Relative importance of the Hercynian and post-Jurassic tectonic phases in the Saharan platform: a palaeomagnetic study of Jurassic sills in the Reggane Basin (Algeria)   总被引：2，自引：0，他引：2  

B. Smith  M. E. M. Derder  B. Henry  B. Bayou  A. K. Yelles  H. Djellit  M. Amenna  M. Garces  E. Beamud  J. P. Callot  R. Eschard  A. Chambers  T. Aifa  R. Ait Ouali  H. Gandriche 《Geophysical Journal International》2006,167(1):380-396

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Surface wave tomography: finite-frequency effects lost in the null space   总被引：2，自引：1，他引：2  

Jeannot Trampert  Jesper Spetzler 《Geophysical Journal International》2006,164(2):394-400

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Computation of Large Anisotropic Seismic Heterogeneities (CLASH)     

Éric Beucler  Jean-Paul Montagner 《Geophysical Journal International》2006,165(2):447-468

A general tomographic technique is designed in order (i) to operate in anisotropic media; (ii) to account for the uneven seismic sampling and (iii) to handle massive data sets in a reasonable computing time. One modus operandi to compute a 3-D body wave velocity model relies on surface wave phase velocity measurements. An intermediate step, shared by other approaches, consists in translating, for each period of a given mode branch, the phase velocities integrated along ray paths into local velocity perturbations. To this end, we develop a method, which accounts for the azimuthal anisotropy in its comprehensive form. The weakly non-linear forward problem allows to use a conjugate gradient optimization. The Earth's surface is regularly discretized and the partial derivatives are assigned to the individual grid points. Possible lack of lateral resolution, due to the inescapable uneven ray path coverage, is taken into account through the a priori covariances on parameters with laterally variable correlation lengths. This method allows to efficiently separate the 2ψ and the 4ψ anisotropic effects from the isotropic perturbations. Fundamental mode and overtone phase velocity maps, derived with real Rayleigh wave data sets, are presented and compared with previous maps. The isotropic models concur well with the results of Trampert & Woodhouse. Large 4ψ heterogeneities are located in the tectonically active regions and over the continental lithospheres such as North America, Antarctica or Australia. At various periods, a significant 4ψ signature is correlated with the Hawaii hotspot track. Finally, concurring with the conclusions of Trampert & Woodhouse, our phase velocity maps show that Rayleigh wave data sets do need both 2ψ and 4ψ anisotropic terms.  相似文献   

Calculated Phase Relations in the System Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2-H2O with Applications to UHP Eclogites and Whiteschists   总被引：2，自引：0，他引：2  

YANG  JIAN-JUN; POWELL  ROGER 《Journal of Petrology》2006,47(10):2047-2071

Pressure–temperature grids in the system Na₂O–CaO–K₂O–FeO–MgO–Al₂O₃–SiO₂–H₂O and its subsystems have been calculatedin the range 15–45 kbar and 550–900°C, usingan internally consistent thermodynamic dataset and new thermodynamicmodels for amphibole, white mica, and clinopyroxene, with thesoftware THERMOCALC. Minerals considered for the grids includegarnet, omphacite, diopside, jadeite, hornblende, actinolite,glaucophane, zoisite, lawsonite, kyanite, coesite, quartz, talc,muscovite, paragonite, biotite, chlorite, and plagioclase. Compatibilitydiagrams are used to illustrate the phase relationships in thegrids. Coesite-bearing eclogites and a whiteschist from Chinaare used to demonstrate the ability of pseudosections to modelphase relationships in natural ultrahigh-pressure metamorphicrocks. Under water-saturated conditions, chlorite-bearing assemblagesin Mg- and Al-rich eclogites are stable at lower temperaturesthan in Fe-rich eclogites. The relative temperature stabilityof the three amphiboles is hornblende > actinolite > glaucophane(amphibole names used sensu lato). Talc-bearing assemblagesare stable only at low temperature and high pressure in Mg-and Al-rich eclogites. For most eclogite compositions, talccoexists with lawsonite, but not zoisite, in the stability fieldof coesite. Water content contouring of pressure–temperaturepseudosections, along with appropriate geotherms, provides newconstraints concerning dehydration of such rocks in subductingslabs. Chlorite and lawsonite are two important H₂O-carriersin subducting slabs. Depending on bulk composition and pressure–temperaturepath, amphibole may or may not be a major H₂O-carrier to depth.In most cases, dehydration to make ultrahigh-pressure eclogitestakes place gradually, with H₂O content controlled by divariantor higher variance assemblages. Therefore, fluid fluxes in subductionzones are likely to be continuous, with the rate of dehydrationchanging with changing pressure and temperature. Further, eclogitesof different bulk compositions dehydrate differently. Dehydrationof Fe-rich eclogite is nearly complete at relatively shallowdepth, whereas Mg- and Al-rich eclogites dehydrate continuouslydown to greater depth. KEY WORDS: dehydration; eclogites; phase relations; THERMOCALC; UHP metamorphism; whiteschists  相似文献   

Calculated Phase Relations in the System NCKFMASH (Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2-H2O) for High-Pressure Metapelites   总被引：5，自引：0，他引：5  

