江西赣县大埠钨多金属矿田成岩成矿时空结构与找矿预测

大埠矿田位于南岭成矿带东段,是于都-赣县钨多金属矿集区重要组成,区内已发现钨多金属矿床（点）五十余处,矿床类型包括石英脉型、矽卡岩型、云英岩型和细脉浸染型等,各类矿化主要围绕大埠复式花岗岩体产出。然而,大埠矿田岩浆作用具有明显的多期次、多阶段的特点,各期次成岩成矿时代尚缺乏系统研究,各类岩浆岩与矿化关系争议较大。文章在岩体地质和矿床地质调查基础上,通过LA-(MC)-ICP-MS锆石U-Pb定年、锆石微量元素和Hf同位素分析,精确厘定了大埠花岗岩的成岩时代,探讨了多期次岩浆活动对区内成矿作用的贡献。锆石U-Pb定年结果分别为(429.1±4.7)Ma、(430.0±5.8) Ma、(431.8±4.7) Ma和(158.3±4.1) Ma,结合岩体地质填图信息,笔者认为大埠复式花岗岩基由加里东期和燕山期两部分组成。两期花岗岩均属于高钾钙碱性、过铝质S型花岗岩系列,两者均出现Eu负异常,燕山早期Eu负异常更明显。两期岩体锆石的ε_Hf(t)值分别为-6.3~-1.3与-11.4~-7.1,对应二阶段模式年龄为1.49~1.82 Ga与1.66~1.93 Ga,指示其母岩浆为中元古代的地壳部分熔融形成。锆石微量元素特征显示,两期花岗岩均为陆壳源区、具有相近的结晶温度,燕山早期花岗岩相对于加里东期有更高的结晶分异程度,有更高的氟含量,与钨成矿具有更强的相关性。大埠矿田钨多金属成矿时代集中在159~155 Ma,紧随燕山早期花岗质岩浆侵位而形成。基于大埠矿田成岩成矿时代格架研究,结合花岗岩成矿专属性和成矿地质条件分析,构建了区内钨多金属矿勘查模型,指明了大埠矿田细脉浸染型、云英岩型、内带石英脉型钨矿的找矿方向,预测大埠岩体东北部的燕山早期隐伏岩体具有寻找“合龙式”石英大脉型和细脉-云英岩型钨矿的潜力。     

The deep thermal structure of the lithosphere in the northwestern South China Sea and its control on the shallow tectonics

The northwestern sub-basin of South China Sea(SCS) is a unique tectonic unit formed in the early spreading of the SCS. The northwestern Sub-basin has a series of complex geological structures such as seamounts and fault zones surrounded by the Xisha Trough, the Zhongsha Massif, and the Pearl River Valley. These extensional structures and magmatic activity in the northwestern sub-basin are closely related to the lithospheric structure and its deformation. However, details of the deep lithosphere structure are still poorly known. Here, we obtained detailed data of water and Moho depth using sonar buoys,Extended Spread Profiles(ESP), Ocean Bottom Seismometer(OBS), both Multi-beam and land-sea joint seismic surveys in the northwestern sub-basin and its surrounding areas. Then we adopted a thermal isostasy method to calculate the depth of the Lithosphere-Asthenosphere Boundary(LAB) in the northwestern sub-basin of the SCS and its surrounding regions. Results show that the range of LAB depth is ～25–110 km. The shallowest burial depth is 25–60 km occurring in the ocean basin. The depth increases to 60–110 km toward the continental margin. The lithospheric structure on the north and south sides of the Xisha Trough is symmetrical and shows the deep structure and thermal features of aborted rifts. The LAB depth in the Zhongsha Trough and the Zhongsha Massif increased from 60 to 70 km southwestwards, consistent with the trend of surface morphology.The LAB depth to the west side of the Pearl River Valley is 60–80 km, and the thinning of the lithosphere is related to the distribution of faults, depressions and the magmatic activity. The LAB depth in the northwestern sub-basin and the eastern subbasin is less than 60 km with the thinnest part being less than 46 km. Combining ocean drilling, seismic investigation, and seafloor topography, we show that the ocean basin of the northwestern sub-basin of the SCS locates within the 46 km isobath of the LAB. The formation of the rifted valleys and discrete blocks surrounding the ocean basins is both controlled by the regional tectonic movement and the deep thermal state, where their lithospheric structures show strong heterogeneity.     

标度律视角的城市效能测度及中国城市多维要素效能分析

"城市标度律"(urban scaling laws)揭示了城市系统中城市人口和城市要素间普遍存在的非线性规模缩放关系,但目前大多数城市评价忽视了这种关系,常使用人均指标比较不同规模的城市,这会导致评价结果偏差.为此,考虑城市人口和城市要素间的非线性规模缩放关系构建了要素效能指数,用以修正城市规模的影响,度量城市要素实...     

