湖南玉横塘金矿区地质特征及找矿前景分析

玉横塘金矿区位于扬子地台与华南褶皱系过渡地带,雪峰弧形构造成矿带中段与白马山-龙山EW向隆起带的接合处,区内出露地层为新元古界板溪群五强溪组。通过野外地质工作及室内测试分析,认为区内赋矿层位为五强溪组第一段。矿脉的形态、产状和含矿性受NE向导矿断裂及一系列具多期活动的NW向含矿断裂的控制,矿化蚀变主要为毒砂化和黄铁矿化。通过对矿区地质特征、成矿条件、控矿因素、成矿规律和找矿标志的分析研究,认为区内主要矿脉体的深部及南东段NW向次要矿脉（尤其是与五强溪组第一段交会部位）找矿潜力较大,资源储量有望进一步增加。     

内蒙古阿拉善右旗塔木素地区三叠纪正长花岗岩成因及构造环境分析

塔木素地区三叠纪正长花岗岩岩石化学特征显示其总体呈富硅、碱,高FeOT/MgO比值和10 000×Ga/Al值,贫钙、镁的特征,属准铝质-弱过铝质、高钾钙碱性系列-钾玄岩系列;轻重稀土分馏明显,Eu负异常明显,稀土曲线右倾,属轻稀土富集型;微量元素表现出Zr、Hf、K元素相对富集,而Rb、Sr、Nb、Ta、U、Ti、Cr、Co、Ni元素亏损;同时具有较高的Y/Nb和Rb/Nb值,显示A2型花岗岩的特征。结合相关花岗岩构造图解分析,塔木素三叠纪正长花岗岩为在大陆边缘正常岩浆弧上,由地壳重熔而形成的增生于大陆边缘上的花岗岩,岩浆来源应为壳幔混合。其作为新生地壳的一部分,代表了碰撞晚期或碰撞后地壳增厚、抬升、拉张的构造环境。     

Climatic aging of composite aviation materials: II. Relaxation of the initial structural nonequilibrium and through-thickness gradient of properties

The climatic aging of composite aviation materials is analyzed. It is shown that changes in their mechanical properties are affected by the initial structural nonequilibrium of the binder and reinforcing fibers. A characteristic feature is the formation of a through-thickness gradient of sample properties at their exposure to natural climatic conditions.     

郯庐断裂带的几个关键问题探讨

郯庐断裂是中国东部的一个巨型断裂，目前关于郯庐断裂的几个关键问题仍存在较大争议：一是郯庐断裂的长度；二是郯庐断裂的走滑距离和走滑深度；三是郯庐断裂的形成与活动时间；四是郯庐断裂与胶东金矿的关系。基于地质、地球物理和地球化学研究结果，结合近期郯庐断裂带区域高精度石油地震勘探资料和地质测年资料，通过大地构造演化史恢复说明，郯庐断裂的雏形出现在中生代的中央造山带东段，走滑开始于新生代初期，大规模平移走滑发生在45～24 Ma，并持续活动至今。郯庐断裂总体左行走滑量约为760 km，总长度约为3 000 km。对于胶东金矿，郯庐断裂主要是一个改造断裂。郯庐断裂带的形成和演化与中新生代欧亚板块东缘的构造环境变化密切相关。研究结果为中国东部大地构造动力演化及成矿过程研究提供了新思路。     

The role of ledges in stress tensor-mediated surface processes for Si and GaAs

Calculation results of terrace and ledge reconstruction-induced surface stress tensors, using semiempirical potential energy functions for Si, GaAs, GaAs/Al, and GaAs/Si, are reviewed. Long-range (～50 to 100 Å) interaction effects between ledges and between interfaces are pre sented. Two-dimensional homogeneous and heterogeneous nucleation effects are also presented, showing that Actatom cluster populations are strongly influenced by these reconstruction events. The consequences of these reconstruction-induced surface fields on γ plots, ledge motion kinetic laws, surface Actatom transport, and solute partitioning at ledges are discussed. The numerical results were generated largelyvia Monte Carlo calculations and thus neglect entropy effects.     

