滑坡变形立体监测网建设   总被引：1，自引：0，他引：1  

李长明 《中国地质灾害与防治学报》2005,16(B12):19-22

论文简要介绍了滑坡监测工作内容和监测方法，对现有技术方法在实际工作中的优缺点进行了简要评述。认为在滑坡稳定性监测工作中应该建立全方位、多种手段的立体监测网，仅仅运用某一种或者某一单方面的监测方法是不行的，是片面的，无法准确了解滑坡的动态。所说的立体监测网既有水平位移监测又有垂直位移监测，既有滑坡地表表层变形监测又有滑体深部变形监测，既有专业监测又有群测群防体系。同时监测有可能准确地掌握使滑坡失稳的各种因素（自然因素和人为因素）。因此建议在滑坡监测中建立全方位、多种手段的立体监测网，并提出了立体监测网建设的主要内容。  相似文献   

Determination of regional soil geochemical baselines for trace metals with principal component regression: A case study in the Jianghan plain,China     

《Applied Geochemistry》2014

The soil geochemical baseline is an important index in environmental assessment. Detailed baseline studies are necessary in large areas with complex geological settings, landforms and soil types. The Jianghan plain, a major industrial and agricultural region located in central China, has a soil geochemical baseline that has yet to be fully defined. The objective of this paper is to study the baseline of Cd, Pb and Zn in the topsoil of the Jianghan plain in a subarea using principal component regression (PCR). A total of 9030 samples were collected from the surface layer, and 2 soil profiles and 2 sedimentary columns were sampled near the Yangtze and Han rivers. Fifty-two elements and two parameters were analyzed. Data processing and the creation of spatial distribution maps of the elements were performed using MapGIS, R and SPSS software. The results show that the distributions of Cd, Pb and Zn are mainly controlled by parent material, drainage system and soil type. The study area is divided into 3 subareas, with factors reflecting the physico-chemical characteristics of the soil using factor analysis (FA). The geochemical baseline model is established in every subarea to predict the Cd, Pb and Zn values using principal component regression analysis (PCR); the exceptional values (as a result of anthropogenic input or mineralization) are distinguished by residuals (γ); and the natural background values and anthropogenic contributions are clearly distinguished. Therefore, the PCR method in these subareas is objective and reasonable, and the conclusion provides effective evidence of exceptional high values for further environmental assessment.  相似文献   

Late Cretaceous magmatism and related metallogeny in the Tengchong area: Evidence from geochronological,isotopic and geochemical data from the Xiaolonghe Sn deposit,western Yunnan,China     

《Ore Geology Reviews》2016

Xiaolonghe is a poorly studied greisen-type tin deposit that is hosted by biotite granite in the western Yunnan tin belt. The mineralisation-related metaluminous and weak peraluminous granite is characterised by high Si, Al and K and low Mg, Fe and Ca, with an average A/CNK of 1.02. The granite is enriched in LILEs (K and Rb), LREEs and HFSEs (Zr, Hf, Th, U and Ce) and depleted in Ba, Nb, Sr, P, and Ti, with zircon εHf(t) = − 10.8 to − 7.5 (T_DM2 = 1.61–1.82 Ga). These characteristics indicate that the magma was generated by the partial melting of a thickened ancient crust. LA-ICP-MS U–Pb dating of igneous zircon and hydrothermal cassiterite yield ages of 71.4 ± 0.4 Ma and 71.6 ± 4.8 Ma, respectively. The igneous biotite and hydrothermal muscovite samples show Ar–Ar plateau ages of 72.3 ± 0.4 Ma and 70.6 ± 0.2 Ma, respectively. The close temporal relationship between the igneous emplacement and hydrothermal activity suggests that the tin mineralisation was closely linked to the igneous emplacement. The δ¹⁸O and δD values for the deposit range from + 3.11‰ to − 4.5‰ and from − 127.3‰ to − 94.7‰, respectively. The hydrothermal calcite C and O isotopic data show a wide range of δ¹³C_PDB values from − 5.7‰ to − 4.4‰, and the δ¹⁸O_SMOW values range from + 1.4‰ to + 11.2‰. The δ³⁴S_V-CDT data range from + 4.8‰ to + 8.9‰ for pyrite, and the ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb ratios range from 18.708 to 18.760, from 15.728 to 15.754 and from 39.237 to 39.341, respectively. The stable isotopic (C–H–O–S–Pb) compositions are all similar to those of magmatic and mantle-derived fluids, which indicate that the ore-forming fluids and materials were mainly derived from magmatic sources that were accompanied by meteoric water. The tin mineralisation in the Xiaolonghe district was closely associated with the Late Cretaceous crustal-melting S-type granites that formed during the subduction of the Neo-Tethys oceanic lithosphere. Combined with the tin deposits in the Southeast Asian tin belt, Tengchong block and Central Lhasa, we interpreted that a giant intermittent tin mineralisation belt should be present along the Asian Neo-Tethys margin.  相似文献   

Mineralogy and mineral chemistry of Bi-minerals: Constraints on ore genesis of the Beiya giant porphyry-skarn gold deposit,southwestern China     

