塔里木盆地塔东2井奥陶系笔石化石层

塔里木盆地东部塔东 2井岩心中新发现了一些奥陶系笔石化石 ,这些笔石标本呈炭质薄膜状 ,保存在该井4 5 5 0 .2 m至 4 5 5 5 .3m的灰黑色泥岩之中。经研究 ,笔石动物群的时代属于玉山晚期至达瑞威尔早期 ,含笔石化石层顶部层位可与塔里木盆地东北缘却尔却克山剖面中奥陶统却尔却克组底部 Pseudamplexograptus confertus笔石带相对比     

Migration from the city to the countryside in Hungary and Poland

After the changes of 1989, urban-to-rural migration in Poland and Hungary remained stable compared to rural-to-urban migration. This was connected to a growing importance of suburbanisation around major Hungarian and Polish cities. Suburban areas around these cities are attracting increasing numbers of migrants from the major cities. Pollution and higher crime rates, as well as rising living costs and increasing uncertainties make many people to decide to leave the city for the surrounding countryside. Not only upper middle-class people move to the suburbs, but also lower status people, for whom life in the big city became too difficult. Long-distance migration from the cities to the rural areas is declining. Economic problems together with low employment opportunities prevent people from making such a move. Though the overall level of urban-to-rural migration did not change too much, this article shows the rapidly increasing importance of suburbanisation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Intelligent modelling of clay compressibility using hybrid meta-heuristic and machine learning algorithms

Compression index Ccis an essential parameter in geotechnical design for which the effectiveness of correlation is still a challenge.This paper suggests a novel modelling approach using machine learning(ML)technique.The performance of five commonly used machine learning(ML)algorithms,i.e.back-propagation neural network(BPNN),extreme learning machine(ELM),support vector machine(SVM),random forest(RF)and evolutionary polynomial regression(EPR)in predicting Cc is comprehensively investigated.A database with a total number of 311 datasets including three input variables,i.e.initial void ratio e0,liquid limit water content wL,plasticity index Ip,and one output variable Cc is first established.Genetic algorithm(GA)is used to optimize the hyper-parameters in five ML algorithms,and the average prediction error for the 10-fold cross-validation(CV)sets is set as thefitness function in the GA for enhancing the robustness of ML models.The results indicate that ML models outperform empirical prediction formulations with lower prediction error.RF yields the lowest error followed by BPNN,ELM,EPR and SVM.If the ranges of input variables in the database are large enough,BPNN and RF models are recommended to predict Cc.Furthermore,if the distribution of input variables is continuous,RF model is the best one.Otherwise,EPR model is recommended if the ranges of input variables are small.The predicted correlations between input and output variables using five ML models show great agreement with the physical explanation.     

南海北部边缘盆地油气勘探现状与深水油气资源前景

自20世纪60年代初开展浅海油气苗调查及浅井钻探以来,南海北部边缘盆地迄今在陆架浅水区已勘探发现多个油气田,建成了一定储量规模的油气产能,基本构成了南海北部油气富集区的格[JP2]局。然而,如何保持油气可持续发展,尽快寻找油气储量接替的新领域,这是该区油气勘探所面临的关键问题。南海北部陆坡深水区与世界深水盆地一样,颇具油气资源潜力和勘探前景,近期LW311深水探井钻探的新发现表明,其应是该区油气资源接替非常现实的战略选区和勘探靶区。     

New Thorium Isotope Ratio Measurements in Silicate Reference Materials: A‐THO,AGV‐2, BCR‐2, BE‐N,BHVO‐2 and BIR‐1

A two‐step Th isolation protocol, involving micro‐columns of TRU‐Spec extraction chromatography material and AG1 resin, was evaluated. The MC‐ICP‐MS procedure included ²³²Th tailing characterisation and correction, and calibrator bracketing using an in‐house standard solution (ThS1) to correct for instrumental mass bias and Faraday cup to secondary electron multiplier relative gain. Repeated analyses of reference solutions (UCSC Th ‘A’, WUN, OU Th ‘U’, IRMM‐36) were consistent with published data. Six reference materials (A‐THO, BCR‐2, AGV‐2, BHVO‐2, BE‐N and BIR‐1) were processed. The average ²³⁰Th/²³²Th values obtained for these samples are in excellent agreement with published data. In addition, we report the first ²³⁰Th/²³²Th values for BE‐N and BIR‐1. The intermediate precisions for rock samples ranged from ± 0.24 to ± 0.49% (2 RSD) and were similar to those achieved for synthetic solutions, thereby supporting the overall validity of the chemical separation, data acquisition and reduction procedures. Counting statistics on the ²³⁰Th isotope was the most significant source of uncertainty. The intermediate precision of the mean ²³⁰Th/²³²Th for the Th‐depleted BIR‐1 (5.64 × 10^?6 ± 0.27%, 2 RSD) is in the range of the analyses of other reference materials analysed in this study.     

