Hydrothermal Redistribution of Rare—Earth Elements in Pingxiang Dacite,Guangxi     

顾尚义  万国江  毛健全  张启厚 《中国地球化学学报》2002,21(2):170-174

Distribution of the rare-earth elements (REE) in dacite has been studied so as to get a better understanding of the migration behavior of REE during alteration. Both unaltered and altered samples were collected in an unpolluted area of Guangxi Zhuang Autonomous Region, southwest China. The REE concentrations were analyzed by ICP-MS. It is concluded that the REE were enriched during dacite alteration in varying degrees. The chondrite-normalized REE patterns of altered samples approximately maintain the characteristics of unaltered samples. However, if we normalize the REE concentrations of altered samples with unaltered dacite, fractionation of REE will appear. The LREE are more enriched than HREE in all altered samples with the LREE possibly precipitated as carbonate minerals. Both positive and negative Eu anomalies exist. Enrichment, immobility and depletion are noticed for the element Lu. Heavy mineral alteration, difference in stability constant between carbonate LREE and HREE complexes, downward migration of weathering fluid and microenvironment change may be responsible for the fractionation of REE in the altered dacite.  相似文献   

大姚地热动态特征分析   总被引：3，自引：1，他引：3  

毛德培  王树明  胡智文  万登堡  石绍先 《地震研究》2002,25(1):42-47

通过大姚高精度水温观测井水地质、井孔条件的分析，震例观测资料、实验观测数据的处理，以及井水水质分析结果，表明大姚水温周期性变化的突出位置是井深75m左右，根本原因是该地层石膏脉稳定释热，含水层热水与井内冷水混合过程中，在通道内形成钙盐类沉淀物（如CaSO4CaCO3），堵塞对流通道，含水层内外压差突破被阻塞通道，热水反复侵入井内，便形成水温周期性变化。地震的孕育、发生和调整过程，由于应力场作用，产生附加地热场，水温基值发生变化，周期畸变或消失，这种附加地热动态是可以恢复的。所以认为大姚地热动态是井区特殊地层地热信息的反映。  相似文献   

Tiller recruitment and mortality in the dryland bunchgrass Eragrostis curvula as affected by defoliation intensity     

Changgui Wan  Ronald E. Sosebee 《Journal of Arid Environments》2002,51(4):577

A greenhouse experiment was conducted to investigate the effects of moderate (14 cm) vs. severe (7 cm) defoliation on tiller recruitment and mortality within the interior and on the perimeter of weeping lovegrass (Eragrostis curvula) tussocks. Tiller number per marked shoot within the interior was significantly greater in plants defoliated at 14-cm stubble height than at 7-cm stubble height (2·37 vs. 0·43, p<0·05) 28 weeks after defoliation; likewise, tiller number per marked shoot was also greater on the perimeter of tussocks in the higher stubble than the lower stubble defoliation treatment (5·10 vs. 2·03, p<0·05). Tiller natality increased significantly 4 weeks after defoliation except for tillers cut to 7-cm stubble height within the interior of tussocks where tiller natality reached a peak at 4·5 weeks after defoliation. During the later stages of canopy development, tiller numbers per marked shoot gradually declined as tiller mortality increased. Tillers began senescing 13 weeks after defoliation, and the senescence rate was 52% greater in the 7-cm stubble height treatment than in the 14-cm stubble height treatment (2·33 vs. 1·53, p<0·0001). Within the interior of tussocks, number of the marked tillers more than doubled under the 14-cm stubble height treatment, whereas the plants lost 57% of the monitored tillers under the 7-cm stubble height treatment. We concluded that the central dieback process in weeping lovegrass is accelerated by severe defoliation.  相似文献   

塔里木盆地西部含盐系地层成盐元素的地球化学初步研究   总被引：3，自引：1，他引：3       下载免费PDF全文

马万栋  马海州  谭红兵  张西营 《盐湖研究》2003,11(2):35-40

钾矿是我国目前紧缺的矿种之一 ,钾矿的寻找对我国有着十分重要的意义。塔里木盆地是我国第三系地层的广泛发育区域 ,有一定的找钾远景 ,尤其是库车、莎车等地区。通过对塔里木盆地 (坳陷 )西部的区域地质概况、成矿条件等的介绍 ,运用地球化学的分析测试手段 ,对塔里木盆地西部采集到的样品作了地球化学分析。论述了该区成盐沉积的地球化学特征 ,并讨论了该区形成钾矿的可能性。  相似文献   

重油凝胶色谱制备样品中痕量镍的分析研究          下载免费PDF全文

朱玉霞许世科  陆婉珍 《岩矿测试》2003,22(2):129-133

研究表明微波密闭消解法对重油凝肢色谱制各样品的前处理，不造成易挥发有机金属化合物的损失，对样品无污染。采用消解前定容，配合石墨炉二次进样富集样品，可以测定样品中低至10^—9级的镍。方法应用于镍在渣油中随相对分子质量分布分析中，标准样品对照数据吻合好，相对标准偏差(RSD，n＝11)为8％。  相似文献   

