Lead isotope evolution of the Central European upper mantle:Constraints from the Bohemian Massif

The Pb isotope composition of the upper mantle beneath Central Europe is heterogeneous due to the subduction of regionally contrasting material during the Variscan and Alpine orogenies.Late Variscan to Cenozoic mantlederived melts allow mapping this heterogeneity on a regional scale for the last ca.340 Myr.Late Cretaceous and Cenozoic anorogenic magmatic rocks of the Bohemian Massif(lamprophyres,volcanic rocks of basanite/tephrite and trachyte/phonolite series) concentrate mostly in the Eger Rift.Cretaceous ultramafic lamprophyres yielded the most radiogenic Pb isotope signatures reflecting a maximum contribution from metasomatised lithospheric mantle,whereas Tertiary alkaline lamprophyres originated from mantle with less radiogenic ^(206)Pb/^(204)b ratios suggesting a more substantial modification of lithospheric source by interaction with asthenosphericderived melts.Cenozoic volcanic rocks of the basanite/tephrite and trachyte/phonolite series define a linear mixing trend between these components,indicating dilution of the initial lithospheric mantle signature by upwelling asthenosphere during rifting.The Pb isotope composition of Late Cretaceous and Cenozoic magmatic rocks of the Bohemian Massif follows the same Pb growth curve as Variscan orogenic lamprophyres and lamproites that formed during the collision between Laurussia,Gondwana,and associated terranes.This implies that the crustal Pb signature in the post-Variscan mantle is repeatedly sampled by younger anorogenic melts.Most Cenozoic mantle-derived rocks of Central Europe show similar Pb isotope ranges as the Bohemian Massif.

对于“Stuart Crampin对Jordan等‘可操作性地震预报:发展现状和使用手册[2011]’评论”的回复

在对国际地震预报委员会（ICEF）报告[1]的评论中,Crampin[2]声称剪切波分裂变化可以在短时间尺度上预测地震,并且可靠性高,技术性强。他对ICEF的一个重要发现提出挑战到目前为止,没有任何方法具有如此高的预测能力。特别是,Crampin宣称,

大陆深俯冲的深浅动力学响应:来自帕米尔高原地壳精细结构的约束

帕米尔高原位于青藏高原西构造结,强烈的陆内中源地震活动指示帕米尔高原下方正发生着大陆深俯冲过程.文章基于帕米尔高原现有流动地震台阵观测资料,利用接收函数谐波分析和环境噪声方法,在有效协调接收函数与面波频散分辨尺度的情况下,通过接收函数和面波频散联合反演,重建了横跨帕米尔高原到费尔干纳盆地等主要构造单元的壳幔二维S波速度结构.通过与接收函数CCP叠加成像剖面之间的对比分析,可靠地揭示了帕米尔高原中源地震分布、Moho面形态、上地幔和壳内低速异常分区/分层之间的空间配置关系,不仅进一步证实了亚洲大陆下地壳在帕米尔高原下方与岩石圈地幔耦合在一起发生了深俯冲,而且指示了深俯冲地壳物质的变质脱水反应在该区中源地震活动和壳内变形中起到的重要作用,从而为认识和理解大陆深俯冲过程及其动力学响应提供了新的地震学制约.

呈现科研数据知识库：re3data．org注册机制

科研人员在钻研科研问题与分享科研数据的过程中,需要某种基础设施来确保数据最大程度的获取性、稳定性和可用性。这类基础设施可以统称为科研数据知识库(Research Data Repository,RDR)。自2012年启动的re3data.org项目,主要从事科研数据知识库的登记注册,以及为科研人员、科研资助组织、图书馆和出版商等提供有关异构科研数据知识库的全景概述。截至2013年7月,已有400个科研数据知识库向re3data.org登记,其中288个采用re3data.org的信息图标,以协助科研人员遴选合适的知识库,并且存储与重用他们的数据。这篇论文描绘异构RDR的全景,表述机构的、学科的、跨学科的以及项目专业的RDR类型。深入描述re3data.org的特性,以及这套注册系统如何协助科研人员分辨适合存储和搜索科研数据的知识库。

