大别山地震波速度剖面的重力拟合及花岗岩带

笔者对穿越大别山造山带的六安—大冶宽角反射地震剖面进行了重力拟合。拟合结果表明严格按宽角反射地震速度换算成的密度剖面所产生的是一个重力高,它反映出大别山是一个穹隆,与实测大别山重力低大相径庭。只有将位于大别山山根上,南北大别之间设置一个从地表直达莫霍界面的巨大低密度体,重力曲线才能得到很好的拟合。这个低密度体应为近北西走向的花岗岩带。它与反射地震剖面上石镇透明反射地震带位置吻合,但宽度远较反射地震透明带为大。重力曲线的拟合进一步说明,在华北陆块与扬子陆块碰撞后的白垩纪时,大别山出现一个伸展期,在这个时期,大别山穹隆形成,并伴随有大规模花岗岩的侵入,超高压变质岩从地壳中下部折返到地表。研究说明,联合应用反射地震、宽角反射地震和重力,进行综合解释是必要的,可以得到更令人信服的地质结论。     

Hillslope Topography from Unconstrained Photographs

Quantifications of Earth surface topography are essential for modeling the connections between physical and chemical processes of erosion and the shape of the landscape. Enormous investments are made in developing and testing process-based landscape evolution models. These models may never be applied to real topography because of the difficulties in obtaining high-resolution (1–2 m) topographic data in the form of digital elevation models (DEMs). Here we present a simple methodology to extract the high-resolution three-dimensional topographic surface from photographs taken with a hand-held camera with no constraints imposed on the camera positions or field survey. This technique requires only the selection of corresponding points in three or more photographs. From these corresponding points the unknown camera positions and surface topography are simultaneously estimated. We compare results from surface reconstructions estimated from high-resolution survey data from field sites in the Oregon Coast Range and northern California to verify our technique. Our most rigorous test of the algorithms presented here is from the soil-mantled hillslopes of the Santa Cruz marine terrace sequence. Results from three unconstrained photographs yield an estimated surface, with errors on the order of 1 m, that compares well with high-resolution GPS survey data and can be used as an input DEM in process-based landscape evolution modeling.     

Effects of different boundary conditions on the simulation of groundwater flow in a multi-layered coastal aquifer system (Taranto Gulf,southern Italy)

The evaluation of the accuracy or reasonableness of numerical models of groundwater flow is a complex task, due to the uncertainties in hydrodynamic properties and boundary conditions and the scarcity of good-quality field data. To assess model reliability, different calibration techniques are joined to evaluate the effects of different kinds of boundary conditions on the groundwater flow in a coastal multi-layered aquifer in southern Italy. In particular, both direct and indirect approaches for inverse modeling were joined through the calibration of one of the most uncertain parameters, namely the hydraulic conductivity of the karst deep hydrostratigraphic unit. The methodology proposed here, and applied to a real case study, confirmed that the selection of boundary conditions is among the most critical and difficult aspects of the characterization of a groundwater system for conceptual analysis or numerical simulation. The practical tests conducted in this study show that incorrect specification of boundary conditions prevents an acceptable match between the model response to the hydraulic stresses and the behavior of the natural system. Such effects have a negative impact on the applicability of numerical modeling to simulate groundwater dynamics in complex hydrogeological situations. This is particularly important for management of the aquifer system investigated in this work, which represents the only available freshwater resource of the study area, and is threatened by overexploitation and saltwater intrusion.     

