共查询到20条相似文献，搜索用时 46 毫秒
1.
川西坳陷孝泉地区深层须家河组致密砂岩气藏属于典型非常规裂缝性气藏,储层识别、裂缝检测、含气性识别是气藏研究的重点和难点.转换波3D3C勘探可同时获得反映岩石骨架和各向异性特性的C波资料及反映骨架及流体特性的P波资料,因而适用于川西孝泉深层超致密裂缝性气藏.在3D3C地震勘探中,三维三分量地震采集方法是采集到高质量多分量原始资料的技术保障,本文重点研究这种采集方法.首先根据地球物理参数,结合地质任务要求,分析了三维三分量观测系统设计的方法及观测系统参数,然后根据分析结果和勘探目的层的实际情况设计了同时适合纵波勘探和转换波勘探的面元尺寸、最大和最小炮检距、接收线距、束间滚动距等参数并确定了三维三分量观测系统.该观测系统在孝泉地区资料采集中,获得的三分量资料波组特征清楚,同相轴连续,反射信息丰富;Z分量剖面和R分量剖面反射层次清楚,目的层反射特征明显,具有非常好的构造形态一致性. 相似文献
2.
Liquefaction mitigation in silty soils using composite stone columns and dynamic compaction 总被引：2，自引：1，他引：1
T.Shenthan R.Nashed S.Thevanayagam G.R.Martin 《地震工程与工程振动(英文版)》2004,3(1):39-50
The objective of this study is to develop an analytical methodology to evaluate the effectiveness ofvibro stone column (S. C.) and dynamic compaction (D.C.) techniques supplemented with wick drains to densify and mitigate liquethctionin saturated sands and non-plastic silty soils. It includes the following: (i) develop numerical models to simulate and analyze soil densification during S.C. installation and D.C. process, and (ii) identify parameters controlling post-improvement soil density in both cases, and (iii) develop design guidelines for densification of silty soils using the above techniques. An analytical procedure was developed and used to simulate soil response during S.C. and D.C. installations, and the results were compared with available case history data. Important construction design parameters and soil properties that affect the effectiveness of these techniques, and construction design choices suitable for sands and non-plastic silty soils were identified. The methodology is expected to advance the use of S.C. and DC. in silty soils reducing the reliance on expensive field trials as a design tool. The ultimate outcome of this research will be design charts and design guidelines for using composite stone columns and composite dynamic compaction techniques in liquefaction mitigation of saturated silty soils. 相似文献
3.
食物质量会影响浮游动物的生长和繁殖,表征食物质量的指标包括食物大小、元素比、生物化学组成和毒性有无等.用斜生栅藻(Scenedesmus obliquus)的碳磷比(C/P)表征食物质量,分析不同C/P斜生栅藻对同型溞(Daphnia similis)生长和繁殖的影响.研究中4个处理组斜生栅藻C/P分别为881.8、512.3、124.3和42.4.培养9 d后不同处理组同型溞的生长速率分别为0.15、0.27、0.47和0.44 d-1.C/P比为881.8的处理组同型溞在整个培养过程中没有产仔,其余3个处理组的同型溞第1成龄期的产仔量分别为1.2±1.3、9.8±2.3和9.5±2.5 ind./female.结果表明,与斜生栅藻C/P为124.3处理条件相比,斜生栅藻C/P过高(512.3和881.8)及C/P过低(42.4)处理条件下同型溞生长速率和产仔量均降低.本研究表明食物C/P的高低会影响溞的生长和繁殖,从而影响其在湖泊中的生存. 相似文献
4.
利用全球电离层台站提供的观测数据，分析 了5次不 同类型磁暴事件期间全球电离层F2层f0F2和hmF2的扰动变化. 主要结果 表明：对于延迟型主相磁暴S（C）和S（E），中高纬电离层首先会出现明显的正相扰动，随 后是明显延迟的负相扰动，负相扰动覆盖范围广，甚至扩展到低纬区, 且持续时间很长, 恢 复及其缓慢，其中S（C）型的扰动更为明显; 对于非延迟型主相磁暴S（A）、S（B）和 S（D ），高纬电离层正相扰动持续时间较短甚至不出现，中高纬电离层负相扰动的出现、发展和 恢复也相对较快; 磁暴主相强度的大小会对电离层负相扰动的强度、发展和持续时间产生一 定的影响; 高纬电离层扰动在非延迟型主相磁暴恢复相期间会出现明显的地方时效应，地方 时效应随纬度的降低而增强，并且会明显影响到中低纬电离层的扰动；电离层扰动从高纬到 低纬的变化趋势为：f0F2的扰动由负相向正相转化，hmF2的增加由全天出现趋向于只存在于夜间，反映了不同扰动物理机制的作用. 相似文献
5.