利用高铁钾长石粉合成13X沸石分子筛的实验研究   总被引：6，自引：3，他引：6       下载免费PDF全文

章西焕  马鸿文杨静 肖万 《岩石矿物学杂志》2003,22(2):167-172

对江苏丰县的富钾页岩进行预处理，得到钾长石含量达76．4％的钾长石粉，其Fe2O3含量高达7．52％。以此钾长石粉为原料经过焙烧处理、水热合成实验，在铁含量较高情况下成功合成了13X沸石分子筛，并采用正交实验法确定了优化工艺参数。对实验产物的主要性能测试表明，合成的富铁沸石产品与13X沸石分子筛工业产品相似，吸附量达到国家化学工业产品标准，可用于对含重金属离子废水的吸附处理。  相似文献   

贵州红枫湖沉积物有机质的酶及微生物降解   总被引：8，自引：1，他引：8  

梁小兵  朱建明  刘丛强  魏中青  汪福顺  万国江  黄荣贵 《第四纪研究》2003,23(5):565-572

文章通过DNA、α-葡萄糖苷酶和硫酸盐还原菌等的变化,研究了贵州红枫湖沉积物中有机质的酶及微生物降解.有机质在微生物及其分泌的胞外酶的作用下被降解,在沉积物深度11cm以下被降解到相对较低的含量.DNA的分布表明表层9cm的沉积物深度内微生物的活动较为强烈,是微生物降解有机质的主要位置.α-葡萄糖苷酶在悬浮层含量最高,达0.75μmol/min*g干沉积物,提示有机质中的淀粉和糖原等物质在悬浮层降解较为激烈,被大量分解;随着沉积物深度的增加α-葡萄糖苷酶活性减弱,在有机质降解明显开始变缓的11cm沉积物中,α-葡萄糖苷酶活性已降低到0.17μmol/ming干沉积物.分子生物学的研究表明红枫湖沉积物表层7cm是硫酸盐还原菌的主要分布位置,结合有机质和SO_2-4含量的研究结果,提示红枫湖沉积物中SO_2-4不可能成为有机质氧化的主要电子受体,硫酸盐还原的限制因素也不是有机质供应.  相似文献   

Dinosaur tracks from the Cretaceous of South Korea: Distribution, occurrences and paleobiological significance   总被引：2，自引：0，他引：2  

Min Huh  Koo Geun Hwang  In Sung Paik  Chull Hwan Chung  Bo Seong Kim 《Island Arc》2003,12(2):132-144

Abstract   Abundant dinosaur fossils including dinosaur footprints, eggs and nests, teeth and bones have been found from the Cretaceous non-marine deposits of Korea. Among them, dinosaur tracks are the most distinctive, and some track sites are among the most famous in the world. Until now, 27 dinosaur track localities have been discovered from the Cretaceous strata in the Gyeongsang Basin and several small basins. Ornithopod tracks are most abundant at most Korean track sites, and most of them are identified as Caririchnium ; that is, large ornithopod footprints with wide hoof impressions. Most theropod tracks are found in Neungju Basin and they consist of various types of small or medium-sized bird-like footprints, and other large footprints. Sauropod tracks are also abundant in the Gyeongsang Basin. The sauropod tracks vary in size, shape, and pattern of trackway, and suggest that diverse sauropods existed in this area. These diverse tracks in South Korea suggest that various dinosaurs flourished at the margins of lakes distributed in the southern part of the Korean Peninsula during the Cretaceous.  相似文献   

A procedure for evaluating seismic energy demand of framed structures     

Chung‐Che Chou  Chia‐Ming Uang 《地震工程与结构动力学》2003,32(2):229-244

Energy serves as an alternative index to response quantities like force or displacement to include the duration‐related seismic damage effect. A procedure to evaluate the absorbed energy in a multistorey frame from energy spectra was developed. For low‐ to medium‐rise frames, it required a static pushover analysis of the structure to determine the modal yield force and ductility factor of an equivalent single‐degree‐of‐freedom system for the first two modes. The energy spectra were then used to determine the energy contribution of each mode. A procedure was also developed to distribute the energy along the frame height based on energy shapes. This study showed that the second‐mode response in some cases needs to be considered to reflect the energy (or damage) concentration in the upper floors. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Is Prediction of Future Landslides Possible with a GIS?   总被引：5，自引：0，他引：5  

Fabbri  Andrea G.  Chung  Chang-Jo F.  Cendrero  Antonio  Remondo  Juan 《Natural Hazards》2003,30(3):487-503

This contribution explores a strategy for landslide hazard zonation inwhich layers of spatial data are used to represent typical settings inwhich given dynamic types of landslides are likely to occur. Theconcepts of assessment and prediction are defined to focus on therepresentation of future hazardous events and in particular on themyths that often provide obstacles in the application of quantitativemethods. The prediction rate curves for different applications describethe support provided by the different data layers in experiments inwhich the typical setting of hazardous events is approximated bystatistically integrating the spatial information.  相似文献