Optimal Cross-Sectional Spacing in Preissmann Scheme 1D Hydrodynamic Models

Choosing a suitable set of cross sections for the representation of the natural geometry of a river is important for the efficiency of one-dimensional (1D) hydraulic models, but only few guidelines are available for the selection of the most suitable distance between cross sections, depending on the hydraulic problem at hand. This issue is investigated by examining models of a ～ 55?km reach of the River Po, Italy, and a ～ 16?km reach of the River Severn, United Kingdom, for both of which high quality laser scanning altimetry are available. The high-resolution digital terrain models of the two river reaches enabled the construction of a series of hypothetical topographical ground surveys with different spacing between cross sections, which could be used as input to a standard 1D model (UNET). Both historical and synthetic flood events for the two river reaches were simulated, and the results were then analyzed to quantify the accuracy associated with each resolution and to assess how survey resolution impacts the performance of standard 1D models. The study results agree with the available suggestions in the literature and provide useful guidelines for 1D hydrodynamic modeling.     

Transient Head Development due to Flood Induced Seepage under Levees

The purpose of this study was to predict the uplift force during floods on confining layers that overlay extensive horizontal confined aquifers that intersect a large river in response to the water level changes that occur with time in a flooding river. Transient flow of water through the confined aquifer was described by a diffusion type of equation with a boundary condition at the river in which the river head varied with time. The transient head distribution developed from the unsteady flow model applied to the aquifer was compared with the hydraulic head distributions obtained from U.S. Army Corps of Engineers steady-state flow model and a finite-element seepage model. This study concluded that the transient flow model has the potential to analyze time lag in head development, and to predict the seepage condition and heaving potential at various times and distances landside of a levee during a flood cycle, but additional case histories are needed to justify widespread use of the model.     

Correlation Studies of Rare Earth Elements in Syntectonic Intrusions of Strike-Slip Stage along Southern Segment of Tan-Lu Fault Zone

Intrusions in the Zhangbaling uplift zone and the eastern margin of the Dabie orogenic belt belong to the svntectonic intrusions developed during the strike-slip stage in the southern segment of the Tan-Lu fault zone. However, characteristics of rare earth elements show that intrusions in the Zhangbaling uplift zone have the characteristics of mantle source type and those in the eastern margin of Dable belt are the typical crust source type. Therefore, Au-deposits related to the intrusions in the Zhangbaling uplift zone are developed better than those in the eastern margin of the Dabiesban. The research results of the rare earth elements coincide with the studies of geophysics, tectonic setting and stable is otope. It isfurther indicated that the rare earth elements offer effective approach to tracing the material sources of magmatic rocks.     

四川若尔盖阿西金矿床地质特征及成因探讨

通过对阿西金矿床地质特征、成矿条件和矿床成因的研究,认为阿西金矿床产于中三叠统扎尕山组第三、四段的碎屑岩和碳酸盐岩中,赋存于闪长岩体的内、外接触带,受NW向断裂带控制。金矿(化)带的形成与闪长岩体有密切关系,产于岩体外接触带围岩构造破碎带中的金矿体是阿西金矿床最重要的矿体。矿体形态为脉状、似层状及透镜状,矿体厚度及品位变化不大,矿化相对均匀。金矿化与硅化、碳酸盐化、黄铜矿化、黄铁矿化关系密切。中酸性岩浆活动与断裂构造是矿床形成的先决条件。该矿床成因为岩浆及(期后)热液改造型矿床。     

The Impact of Agricultural Practices in China on Land-Atmosphere Interactions

Human-induced land use changes and the resulting alterations in vegetation features are major but poorly recognized drivers of regional climatic patterns.In order to investigate the impacts of anthropogenicallyinduced seasonal vegetation cover changes on regional climate in China,harmonic analysis is applied to 1982-2000 National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVVHRR)-derived normalized difference vegetation index (NDVI) time series (ten day interval data).For two climatic divisions of South China,it is shown that the first harmonic term is in phase with air temperature,while the second and third harmonics are in phase with agricultural cultivation.The Penman-Monteith Equation and the Complementary Relationship Areal Evapotranspiration (CRAE) model suggest that monthly mean evapotranspiration is out of phase with temperature and precipitation in regions with significant second or third harmonics.Finally,seasonal vegetation cover changes associated with agricultural cultivation are identified:for cropped areas,the temperature and precipitation time series have a single maximum value,while the monthly evapotranspiration time series has a bimodal distribution.It is hypothesized that multi-cropping causes the land surface albedo to sharply increase during harvesting,thereby altering the energy distribution ratio and contributing to observed seasonal vegetation cover changes.     