黄山高速滑移弯曲边坡变形机理分析及应急治理对策

黄山高速公路穿行于皖南山区,公路建设过程中,汤口互通A匝道高边坡产生了大范围变形,严重威胁已有构筑物和施工安全。为保证边坡稳定,成立“应急指挥小组”,建立快速反应机制,并采用工程地质测绘、勘探、监测等手段,快速查明边坡结构特征,分析边坡变形机理和稳定性,提出应急治理方案。分析表明,该边坡为层间软弱夹层[JP2]发育的砂泥岩互层型顺向边坡,地质历史上边坡曾发生滑移—弯曲变形,公路施工时对弯曲隆起部位岩体进行开挖,引起坡体产生快速变形,在降雨、开挖等条件下,边坡产生整体失稳的可能性极大。在分析边坡变形机制基础上,应用变形控制理论,确定对边坡采取桩锚结合、综合排水的应急治理措施,并根据变形特点提出了应急治理施工步骤。应急治理措施实施后,边坡变形得到了有效控制,稳定性达到了高速公路的安全要求     

Multiscale characteristics of the wetting deformation of Malan loess in the Yan'an area,China

Loess is prone to collapse upon wetting due to its open metastable structure, which poses a considerable threat to the environment, construction processes and human life. In this study, double oedometer tests and scanning electron microscopy and mercury intrusion porosimetry analyses were conducted on loess from Yan'an to study the macroscopic and microscopic characteristics of loess wetting deformation and the underlying mechanism. The wetting collapse of loess under loading depends on the changes in different microstructure levels and elements. This collapse chain reaction is manifested by the dissipation, scattering and recombination of the cementation, deformation and reorganization of the particles, blocking of the pore channels, decrease in the dominant size and volume of unstable macropores(14 μm) and abundant mesopores(2.5-14 μm), increase in the volume of small pores(0.05–2.5 μm), and volume contraction at the macroscale. This process is dependent on the initial water content,stress level and wetting degree. These findings can facilitate collapsible loess hazard prevention and geological engineering construction.     

三峡库区重庆段水土流失的时空格局特征

在TM 解译的三峡库区重庆段1999 年和2004 年水土流失数据及相关辅助数据的支持下, 借助GIS 技术, 分析了研究区5 年来水土流失的时空演变及地理空间分异特征与规律。 研究结果表明: (1) 研究区水土流失总体呈现好转趋势, 极强度和剧烈水土流失面积下降变幅最大。(2) 水土流失主要分布在紫色土、黄壤、石灰(岩) 土、水稻土和黄棕壤分布区。(3) 水 土流失主要发生在受人类活动影响最为剧烈的旱坡地和疏林地。(4) 水土流失表现出明显的垂直分异特征, 主要集中于高程200~1500 m 的低山、丘陵地区。(5) 水土流失与坡度具有很好的相关性, 主要分布在15^o以上的陡坡地。(6) 水土流失与坡向分异无明显的相关关系。各坡向水土流失面积和强度分布基本相当。(7) 水土流失主要集中在300~320 和320~340 j.cm/hm². h 的降雨侵蚀力(R) 值分布区。剧烈水土流失与高降雨侵蚀力具有较好的对应关系。     

基于集群理论的产业规划模式探析

传统产业规划在信息网络时代正受到诸多挑战,地方化、信息化正成为地区产业发展的重要驱动力量,在此思路上,本文试图构建一种新型的产业规划模式——集群理论下的产业规划模式。文章首先分析了传统产业规划的概念、基础理论及其存在问题,在此基础上引入了集群理论并梳理了其理论要点,同时借鉴国外集群创导理论和一些具体规划范式构建了基于集群理论的产业规划的一般模式,并对该模式实施的误区及其与传统产业规划的区别联系进行了分析,最后提出了模式实施的相关保障措施。     

工程建筑物变形监测方案设计及应用

首先介绍了工程建筑物变形监测的基本原理,并在此基础上详细阐述了工程建筑物沉降变形监测的方案设计过程,最后通过一个工程应用实例验证该方案设计的合理性与可行性。     

全站仪断面测量方法

从野外断面测量的角度出发,主要讨论全站仪在断面测量中的野外观测方法、数据处理思路以及相应的软件研制.     

VirtuoZo AAT在高山地地形中的应用

结合高山地地形特点,分析VirtuoZo AAT在生产中常见的问题,并提出相应的解决方法.