Integrated 3D density modelling and segmentation of the Dead Sea Transform     

H.-J. Götze  R. El-Kelani  S. Schmidt  M. Rybakov  M. Hassouneh  H.-J. Förster  J. Ebbing  DESERT Group 《International Journal of Earth Sciences》2007,96(2):289-302

A 3D interpretation of the newly compiled Bouguer anomaly in the area of the “Dead Sea Rift” is presented. A high-resolution 3D model constrained with the seismic results reveals the crustal thickness and density distribution beneath the Arava/Araba Valley (AV), the region between the Dead Sea and the Gulf of Aqaba/Elat. The Bouguer anomalies along the axial portion of the AV, as deduced from the modelling results, are mainly caused by deep-seated sedimentary basins (D > 10 km). An inferred zone of intrusion coincides with the maximum gravity anomaly on the eastern flank of the AV. The intrusion is displaced at different sectors along the NNW–SSE direction. The zone of maximum crustal thinning (depth 30 km) is attained in the western sector at the Mediterranean. The southeastern plateau, on the other hand, shows by far the largest crustal thickness of the region (38–42 km). Linked to the left lateral movement of approx. 105 km at the boundary between the African and Arabian plate, and constrained with recent seismic data, a small asymmetric topography of the Moho beneath the Dead Sea Transform (DST) was modelled. The thickness and density of the crust suggest that the AV is underlain by continental crust. The deep basins, the relatively large intrusion and the asymmetric topography of the Moho lead to the conclusion that a small-scale asthenospheric upwelling could be responsible for the thinning of the crust and subsequent creation of the Dead Sea basin during the left lateral movement. A clear segmentation along the strike of the DST was obtained by curvature analysis: the northern part in the neighbourhood of the Dead Sea is characterised by high curvature of the residual gravity field. Flexural rigidity calculations result in very low values of effective elastic lithospheric thickness (t _e < 5 km). This points to decoupling of crust in the Dead Sea area. In the central, AV the curvature is less pronounced and t _e increases to approximately 10 km. Curvature is high again in the southernmost part near the Aqaba region. Solutions of Euler deconvolution were visualised together with modelled density bodies and fit very well into the density model structures. An erratum to this article can be found at  相似文献   

Deep array electromagnetic sounding on the Baltic Shield: External excitation model and implications for upper mantle conductivity studies   总被引：1，自引：0，他引：1  

Elena Yu. Sokolova  Ivan M. Varentsov  BEAR Working Group 《Tectonophysics》2007,445(1-2):3

The BEAR array of simultaneous electromagnetic (EM) observations probes the deep crustal and upper mantle conductivity structure of the Baltic Shield searching for the lithosphere–asthenosphere boundary beneath. The adequate interpretation of the results of this unique high latitude natural field EM sounding requires proper understanding of the actual external excitation conditions because conventionally used plane wave model assumptions may be substantially violated in the vicinity of inhomogeneous polar sources. The paper presents an overview of the morphology and statistics of source distortions in the BEAR EM field transfer functions (TF) and the ways of their suppression. The stability of the final TF estimates obtained with the exclusion of intensive non-stationary auroral effects is further justified. The external excitation model effective for the whole BEAR observation period is inferred from the array distribution of the inter-station geomagnetic transfer functions. The model is supported by the results of polar ionosphere–magnetosphere current system studies, based on the simultaneous ground and satellite geomagnetic observations, and sets bounds for the “plane wave” approach in the BEAR data interpretation to avoid unfounded inferences on the upper mantle electrical properties. The signatures of the lithosphere–asthenospere boundary under Fennoscandia derived from the BEAR data are summarized and its resolution within the traditional plane wave interpretational paradigm is analysed assuming the presented external source pattern and estimated TF uncertainties caused by the source inhomogeneity.  相似文献   

GEOTRACES - An international study of the global marine biogeochemical cycles of trace elements and their isotopes   总被引：1，自引：0，他引：1  

SCOR Working Group 《Chemie der Erde / Geochemistry》2007,67(2):85-131

Trace elements serve important roles as regulators of ocean processes including marine ecosystem dynamics and carbon cycling. The role of iron, for instance, is well known as a limiting micronutrient in the surface ocean. Several other trace elements also play crucial roles in ecosystem function and their supply therefore controls the structure, and possibly the productivity, of marine ecosystems. Understanding the biogeochemical cycling of these micronutrients requires knowledge of their diverse sources and sinks, as well as their transport and chemical form in the ocean.Much of what is known about past ocean conditions, and therefore about the processes driving global climate change, is derived from trace-element and isotope patterns recorded in marine deposits. Reading the geochemical information archived in marine sediments informs us about past changes in fundamental ocean conditions such as temperature, salinity, pH, carbon chemistry, ocean circulation and biological productivity. These records provide our principal source of information about the ocean's role in past climate change. Understanding this role offers unique insights into the future consequences of global change.The cycle of many trace elements and isotopes has been significantly impacted by human activity. Some of these are harmful to the natural and human environment due to their toxicity and/or radioactivity. Understanding the processes that control the transport and fate of these contaminants is an important aspect of protecting the ocean environment. Such understanding requires accurate knowledge of the natural biogeochemical cycling of these elements so that changes due to human activity can be put in context.Despite the recognised importance of understanding the geochemical cycles of trace elements and isotopes, limited knowledge of their sources and sinks in the ocean and the rates and mechanisms governing their internal cycling, constrains their application to illuminating the problems outlined above. Marine geochemists are poised to make significant progress in trace-element biogeochemistry. Advances in clean sampling protocols and analytical techniques provide unprecedented capability for high-density sampling and measurement of a wide range of trace elements and isotopes which can be combined with new modelling strategies that have evolved from the World Ocean Circulation Experiment (WOCE) and Joint Global Ocean Flux Study (JGOFS) programmes. A major new international research programme, GEOTRACES, has now been developed as a result of community input to study the global marine biogeochemical cycles of trace elements and their isotopes. Here, we describe this programme and its rationale.  相似文献   