二叠纪海相碳酸盐的锶同位素演化及其意义

本文从沫阳和熊家场剖面二叠纪海相碳酸盐和玄武岩的锶同位素变化出发,讨论了碳酸盐的锶同位素组成与峨嵋山玄武岩喷发之间的关系,以及玄武岩中海相碳酸盐的锶同位素贫化原因,指出海相碳酸盐的锶同位素组成可作为了解地球构造演化的工具。     

基于大比例尺矢量数据库建设的ArcInfo软件应用及二次开发

结合"数字平顶山"基础地理空间数据库建设项目,用ArcInfo的AML语言开发实现数据转换、数据编辑、数据检查的矢量数据处理实用工具。     

利用小波变换提取川滇地区流动重力异常特征 ——以2014年鲁甸MS6.5、景谷MS6.6地震为例

首先介绍小波变换的基本原理,分析影响小波多分辨率分解效果的因素,提出选择coif5小波基函数、交叉验证确定分解阶次的小波多尺度分解方法;然后在模型实验中利用该方法对模型局部和区域异常实现有效分离,并结合径向对数功率谱方法对分解重构异常进行定性、半定量分析;最后对川滇地区201309~201404期流动重力差分动态变化异常进行多尺度分解。在分解得到的D4~D6异常、重构的局部和区域异常中,2014年鲁甸MS6.5和景谷MS6.6地震主震位置均存在明显的异常变化特征。结合地质构造背景信息对该异常特征进行分析解释。     

苍梧M_S5.4地震孕震环境的多尺度重力场分析及动力学意义

基于EGM2008研究苍梧震源区及华南块体不同尺度重力场的横向和纵向分布特征,探讨深部物质密度变化及可能的动力学意义,为该区地震孕育环境研究提供深部依据。扬子克拉通重力异常横向变化相对较小,显示出其相对稳定的克拉通结构特征;华夏地块上地幔存在与西太平洋板块俯冲角度较为一致的重力正异常和相间分布的重力负异常,其高低密度体分布可能与中生代以来西太平洋板块俯冲作用下岩石圈拆沉和软流圈物质上涌有关;扬子克拉通和华夏地块过渡带呈现显著的重力异常高梯度带和东西差异性特征,揭示了深部复杂构造变形的过渡带特征。本文研究区多尺度布格重力异常横向的复杂性和非均一性及在地壳和上地幔深浅差异性的重力异常特征,反映了研究区深浅物质结构和动力学不平衡的差异相互运动的动力学过程,可能是地震孕育的深部动力学环境。苍梧地震位于重力正负异常的过渡带,与深部物质扰动和密度分布的不均匀密切相关。     

内蒙古毕力赫斑岩型金矿成矿岩体地球化学、锆石U-Pb年代学及Hf同位素研究

毕力赫金矿位于中亚造山带东南段华北克拉通北缘白乃庙早古生代弧增生杂岩带内,该矿床为一个斑岩型矿床,成矿岩体为早中二叠世花岗闪长岩。文中对成矿岩体进行了主微量元素地球化学以及锆石U-Pb年代学和Lu-Hf同位素研究。毕力赫花岗闪长岩具有安第斯型陆缘弧岩浆岩的地球化学亲缘性：岩体SiO2含量(质量分数)介于61.3%~64.4%,K2O/Na2O值介于0.52~0.87,A/CNK值介于0.82~0.95,属准铝高钾钙碱性系列岩石;岩体相对富集Rb、Th、U等大离子亲石元素和轻稀土元素,亏损Nb、Ta、Ti等高场强元素和重稀土元素,显示负Eu异常(δEu=0.50~1.03)。岩体浅部(zk086-53)与深部(zkI005-105)两个样品的锆石206Pb/238U加权平均年龄分别为(268.1±1.8) Ma(MSWD=1.17,1σ)和(267.7±4.1) Ma(MSWD=1.06,1σ);继承锆石除外,样品中锆石εHf(t)值分别为3.2~8.7和-0.6~8.3,二阶段模式年龄TDM2分别为1 085~737 Ma和1 330~762 Ma。成矿岩体可能源于洋壳俯冲脱水导致的新生地壳部分熔融而产生的底侵中基性岩浆与由底侵导致的古老基底物质部分熔融形成的长英质岩浆的混合。