城市化过程中土地征用风险表征及对策     

骆东奇  罗光莲 《地域研究与开发》2006,25(4):103-106,116

从土地征用基本概念和基本特征着手，描述了土地征用的主要风险，其表现为土地征用权力滥用、侵害失地农民的权益、诱发集体土地黑市、诱发社会矛盾等方面。分析了产生风险的“公共利益需要”缺乏明确界定、土地征用的补偿标准偏低或滞后、土地征用及相关制度不健全或存在缺陷等主要原因。提出了控制与规避风险的对策与措施：严格限定公益性用地范围，提高征地补偿标准，扩大补偿范围，完善相关制度，严格土地征用程序。  相似文献   

Spinel–sapphirine–quartz bearing composite inclusion within garnet from an ultrahigh-temperature pelitic granulite: Implications for metamorphic history and P–T path     

Toshiaki Tsunogae  M. Santosh 《Lithos》2006,92(3-4):524-536

We report here a multiphase mineral inclusion composed of quartz, plagioclase, K-feldspar, sapphirine, spinel, orthopyroxene, and biotite, in porphyroblastic garnet within a pelitic granulite from Rajapalaiyam in the Madurai Granulite Block, southern India. In this unique textural association, hitherto unreported in previous studies, sapphirine shows four occurrences: (1) as anhedral mineral between spinel and quartz (Spr-1), (2) subhedral to euhedral needles mantled by quartz (Spr-2), (3) subhedral to anhedral mineral in orthopyroxene, and (4) isolated inclusion with quartz (Spr-4). Spr-1, Spr-2, and Spr-4 show direct grain contact with quartz, providing evidence for ultrahigh-temperature (UHT) metamorphism at temperatures exceeding 1000 °C. Associated orthopyroxene shows high Mg/(Fe + Mg) ratio ( 0.75) and Al₂O₃ content (up to 9.6 wt.%), also suggesting T > 1050 °C and P > 10 kbar during peak metamorphism.

Coarse spinel (Spl-1) with irregular grain morphology and adjacent quartz grains are separated by thin films of Spr-1 and K-feldspar, suggesting that Spl-1 and quartz were in equilibrium before the stability of Spr-1 + quartz. This texture implies that the P–T conditions of the rock shifted from the stability field of spinel + quartz to sapphirine + quartz. Petrogenetic grid considerations based on available data from the FMAS system favour exhumation along a counterclockwise P–T trajectory. The irregular shape of the inclusion and chemistry of the inclusion minerals are markedly different from the matrix phases suggesting the possibility that the inclusion minerals could have equilibrated from cordierite-bearing silicate-melt pockets during the garnet growth at extreme UHT conditions.  相似文献   

萨拉乌苏河流域萨拉乌苏组沙丘砂沉积特征   总被引：7，自引：1，他引：7  

欧先交  李保生  靳鹤龄  吴正  温小浩  董光荣  曾兰华  欧阳椿陶  杨艺  刘宇飞 《地理学报》2006,61(9):965-975

萨拉乌苏河流域米浪沟湾剖面萨拉乌苏组含7层古流动沙丘砂、4层古固定-半固定沙丘砂.对这些沙丘砂的沉积构造观察以及粒度、扫描电镜和常量化学元素分析结果表明：（1）这些沙丘砂具有与现代沙丘砂相似的风成沉积构造特征;（2）粒度及其参数——Mz、σ、Sk和Kg,以及主要化学组分SiO2、Al2O3和TOFE也与现代沙丘砂相近;（3）Mz-σ、SiO2-Al2O3＋TOFE散点图和概率累积曲线显示这些沙丘砂与萨拉乌苏组中的河湖相、古土壤差别明显,而与现代沙丘砂一致;（4）石英砂颗粒具有良好的磨圆以及碟形坑、新月形坑、麻坑、上翻解理薄片、硅质沉淀和硅质裂纹等表面结构特征,反映其曾受持久的风力搬运作用.沉积构造、粒度、石英砂颗粒表面结构和化学元素等多个方面具备了与现代沙丘砂类似的风成特征,证明这些沙丘砂的成因是风成的.  相似文献   

