冲绳海槽南部沉积层序的粒度特征

对取自冲绳海槽南部的A2 3孔经前处理后的沉积物样品进行了粒度测试,探讨了陆源沉积层序的粒度特征。沉积物平均粒径、分选系数、偏态、峰态等粒度参数的变化显示出A2 3孔的沉积层序以 4 0 0cm为界可分为上、下两段,下段各参数稳定,代表了比较稳定的水动力条件的沉积环境;上段则波动较大,小规模浊流沉积频繁发育,暗示了不稳定的沉积环境。浊流层内粗粒与细粒组分含量及粒度分布的变化具有明显的规律性。通过分析A2 3孔陆源沉积层序的各沉积参数特征,认为冲绳海槽南部的沉积环境和动力在时间尺度上有较大的变化,东海陆架物质向南部海槽的输运可能是以峡谷为通道的重力作用引起的床底沉积作用为主。另外,对陆源碎屑和全样粒度结果的对比,显示了前处理方法对于海洋沉积物粒度分析的重要性.     

岩石断裂作用的复杂性和混沌动力学

断裂是一个复杂的动力学体系,受到岩石结构、反应、流体迁移、应力、岩石变形和力学等多种地质因素和过程的耦合控制。本文建立了断裂体系的反应-输运-力学耦合动力学模型并编制了模拟程序。以湖南水口山矿区为例,通过动力学模拟表明不同地层岩性的断裂渗透率大小和演化特征存在显著差异,断裂作用促使岩石渗透率的空间非均匀性增强,从而有利于流体的局部汇聚和矿体的形成。断裂中压力随时间呈现出非周期振荡变化,反映了断裂演化的混沌特征。     

Continental subduction and exhumation of UHP rocks. Structural and geochronological insights from the Dabieshan (East China)

In the Dabieshan, the available models for exhumation of ultrahigh-pressure (UHP) rocks are poorly constrained by structural data. A comprehensive structural and kinematic map and a general cross-section of the Dabieshan including its foreland fold belt and the Northern Dabieshan Domain (Foziling and Luzenguang groups) are presented here. South Dabieshan consists from bottom to top of stacked allochtons: (1) an amphibolite facies gneissic unit, devoid of UHP rocks, interpreted here as the relative autochton; (2) an UHP allochton; (3) a HP rock unit (Susong group) mostly retrogressed into greenschist facies micaschists; (4) a weakly metamorphosed Proterozoic slate and sandstone unit; and (5) an unmetamorphosed Cambrian to Early Triassic sedimentary sequence unconformably covered by Jurassic sandstone. All these units exhibit a polyphase ductile deformation characterized by (i) a NW–SE lineation with a top-to-the-NW shearing, and (ii) a southward refolding of early ductile fabrics.

The Central Dabieshan is a 100-km scale migmatitic dome. Newly discovered eclogite xenoliths in a Cretaceous granitoid dated at 102 Ma by the U–Pb method on titanite demonstrate that migmatization post-dates HP–UHP metamorphism. Ductile faults formed in the subsolidus state coeval to migmatization allow us to characterize the structural pattern of doming. Along the dome margins, migmatite is gneissified under post-solidus conditions and mylonitic–ultramylonitic fabrics commonly develop. The north and west boundaries of the Central Dabieshan metamorphics, i.e. the Xiaotian–Mozitan and Macheng faults, are ductile normal faults formed before Late Jurassic–Early Cretaceous. A Cretaceous reworking is recorded by synkinematic plutons.

North of the Xiaotian–Mozitan fault, the North Dabieshan Domain consists of metasediments and orthogneiss (Foziling and Luzenguang groups) metamorphosed under greenschist to amphibolite facies which never experienced UHP metamorphism. A rare N–S-trending lineation with top-to-the-south shearing is dated at 260 Ma by the ⁴⁰Ar/³⁹Ar method on muscovite. This early structure related to compressional tectonics is reworked by top-to-the-north extensional shear bands.

The main deformation of the Dabieshan consists of a NW–SE-stretching lineation which wraps around the migmatitic dome but exhibits a consistently top-to-the-NW sense of shear. The Central Dabieshan is interpreted as an extensional migmatitic dome bounded by an arched, top-to-the-NW, detachment fault. This structure may account for a part of the UHP rock exhumation. However, the abundance of amphibolite restites in the Central Dabieshan migmatites and the scarcity of eclogites (found only in a few places) argue for an early stage of exhumation and retrogression of UHP rocks before migmatization. This event is coeval to the N–S extensional structures described in the North Dabieshan Domain. Recent radiometric dates suggest that early exhumation and subsequent migmatization occurred in Triassic–Liassic times. The main foliation is deformed by north-verging recumbent folds coeval to the south-verging folds of the South Dabieshan Domain. An intense Cretaceous magmatism accounts for thermal resetting of most of the ⁴⁰Ar/³⁹Ar dates.

A lithosphere-scale exhumation model, involving continental subduction, synconvergence extension with inversion of southward thrusts into NW-ward normal faults and crustal melting is presented.     