《Ore Geology Reviews》2016

The Beiya deposit, located in the Sanjiang Tethyan tectonic domain (SW China), is the third largest Au deposit in China (323 t Au @ 2.47 g/t). As a porphyry-skarn deposit, Beiya is related to Cenozoic (Himalayan) alkaline porphyries. Abundant Bi-minerals have been recognized from both the porphyry- and skarn- ores, comprising bismuthinite, Bi–Cu sulfosalts (emplectite, wittichenite), Bi–Pb sulfosalts (galenobismutite, cosalite), Bi–Ag sulfosalt (matildite), Bi–Cu–Pb sulfosalts (bismuthinite derivatives), Bi–Pb–Ag sulfosalts (lillianite homologs, galena-matildite series), and Bi chalcogenides (tsumoite, the unnamed Bi₂Te, the unnamed Ag₄Bi₃Te₃, tetradymite, and the unnamed (Bi, Pb)₃(Te, S)₄). Native bismuth and maldonite are also found in the skarn ores. The arsenopyrite geothermometer reveals that the porphyry Au mineralization took place at temperatures in the range of 350–450 °C and at log fS₂ in the range of − 8.0 to − 5.5, respectively. In contrast, the Beiya Bi-mineral assemblages indicate that the skarn ore-forming fluids had minimum temperatures of 230–175 °C (prevailing temperatures exceeding 271 °C) and fluctuating fS₂–fTe₂ conditions. We also model a prolonged skarn Au mineralization history at Beiya, including at least two episodes of Bi melts scavenging Au. We thus suggest that this process was among the most effective Au-enrichment mechanisms at Beiya.  相似文献   

湖南寒武系第三统混积岩沉积特征与成因探讨     

梁薇  牟传龙  周恳恳  王瑞华  葛祥英  徐鹏辉  郑斌嵩  谭志远 《地质论评》2016,62(4):881-896

湖南地区寒武系第三统发育大量的混积岩及混积层系,其沉积特征、成因及时空分布,对研究寒武纪中上扬子地区东南缘的沉积环境及碳酸盐台地的形成演化具有重要的意义。本文采用野外观察、微观岩石学分析方法对混积岩时空分布、沉积特征、矿物组分进行了研究,首次系统总结了湖南地区寒武系第三统发育的混积层系类型与组合方式,及其分布的6类不同的岩相分区,并按照成分分类依据划分出4种混积岩类型。研究表明,混积岩分布在湘西北地区及湘中地区,靖州—涟源—隆回—宁乡一线以北的区域。混积层系的沉积特征表明,其形成于受周期性强风浪、风暴作用影响的浅水混积陆棚环境或风暴浪基面以下的深水混积陆棚环境,主要成因为机械成因的相缘渐变沉积混合及事件突变沉积混合。混积陆棚的存在,表明寒武纪第三世时期,中上扬子东南缘湘西北地区不发育台缘相带,未建立起完整的镶边碳酸盐台地模式,而为相对平缓的碳酸盐岩为主的浅海混积陆棚模式,混有碎屑岩沉积物。  相似文献   

国内外前寒武纪条带状铁建造研究现状   总被引：4，自引：0，他引：4  

代堰锫  朱玉娣  张连昌  王长乐  陈超  修迪 《地质论评》2016,62(3):735-757

条带状铁建造(BIFs)主要发育于早前寒武纪时期(3.8~1.8Ga),记录了早期地球演化的重要信息且蕴含丰富的铁矿石资源。本文梳理总结了国内外BIF相关领域的研究认识及存在问题:1统计对比显示,BIF沉积事件与地幔柱、地壳增生等重大地质事件相关;2稀土元素及Nd同位素示踪表明,Fe来源于海水与海底高温热液的混合溶液,其中高温热液与海水比例为1:1000;3 BIFs缺乏负Ce异常且富集重Fe同位素,暗示沉积时古海洋整体处于缺氧环境以避免Fe~(2+)发生氧化;4一些重要科学问题尚未解决,例如Si的主要来源、沉淀机制及条带成因等;5华北克拉通BIFs多形成于约2.54Ga,BIF类型、形成时代与富矿成因等问题有待深入研究。本文认为,加强国内外典型BIFs的对比研究并适当应用现代先进测试技术,有利于探索BIF沉积的精细过程及古老克拉通的早期演化。  相似文献   

青藏高原片麻岩穹窿与找矿前景   总被引：4，自引：0，他引：4  

许志琴  付小方  马绪宣  戚学祥  吴婵  侯立伟  赵中宝 《地质学报》2016,90(11):2971-2981

片麻岩穹窿是研究俯冲-折返和碰撞-折返造山过程的重要窗口。已查明的大量青藏高原片麻岩穹窿(群)分布在古特提斯和新特提斯大洋俯冲-折返以及地体碰撞-折返过程中。松潘-甘孜造山带中雅江甲基卡片(麻)岩穹窿的三叠纪变质片岩的含矿伟晶岩脉中发现了超大型锂矿床,揭示片(麻)岩穹窿构造与同构造花岗岩、含矿伟晶岩脉以及大型印支滑脱带在时空和成因上有天然联系,为片麻岩穹窿的找矿前景提供了范例。  相似文献   