梅子窝钨矿加里东期花岗闪长岩的地球化学特征及岩石成因探讨

加里东期花岗岩在华南地区分布甚广,对其开展深入研究有助于加深对华南早古生代构造演化及地质背景的理解。对梅子窝钨矿的赋矿岩体-加里东期花岗闪长岩的岩石学和地球化学研究结果表明：该岩体属于偏铝质-弱过铝质的高钾钙碱性系列岩石,具有较高的SiO2含量、K2O/Na2O比值和较低的ACNK值;大离子元素明显富集,Ba、Sr、P、Ti负异常明显;在（La/Yb）N-δEu图解中,投影于S型或壳源型花岗岩范围内;在Rb/Sr-Rb/Ba和A/MF-C/MF图解中,该花岗闪长岩的源区物质为砂质岩而不是幔源基性岩。这些特征表明,梅子窝加里东期花岗闪长岩应归属于S型花岗岩;推测其形成机制可能与早古生代晚期的板内作用有关,先受区域挤压应力场影响,导致地壳加厚;稍后,由于应力场的转化,进入后碰撞伸展环境。并在减压、挥发分的加入等因素综合影响下,位于中、上地壳的低成熟度的变杂砂岩发生部分熔融,形成S型或壳源型花岗岩。     

塔尔沟地区1/5万矿产远景调查地质特征及找矿方向

祁连山西段塔尔沟地区,大地构造位置位于祁连山中间隆起带和北祁连地向斜带的结合部位。区域内构造发育,地层出露较齐全,前长城系是钨、钼、铜、铅、锌的主要赋矿层位;长城系朱龙关群浅变质低绿片岩相,是钨、钼、铜、铁的主要赋矿层位;蓟县系镜铁山群变质绿片岩相,是铁、铜矿床的主要赋矿层位。奥陶系阴沟群,为典型蛇绿岩建造,是北祁连火山岩型铜矿床的主要赋矿地层。因此,根据区域成矿条件和矿产分布规律分析,该区域为有色金属、黑色金属、贵金属矿产的产出地,矿产调查具有较好的前景。     

新疆阿和栏杆银铅矿床A1区Ⅳ号矿体地质特征及成因研究

阿和栏杆银铅矿床位于西昆仑山腹地,麻扎-康西瓦缝合带,A1区Ⅳ号矿体赋存于F9断层与F13断层在延伸方向上交汇部位。据区内构造、岩浆、变质作用与矿区地质特征研究,初步判定该矿床大致经历热液期和表生期两个成矿阶段。详细为:首先,岩浆活动为铅锌(银)成矿提供物源和热源,构造提供成矿流体运移通道和矿体储存空间,形成先期银铅矿体。其次,变质作用叠加先期矿体,中温热液型银铅矿体得以定型。再次,区域构造作用使矿区隆起,接受表生期成矿作用叠加,形成了现今矿体构架。     

Formation Processes and Configuration of Channel-Flow Dominated Alluvial Deltas by Numerical Simulation

A horizontal two-dimensional mobile bed model for simulating the formation of river-dominated deltas in the river mouth or reservoir is presented, which is composed of shallow water equations, sediment transport formula, and a sediment continuity equation. Geometry similarity of river deltas during the processes of formation is discussed. Stability analysis and sensitivity analysis of parameters in the model are analyzed, which indicates that bed configuration is sensitive to the incipient-motion criteria of bed–load particles. The effect of gravity component on the initiation of sediment movement, therefore, is recommended to be considered in the modeling. The bed configuration including the reverse slope in the longitudinal profile and concave in the transverse profiles are correctly simulated with help from the correction of incipient-motion criteria. Simulation results are verified with a series of experiments and are consistent with series geometric functions and dimensionless profiles inducted from experimental data. This reflects the great reliability of the model. Historical topographical records of two typical in-land deltas depicting their earlier developmental stages are discussed to show the usefulness of this study.     

辽宁青城子逆冲推覆构造变形与金矿控矿作用探讨

青城子矿田位于辽吉裂谷中部,中朝准地台胶辽台隆营口—宽甸台拱北翼,经受了多期构造运动。自20世纪以来青城子矿区先后发现了白云、高家堡子等10多处金矿床,是国内比较知名的金矿田,然而关于该金矿的成因到目前仍然是很多学者争论的焦点。为了确定推覆构造与控矿作用的关系,从推覆构造变形的角度对金矿成因加以探讨。根据金矿的形态、与推覆构造变形的关系和与岩浆热液蚀变的关系,构建了韧性变形—热液改造成矿模式,且把金矿的成矿类型分为2类:(1)发育于剪切带中,受剪切变形和热液叠加改造综合作用的矿床;(2)发育于次级断层交会处或地层接触带,受断层和热液控制的矿床。     