铅—试铁灵络合物吸附波及溴化十六烷基三甲基铵增敏效应的研究

在０３０ｍｏｌ／ＬＨＡｃ介质中，Ｐｂ（Ⅱ）与７＿碘＿８＿羟基喹啉＿５＿磺酸（试铁灵，Ｆｅｒｏｎ）的络合物于－０５４Ｖ（ｖｓ．ＳＣＥ）产生一尖锐的极谱波，加入溴化十六烷基三甲基铵（ＣＴＭＡＢ）显著增敏，可使极谱波增高约４倍。峰电流与Ｐｂ（Ⅱ）浓度在９６×１０－９～４８×１０－６ｍｏｌ／Ｌ呈良好的线性关系，检出限为４８×１０－９ｍｏｌ／Ｌ。用多种电化学方法研究了该极谱波的性质及电极反应机理表明，络合物组成比为ｎＰｂ（Ⅱ）∶ｎＦｅｒｏｎ＝１∶１，极谱波为吸附波，峰电流由中心离子Ｐｂ（Ⅱ）还原产生，电子转移数为２。试验了多种离子对峰电流的影响，拟定的方法用于矿样分析，结果与原结果相符。     

Crust-Mantle Electrical Structure in the Area along the Yadong-Burn Co Profile

1.IntroductionUntilnowTibetisstillthearchetypalregionwithcontinentalcollisiongoingoninit,henceitisanidealnaturallaboratoryforstudyingthegeologicevolutionofintracontinentalorogenicbeltandthecrust-mantledeepprocesses,aswellastheinteractionbetweenthemandthesupracrustalmovements.Forthisreason,forseveraldecadesgeologistsandgeophysicistsfromvariouscountrieshavemadeunremittingeffortsinthisregiontoprobeintotheoriginandprocessoftheplateauformation,withavarietyofcognitionsproposed.TheCMPresultsoftheSi…     

中国兴凯湖北岸平原晚全新世花粉记录及泥炭沼泽形成

通过兴凯湖北岸平原泥炭剖面高分辩率花粉分析研究，对晚全新世花粉划分4个组合带。XKH-4组合时期(1857～1746aB．P．)为沼泽发育前期，这一时期花粉浓度小，陆生草本植物占优势，气候干冷。XKH-3组合时期(1746～1287aB．P．)为沼泽发育早期，这一时期花粉浓度较大，且水生植物花粉含量为剖面最高，喜温落叶阔叶植物大发展时期，气候温和湿润。XKH-2组合时期(1287～602aB．P．)为沼泽发育中期，这一时期花粉浓度最小，但以陆生草本植物为主，木本植物为辅，水生植物急剧减少，针叶植物出现两次高峰，气候向冷干方向发展。XKH-1组合时期(602aB．P．至今)为沼泽发育盛期，这一时期花粉浓度最大，陆生草本植物大发展时期，气候波动较大。     

Regional comprehensive assessment on environment-health of China

The aim of the study was to assess the environment-health development in different regions of China. 175 indicators, such as average life expectancy at birth, emission intensity of waste gas, GDP etc. were chosen to describe various aspects of the environment, health and development of China. Of all the indicators, life expectancy can sufficiently reflect health situation of population. Consequently, life expectancy was identified as key indicator, and 42 out of 175 indicators were selected for establishing the environment-health indicator framework with three grades of integrative indices to assess the development of environment-health of China. Based on the hierarchical relation between various grades of indices, the comprehensive environment-health index was calculated and contributed to classify the environment-health situation of 30 provinces, municipalities and autonomous regions in China which were divided into five grades by four predefined limits. Comprehensive assessment indicates that the environment-health situation of the eastern and coastal areas is superior to that of inland which is the western regions with underdeveloped economy and rigorous natural condition. Especially, the Qinghai-Tibet and Yunnan-Guizhou plateaus in southwestern China are most vulnerable in the environment and population health. These fit in with the pattern of national socio-economic development, which fully shows that socio-economic context plays a dominant role in the improvement of environment-health in China.     

Sedimentation rates in the Wanggang salt marshes, Jiangsu

1 IntroductionLand-ocean interaction in coastalzone is one of the key m atters of the International G eosphereand Biosphere Program (IG BP). The key problem s of the second phase in the next decadeinclude the m aterial cycle, the system evolution process …     

湿式旋挖工法中埋钻事故的处理

介绍了在静态泥浆护壁的湿式旋挖工法中出现的埋钻事故的处理工艺以及在使用湿式旋挖工法中出现的一些实际问题的处理办法。     

Snow loads on wire mesh and cable net rockfall slope protection systems

Snow load on mesh systems is complicated by many factors. This paper presents field instrumentation data on snow load variation with temperature, snowfall and snow depth on a mesh system. It was found that snow load pattern on mesh systems changed with temperature even without variation in snow depth. It reached its maximum value when the temperature rose just above freezing to melt the interface. The field data was used to formulate appropriate snow load models for the various conditions of temperature in the field. The snow load models were used to study the performance of a number of mesh systems in North America and estimate the interface friction that was prevalent for the different surface conditions.