东昆仑造山带早中生代镁铁质岩墙群LA-ICP-MS锆石U-Pb定年、元素和Sr-Nd-Hf同位素地球化学

东昆仑造山带白日其利镁铁质岩墙群以苏长辉长岩为主,含少量含斑辉绿岩,LA-ICP-MS锆石U-Pb年代学指示该套岩墙群结晶侵位年龄为251±2Ma.岩石具有中等的Mg#(31～50)和高铝(16.25％～19.49％)的特征,整体属于钙碱性玄武岩系列岩石(Na2O+ K2O =2.75％～3.51％;FeOT/MgO=1.02～2.22);微量和稀土元素方面,岩石具有较低的稀土总量、轻稀土轻微富集和Eu正异常特征(ΣREE =52.16×10-6～99.81×10-6,(La/Yb)N =2.08～5.49,δEu=1.0～1.3),所有岩石富集LILE(如Rb、Ba和Pb等)而亏损HFSE(如Nb、Ta、P和Ti等),且具有显著不同于地壳的不相容元素组成(如Nb/Ta比值).岩墙具有富集的Sr-Nd同位素组成((87Sr/86 Sr)i=0.71103～0.71502,εNd(t)=-7.4～-3.6),具有相对集中且显著不同于地壳岩浆的Hf同位素组成(εHf(t)=-2.37～1.07).元素地球化学和同位素研究指示镁轶质岩浆起源于流体交代的富集地幔Ⅱ,并未受到显著的地壳混染.构造环境分析表明,岩石具有岛弧和洋中脊玄武岩双重特征.结合区域构造演化分析,我们认为,在晚二叠世-早三叠世时期,在俯冲环境下,板片流体交代使上覆地幔楔发生富集,形成富集地幔Ⅱ,随着该区伸展作用的加强,在早三叠世,进一步诱发了富集地幔的部分熔融并产生镁铁质岩浆,最终侵位结晶就形成了白日其利镁铁质岩墙群.     

基于概率统计的可拓学分析方法在边坡岩体质量分级中的应用

在可拓学理论基础上添加了统计学思想,形成了一种基于概率统计的可拓学分析方法。以延边州和龙市红旗河引水工程项目为例,通过Matlab软件,采用蒙特卡洛模拟,将每个对象对应的因素值进行模拟,产生出服从一定分布的随机待评物元;再利用岩体边坡稳定性等级和影响因子,构造出经典域和节域物元,借助物元和可拓中的关联函数,建立起分析对象隶属于不同类别的概率值。利用此概率值,确定边坡岩体质量分级,并提出对工程设计和建设中的支护建议。对象2的最大概率值所属的类别为Ⅱ类,但对象2属于Ⅲ类的概率值为27%,由于工程采样存在的随机性,将对象2划分为Ⅲ类可以确保其安全性。     

农用地自然质量等级划分的可拓评价方法

农用地自然质量等级划分是农用地分等的前提和基础,其划分合理与否直接关系到农用地分等能否川页利进行,但现有研究方法难以全面反映农用地自然质量的差异性及其性质的可变性。依据浙江省的地形地貌等自然条件差异,将其划分为六大区域,并选择性地构建了不同的农用地自然质量等级划分的因素指标（基础肥力、土壤质地、有机质、耕层厚度、灌溉、排涝、pH、地下水位、坡度等）和评分标准,在此基础上基于可拓理论建立了农用地自然质量等级划分的可拓评价模型,并运用模型对水稻、小麦和油菜作物分别进行可拓评价及多作物综合分等,最终得到浙江省农用地自然质量分等结果。研究表明,可拓评价方法能反映农用地自然质量等级的动态性和可变性,使评价更为精细化和客观化,结果更符合浙江省农用地实际情况。     

The recent expansion of an avian invasive species (the Cattle Egret Ardea ibis) in Algeria

This study identifies new information on the recent distribution of an invasive bird species, the Cattle Egret Ardea ibis, in Algeria. Breeding and wintering distributions as well as breeding numbers were obtained from large-scale surveys in 1999 and 2007, and from historical data. Between 1999 and 2007, the total number of colonies found increased from 51 to 87, and most were located in the northern part of the country. The breeding distribution area, confined to the coastal areas in the 1970s, has shifted further south, and reached the northern part of the Sahara since the 2000s. Most colonies were established during the period 1980-1995. The oldest colonies were generally larger than the recent ones. The number of colonies increased by 83% between 1999 and 2007 in the 12 administrative units (wilayas) surveyed. The number of breeding pairs increased from 7765 in 1999 to 28544 in 2007, corresponding to an annual population growth rate of 17.7%. The changes in distribution and population dynamics since the 1970s and the potential factors affecting these changes are discussed.     

GPS监测滑坡形变的基准研究

讨论了GPS监测网基准稳定性检验的模型和方法,且针对不同期GPS基线向量观测值存在尺度和方位基准系统差异,给出了考虑基准参数的平差模型和基准参数显著性检验方法.     