岩浆岩在青藏高原的大陆动力学研究中有着重要的作用,它既是构造演化的记录,又是重要构造-岩浆-成矿带的指示.本文主要基于冈底斯带及邻区的地面重力和航磁数据,首先进行地质-地球物理先验信息约束下的重磁2.5维交互式反演,再将2.5维反演结果作为参考模型加入到三维反演计算中,得到地下三维密度和磁化率结构.结合岩浆岩密度、磁化率统计资料和岩浆岩地球化学成果,推断研究区基性岩、I型花岗岩和S型花岗岩的三维分布图,得到如下结论:S型花岗岩主要分布在冈底斯东带和冈底斯弧背断隆带以北;北冈底斯的西部无明显的岩浆活动,而在其南侧和北侧,发现大量的隐伏基性岩和零散分布的I型花岗岩;中生代I型花岗岩在南冈底斯和冈底斯弧背断隆带广泛分布,且到新生代才出现大量的S型花岗岩.上述结果为中生代班公湖—怒江洋壳和新特提斯洋壳的双向剪刀式俯冲模式的观点提供了重要佐证,并认为班公湖—怒江洋壳在北冈底斯西部约84°E—88°E的范围内先后存在向北和向南俯冲的可能,北向羌塘地体下俯冲,南向冈底斯地体下俯冲. 相似文献
6.
SHEN Ping SHEN Yuanchao LIU Tiebing LI Guangming & ZENG Qingdong Institute of Geology Geophysics Chinese Academy of Sciences Beijing China 《中国科学D辑(英文版)》2005,48(11)
The Kuoerzhenkuola gold field (including the Kuo- erzhenkuola and the Buerkesidai gold deposits), lo- cated 68 km east of Jimunai County in northern Xing- jiang, China, is an important component of the Sawuer gold belt which is the eastward extending part of the Zarma-Sawur gold-copper belt in Kazakhstan. Some studies are concerned with the geology of the gold ores[1―3], the associated volcanic rocks[4], radiogenic isotope[5―8], and the ore-forming environment[8]. Most researchers inferr… 相似文献
7.
Geochemistry of ore-forming fluids and geological significance 总被引：1，自引：0，他引：1
The Kuoerzhenkuola gold field (including the Kuoerzhenkuola and the Buerkesidai gold deposits) is the most important one in
the Sawuer gold belt, northern Xinjiang, China. Isotopic studies including D, O, He, C, S, Pb and Sr reveal that the ore-forming
fluids of the Kuoerzhenkuola and the Buerkesidai deposits shared the same source: the water of ore fluids was magmatic water
and minor meteoric water; the mineralizers and ore materials derived mainly from mantle beneath the island arc, and partially
from crust. The ore-forming fluids of two deposits are a mixture of mantle-derived fluids incorporated by crust-derived fluid,
and meteoric water. Based on these results, combined with the consideration of the tectonic setting and geological features,
we suggest that the two gold deposits in the Kuoerzhenkuola gold field, Sawur gold belt share the same genesis, and are volcanogenic
hydrothermal gold deposits occurring in the same caldera. 相似文献
8.
鄱阳湖浮游植物功能群的长期变化特征(2009-2016年) 总被引：5，自引：3，他引：2
鄱阳湖是中国最大的淡水湖,每年都有剧烈的季节性水位变化.为了解鄱阳湖浮游植物功能群特征及其与环境因子的关系,2009-2016年每季度在鄱阳湖15个采样点采集水样,分析鄱阳湖的水质和浮游植物群落结构,并对浮游植物进行功能群划分.研究结果表明,鄱阳湖共检出浮游植物8门106属.2009-2016年平均生物量分别为0.044、0.252、0.335、6.379、3.945、2.912、3.562和1.550 mg/L.硅藻门为鄱阳湖浮游植物的优势门类.鄱阳湖浮游植物可划分为27个功能群,其中15个功能群（C、D、G、H1、J、Lo、M、MP、N、P、S1、Tc、Wo、W1和Y）为优势功能群.2009-2011年,功能群P、Y、MP、D为优势类群,2012-2016年,功能群P、Y、MP、H1、Lo为优势类群.鄱阳湖浮游植物优势功能群不同水文阶段的演替规律为：枯水期P、MP、Y、Lo、D,涨水期P、Y、D、MP、H1,丰水期P、Y、D、MP、Lo、H1,退水期P、Y、MP、G.RDA分析结果显示,水位变化、水温、透明度、电导率、悬浮物浓度和亚硝态氮浓度是影响鄱阳湖浮游植物功能群的主要环境因子. 相似文献
9.