WEI  CHUNJING; POWELL  ROGER 《Journal of Petrology》2006,47(2):385-408

Petrogenetic grids in the system NCKFMASH (Na₂O–CaO–K₂O–FeO–MgO–Al₂O₃–SiO₂–H₂O)and the subsystems NCKMASH and NCKFASH calculated with the softwareTHERMOCALC 3.1 are presented for the P–T range 7–30kbar and 450–680°C, for assemblages involving garnet,chloritoid, biotite, carpholite, talc, chlorite, kyanite, staurolite,paragonite, glaucophane, jadeite, omphacite, diopsidic pyroxene,plagioclase, zoisite and lawsonite, with phengite, quartz/coesiteand H₂O in excess. These grids, together with calculated compatibilitydiagrams and P–T and T–X_Ca and P–X_Ca pseudosectionsfor different bulk-rock compositions, show that incorporationof Ca into the NKFMASH system leads to many of the NKFMASH invariantequilibria moving to lower pressure and/or lower temperature,which results, in most cases, in the stability of jadeite andgarnet being enlarged, but in the reduction of stability ofglaucophane, plagioclase and AFM phases. The effect of Ca onthe stability of paragonite is dependent on mineral assemblageat different P–T conditions. The calculated NCKFMASH diagramsare powerful in delineating the phase equilibria and P–Tconditions of natural pelitic assemblages. Moreover, contoursof the calculated phengite Si isopleths in P–T and P–X_Capseudosections confirm that phengite barometry in NCKFMASH isstrongly dependent on mineral assemblage. KEY WORDS: phase relations; metapelites; NCKFMASH; THERMOCALC; phengite geobarometry  相似文献   

地震信号的相位恢复及误差分析     

WU Yuan-yuan LIU Cai WANG Dian WANG Shi-yu College of GeoExploration Science  Technology  Jilin University  Changchun  China 《吉林大学学报(地球科学版)》2006,(Z2)

常见的几种地震子波有:零相位子波、最小相位子波、最大相位子波和混合相位子波。以不同类型的信号为激发子波,对不同地层模型合成地震道。仅用原始合成地震道记录的振幅谱来恢复原始记录,讨论不同方法下,由于激发子波的不同,对比分析原始记录与恢复记录的差异,及其恢复效果。  相似文献   

GPS接收机专用芯片组技术发展   总被引：5，自引：0，他引：5  

寇艳红  沈吉  张其善 《全球定位系统》2005,30(2):15-20

在总结国外现有的完整GPS接收机专用芯片组最新情况的基础上，结合典型的芯片产品，阐述了GPS接收机专用芯片组从分立式器件到片上系统、再到单片式接收机的技术发展过程、现状和趋势。  相似文献   

层次化网络SCADA通讯模型及其应用   总被引：1，自引：1，他引：1  

陈志文 《物探化探计算技术》2005,27(4):354-357

为在大型网络分布式SCADA（Super Control and Data Acquisition）应用系统中解决诸如电力、通信、石油、化工、制造业等行业或领域，在过程、流程、状态方面的数据监视、数据控制、数据采集与数据管理的高效、实时问题，解决各级子系统之间人工逐级汇接的问题，提高应用系统的稳定性、可维护性，这里提出了一种层次化网络SCADA通讯模型。该模型是通过在层次化网络SCADA模型中，引入基于TCP／IP协议的客户机／服务器查询方式数据通讯技术和点对点主动数据传递技术而建立的。根据该模型所设计的产品，经过生产实践证明，应用该模型可以较方便地构造分布在不同区域计算机上的SCADA系统，进行高效的实时通信。该模型为具有多层结构的大型分布式网络化集中SCADA系统的设计、开发，探索出了一条十分有效的新路径。  相似文献   

微量相X射线衍射定量分析的一种简便方法     

何泽能李振山  斯永敏 《岩矿测试》2005,24(2):81-86

阐述了关于微量相X射线衍射定量分析的一种简便方法———近似线性关系法,它适用于二相体系(或基体吸收系数基本恒定的多相体系)材料中微量相的定量分析。该方法不需要在待测样品中加入参考物相,分析时仅需对一条衍射线进行测定,因而分析时间很短,其测定结果与实际含量的相对误差为-10.2%～ 21.4%,与外标法和内标法的测量结果的精度相当。  相似文献   

三种类型烃-烃不混溶包裹体组合的特征和热力学条件的计算     

刘斌 《岩石学报》2005,21(5):1416-1424

在自然界广泛分布着烃-烃不混溶体系中捕获的流体包裹体,由于这些包裹体具有复杂的组成和相态,因此不混溶包裹体组合的判别和热力学参数的计算常常难以进行。根据烃-烃不混溶体系中两个端员组分流体包裹体室温下的相态特征和在温度-压力平面图上等容线交点显示的位置,划分成三种类型流体包裹体组合,本介绍了三种类型流体包裹体组合特征,叙述了不混溶烃-烃包裹体组合的测定和判别方法,并且阐述均一化包裹体相态方程和气-液平衡常数原理和方法与此同时列举了自然界简单的三种类型不混溶烃-烃包裹体组合的测定、判别和计算的几个实例,利用相态方程和气-液平衡常数,不但精确地计算出包裹体均一压力,并且精确地计算出流体密度和体积等热力学参数。最后,利用均一成气相和液相的两种包裹体在 p-T 平面图上等容线交点同样计算出流体包裹体组合的捕获温度和压力。  相似文献