枣庄市转型期土地利用综合效益及制约因素分析

分析资源型城市转型期间土地利用综合效益变化规律和制约因素有利于优化配置土地资源。从经济因子、社会因子和生态因子3个方面构建土地利用综合效益评价指标体系,综合熵权法和层次分析法确定权重,运用物元模型评价枣庄市土地利用综合效益,并揭示其变化规律与转型阶段之间的内在联系,最后总结相关制约因素。研究表明,转型政策对于土地利用综合效益具有明显影响;通过单指标关联度归纳的6个制约因素为转型过程中提升土地利用综合效益指明了方向;物元可拓模型可操作性强,可以有效评价土地利用综合效益。     

MVLL算法中地表断裂特征的自适应窗口变化策略研究

针对线阵CCD影像,研究了MVLL算法的匹配走向,得出了匹配走向即建筑物底部至对应屋顶的连线在匹配过程中为近似直线的结论。分析了MVLL算法中地表断裂特征通常匹配至屋底的匹配难点,改进了相关参数自适应调整算法,给出了自适应窗口变化算法的流程。两组ADS40线阵影像的断裂特征匹配实验表明,经过自适应窗口变化后,地表断裂特征能够成功匹配,MVLL算法的自适应性增强。     

胶东地区玲珑岩基隆升机制探讨

本文通过详细的野外构造观察,综合主干正断层运动学观测、擦痕应力场反演、岩体变形分析、岩脉与石英脉展布方位等多个方面,对胶东地区玲珑岩基的构造演化进行了有效地制约.研究结果表明,其为早白垩世的伸展穹窿构造,是NW—SE向区域性伸展的结果,并且北部的伸展与岩浆活动及金矿化作用要强于南部.在早白垩世强烈伸展与岩浆活动背景下,晚侏罗世侵位的玲珑岩基沿着倾向相背的两条大型脆性正断层(招平断裂带与焦家断裂带)以地垒构造形式发生隆升而最终出露地表,并非变质核杂岩型伸展构造.玲珑岩基在晚侏罗世侵位后并没有立即出露地表,而是在早白垩世区域伸展中才隆升与剥露,并伴随区内大规模金矿形成.玲珑伸展穹窿的厘定,一方面证实了区内早白垩世强烈岩浆活动是发生在NW—SE向伸展背景下,另一方面进一步验证了华北克拉通东部破坏的峰期出现在早白垩世.     

Structural architecture of the Owen Conglomerate,West Coast Range,western Tasmania: field evidence for Late Cambrian extension.

The Owen Conglomerate comprises coarse-grained siliciclastics that were deposited in response to Late Cambrian extension. The identification of normal faults that host thickened accumulations of siliciclastics is used here to support interpretation of syn-fill extension. Local mapping and section construction have identified a series of north-trending, en échelon, segmented normal faults that exhibit changes in along-strike polarity. The Late Cambrian faults are adjacent to sedimentary packages that define half-graben geometries, with an unconformity that defines basal contacts with underlying Mt Read Volcanics and onlap geometries onto the opposing basin margin. Faults that were active during deposition of the Owen Conglomerate were subsequently reversed during D₁ Middle Devonian deformation, with reverse displacement controlling the development of inversion structures defined by north-trending fold structures. Pervasive northwest-trending D₂ deformation extensively overprints earlier deformation features, and has led to the spectacular development of type 1 interference patterns that largely control outcrop distributions along the West Coast Range. Field evidence is documented in support for a simple structural history that accounts for geometries associated with Late Cambrian extension, prior to Middle Devonian inversion (D₁) and subsequent shortening (D₂).     

Structural inversion and its controls : examples from the Alpine foreland and the French Alps

Abstract

Positive structural inversion involves the uplift of rocks on the hanging-walls of faults, by dip slip or oblique slip movements. Controlling factors include the strike and dip of the earlier normal faults, the type of normal faults — whether they were listric or rotated blocks, the time lapsed since extension and the amount of contraction relative to extension. Steeply dipping faults are difficult to invert by dip slip movements; they form buttresses to displacement on both cover detachments and on deeper level but gently inclined basement faults. The decrease in displacement on the hanging-walls of such steep buttresses leads to the generation of layer parallel shortening, gentle to tight folds — depending on the amount of contractional displacement, back-folds and back-thrust systems, and short-cut thrust geometries — where the contractional fault slices across the footwall of the earlier normal fault to enclose a “floating horse”. However, early steeply dipping normal faults readily form oblique to strike slip inversion structures and often tramline the subsequent shortening into particular directions.

Examples are given from the strongly inverted structures of the western Alps and the weakly inverted structures of the Alpine foreland. Extensional faulting developed during the Triassic to Jurassic, during the initial opening of the central Atlantic, while the main phases of inversion date from the end Cretaceous when spreading began in the north Atlantic and there was a change of relative motion between Europe and Africa. During the mid-Tertiary well over 100 km of Alpine shortening took place; Alpine thrusts, often detached along, or close to, the basement-cover interface, stacking the late Jurassic to Cretaceous sediments of the post-extensional subsidence phase. These high level detachments were joined and breached by lower level faults in the basement which, in the external zones of the western Alps, generally reactivated and rotated the earlier east dipping half-graben bounding faults. The external massifs are essentially uplifted half-graben blocks. There was more reactivation and stacking of basement sheets in the eastern part of this external zone, where the faults had been rotated into more gentle dips above a shallower extensional detachment than on the steeper faults to the west.

There is no direct relationship between the weaker inversion of the Alpine foreland and the major orogenic contraction of the western Alps; the inversion structures of southern Britain and the Channel were separated from the Alps by a zone of rifting from late Eocene to Miocene which affected the Rhone, Bresse and Rhine regions. Though they relate to the same plate movements which formed the Alps, the weaker inversion structures must have been generated by within plate stresses, or from those emanating from the Atlantic rather than the Tethyan margin.