特提斯喜马拉雅构造带雅拉香波穹隆构造热事件LA-ICP-MS锆石U-Pb年龄证据

雅拉香波穹隆位于特提斯喜马拉雅构造带东部,出露显生宙不同时期的岩石地层,发育强烈韧性剪切变形和多期岩浆热事件,良好地记录了印度大陆俯冲导致的构造变形和岩浆热历史。对雅拉香波穹隆不同构造部位的花岗质岩石进行LA-ICP-MS锆石U-Pb同位素测年,获得4期构造岩浆事件的高精度测年数据。早期锆石年龄520.4±6.3Ma与536±12Ma指示喜马拉雅地块结晶基底泛非期岩浆侵位时代,晚期锆石年龄揭示新生代碰撞造山不同阶段构造热事件的发生时代。其中,45.6±1.2--44.16±0.88Ma反映印度大陆向北俯冲的起始时代,35.00±0.48Ma对应于始新世晚期增厚地壳深部构造热事件年龄,15.67±0.50Ma指示雅拉香波核部花岗岩侵位及穹隆的形成时代。     

Terrestrial photogrammetry without ground control points

Terrestrial photogrammetry should be the survey technique of choice when updating large scale urban maps and GIS databases, where 3D data and attribute data are required. Its main drawback is the need for Ground Control Points (GCP) to reference the survey. To make image georeferencing easier and to provide control information, the use of a simple system, made of a photogrammetric camera fastened to a GPS antenna, is proposed. A photogrammetric block, composed by at least three images, is taken around the object with the receiver measuring in kinematic mode. Tie points are automatically extracted by Structure from Motion (SfM) algorithms or measured manually; block orientation is performed by GPS assisted Aerial Triangulation. Advantages as well as limitations of the system are discussed, with particular attention to GPS availability or ill-conditioned block configurations. The issue of system calibration (i.e. measurement of eccentricity between camera and antenna) is also addressed. Several test cases are presented, in which absolute accuracies, verified on check points independently surveyed range from 4 to 7 cm.     

Erratum to: Methodology for the analysis of causes of drought vulnerability on the River Basin scale

An inclinometer is a high-precision instrument used to detect displacement along sliding zones. From the time the inclinometer pipe is embedded to inclinometer calibration and to measured data collection and processing, many errors or misjudgments can occur that affect the measurement data. The most important objective for correctly using the observation results is the accurate interpretation of the horizontal displacement profiles obtained from the observation. This study combines existing inclusive data accumulated by a monitoring system on a test sloping site in a campus. It focuses on a comprehensive interpretation of the displacement relationships among different monitoring instruments. This study uses data interpretation principles, categorizes different mechanisms, and performs quantitative analysis and discussion in order to determine the significance presented by various types of monitored information in terms of slope sliding. In addition, in this study, stairwells in a campus building are used, an inclinometer is set up, and calibration equipment for the experiment is added in order to simulate various configurations and observe patterns for displacement curves. The examples for the various conditions include empty holes in the backfill around the pipe, connection points falling off, pipe torsion, relative sliding between layers reaching an extreme condition and leading to stuck pipes, multi-layered sliding, and different thicknesses in sliding zones. The experiment illustrates changes in behavior in terms of environmental factors. The results can be used for instrument calibration and measurement, and as a reference for disaster warning and prevention in hazardous areas with slopes.     

特提斯喜马拉雅构造带雅拉香波穹隆构造热事件LA-ICP-MS锆石U-Pb年龄证据

雅拉香波穹隆位于特提斯喜马拉雅构造带东部,出露显生宙不同时期的岩石地层,发育强烈韧性剪切变形和多期岩浆热事件,良好地记录了印度大陆俯冲导致的构造变形和岩浆热历史。对雅拉香波穹隆不同构造部位的花岗质岩石进行LAICP-MS锆石U-Pb同位素测年,获得4期构造岩浆事件的高精度测年数据。早期锆石年龄520.4±6.3Ma与536±12Ma指示喜马拉雅地块结晶基底泛非期岩浆侵位时代,晚期锆石年龄揭示新生代碰撞造山不同阶段构造热事件的发生时代。其中,45.6±1.2~44.16±0.88Ma反映印度大陆向北俯冲的起始时代,35.00±0.48Ma对应于始新世晚期增厚地壳深部构造热事件年龄,15.67±0.50Ma指示雅拉香波核部花岗岩侵位及穹隆的形成时代。     