Julie Desarnaud Kyoko Kiriyama Beril Bicer Simsir Katrin Wilhelm Heather Viles 《地球表面变化过程与地形》2019,44(7):1419-1429
The Equotip rebound tester is a simple, non-destructive technique to measure the surface hardness of materials. Having a low impact energy gives the Equotip advantages over the commonly used Schmidt Hammer on weathered rock and stone. In this study we have investigated the influence of different parameters (sample size, moisture content and surface roughness) on the surface hardness values obtained from freshly cut blocks of four types of sandstone. In a series of laboratory experiments both Single Impacts (SIM) and Repeat Impacts (RIM) methods have been used with C and D probes (which have different impact energies). Our results show that whilst sample size is of great importance we find that smaller samples can be reliably evaluated than previously reported. Moisture contents are also found to exert a more important influence on both SIM and RIM results than previously thought, with up to 26% lower hardness values recorded on saturated vs dry sandstone. Conversely, we find that surface roughness (over Sz values of 100 to 800 microns) does not have a significant impact on SIM measurements collected using the D probe. Both SIM and RIM data are found to be good proxies for compressive strength and open porosity, with SIM data collected with the C probe showing the best fits. Data collected using 3D microscopy helps visualize and quantify the small impact marks created by the Equotip and confirms that these are much reduced when using the C vs D probe. The results highlight the benefits of the Equotip to studies of the nature and deterioration of sandstone, the need for careful evaluation of any confounding factors which might influence the values obtained, and illustrate the different advantages of C and D probes. © 2019 John Wiley & Sons, Ltd. 相似文献
10.
千岛湖(新安江水库)是我国大水面生态渔业发展的典型湖库,其渔业主要以鲢、鳙等滤食性鱼类增殖为主,对鱼食性鱼类资源的研究和关注相对匮乏。而鱼食性鱼类是水生食物网的顶级捕食者,对维持水生态系统结构和功能具有重要作用。近年来,受过度捕捞、生境退化等影响,千岛湖鱼食性鱼类资源下降明显。鉴于此,2021年3月—2022年12月,逐月在千岛湖收集4种同域共存的鱼食性鱼类样品1032尾,包括翘嘴鲌(Culter alburnus)、蒙古鲌(Culter mongolicus)、大眼鳜(Siniperca knerii)和斑鳜(Siniperca scherzeri),系统研究并比较了4种鱼食性鱼类年龄、生长、繁殖等生活史策略的分化特征。结果表明,千岛湖4种鱼食性鱼类优势年龄组均未超过3龄,说明其种群呈现低龄化现象。生长式型上,翘嘴鲌和蒙古鲌属正异速生长,而大眼鳜和斑鳜属负异速生长,说明4种鱼食性鱼类具有不同的生长策略。条件系数(CF)的变化趋势与繁殖活动密切相关,其中大眼鳜的条件系数最高(1.92%±0.03%),其次为斑鳜(1.72%±0.02%)和蒙古鲌(1.14%±0.01%),翘嘴鲌的条件系... 相似文献
11.
Surface wave methods are based on the inversion of observed Rayleigh wave phase‐velocity dispersion curves. The goal is to estimate mainly the shear‐wave velocity profile of the investigated site. The model used for the interpretation is 1D, hence results obtained wherever lateral variations are present cannot be considered reliable. In this paper, we study four synthetic models, all with a lateral heterogeneity. When we process the entire corresponding seismograms with traditional f‐k approach, the resulting 1D profiles are representative of the subsurface properties averaged over the whole length of the receivers lines. These results show that classical analysis disregards evidences of sharp lateral velocity changes even when they show up in the raw seismograms. In our research, we implement and test over the same synthetic models, a novel robust automated method to check the appropriateness of 1D model assumption and locate the discontinuities. This new approach is a development of the recent multi‐offset phase analysis with the following further advantages: it does not need previous noise evaluation and more than one shot. Only once the discontinuities are clearly identified, we confidently perform classical f‐k dispersion curve extraction and inversion separately on both sides of the discontinuity. Thus the final results, obtained by putting side by side the 1D profiles, are correct 2D reconstructions of the discontinuous S‐wave distributions obtained without any additional ad‐hoc hypotheses. 相似文献
12.
