Permian High Ba-Sr Granitoids: Geochemistry, Age and Tectonic Implications of Erlangshan Pluton, Urad Zhongqi, Inner Mongolia   总被引：1，自引：0，他引：1  

LUO Hongling  WU Tairan  ZHAO Lei  HE Yuankai  JIN Xu 《《地质学报》英文版》2009,83(3):603-614

Abstract: Erlangshan Pluton from Urad Zhongqi, central Inner Mongolia, is located in the middle segment of the northern margin of the North China Plate. The rocks consist mainly of diorites with gneissic structure. Petrochemical characteristics reveal that the diorites belong to metaluminous, high-potassium calc-alkaline series, with chemical signatures of I-type granites. They are characterized by low SiO2 contents (56.63%–58.53%) and A/CNK (0.90–0.96), high Al2O3 contents (17.30%–17.96%) and Na2O/K2O ratios (1.20–1.70), enrichment in large ion lithophile elements (LILE, e.g., Ba=556–915 ppm, Sr=463–595 ppm), and relative depletion in high field strength elements (HFSE, e.g., Nb, Ta, Ti) in primitive mantle-normalized spidergram, and right-declined rare earth element patterns with slightly negative Eu anomalies (d?Eu=0.72–0.90). They have Sr/Y ratios (20–25) evidently less than Kebu Pluton (49–75) to its east. Sensitive high resolution ion micro-probe U-Pb zircon dating of the diorites has yielded an intrusive age of 270±8?Ma. This leads us to conclude that Erlangshan diorites were formed by mixing between the middle or lower crustal-derived magma and minor mantle-derived mafic magma, followed by fractional crystallization, which was trigged by crustal extension and fault activity in post-collisional setting.  相似文献   

位场各阶垂向导数换算的新正则化方法   总被引：3，自引：1，他引：2       下载免费PDF全文

曾小牛  李夕海  贾维敏  刘代志 《地球物理学报》2015,58(4):1400-1410

位场垂向导数大量应用于位场数据处理与解释中.当前广泛采用的位场各阶垂向导数换算方法为基于Laplace方程并结合波数域和空间域方法的具有递推特性的ISVD(integrated second vertical derivative)算法.本文在位场垂向导数换算的正则化方法和径向平均功率谱的基础上,提出一种位场各阶垂向导数换算的新正则化方法.新正则化方法仅需通过分析位场径向平均功率谱来确定一个截止波数,即可稳定换算位场各阶垂向导数.理论模型和实测数据实验结果表明:(1)新正则化方法物理意义明确、计算简单,且各阶垂向导数换算的稳定性和精度明显优于ISVD算法;(2)在用新正则化方法求得各阶垂向导数的基础上,利用泰勒级数法可以获得大深度、高精度的位场向下延拓结果.  相似文献   

利用加强水平方向总水平导数对位场全张量数据进行边界识别   总被引：3，自引：2，他引：1       下载免费PDF全文

袁园  黄大年  余青露 《地球物理学报》2015,58(7):2556-2565

位场全张量梯度数据以其信息量大、含有更高频的信号成分,能更好地描述小的异常特征等优点在地球物理领域中得到广泛应用.边界检测是位场解释中不可缺少的任务,需要新的边界探测器来处理位场梯度张量数据.为了充分利用位场梯度张量数据的多信息成分,本文定义了方向总水平导数和加强方向总水平导数,并利用其定义新的边界检测器.为了能同时显示不同振幅大小异常的边界,本文对其进行了归一化处理.通过模型试验,证明了归一化方法能更加清晰准确地显示浅部和深部的地质体边界信息.最后将该边界检测方法用于加拿大圣乔治湾实际测得全张量重力梯度数据和中国朱日和地区的磁异常数据中,并得到了较好的边界检测结果.  相似文献   

Dynamic responses of two buildings connected by viscoelastic dampers under bidirectional earthquake excitations   总被引：1，自引：1，他引：0  