基于Helmert变换的GPS动力学轨道平滑(英文)

Orbit fitting is used in many GPS applications. For example, in Precise Point Positioning (PPP), GPS orbits (SP3 orbits) are normally retrieved either from IGS or from one of its Analysis Centers (ACs) with 15 minutes’ sampling, which is much bigger than the normal observation sampling. Therefore, algorithms should be derived to fit GPS orbits to the observation time. Many methods based on interpolation were developed. Using these methods the orbits fit well at the sampling points. However, these methods ignore the physical motion model of GPS satellites. Therefore, the trajectories may not fit the true orbits at the periods in between 2 sampling epochs. To solve this problem, we develop a dynamic approach, in which a model based on Helmert transformation is developed in GPS orbit fitting. In this orbit fitting approach, GPS orbits at sampling points are treated as pseudo-observations. Thereafter, Helmert transformation is built up between the pseudo-observations and dynamically integrated orbits at each epoch. A set of Helmert parameters together with corrections of GPS initial orbits are then modeled as unknown parameters. Results show that the final fit orbits have the same precision as the IGS final orbits.

Timanide(Ediacaran–Early Cambrian) Metamorphism at the Transition from Eclogite to Amphibolite Facies in the Beloretsk Complex,SW-Urals,Russia

The Beloretsk Metamorphic Complex in the SW Urals formed at a convergent eastern margin of Baltica during the Neoproterozoic–Early Cambrian Timanide orogeny.It comprises three major units with lenses of facies-critical metabasites within metasedimentary rocks:A lowermost eclogite unit,an intermediate garnet amphibolite unit and an upper amphibolite-greenschist unit.Pressure(P)-temperature(T)-paths of four rocks from the two lowermost units were determined mainly by PT pseudosection techniques showing similar clockwise loops at different peak metamorphic,watersaturated conditions:A phengite-bearing eclogite shows peak PT conditions of 16.5–18.5 kbar/525–550℃(stage I)followed by stage II at 11.5–13.0 kbar/585–615℃.A garnet amphibolite from the intermediate unit yields lower peak conditions of 11.7–14.5 kbar/480–510℃(stage I)followed by stage II at 9.5–11.0 kbar/535–560℃.However,a granite gneiss in the eclogite unit shows similar maximum pressures as the eclogite,but higher temperatures at 15.6–16.2 kbar/660–675℃,whereas a garnet micaschist contains comparable high pressure relicts,but underwent an advanced midcrustal reequilibration at 7.5–9.0 kbar/555–610℃.We dated the eclogite by a 7-point Rb/Sr mineral isochron(phengite,omphacite,apatite)at 532.2±9.1 Ma interpreted as age of crystallisation of the eclogitic peak PT assemblage.This age is the youngest compared to the known Timanide metamorphic and magmatic ages.

Geodynamic processes of the continental deep subduction: Constraints from the fine crustal structure beneath the Pamir plateau

The Pamir plateau,located north of the western syntaxis of the India-Eurasia collision system,is regarded as one of the most possible places of the ongoing continental deep subduction.Based on a N-S trending linear seismic array across the Pamir plateau,we use the methods of the harmonic analysis of receiver functions and the cubic spline interpolation of surface wave dispersions to coordinate their resolutions,and perform a joint inversion of these datasets to construct a 2-D S-wave velocity model of the crust and uppermost mantle there.A spatial configuration among the intermediate-depth seismicity,Moho topography,and low-velocity anomalies within the crust and upper mantle is revealed,which provides new seismological constraints on the geodynamic processes of the continental subduction.These results not only further confirm the deep subduction of the Asian continental lower crust beneath the Pamir plateau,but also indicate the importance of the metamorphic dehydration of the subducting continental crustal material in the genesis of the intermediate-depth seismicity and the crustal deformation.