印尼Sunda盆地裂陷期层序地层与沉积充填特征

应用高分辨率层序地层学原理和分析方法,以岩心、测井、录井、地震和分析化验资料为基础,通过Sunda盆地古近系层序地层关键界面的识别与对比,建立了盆地裂陷期层序地层格架。Sunda盆地裂陷期发育6个具有等时意义的层序界面,将其划分为5个长期基准面旋回。在盆地结构分析的基础上,确定了主要物源方向,分析了各个层序的沉积特征,认为盆地主要发育有扇三角洲、河流—三角洲、近岸水下扇、滩坝等沉积体系,不同层序发育时期及盆地的不同位置,其沉积体系类型及其分布有较大差异。与渤海湾盆地典型单断箕状断陷盆地相比,尽管断陷结构有相似性,但Sunda盆地裂陷期沉降速率相对较低,持续时间较短,深水湖泊发育规模相对较小。由于与盆缘主控断裂伴生的次级断裂不发育,沉积体系类型与发育特征也与典型的断陷盆地有较大的区别。     

基于全自动标定技术的环物摄影测量平台精度提升策略研究

针对传统的环物摄影测量设备精度不高的缺陷,本文在环物摄影测量法的基础上,提出了基于全自动标定技术的精度提升策略,并成功应用在自主研制的三维环物影像获取系统中。该策略克服了传统相机标定技术需要人工选点,耗时耗力的缺陷,同时有效的解决了环物摄影测量解算中,相机高精度空间参数定位的问题。因此,本文提出的方法可以在保证实时效率的前提下,提高环物摄影测量设备生产的三维数字化模型的精度,具有广泛的应用前景。     

基于MIP图像拼接系统的地质剖面数字化应用研究

野外地质剖面考察是开展地质研究的一项重要工作。在野外地质考察过程中,为了直观展示地质剖面的细节信息,往往需要拍摄大量的影像。同时,为了提高细节信息的展示程度,这些影像往往分辨率高,但视场角小,所以单一的影像注定无法兼顾的展示地质剖面的整体信息和细节信息。因此基于这种同时展示整体和细节信息的需求前提下,本文在自主研发的Mosaic of Image Program(MIP)图像拼接系统的基础上,对野外拍摄的影像进行了拼接处理,形成地质剖面的长条带全景影像。为了提高拼接处理的精度,本文对高精度的相机检校、畸变校正及MIP的地质剖面应用等方面进行了研究。在湖南古丈县地质遗迹剖面的实际处理中,完成了300多张高分辨率影像的快速拼接,获得了良好的数据记录和展示效果,拼接影像几何失真小于2像元。本文实现的技术手段在野外地质剖面考察中具有良好的应用前景。     

桂西北高龙金矿床的控矿构造

高龙穹窿构造是一断块穹窿,而不是"短轴背斜";控制近SN走向金矿化硅化角砾岩带的断裂构造,是典型的调整构造。高龙断块穹窿及其周边的NW向断层和SN向走向调整断层,是高龙金矿床的控矿构造系统。      

