Three-dimensional seismic modelling of crustal structure in the TESZ region based on POLONAISE''97 data

This paper reports the results of 3-D tomographic modelling of crustal structure in the Trans European Suture Zone region (TESZ) of Poland, eastern Germany and Lithuania. The data are the product of a large-scale seismic experiment POLONAISE'97, which was carried out in 1997. This experiment was designed to provide some 3-D coverage. The TESZ forms the boundary between the Precambrian crustal terranes of the East European Craton (EEC) and the younger Phanerozoic terranes to the southwest. The 3-D results generally confirm the earth models derived by earlier 2-D analyses, but also add some important details as well as a 3-D perspective on the structure. The velocity model obtained shows substantial horizontal variations of crustal structure across the study area. Seismic modelling shows low (<6.1 km/s) velocities suggesting the presence of sedimentary rocks down to a depth of about 20 km in the Polish basin. The shape of the basin in the vicinity of the profile P4 shows significant asymmetry. Three-dimensional modelling also allowed tracing of horizontal irregularities of the basin shape as well as variations of the Moho depth not only along profiles, but also between them. The slice between P2 and P4 profiles shows about 10-km variations of the Moho over a 100-km interval. The crustal thickness varies from about 30 km in SW, beneath the Palaeozoic platform, to about 42 km beneath East European Craton in NE. High seismic velocities of about 6.6 km/s were found in the depth range 2–10 km, which coincides with K trzyn anorthosite massif. The results of this 3-D seismic modelling of the POLONAISE'97 data will ultimately be supplemented by inversion of seismic data from previous experiments.     

有关金刚石成因等若干重大问题的新认识

本文从世界范围内阐述金刚石的分布。来源,成因及其形成条件和保存条件,找出了找矿方向,开拓了找矿思路,扩大了找矿领域,对于发现和突破金伯利岩型,橄榄金云火山岩型及新类型的金刚石原生矿床,具有指导意义。     

1991年大同—阳高5.8级地震震害评估

用抽样调查的方法,对大同SXDZ199103阳高1991年3月26日5.8级地震4～7度区的建筑物进行了调查。按倒塌、严重破坏、中等破坏、轻微破坏、基本完好,划分房屋的破坏程度,求出房屋的破坏比、户均房屋数、各烈度区总户数及总房间数。根据当地建筑材料的实际价格,工时费等确定了房屋的单价,又据国家地震局震害防御司颁布的震害评估细则,确定了建筑物破坏的损失比。利用破坏比、损失比、房屋单价、各烈度区房间总数对这次地震的经济损失进行了估算。     

Experimentally validated numerical method for the hydrodynamic design of horizontal axis tidal turbines

Although a lot can be learnt from technology transfer from wind turbines and ship propellers, there have been a few experiments investigating marine current turbines. As a result, a study has been carried out on the power, thrust and cavitation characteristics of 1/20th scale model of a possible 16 m diameter horizontal axis tidal turbine. Cavitation tunnel experiments for different blade pitch settings have been compared with simulations based on a developed blade element-momentum theory. This theory has been shown to provide a satisfactory representation of the experimental turbine performance characteristics. As an example application, the developed theory has been used to design possible horizontal axis tidal turbines for the tidal flows around Portland Bill. The results show that there is a clear balance between design loads and optimisation of energy yields.     

Wave modelling - The state of the art

This paper is the product of the wave modelling community and it tries to make a picture of the present situation in this branch of science, exploring the previous and the most recent results and looking ahead towards the solution of the problems we presently face. Both theory and applications are considered.The many faces of the subject imply separate discussions. This is reflected into the single sections, seven of them, each dealing with a specific topic, the whole providing a broad and solid overview of the present state of the art. After an introduction framing the problem and the approach we followed, we deal in sequence with the following subjects: (Section) 2, generation by wind; 3, nonlinear interactions in deep water; 4, white-capping dissipation; 5, nonlinear interactions in shallow water; 6, dissipation at the sea bottom; 7, wave propagation; 8, numerics. The two final sections, 9 and 10, summarize the present situation from a general point of view and try to look at the future developments.     

Geochemical signature as paleoenvironmental markers in Holocene sediments of the Tinto River estuary (Southwestern Spain)

High absolute concentrations of metals associated to sulfide deposits located at the river source (Fe, Cu, Zn, Pb, Cd, and As) have been determined from the study of major and trace element concentrations in sediment samples obtained in two vibracores in the Tinto River estuary. In most cases, the enrichment factor (EF) for these metals is over 2. Cu, Zn and As have much higher EF, over 10 in surficial samples. Fe oxy-hydroxide precipitation in high-chlorinity zones and its scavenging effect on metals is the main control process on the chemical composition of sediment. Vertical evolution of the sedimentary and geochemical characteristics of the cores show that the estuary has undergone a process of progressive shallowness and a relative increase in acidic river water volume with respect to seawater. This effect has originated a downstream displacement of acid mixing processes affecting the estuary, which is reflected in higher metal concentrations in sediments of the outer zones of the system.     

对“浙江长兴二叠系-三叠系界线层型剖面面临的新问题”一文的商榷

承蒙<地层学杂志>编辑部寄来王成源先生"浙江长兴二叠系-三叠系界线层型剖面面临的新问题"一文(以下简称王文)征求意见,兹将我们对其2、3两段的意见表述如下,供大家讨论:     

台湾省地层多重划分对比研究

台湾省地层多重划分对比研究福建省地矿局台湾省地层研究组（福建省地质矿产局，福州，３５０００３）地层学是地层领域中的基础学科。随着现代地层学和沉积学的发展，地质学家普遍认识到沉积地层叠复是在复杂的侧向堆积过程中形成的，且岩石地层单位具有普遍的穿时性。因...