Petrogenesis and tectonic setting of Cadomian felsic igneous rocks, Sandıklı area of the western Taurides, Turkey     

Semih Gürsu  M. Cemal Göncüoglu 《International Journal of Earth Sciences》2006,95(5):741-757

In the Sandıklı (Afyon) region, western Taurides, the Late Proterozoic rocks of the Sandıklı basement complex are composed of low-grade meta-sedimentary rocks (Güvercinoluk Formation) intruded by felsic rocks (Kestel Cayı Porphyroid Suite, KCPS). The KCPS is a deformed and highly sheared, dome-shaped rhyolitic body with a granitic core. Quartz porphyry dikes intrude both the slightly metamorphic igneous and the sedimentary rocks of the basement complex. Both the quartz porphyries and rhyolites were converted into mylonites with relict igneous textures. Geochemical data show that these felsic igneous rocks are subalkaline and mainly granitic in composition with SiO₂ >72 wt% and Al₂O₃ >11.5 wt%. The chondrite-normalized incompatible trace element patterns are characterized by distinct negative Rb, Nb, Sr, P, Ti, and Eu with enrichment in Th, U, La, Ce, Nd, Sm, and Zr. The REE patterns of the felsic rocks indicate a strong enrichment in LREE but display slightly flat HREE patterns. According to geochemical characteristics and petrogenetic modeling, extrusive and intrusive rocks of the KCPS were probably derived from an upper continental crustal source (partial melting of granites/felsic rocks) by 18–20% fractional melting plus 18–20% Rayleigh fractional crystallization, which seems to be the most effective igneous process during the crystallization of the KCPS. Single zircon age data from the granitoids and fossils from the disconformably overlying sedimentary successions indicate that the metamorphism and the igneous event in the Taurides are related to the Cadomian orogeny. Based on the geological, geochemical and petrogenetic correlation of the post-collisional granitoids it is further suggested that the Tauride belt in western central Turkey was in a similar tectonic setting to the Gondwanan terranes in North Africa (Younger Granitoids) and southern Europe (Spain, France, Bohemia, Brno Massifs) during the Late Cadomian period.  相似文献   

生物气研究现状与勘探前景   总被引：16，自引：1，他引：16  

林春明  李艳丽  漆滨汶 《古地理学报》2006,8(3):317-330

综合论述了生物气的特征及其研究进展,着重探讨了生物气成因、地球化学特征、勘探研究现状、生物气形成机制和控制因素,并介绍了生物气系统概念和特征,最后叙述了生物气藏的分布和我国生物气藏的远景。生物气是在还原环境的生物化学作用带内有机质为厌氧微生物所分解的最终产物,它以甲烷为主,并含部分二氧化碳及少量氮气和其它微量气体组分,生物甲烷气δ13C1值一般小于-55‰。生物甲烷气的形成途径主要有乙酸发酵和CO2还原2种类型。生物气生成与其所处的沉积环境、古气候、有机质的类型和丰度、水介质性质、地质作用、沉积时间等众多因素密切相关。生物气埋藏浅,分布广泛,一般存在于三角洲、大陆架和部分陆相沉积环境中,储层时代主要为白垩纪、古近纪、新近纪和第四纪。白垩纪的储量最丰富,古近纪、新近纪次之,第四纪生物气藏的规模一般较小。我国生物气勘探研究历史虽然不长,但生物气资源量丰富,具有良好的勘探前景。  相似文献   

四川省康定县滑坡灾害发育特征与形成条件   总被引：3，自引：0，他引：3  

刘岁海  刘爱平 《中国地质灾害与防治学报》2006,17(3):27-31

康定县地处四川盆地西缘山地及青藏高原过渡地带。县域内地势险峻,地形切割强烈,地层与地质构造复杂,新构造运动强烈,地震活动频繁。加之降水充沛,致使山地灾害十分发育,其中滑坡灾害占山地灾害的38.32%。通过搜集资料及现场调查,概述了该县县域内滑坡灾害的分布;从行政区划、自然地理及灾害规模等3方面统计分析了滑坡灾害的发育现状;从地形地貌、地层岩性、地质构造、降雨、地震活动、人类工程活动等方面总结了滑坡灾害的形成条件,并提出防治对策与措施,力求有效地预防与减少滑坡灾害的发生。  相似文献   

