关于在闽北西部建立中墩组早白垩世火山岩地层单位的讨论

近年来的最新调研成果表明，闽北酉部原划为上侏罗统南园组的火山岩为一套中性—偏碱性—酸性—偏碱性火山岩组合，形成于大陆边缘拉张构造环境，岩浆来源于地壳，与萤石、叶蜡石、铌钽、放射性矿产关系密切。全岩Ｒｂ－Ｓｒ等时线年龄１１２—１４２Ｍａ，８７Ｓｒ／８６Ｓｒ为０．７０６６１－０．７１９４１，时代为早白垩世。具有一定的区域范围及独特的构造环境，与江西广丰鹅湖岭组相连，而与福建东部的火山岩有很大差异，建议单独建立一个岩石地层单位──中墩组（Ｋ１ｚ）。这对研究福建西部乃至我国东部中生代火山岩地层都有重要意义。     

Statistical Tests of Load-Unload Response Ratio Signals by Lattice Solid Model: Implication to Tidal Triggering and Earthquake Prediction

— Statistical tests of Load-Unload Response Ratio (LURR) signals are carried in order to verify statistical robustness of the previous studies using the Lattice Solid Model (Mora et al., 2002b). In each case 24 groups of samples with the same macroscopic parameters (tidal perturbation amplitude A, period T and tectonic loading rate k) but different particle arrangements are employed. Results of uni-axial compression experiments show that before the normalized time of catastrophic failure, the ensemble average LURR value rises significantly, in agreement with the observations of high LURR prior to the large earthquakes. In shearing tests, two parameters are found to control the correlation between earthquake occurrence and tidal stress. One is, A/(k T) controlling the phase shift between the peak seismicity rate and the peak amplitude of the perturbation stress. With an increase of this parameter, the phase shift is found to decrease. Another parameter, A T/k, controls the height of the probability density function (Pdf) of modeled seismicity. As this parameter increases, the Pdf becomes sharper and narrower, indicating a strong triggering. Statistical studies of LURR signals in shearing tests also suggest that except in strong triggering cases, where LURR cannot be calculated due to poor data in unloading cycles, the larger events are more likely to occur in higher LURR periods than the smaller ones, supporting the LURR hypothesis.     

Spatio-temporal Scanning and Statistical Test of the Accelerating Moment Release (AMR) Model Using Australian Earthquake Data

— The Accelerating Moment Release (AMR) preceding earthquakes with magnitude above 5 in Australia that occurred during the last 20 years was analyzed to test the Critical Point Hypothesis. Twelve earthquakes in the catalog were chosen based on a criterion for the number of nearby events. Results show that seven sequences with numerous events recorded leading up to the main earthquake exhibited accelerating moment release. Two occurred near in time and space to other earthquakes preceded by AMR. The remaining three sequences had very few events in the catalog so the lack of AMR detected in the analysis may be related to catalog incompleteness. Spatio-temporal scanning of AMR parameters shows that 80% of the areas in which AMR occurred experienced large events. In areas of similar background seismicity with no large events, 10 out of 12 cases exhibit no AMR, and two others are false alarms where AMR was observed but no large event followed. The relationship between AMR and Load-Unload Response Ratio (LURR) was studied. Both methods predict similar critical region sizes, however, the critical point time using AMR is slightly earlier than the time of the critical point LURR anomaly.     

The Misis–Andırın Complex: a Mid-Tertiary melange related to late-stage subduction of the Southern Neotethys in S Turkey

The Mid-Tertiary (Mid-Eocene to earliest Miocene) Misis–Andırın Complex documents tectonic-sedimentary processes affecting the northerly, active margin of the South Tethys (Neotethys) in the easternmost Mediterranean region. Each of three orogenic segments, Misis (in the SW), Andırın (central) and Engizek (in the NE) represent parts of an originally continuous active continental margin. A structurally lower Volcanic-Sedimentary Unit includes Late Cretaceous arc-related extrusives and their Lower Tertiary pelagic cover. This unit is interpreted as an Early Tertiary remnant of the Mesozoic South Tethys. The overlying melange unit is dominated by tectonically brecciated blocks (>100 m across) of Mesozoic neritic limestone that were derived from the Tauride carbonate platform to the north, together with accreted ophiolitic material. The melange matrix comprises polymict debris flows, high- to low-density turbidites and minor hemipelagic sediments.The Misis–Andırın Complex is interpreted as an accretionary prism related to the latest stages of northward subduction of the South Tethys and diachronous continental collision of the Tauride (Eurasian) and Arabian (African) plates during Mid-Eocene to earliest Miocene time. Slivers of Upper Cretaceous oceanic crust and its Early Tertiary pelagic cover were accreted, while blocks of Mesozoic platform carbonates slid from the overriding plate. Tectonic mixing and sedimentary recycling took place within a trench. Subduction culminated in large-scale collapse of the overriding (northern) margin and foundering of vast blocks of neritic carbonate into the trench. A possible cause was rapid roll back of dense downgoing Mesozoic oceanic crust, such that the accretionary wedge taper was extended leading to gravity collapse. Melange formation was terminated by underthrusting of the Arabian plate from the south during earliest Miocene time.Collision was diachronous. In the east (Engizek Range and SE Anatolia) collision generated a Lower Miocene flexural basin infilled with turbidites and a flexural bulge to the south. Miocene turbiditic sediments also covered the former accretionary prism. Further west (Misis Range) the easternmost Mediterranean remained in a pre-collisional setting with northward underthrusting (incipient subduction) along the Cyprus arc. The Lower Miocene basins to the north (Misis and Adana) indicate an extensional (to transtensional) setting. The NE–SW linking segment (Andırın) probably originated as a Mesozoic palaeogeographic offset of the Tauride margin. This was reactivated by strike-slip (and transtension) during Later Tertiary diachronous collision. Related to on-going plate convergence the former accretionary wedge (upper plate) was thrust over the Lower Miocene turbiditic basins in Mid–Late Miocene time. The Plio-Quaternary was dominated by left-lateral strike-slip along the East Anatolian transform fault and also along fault strands cutting the Misis–Andırın Complex.     