Z.D. Yang  Eddie S.S. Lam 《地震工程与工程振动(英文版)》2014,13(1):137-150

In this study,dynamic responses of two buildings connected by viscoelastic dampers under bidirectional excitations are extensively investigated.The two buildings are a 10-story building and a 16-story building,with the shorter building on the left.Viscoelastic dampers are installed at all fl oors of the shorter building.Equations of motion are formulated using a fractional derivative model to represent the viscoelastic dampers.Three cases are considered with mass eccentricities at 0,10% and-10% with respect to the dimensions of the buildings.The responses of the buildings are numerically predicted at different damper properties.The simulation results indicated that the maximum horizontal responses of the buildings without eccentricities are signifi cantly mitigated.However,torsional effects are adversely increased.For asymmetric buildings,the effectiveness of the connecting dampers is affected by building eccentricities.As a result,mass eccentricities must be taken into account in damper selection.When compared with vibrations induced by unidirectional excitations,bidirectional excitations can increase the responses of coupled asymmetric buildings.In addition,installing dampers only at the top fl oor of the shorter building may cause a sudden change in lateral stiffness of the taller building.Consequently,the story shear envelopes of the taller building are changed.  相似文献   

空间归一化边界识别方法用于判断地质体的水平位置及深度(英文)   总被引：1，自引：1，他引：0  

李丽丽  韩立国  黄大年 《应用地球物理》2014,11(2):149-157

边界识别是重磁数据解释中的常用方法之一,依据其结果可划分出地质体的水平范围。边界识别结果受地质体埋深及导数计算误差的影响所识别边界与真实边界之间存在一定的差距,且边界识别法无法直观地给出地质体的深度信息。为了获得异常体的水平位置和深度信息,本文提出空间归一化边界识别方法,其对不同深度的边界识别函数进行归一化计算,空间归一化边界识别法的最大值对应于异常体的水平位置和深度。常规边界识别结果的误差随理深的减小而减小,而空间归一化边界识别法是通过最大值来判断地质体的位置,最大值是在地质体处获得,因此归一化边界识别方法所获得的结果是准确的。通过理论模型试验证明归一化边界识别方法能有效地完成异常体的水平位置和深度的计算,所获得的水平位置和深度信息与理论值相一致,为下一步的勘探计划提供了更加可靠的依据。将其应用于实际航磁数据的解释,获得了断裂的具体分布形式。  相似文献   

Unified fractional differential approach for transient interporosity flow in naturally fractured media     

《Advances in water resources》2014

A unified approach to modeling flows of slightly compressible fluids through naturally fractured media is presented. The unified fractional differential model is derived by combining the flow at micro scale for matrix blocks and macro scale for fractures, using the transient interporosity flow behavior at the interface between matrix blocks and fractures. The derived model is able to unify existing transient interporosity flow models formulated for different shapes of matrix blocks in any medium dimensions. The model is formulated in the form of a fractional order partial differential equation that involves Caputo derivative of order 1/2 with respect to time. Explicit solutions for the unified model are derived for different axisymmetrical spatial domains using Hankel or Hankel–Weber finite or infinite transforms. Comparisons between the predictions of the unified model and those obtained from existing transient interporosity flow models for matrix blocks in the form of slabs, spheres and cylinders are presented. It is shown that the unified fractional derivative model leads to solutions that are very close to those of transient interporosity flow models for fracture-dominant and transitional fracture-to-matrix dominant flow regimes. An analysis of the results of the unified model reveals that the pressure varies linearly with the logarithm of time for different flow regimes, with half slope for the transitional fracture-to-matrix dominant flow regime vs. the fracture and matrix dominant flow regimes. In addition, a new re-scaling that involves the characteristic length in the form of matrix block volume to surface area ratio is derived for the transient interporosity flow models for matrix blocks of different shapes. It is shown that the re-scaled transient interporosity flow models are governed by two dimensionless parameters Θ and Λ compared to only one dimensionless parameter Θ for the unified model. It is shown that the solutions of the transient interporosity flow models for different shapes of matrix blocks are almost identical for the re-scaled variables. Furthermore, the driving parameters for solution behavior are identified based on asymptotic approximations for different flow regimes. It is found that the matrix diffusion and the matrix area-to-volume ratio affect the solution behavior only for the transitional fracture-to-matrix dominant flow regime, that the capacitance ratio affects the solution behavior only for transitional and matrix dominant flow regimes and that the fracture diffusion is involved in all three flow regimes. Similar identification of the driving parameters is also presented in the re-scaled case.  相似文献   