论江西气象综合观测体系改革与建设   总被引：1，自引：0，他引：1  

《江西省气象局业务技术体制改革实施方案》编写组 《气象与减灾研究》2005,28(4):19-23

介绍了江西现有的气象综合观测体系,并就江西气象综合观测体系改革与建设的内容进行了论述,认为江西气象综合观测体系的改革与建设,应按照中国气象局调整“国家气候观象台、国家气象观测站、区域气象观测站”3类台站布局,构建“国家气候监测网、国家天气观测网、国家专业气象观测网和区域气象观测网”的总体要求,坚持全面性、开放性、可行性和连续性相统一的原则,根据一站多用、一站多能和一体化、集约化的原则,结合江西经济社会发展、国家安全和可持续发展的实际需要,对全省各台站进行统筹规划、科学布局,形成一站多点、一站多能、满足多轨道业务需求的综合气象观测网。  相似文献   

Decomposition analysis of the BEAR magnetotelluric data: implications for the upper mantle conductivity in the Fennoscandian Shield   总被引：1，自引：0，他引：1  

I. Lahti  T. Korja  P. Kaikkonen  K. Vaittinen  BEAR Working Group 《Geophysical Journal International》2005,163(3):900-914

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Seismic model and geological interpretation of the basement beneath the Doupovské Hory Volcanic Complex (NW Czech Republic)     

Jan Valenta  Milan Brož  Jiří Málek  Bedřich Mlčoch  Vladislav Rapprich  Zuzana Skácelová  the Doupov Working Group 《Acta Geophysica》2011,59(3):597-617

The Doupovské Hory Volcanic Complex (DHVC) is the best-preserved large volcanic suite of the Cenozoic intraplate volcanism in the Bohemian Massif. However, many uncertainties remain in the geological setting of its basement. In summer 2008, two seismic refraction profiles ran across this area to reveal the depth of the volcanic rocks and the underlying geological structure.  相似文献   

深部探测技术与实验研究(SinoProbe)   总被引：14，自引：8，他引：6  

董树文  李廷栋  SinoProbe团队 《地球学报》2011,32(Z1):3-23

“深部探测技术与实验研究”作为国家地壳探测工程的培育性启动计划(2008—2012年), 专项围绕深部探测实验和示范, 在全国部署“两网、两区、四带、多点”的深部探测技术与实验研究工作,“两网”:全国电磁参数标准网和全国地球化学基准网;“两区”: 大华北综合探测实验区、华南综合探测实验区; “四带”: 西秦岭中央造山带、青藏高原腹地、三江活动带、松辽油气盆地;“多点”: 金川铜镍矿集区、罗布莎地幔探针(铬铁矿矿集区)、腾冲火山、长江中下游和南岭矿集区、南北中国板块汇聚边界等。旨在: 自主研发深部探测关键仪器装备,全面提升国产化水平; 为实现能源与重要矿产资源重大突破提供全新科学背景依据和基础信息; 揭示成藏成矿控制因素, 突破深层找矿瓶颈, 开辟找矿“新空间”; 把握地壳活动脉搏, 提升地质灾害监测预警能力; 深化认识岩石圈结构与组成, 全面提升地球科学发展; 为国防安全的需要了解地壳深部物性参数; 为地壳探测工程的全面实施进行关键技术与实验准备。  相似文献   

DEDICATED PRINCIPAL PROPERTIES FOR PEPTIDE QSARS: THEORY AND APPLICATIONS     

BERTSKAGERBERG  MICHAEL  SVANTEWOLD 《地理学报(英文版)》1990,(3)

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Toward IAVCEI guidelines on the roles and responsibilities of scientists involved in volcanic hazard evaluation,risk mitigation,and crisis response     

IAVCEI Task Group on Crisis Protocols 《Bulletin of Volcanology》2016,78(4):31

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An Exploration of Building a Thematic Sub-database within the Framework of DDE:A New Detrital Zircon U-Pb Dating Database     

LI Chao  LAI Wen  HU Xiumian  XU Yajun  YANG Jianghai  DDE Sedimentary Data Group 《《地质学报》英文版》2019,93(Z1):37-39

正Within the framework of the Deep-time Digital Earth (DDE)project,thematic databases driven by scientific issues will have strong scientific vitality.In the field of sedimentology,thematic databases based on the current unified sedimentary knowledge tree established by the Sedimentary Data Group (Fig.1),can solve specific scientific problems effectively and improve the scope and utility of the DDE platform significantly.  相似文献