Application of logistic regression for landslide susceptibility zoning of Cekmece Area, Istanbul, Turkey

As a result of industrialization, throughout the world, cities have been growing rapidly for the last century. One typical example of these growing cities is Istanbul, the population of which is over 10 million. Due to rapid urbanization, new areas suitable for settlement and engineering structures are necessary. The Cekmece area located west of the Istanbul metropolitan area is studied, because the landslide activity is extensive in this area. The purpose of this study is to develop a model that can be used to characterize landslide susceptibility in map form using logistic regression analysis of an extensive landslide database. A database of landslide activity was constructed using both aerial-photography and field studies. About 19.2% of the selected study area is covered by deep-seated landslides. The landslides that occur in the area are primarily located in sandstones with interbedded permeable and impermeable layers such as claystone, siltstone and mudstone. About 31.95% of the total landslide area is located at this unit. To apply logistic regression analyses, a data matrix including 37 variables was constructed. The variables used in the forwards stepwise analyses are different measures of slope, aspect, elevation, stream power index (SPI), plan curvature, profile curvature, geology, geomorphology and relative permeability of lithological units. A total of 25 variables were identified as exerting strong influence on landslide occurrence, and included by the logistic regression equation. Wald statistics values indicate that lithology, SPI and slope are more important than the other parameters in the equation. Beta coefficients of the 25 variables included the logistic regression equation provide a model for landslide susceptibility in the Cekmece area. This model is used to generate a landslide susceptibility map that correctly classified 83.8% of the landslide-prone areas.     

Evolution of the Bayramiç magmatic complex, northwestern Anatolia

During the Oligocene–Middle Miocene period widespread magmatic activity developed in Western Anatolia, following the continental collision between the Sakarya continent and the Tauride–Anatolide platform. This produced both intrusive and extrusive rocks, which appear to be associated in space and time, as exemplified from the Bayramiç area. In the Bayramiç area, the magmatic activity started with the intrusion of the Evciler granite, and the coeval lower volcanic association. This was followed by the development of the upper volcanic association. These rock groups form collectively the Bayramiç magmatic complex, which was generated under an on-going north–south compressional regime. The Bayramiç magmatic complex has a subalkaline composition, displaying a calcalkaline trend. Trace elements and REE contents resemble to island-arc and collision-related magmas. According to the isotope values the Bayramiç magmatic complex was derived from the magmas of lithospheric mantle origin, which were later contaminated, while passing through the thick continental crust, in a post-collisional tectonic setting, during the Oligocene–Early Miocene period. The latest product of the magmatism is the Late Miocene–Pliocene basalt lavas. Their geochemical properties are clearly different from the Oligocene–Early Miocene magmatic rocks. The basalts were generated when the north–south compression gave way to the north–south extensional regime.     

Sur la structure,l'âge et l'origine des « brèches de Bosmendiette » (Pyrénées-Atlantiques)

By us considered as Albo-Aptian in age and generated through halokinetic processes, the Bosmendiette breccias have been recently interpreted as Selandian (Palaeocene) globigerine-bearing sediments deposited in sub-marine canyons within a deep trough crossing the Pyrenees, from the Mediterranean Sea to the Atlantic Ocean. These breccias are really azoic in their lower part and contain a scarce microfauna including radolarians and benthic foraminifera at the top of the formation. They are unconformably covered by the Urgo-Aptian limestones and marls and indicate, under opening marine conditions, Lower Cretaceous collapse movements and northward sliding of the Jurassic slumped cover, related to the growth of the Béloscare–Apoura diapir. To cite this article: J. Canérot et al., C. R. Geoscience 336 (2004).     

区域土地利用转型诊断与调控的分析路径

土地利用转型正表现为城乡地域系统演变的重要特征,土地利用转型分析的意义在于发现土地利用形态转变指示的土地利用问题。本文尝试解析了区域人地耦合关系下的土地利用形态转型逻辑,系统阐释了区域土地利用转型的诊断分析路径,重点探讨了乡村土地利用转型问题诊断与调控途径。研究指出：① 区域土地利用转型侧重考察土地变化趋势性转折对应的土地利用方式的转变要求,阐释转型分析所指示的土地利用问题及其表现特征,以此找寻转型调控的应对策略。② 应依据尺度和梯度分异方式揭示区域土地利用转型特征,理解不同尺度上转型调控的融合过程,研判区域土地利用转型调控措施。③ 土地服务供给变化是引发乡村土地利用显性形态和隐性形态转型发生错位的关键原因,土地利用显性形态与隐性形态之间的互适关系,则反映了土地利用形态空间关系构成的问题特征。④ 基于乡村地域尺度和梯度分异原则、基于城乡融合发展背景、重构农村土地权利体系和开展国土空间规划是探索乡村土地利用转型调控的四个重要分析路径。⑤ 不同尺度区域土地利用转型认知与转型调控对策的融合仍需要进一步拓展,而激活乡村土地资源要素是调控乡村土地利用转型的关键途径。     

绿柱石的成因与特征的研究

绿柱石是提炼稀有金属铍的重要矿石矿物,也是重要的宝石矿物。文章从绿柱石的矿床特点、包裹体和谱学特征、绿柱石的优化处理及人工合成等方面,对国内近年来在绿柱石研究方面的进展进行了综述,并对绿柱石的研究方向提出了一些建议。