基于分数阶导数的非定常蠕变本构模型研究     

何志磊  朱珍德  朱明礼  李志敬 《岩土力学》2016,37(3):737-744

针对锦屏二级水电站深埋长大隧洞围岩在开挖过程中呈现明显的流变劣化特征,基于分数阶微积分理论,用Abel黏壶替换西原模型中的牛顿黏壶,推导出基于分数阶导数的蠕变本构方程,同时考虑岩石在蠕变过程中,尤其是所受应力超过其长期强度时,蠕变参数是非定常的特征,把蠕变参数的非定常性引入本构方程中,建立了基于分数阶导数的非定常蠕变本构模型。结合锦屏二级水电站引水隧洞主要围岩之一的大理岩的室内剪切蠕变试验的结果,对模型中的参数进行反演,结果表明,基于分数阶导数的非定常蠕变本构模型能够在蠕变初期和拐点处与试验结果很好地吻合,并且可以克服西原模型不能反映蠕变第3阶段的不足。通过对模型中参数的敏感性进行分析,得出分数阶阶数、非定常参数对岩石蠕变的影响规律。研究结果表明,提出的基于分数阶导数的非定常蠕变模型能够很好地反映大理岩的蠕变全过程。  相似文献   

WorldView-2近红外光谱波段反演马尾松植被信息的比较研究   总被引：1，自引：0，他引：1  

胡秀娟  徐涵秋  黄绍霖  张灿  唐菲 《地球信息科学学报》2016,18(4):537-543

WorldView-2卫星自2009年发射至今,已为用户提供了大量高性能的影像产品。与众多高分辨率卫星影像不同,WorldView-2有2个近红外波段,即近红外1(Near-infrared1,NIR1)和近红外2(Near-infrared2,NIR2),但目前这2个波段在应用上的区别并不清楚。因此,本文以福建省长汀县河田地区的马尾松林为例,采用NIR1和NIR2这2个近红外波段分别构建了3种植被指数(NDVI、ARVI和NDMVI),以探索二者在植被信息反演方面的差异。结果表明,NIR1构建的植被指数在马尾松林提取精度上高于NIR2,并具有更丰富的植被信息量。经统计可知,NIR1所构建的植被指数信息量比NIR2分别大8.0%(NDVI)、12.3%(ARVI)和7.3%(NDMVI);在反演植被覆盖度方面,NIR1也比NIR2具有更高的精度,其模拟的植被覆盖度与实际植被覆盖度的拟合度更高,误差更小。NIR1和NIR2所表现出的差异是因为马尾松在这2个近红外波段的光谱反射不同,其反射在NIR1的波长范围内达到最强,而在NIR2的波长范围内则出现了小幅下降。  相似文献   

归一化总水平导数法在位场数据解释中的应用          下载免费PDF全文

李丽丽  黄大年  韩立国 《地球物理学报》2014,57(12):4123-4131

本文提出归一化总水平导数法,通过对总水平导数进行空间归一化计算实现了异常体水平位置和深度的估计,此外还推导出基于归一化总水平导数的欧拉反褶积法来估算地下地质体的空间位置,两种方法反演结果的相互验证可有效地提高反演结果的可信度.理论模型试验证明空间归一化总水平导数法和归一化总水平导数欧拉反褶积法均能有效地完成异常体的水平位置和深度的估计,所获得的位置参数与理论值相一致.在利用归一化总水平导数法进行磁异常解释时,对数据进行化磁极计算可得到更加准确的结果.将其应用于实际航磁数据的解释,获得了岩脉的大致分布特征.  相似文献   

Spectral Reflectance Analysis of the Caribbean Sea     

《Geofísica Internacional》2014,53(4):385-398

Reflectance spectral curves were analysed by a derivative method. Derivative reflectance spectra revealed concealed peaks of both reflectance and absorption curves of Caribbean seawater and elements contained within it. Reflectance curves showed a predominant blue colour (400–500 nm) characteristic of Caribbean oligotrophic waters, conspicuous peaks result from the optical properties of chlorophyll a and seawater. Reflectance curves had a similar spectral response. This paper analyses reflectance spectra of surface seawater at 31 stations in the Caribbean Sea during the summer of 2001.  相似文献