagenetic model explains the co‐occurrence of palygorskite and dolomite in the rock record, and provides valuable insight into the specific diagenetic conditions under which these minerals may form.  相似文献   

河北阳原新生代玄武岩中橄榄岩捕虏体矿物化学:华北岩石圈地幔演化   总被引：1，自引：0，他引：1  

陈曦  郑建平 《地球科学》2009,34(1):203-219

橄榄岩及其中矿物的组成, 特别是单斜辉石的微量元素, 可以很好的揭示岩石圈地幔性质.在对河北阳原新生代玄武岩中橄榄岩捕虏体详细岩相学和矿物化学研究基础上, 重点分析了单斜辉石的激光原位微量元素, 讨论了新生代华北内部山带岩石圈地幔特征及其演化机制.阳原地区陆下岩石圈, 除个别样品的部分熔融程度为15%~20%外, 多数样品<5%, 显示该区的地幔演化是不均一的, 并表现为饱满与难熔-过渡型地幔的交叉并存.这种共存现象可以用软流圈物质对古老地幔进行不均匀侵蚀、改造和置换作用来解释.   相似文献