北喜马拉雅双穹隆构造的建立：来自藏南错那洞穹隆的厘定

错那洞穹隆属于北喜马拉雅片麻岩穹隆带(NHGD)的东南部重要组成部分,是本次研究首次发现并确立的穹隆构造。穹隆位于藏南扎西康矿集区南部,由外向内被两条环形断裂划分为三个岩石-构造单元:特提斯喜马拉雅沉积岩系上部单元、中部单元以及核部,其中内侧断裂为下拆离断层,外侧为上拆离断层。上部单元主要由侏罗系日当组的泥质粉砂质板岩和片岩组成,由外向穹隆中心靠近,根据变质矿物组合特征,其岩性呈较明显的渐变过程,即含或者不含变质矿物的泥质粉砂质板岩、含堇青石粉砂质板岩、含石榴石堇青石粉砂质板岩和含石榴石黑云母粉砂质板岩;中部单元从上至下岩石变质程度逐渐加深,构造变形依次增强,岩性依次为日当组低-高变质的片岩(包括含石榴石黑云母石英片岩、含蓝晶石-十字石二云母石英片岩、含矽线石二云母二长片麻岩)、含电气石(化)花岗质黑云母片麻岩、石榴石云母片麻岩和糜棱状石英二云母片麻岩,其典型变质矿物有石榴石、十字石、矽线石和蓝晶石;核部主要由糜棱状花岗质片麻岩夹少量的副片麻岩和错那洞淡色花岗岩组成。错那洞穹隆主要发育四期线理构造:近N-S向逆冲、N-S向伸展线理、近E-W向线理和围绕核部向四周外侧倾伏线理,分别对应了穹隆构造经历的四期主要变形:初期向南逆冲、早期近N-S向伸展、主期近E-W向伸展和晚期滑塌构造运动,其中主期近E-W向伸展对应于错那洞穹隆的形成,其动力学背景可能是印度板块斜向俯冲及由俯冲引起的中地壳向东流动双重作用。错那洞穹隆的发现和确立丰富了NHGD近E-W向伸展构造,进一步将NHGD划分为由近N-S向伸展所形成的穹隆带(简称NS-NHGD)和近E-W向伸展所形成的穹隆带(EW-NHGD)。     

基于单目视觉的钻杆位姿识别技术研究

钻杆自动装卸技术作为智能钻探装备领域的关键技术,制约着煤矿井下钻探装备的自动化和智能化发展,现有钻杆自动装卸系统主要依靠机械结构和接近开关进行定位,存在定位精度差自动化程度低的问题。针对此问题,提出一种基于单目视觉技术的钻杆位姿识别算法,利用摄像机拍摄含有合作目标的图像,解算摄像机与合作目标之间的相对距离和姿态,通过固定坐标变换,推导钻杆相对于机械手的位姿,引导机械手进行钻杆自动装卸。首先,确定系统总体方案,利用小孔成像原理和张正友标定法建立摄像机成像数学模型,求解摄像机内外参数;然后,使用棋盘格标定板作为被测钻杆的合作目标,根据小孔成像模型和空间成像关系,建立空间任意平面的单目测距模型,计算得到相机光心与合作目标点的距离;最后,通过摄像机成像模型得出合作目标的姿态矩阵,结合摄像机内外参数,经坐标转换求解得到合作目标在世界坐标系中的姿态矩阵,再通过固定坐标变换完成钻杆位姿识别。为验证算法准确性,在室内进行了钻杆位姿识别试验,试验中对每张现场图片进行重复测距与姿态估计,结果显示钻杆距离识别偏差在0.12%之内,钻杆姿态识别偏差在1.08%之内,满足钻杆自动装卸精度要求。试验结果表明,基于单目视觉技术的钻杆位姿识别算法真实有效,利用该算法可实现钻杆定位智能识别,提高钻杆自动装卸精度和钻探装备的智能化水平。      

Morphometric analysis of magmatic enclaves: a tool for understanding magma vesiculation and ascent

The extent of deformation of magmatic enclaves that occur in different portions of the Khaggiar endogenous lava dome (Island of Pantelleria, Italy) has been quantified using two morphometric techniques: thin-plate splines and fractals. Deformation of enclaves decreases from the outer portions of the dome to the more internal portions, defining two exponential trends. The amount and distribution of vesicles have also been quantified using image analysis of digital images obtained by a scanning electron microscope. The variation of deformation of enclaves correlates with the variation of their vesicle content, suggesting that deformation and vesiculation are related. We envisaged a continuous feedback system between vesiculation of enclaves and radial forces exerted by the surrounding host magma during the growth of the dome. These relationships are used as dynamic markers to infer the eruptive style of the endogenous dome. In particular, it is suggested that the variation of vesicularity of enclaves is related to the pressure exerted by magma on the extrusion vent. This resulted in enclaves being more vesicular and more deformed in the outer portions of the dome that emplaced first and at lower pressure, and less vesicular and less deformed in the more internal portions that emplaced later and at higher pressure. We interpret the occurrence of the two trends in the variation of deformation and porosity as related to two main eruptive pulses of dome growth.     

