Crustal structure beneath the Songpan—Garze orogenic belt

The Benzilan-Tangke deepseismic sounding profile in the western Sichuan region passes through the Song-pan-Garze orogenic belt with trend of NNE.Based on the travel times and the related amplitudes of phases in the record sections,the 2-D P-wave crustal structure was ascertained in this paper.The velocity structure has quite strong lateral variation along the profile.The crust is divided into 5layers,where the first,second and third layer belong to the upper crust,the forth and fifth layer belong to the lower crust.The low velocity anomaly zone gener-ally exists in the central part of the upper crust on the profile,and it integrates into the overlying low velocity basement in the area to the north of Ma‘erkang.The crustal structure in the section can be divided into 4parts:in the south of Garze-litang fault,between Garze-Litang fault and Xianshuihe fault,between Xianshuihe fault and Longriba fault and in the north of Longriba fault,which are basically coincided with the regional tectonics division.The crustal thickness decreases from southwest to northeast along the profile,that is ,from62km in the region of the Jinshajiang River to 52km in the region of the Yellow River.The Moho discontinuity does not obviously change across the Xianshuihe fault basesd on the PmP phase analysis.The crustal average velocity along the profile is lower,about 6.30 km/s.The Benzilan-Tangke profile reveals that the crust in the study area is orogenic.The Xianshuihe fault belt is located in the central part of the profile,and the velocity is positive anomaly on the upper crust,and negative anomaly on the lower crust and upper mantle.It is considered as a deep tectonhic setting in favor of strong earthquake‘s accumulation and occurrence.     

Effect of asymmetry and irregularity of seismic waves on earthquake-induced differential settlement of buildings on natural subsoil

The effect of asymmetry and irregularity of the inputted seismic waves on the earthquake-induced differential settlement of the buildings on natural subsoil is investigated in terms of the earthquake damage phenomena, theoretical analyses, dynamic triaxial tests and shaking table tests. A conclusion can be drawn from the investigation results that, the asymmetrical and irregular character of the inputted seismic waves themselves may have a significant contribution to the differential settlement of subsoil and buildings in some cases, and this is a necessary factor to be considered in reasonable evaluation for the differential settlement and other problems relating to the soil deformation due to earthquakes.     

Inelastic dynamic analysis of RC bridges accounting for spatial variability of ground motion,site effects and soil–structure interaction phenomena. Part 1: Methodology and analytical tools

During strong ground motion it is expected that extended structures (such as bridges) are subjected to excitation that varies along their longitudinal axis in terms of arrival time, amplitude and frequency content, a fact primarily attributed to the wave passage effect, the loss of coherency and the role of local site conditions. Furthermore, the foundation interacts with the soil and the superstructure, thus significantly affecting the dynamic response of the bridge. A general methodology is therefore set up and implemented into a computer code for deriving sets of appropriately modified time histories and spring–dashpot coefficients at each support of a bridge with account for spatial variability, local site conditions and soil–foundation–superstructure interaction, for the purposes of inelastic dynamic analysis of RC bridges. In order to validate the methodology and code developed, each stage of the proposed procedure is verified using recorded data, finite‐element analyses, alternative computer programs, previous research studies, and closed‐form solutions wherever available. The results establish an adequate degree of confidence in the use of the proposed methodology and code in further parametric analyses and seismic design. Copyright © 2003 John Wiley & Sons, Ltd.     

Inelastic dynamic analysis of RC bridges accounting for spatial variability of ground motion,site effects and soil–structure interaction phenomena. Part 2: Parametric study

The methodology for dealing with spatial variability of ground motion, site effects and soil–structure interaction phenomena in the context of inelastic dynamic analysis of bridge structures, and the associated analytical tools established and validated in a companion paper are used herein for a detailed parametric analysis, aiming to evaluate the importance of the above effects in seismic design. For a total of 20 bridge structures differing in terms of structural type (fundamental period, symmetry, regularity, abutment conditions, pier‐to‐deck connections), dimensions (span and overall length), and ground motion characteristics (earthquake frequency content and direction of excitation), the dynamic response corresponding to nine levels of increasing analysis complexity was calculated and compared with the ‘standard’ case of a fixed base, uniformly excited, elastic structure for which site effects were totally ignored. It is concluded that the dynamic response of RC bridges is indeed strongly affected by the coupling of the above phenomena that may adversely affect displacements and/or action effects under certain circumstances. Evidence is also presented that some bridge types are relatively more sensitive to the above phenomena, hence a more refined analysis approach should be considered in their case. Copyright @ 2003 John Wiley & Sons, Ltd.     