西藏昌都镇地质灾害发育特征及防治对策   总被引：1，自引：1，他引：1  

汤明高  许强  马和平  成民  杜先兴 《中国地质灾害与防治学报》2006,17(4):11-16

昌都镇位于澜沧江上游“三河一江”地带(即昂曲、扎曲、色曲、澜沧江)。地质构造条件复杂,气候较恶劣,昼夜温差大,物理风化强烈,植被稀疏,地质灾害发育。该区是藏东的政治、经济、文化中心。随着地区的经济发展,其城镇建设与地质灾害之间的矛盾日益突出。调查研究显示昌都镇发育地质灾害33处,其中崩塌16处,占灾害点总数48.5%,主要发育于路堑边坡和河流下切侧蚀形成的自然边坡;滑坡13处,占灾害点总数的39.4%,且90%为土质滑坡,多与人类工程活动有关;泥石流4处,占灾害点总数的12.1%,以中小型为主。文章总结了昌都镇崩塌、滑坡和泥石流灾害的发育分布特征,地质灾害与地层岩性、空间位置和人类工程活动等之间的关系,以及对昌都城镇建设和发展的影响。结合调查分析提出了昌都镇地质灾害防治的总体策略———治灾、设防、治水、治坡、生态建设和加强环保意识。  相似文献   

Adsorption of Pentachlorophenol onto Oxide and Clay Minerals： Surface Reaction Model and Environmental Implications     

WU Daqing DIAO Guiyi YUAN Peng PENG Jinlian 《《地质学报》英文版》2006,80(2):192-199

The adsorption of pentachlorophenol （PCP） onto quartz, kaolinite, illite, montmorillonite and iron oxides has been investigated by batch equilibrium techniques. The pH-dependent isotherms are curves with peak values, the position of which is at about pH = 5-6 depending on the mineral species. Based on distribution of both speciation of surface hydroxyls on minerals and PCP in solution a surface reaction model involving surface complexation and surface electrostatic attraction is presented to fit the pH-dependent isotherms, and both reaction constants are calculated. The results show that on quartz and phyllosilicate minerals the predominant adsorption reaction is surface complexation, meanwhile both of surface electrostatic attraction and surface complexation are involved on the iron oxide minerals. The reaction constants of surface electrostatic adsorption are usually one to three orders in magnitude, larger than that of surface complexation. The concentration-dependent isotherms can be well fitted by Langmnir equation with the correlation coefficient R〉0.93 for kaolinite and iron oxides. The maximum adsorption is found in the order： hematite 〉 lepidocrocite 〉 goethite 〉 kaolinite 〉 quartz 〉 montmorillonite ≈ illite, which can be interpreted by consideration of both reaction mechanism and surface hydroxyl density. The significant adsorption of PCP onto mineral surfaces suggests that clay and iron oxide minerals will play an important role as HIOCs are adsorbed in laterite or latertoid soil, which is widespread in South China.  相似文献   

地物波谱研究现状及方法的初步探讨   总被引：5，自引：0，他引：5  

刘峰  张继贤  靳奉祥  邵飞  张恒铁 《北京测绘》2005,(3):1-6,10

地物波谱特性是遥感技术应用的物理基础,是遥感定量分析的基础,地物波谱研究是遥感基础研究的重要内容。文中阐述了几种典型地物的波谱特征,介绍了测量方法及影响因素,并对国内外波谱数据库建设现状作了描述和分析,系统总结了前人研究成果后对地物波谱研究的发展方向提出了构想。  相似文献   

微波消解-火焰原子吸收光谱法测定石英砂中的氧化钙和氧化镁     

鲁青庆 《岩矿测试》2005,24(4):314-316

采用微波消解-硼酸络合-火焰原子吸收光谱法测定石英砂中的氧化钙和氧化镁。样品在MK-Ⅲ型实验室微波炉上消解,消解压力为2.0 MPa、消解时间为5 m in,以硼酸络合消除氢氟酸的影响。方法已用于实际样品的测定,7次测定的相对标准偏差(RSD)小于5%,加标回收率为95.0%~104.2%。  相似文献