中心型火山构造的动力学机制

地球表层的环圈构造,是六十年代以来航天技术发展所带来的对地壳构造的一种新认识。这类构造,早在三十年代,就已经有人提出,这是火山活动形成的一种特殊的“中心型”构造。浙江中生代陆相火山岩覆盖区的卫片解释和区测资料表明,一系列大小火山环圈构造,彼此包容、交切,在总体上构成火山环圈条带,且大部受区域构造所控制。     

Boundary element analysis of axially loaded piles embedded in a multi-layered soil

In a field, piles are likely installed in a multi-layered soil. Analysis of axially loaded piles in a multi-layered soil is complicated and deserves more attention. A boundary element method is used in this study to analyze an axially loaded single pile in a multi-layered soil using the solution for vertical and horizontal axisymmetric ring loads in a multi-layered elastic medium. Good and reasonable agreement is obtained between the proposed and published solutions for a single pile in a homogenous soil, a finite soil, and a Gibson soil. The proposed solution is also used to evaluate an axially loaded single pile in a multi-layered (8 layers) soil.     

Analytical solution for the 1D consolidation of unsaturated multi-layered soil

The 1D consolidation of unsaturated multi-layered soil is studied based on the theory proposed by Fredlund and Hasan, and an analytical solution for a typical boundary condition is obtained by assuming all material parameters remain constant during consolidation. In the derivation of the analytical solution, the eigenfunction and eigenvalue for the multi-layered problem are first derived through the transfer matrix method. Then, by using the method of undetermined coefficients and the orthogonal relation of the eigenfunction, the analytical solution is obtained. The present method is applicable to various types of boundary conditions. Finally, numerical examples are provided to investigate the consolidation behavior of unsaturated multi-layered soil.     

Atmospheric oxygen exchange in the Hudson River: Dome measurements and comparison with other natural waters

The measurement of metabolism using diel free-water oxygen techniques requires the estimation of atmospheric oxygen exchanges. We measured such exchange on nine different occasions in the freshwater, tidally-influenced Hudson River estuary using a floating dome technique. We also analyzed previously published data on the exchange of a variety of gases measured in lakes, estuaries, and open ocean waters using a wide variety of techniques. Data were expressed as a “transfer velocity” and normalized to an exchange of oxygen at 20°C. Considered together, these data indicate a significant predictive relationship when the natural log of transfer velocity is regressed with measured wind speed (r² = 0.55; p = 0.0001). The influence of wind was particularly pronounced in estuaries and in lakes. Data from open-ocean waters showed much less influence of wind, probably because surface turbulence in these deeper waters can be temporally and spatially decoupled from wind. Our Hudson data agreed well with data collected in other systems. In general, data from estuaries—including the Hudson—indicated slightly higher transfer velocities at any given wind speed than do data from lakes (although this difference was less pronounced for our Hudson data than for other estuaries). The difference may result from some interaction of wind and tidal currents, or it may reflect a bias in the dome method of measurements; all of the estuarine data were collected using the dome approach, while the majority of the lake data were determined using an added tracer. If the dome method actually gives a biased, high estimate of oxygen flux, this is in contradiction to previous criticisms of this method that domes may underestimate fluxes by blocking wind at the water surface. We have used the regression of the natural log of transfer velocity versus wind speed developed here to estimate respiration in the Hudson estuary from diel changes in dissolved oxygen. To allow for possible biases in technique and for measurement error, we estimated 95% confidence limits around the regression. Estimates of respiration in the Hudson determined using the upper and lower 95% confidence limits are 30% higher and 12% lower than that determined when using the best-fit regression. An independently-constrained carbon budget for the tidally-influenced, freshwater Hudson River estuary indicates that respiration rates cannot be much higher than our mean estimate as calculated using the linear regression of the gas transfer and wind data to correct for air-water oxygen exchange. Gas transfer in natural systems is difficult to measure and is controlled by many interrelated physical factors. In the absence of extensive, system-specific field studies, the regression presented here should be useful in estimating atmospheric oxygen exchange in other estuarine or riverine ecosystems which are relatively deep and wide.     