松辽盆地南部十屋断陷古构造对营城组扇三角洲发育的控制

在恢复古构造的基础之上，对比了松辽盆地南部十屋断陷营城组沉积时期的古构造格局与现令构造格局的异同。古构造对扇三角洲沉积体系的控制作用主要表现在：(1)主要基底断裂控制了扇三角洲的展布方向；(2)倾向与物源方向相反的断层和古地貌阻滞了扇三角洲的展布；(3)沉降中心控制了扇三角洲前缘的纵向叠置和发育。     

电法在濒海及岛屿地区寻找地下淡水中的应用

采用电法的基本原理，研究各种不同岩性和成淡水的电性差畀，划分地下成淡水分界面。在严重缺水的濒海及岛屿地区找到了较好的地下淡水，解决了守岛部队吃水难的问题。     

煤岩显微组分热解气相色谱特征与化学结构剖析

煤结构是目前地球化学研究领域中的一个难点，但却具有极其重要的理论及实际意义，本文采用分步热解气相色谱技术将树皮体，镜质体和丝质体分解为分子量较小的可测定的有机化合物，在此基础上，据不同温度下热解产物的组成特征来还原显微组分的化学结构，实验结果表明，煤显微组分主要由四大类官能团组成，一是热稳定性较低的NOS杂原子官能团；二是脂族（脂链、脂环）结构；三是苯、烷基苯（甲苯、二甲苯）、萘等芳香族化合物，四是热稳定性很高的难以分解的稠环芳烃。上述四类化合物集中于显微组分的不同结构简单中，树皮体和镜质体结构单元外侧主要由热稳定性较低的杂原子化合物以及分子量较小的苯和烷基苯组成，而丝质体结构单元外侧则主要以短链脂族结构为主，三组分结构核部由热稳定性很高的难以分解的稠环芳烃组成。连结核部稠环芳烃与结构单元外侧杂原子等官能团的主要是热稳定性较高的脂链结构，煤显微组分热成烃主要按结构中各官能团键的强弱随热演化程度的加深依次脱除，生成油气，基本上属平行独立依次反应机制，亦“官能团脱除型”，此外，还包括少量的长链脂族结构裂解为短链脂肪烃的“解聚”过程。     

苏北榴辉岩中水晶的形成时代及其对超高压变质岩折返的示踪意义

江苏东海水晶以其晶体粒大和产量巨大而闻名，在地质上也因其产于高压超高压变质带而独具特色。在对大别—苏鲁超高压变质带的区域成矿作用进行研究和对中国大陆科学钻探工程(CCSD)主孔岩心进行编录的过程中，认识到超高压带存在着超低压成矿现象，包括中国最主要的水晶矿床成矿带在内的许多矿床都可能是在超高压变质之后退变质结束阶段的超低压环境中形成的，对水晶进行流体包裹体的Rb-Sr等时线年代学研究，获得208Ma的等时线年龄，表明成矿时代为印支期。该年代可视为超高压变质带折返并经历了退变质之后而“稳定”下来的时间。     

冀北地区金矿床He、Ar、Pb同位素组成及其成矿物质来源

成矿物质来源一直是成矿理论研究和找矿实践的焦点问题。选择了冀北地区3个幔枝构造金矿集中区11个金矿床黄铁矿及部分围岩进行了He、Ar同位素测定。研究表明,冀北地区主要金矿的3He/4He的值域为(0.93～7.30)×10-6,平均3.55×10-6;R/Ra=0.66～4.93,平均2.53;40Ar/36Ar=426～2073,40Ar平均为8.20×10-7cm3/g,4He/40Ar平均为2.17。矿区外围片麻岩和花岗岩的3He/4He值仅为(0.001～0.55)×10-6,反映来源上有明显差别。3He和4He在He同位素浓度图上落于地幔区附近。64个Pb同位素数据表现为矿质以幔源为主,确有部分壳源物质加入。研究认为,本区成矿物质应源于地球深部,随地幔柱多级演化,深部成矿流体由地球深部迁移到浅部,期间不可避免地存在壳幔流体的混合作用,故其值域往往界于地幔和地壳之间。     

Re-discussion on the Jiaochang Arcuate Structure, Sichuan Province, and the Seismogenic Structure for Diexi Earthquake in 19331

The Jiaocbang arcuate structure is one of the numerous arcuate structural belts in Sichuan. The present paper gives a further argument about the characteristics of that arcuate structure and the new activity of the Songpinggou fault and affirms that the Songpinggou fault is an active fault in the Holocene epoch. The Diexi M7.5 earthquake took place in 1933 on the west wing of that arcuate structure, near the apex of the arc. Many authors have given quite different opinions about the genetic structure of that earthquake. The authors have made on-the-spot investigations time and again over recent years. Besides this, the authors have also further studied the shape of intensity contour lines, the distribution characteristics of ground surface seismic hazards, the left-lateral dislocation of buildings along the Songpinggou fault, the NWtrending ground fissures that developed on the ground surface after earthquake, and so on. On this basis, it is still considered that the seismogenic fault of the 1933 Diexi M7.5 earthquake was the Songpinggou fault on the west wing of the Jiaochang arcuate structure.