黑龙江十五里桥金矿床成矿地质背景及成矿机制探讨

十五里桥金矿床处于上黑龙江盆地南缘,是近年来新发现的具有较大找矿潜力的岩金矿床,矿体赋存于伊利克得组次火山岩与上库力组火山岩内。岩石地球化学特征表明：伊利克得组次火山岩为钙碱性向碱性岩石过渡系列,总体为安山岩类;而上库力组火山岩为高钾钙碱性岩石类型,总体与流纹岩相当。区内火山岩是造山带分异出来的钙碱性岩浆,具有活动陆缘环境的特征,是早白垩世伸展环境下火山-岩浆活动的产物,形成深度为230 km左右,而十五里桥金矿床是火山活动后期拉张环境下构造、热液活动的产物,成矿物质主要来源于火山岩地层。     

Uplift Performance of Transmission Tower Foundations Embedded in Clay

The contribution to the uplift stiffness and capacity provided by the clay beneath the base of shallow footings typical in configuration to those employed to support high voltage electricity transmission towers is examined. Pore pressures developed at the base of appropriately scaled footings founded on clay were measured over a wide range of uplift rates in a geotechnical centrifuge. These measurements, coupled with data from tests on identical footings founded on sand, are used to provide insights into the influence of uplift rate on the failure mechanism and footing capacity. Data from a series of undrained triaxial extension tests, conducted over a range of strain rates, are presented and these data combined with finite element back-analyses of the centrifuge uplift tests are used to provide designers with a means of assessing the capacity and load–displacement response of footings on clay subjected to high rates of uplift in service.     

湖北泗峡口金多金属矿床控矿因素分析

泗峡口矿区是近年来湖北西部郧西县有较大突破的一个多金属成矿区。通过对岩相古地理、地层建造及岩石类型、构造、岩浆岩、剥蚀作用等控矿因素的研究, 总结了矿区的成矿规律, 认为研究区内各时代地层含矿性具有上泥盆统南羊山组-下石炭统袁家沟组中以Au、Ag 为主, 上泥盆统冷水河组中以Sb矿为主, 中、下泥盆统中以Pb、Zn 矿为主的特点; 空间上, 由南向北可根据厚层灰岩与薄片灰岩及页岩、砂岩的互层关系, 划分为不同的成矿带, 由东向西存在矿床(点) 呈等间距(1 000 m) 分布的特点。建立了研究区区域成矿模式和含矿岩系控矿模式, 为该区下一步找矿提供了理论指导。     

Uridylate-containing RNA sequences determine specificity for binding and polyadenylation by the catalytic subunit of vaccinia virus poly(A) polymerase

VP55, the catalytic subunit of vaccinia virus poly(A) polymerase, has the remarkable property of adding 30-35 adenylates to RNA 3' ends in a rapid processive burst before an abrupt transition to slow, non-processive adenylate addition. Here, we demonstrate that this property results from the affinity of the enzyme for uridylate residues within the 3' 31-40 nt of the RNA primer. At physiological salt concentrations, both polyadenylation and stable VP55 binding required the presence of multiple uridylates within a 31-40 nt length of RNA, though specific RNA sequences were not necessary. Even DNA in which the deoxythymidylate residues were replaced with ribouridylates, could be polyadenylated in a processive manner. Both the unmethylated pyrimidine ring and a 2'-OH on the associated sugar are features of ribouridylates that are important for priming. The abrupt termination of processive polyadenylation was attributed to translocation of VP55 along the nascent poly(A) tail, which lacks uridylates for stable binding. As evidence for translocation and interaction with newly synthesized RNA, other homopolymer tails were synthesized by VP55 in the presence of Mn2+, which relaxes its donor nucleotide specificity. Only during poly(U) tail synthesis did processive nucleotide addition fail to terminate.     

湖南奥陶纪天马山组中沉积型氧化锰矿成矿地质条件

在湖南常宁市茶潦村的天马山组下段地层中,首次发现有沉积型氧化锰矿存在。矿区位于南岭纬向成矿构造带的中段北缘,属于塔山隆起构造变形区,矿区天马山组主要由浅变质砂岩和板岩组成,矿床产于天马山组下段,矿区内褶皱、断裂构造与成矿关系密切。矿区内锰矿带断续延展3 km,有3个锰矿层,深度目前未探明,找矿前景良好。