羌塘盆地羌资3井索瓦组泥岩生物标志化合物特征及其地质意义   总被引：1，自引：1，他引：0       下载免费PDF全文

杜佰伟  彭清华  何江林 《中国地质》2016,(1):298-305

本文对羌塘盆地羌资3井索瓦组样品开展了详细的有机地球化学特征研究,探讨了其有机母质来源及形成的沉积环境。样品中检测出丰富的正构烷烃、类异戊二烯烷烃、萜类化合物和甾类化合物。在GC图谱上,主碳数分别为n C17、n C18、n C23或n C25,OEP值为0.4~1.24,Pr/n C17值为0.68~0.99、Ph/n C18值为0.55~0.98,Pr/Ph为0.50~0.90。萜类化合物以C30藿烷占优势的五环三萜烷为主,含有三环萜烷和伽马蜡烷。甾类化合物以规则甾烷为主,C27、C28和C29规则甾烷构成了不对称的"V"字型,C29ααα20S/(20S+20R)和C29αββ/(ααα+αββ)的值分别为0.30~0.49、0.40~0.54。饱和烃色谱/质谱特征表明泥岩有机母质来源来源于具有水生生物的混合来源,揭示了其母质形成于一定盐度缺氧还原环境。镜质体反射率与成熟度参数均显示泥岩与沥青处于生油高峰阶段。生物标志物研究显示羌资3井沥青与泥岩在母质性质、沉积环境、成熟度等方面有相近的特征,它们具有较好的亲缘关系。  相似文献   

昌宁-孟连结合带牛井山早古生代埃达克岩锆石U-Pb年龄、岩石成因及其地质意义   总被引：12，自引：6，他引：6  

王冬兵  罗亮  唐渊  尹福光  王保弟  王立全 《岩石学报》2016,32(8):2317-2329

昌宁-孟连结合带是西南三江地区重要的古特提斯结合带,本文报道该带牛井山蛇绿混杂岩带内的早古生代英云闪长岩的锆石U-Pb年龄和Hf同位素、全岩地球化学特征,探讨其岩石成因,揭示早古生代(原)特提斯演化过程和恢复古地理格局。利用LA-ICP-MS对英云闪长岩进行锆石U-Pb定年,获得~(206)Pb/~(238)U加权平均年龄为468±2Ma(MSWD=1.4,n=22),代表岩浆岩结晶时代。对锆石进行原位微区Hf同位素分析获得锆石ε_(Hf)(t)=+1.6~+2.8。牛井山英云闪长岩具有高的SiO_2(61.6%~67.16%),Al_2O_3(15.4%~17.64%),Na_2O(2.93%~3.25%)含量,高的Na_2O/K_2O(3.9~5.4)比值。微量元素具有高Sr(469×10~(-6)~533×10~(-6)),低Yb(0.66×10~(-6)~1.22×10~(-6))和Y(8.5×10~(-6)~16.3×10~(-6)),Eu正异常(1.01~1.37)的特征。此外,在同等SiO 2条件下,还具有相对高的Mg~#和MgO(Mg~#=50~51,MgO=2.84%~3.58%)。这些特征表明英云闪长岩具有高镁埃达克岩的性质。岩石成因研究表明牛井山高镁埃达克岩很可能是俯冲洋壳加上部分大洋沉积物部分熔融并与上覆地幔橄榄岩反应的产物。早古生代洋壳俯冲成因的埃达克岩的发现证明昌宁-孟连特提斯洋演化历史可追溯至约468Ma。昌宁-孟连结合带早古生代岩浆作用与龙木错-双湖结合带早古生代洋壳残片的时代一致、构造属性相似,我们认为昌宁-孟连结合带与木错-双湖结合带可对比,它们代表了一个统一的古生代特提斯大洋残余。  相似文献   

川滇黔相邻区碳酸盐岩容矿铅锌矿成矿特征   总被引：9，自引：0，他引：9       下载免费PDF全文

秦建华  廖震文  朱斯豹  赖杨 《沉积与特提斯地质》2016,36(1):1-13

本文对川滇黔相邻区碳酸盐岩容矿铅锌矿成矿特征进行系统总结,并对区域成矿过程进行讨论。该区碳酸盐岩容矿铅锌矿发育3种矿床类型,主要分布在泸定-荥经-汉源、雷波-金阳-巧家-会东、赫章-威宁-水城和会泽-彝良4个矿集区,震旦系和古生代地层为主要容矿层。铅锌矿形成于3个成矿期和3类构造环境:以黑区-雪区铅锌矿床为代表的喷流沉积型(SEDEX型),形成于早寒武世海底地震同生断裂环境;以会泽矿床为代表的与侵入作用有关的碳酸盐岩容矿铅锌银矿床类型(IRCH Pb-Zn-Ag型),形成于晚三叠世前陆早期局部引张环境;以大梁子和天桥矿床为代表的密西西比河谷型(MVT型),形成于前陆晚期冲断挤压环境。与世界其它地方不同,川滇黔相邻区MVT铅锌成矿作用主要发生于早侏罗世。  相似文献