Relationships between lower and upper crust tectonic during doming: the mylonitic southern edge of the Velay metamorphic core complex (Cévennes-French Massif Central)

Petrological, structural, and thermochronological analyses have been focused on the Mylonitic Metamorphic Vellave Zone (MMVZ), which wraps around the southern edge of the Velay metamorphic core complex dome. Mineral-stretching lineations in the Sil-Bt zone are everywhere perpendicular to the dome edge, the strong mylonitic foliation displays top-to-the south normal shearing, and preferential quartz orientations show high-temperature prismatic <a> deformation interpreted as pure shear patterns. The Sil-Bt zone reflects the dome dynamics during its forced emplacement and uplift. From the contact aureole of the Borne monzogranite, through greenschist facies, and until the And-Crd-Bt zone of the MMVZ, the series are affected by constant syn-metamorphic top-to-the-northeast shearing, acting since at least 320 Ma and reflecting upper crust tectonics during doming: the detachment system. A constriction-dominated deformation regime characterizes the And-Crd-Bt zone, together with the fact that thermochronometers (micas Ar/Ar, U-Th/Pb monazite) are set at 310 Ma, reflecting fast cooling and uplift high in the crust, consequently, the MMVZ is a mylonite that represents the interaction of dome dynamics and the tectonic environment of the upper crust. The Velay dome was forcibly emplaced in the country rocks, and has intruded its own detachment, showing the relationship between the detachment and the dynamic of the dome on its southern edge.     

特提斯喜马拉雅错那洞穹隆的岩石组合、构造特征与成因

目前关于新近发现的错那洞穹隆的精细构造、岩石组成、变质变形运动学特征等方面均不清楚,严重阻碍了其演化历程的还原以及成穹与成矿耦合关系的解剖工作.在详实的野外地质调查基础上,补充采集了穹隆中新发现的岩浆岩进行年代学研究.结果表明,错那洞穹隆由上（边部）-中（幔部）-下（核部）3个构造层组成,分别以上、下拆离断层为分界线.核部岩石组合主要为片麻岩、淡色花岗岩以及少量深熔混合岩,可见大量伟晶岩脉穿插;幔部为古生界,岩石组合为一套强变质变形片岩夹碳酸盐岩,从内至外具有蓝晶石+十字石+石榴石+黑云母的蓝晶石带→十字石+石榴石+黑云母的十字石带→石榴石+堇青石+黑云母的石榴石带→绿泥石+黑云母的绿泥石带的巴罗式变质分带特征;边部主要为三叠纪-侏罗纪浅变质沉积岩系,岩石组合为一套砂板岩及少量千枚岩.穹隆内从早至晚经历了南北向逆冲推覆、南北向伸展、东西向伸展3期次的构造运动,穹隆的形成主要与南北向伸展作用有关.穹隆中岩浆活动从早至晚可见有早古生代片麻岩（约500 Ma）、中生代辉绿岩（140 Ma）、渐新世变形二云母花岗岩/伟晶岩（26 Ma）、中新世弱定向二云母花岗岩（18 Ma）、含石榴石电气石花岗岩（16.8~15.9 Ma）5期.综合研究表明,错那洞穹隆的形成是早期伸展拆离核杂岩叠加晚期岩浆底劈热穹隆综合作用的结果,成穹构造的初始阶段与始新世-渐新世藏南拆离系（STDS）的运动密切相关.