利用双差定位法对瀑布沟水库及邻区1 834次小震进行了重新定位,并对距水库水域最近的2个小震集中区的地震性质进行了分析。重新定位后得到1 708次小震结果,定位残差由原来的0.93s降为0.21s,水平向估算误差平均为0.6km,垂直向估算误差平均为2.9km; 平面空间分布显示,重新定位地震主要分布在研究区的西南(A区)、库中区(C区)和水库大坝附近(D区); A区小震密集与其处于鲜水河断裂中南段、安宁河北段和大凉山断裂北段交会区的特殊地理位置有关。C,D区高度集中分布的小震与水库蓄水无关,属于各种建设施工造成的爆破地震。 相似文献
13.
14.
Electromagnetic study of lithospheric structure in the marginal zone of East European Craton in NW Poland 总被引：1，自引：0，他引：1
Waldemar Jóźwiak 《Acta Geophysica》2013,61(5):1101-1129
The marginal zone of the East European Platform, an area of key importance for our understanding of the geotectonic history of Europe, has been a challenge for geophysicists for many years. The basic research method is seismic survey, but many important data on physical properties and structure of the lithosphere may also be provided by the electromagnetic methods. In this paper, results of deep basement study by electromagnetic methods performed in Poland since the mid-1960s are presented. Over this time, several hundred long-period soundings have been executed providing an assessment of the electric conductivity distribution in the crust and upper mantle. Numerous 1D, 2D, and pseudo-3D electric conductivity models were constructed, and a new interpretation method based on Horizontal Magnetic Tensor analysis has been applied recently. The results show that the contact zone is of lithospheric discontinuity character and there are distinct differences in geoelectric structures between the Precambrian Platform, transitional zone (TESZ), and the Paleozoic Platform. The wide-spread conducting complexes in the crust with integral conductivity values reaching 10 000 S at 20–30 km depths are most spectacular. They are most likely consequences of geological processes related to Caledonian and Variscan orogenesis. The upper mantle conductivity is also variable, the thickness of high-resistive lithospheric plates ranging from 120–140 km under the Paleozoic Platform to 220–240 km under the East European Platform. 相似文献
15.
太湖流域地处长江下游,水系发达,是典型的平原水网地区,为明确空间和环境因子对太湖流域浮游植物功能类群分布的影响,本研究于2019年8—9月期间比较太湖流域包括河流、湖泊和水库的85个采样点的浮游植物、空间和环境特征. 首次利用“人工智能图像识别技术”,并结合传统人工镜检,共鉴定浮游植物250个分类单位,隶属于9门13纲28目57科110属,以绿藻门(45.6%)、硅藻门(19.2%)和蓝藻门(16.4%)为主. 共划分功能类群31个,包括M、D、J、S1、C、Y、F、P、MP、H1、SN、W1、G、K和TB共15个优势功能类群. 结果表明：1)太湖流域不同水体功能类群组成差异显著,差异主要来自M、J、S1、Y、P、H1类群;2)浮游植物功能类群分布具有一定的空间异质性,以太湖为中心向外形成3个聚类组,物种组成类型依次为蓝藻型、蓝藻-绿藻-硅藻型、绿藻-硅藻-蓝藻型,主要贡献类群依次为M、S1类群,M、S1、P、J类群,P、S1、J、D、C类群;3)在太湖流域,相对于环境因子而言,空间因子对浮游植物功能类群组成的影响更大. RDA分析表明,CODMn、NO3--N、TN、SD、pH值和DO与太湖流域浮游植物优势功能类群呈显著相关. 过去十年,以控源截污为主导的环境管理政策已在太湖流域取得显著成效,但是对于以M、S1类群水华为特征的夏季太湖流域而言,蓝藻水华防控仍是必须面对的难题,有机污染物和氮的控制仍是关注重点,不同水体类型和浮游植物功能类群因地制宜的管控模式仍是关键. 相似文献
16.
将S变换引入到地震地层研究中,用广义S变换代替短时Fourier变换或连续小波变换,用于地震数据频谱分解和提取地震旋回特征.为此,首先研究了S变换的性质及其与短时Fourier变换、连续小波变换的比较,进一步给出广义S变换的特点,说明其如何获得更高分辨率.同时,对前述方法进行数值实现,模型数据试算结果表明算法的正确和有效性.在上述工作基础上,本文首次提出用广义S变换进行地震频谱分解和研究地震旋回,给出实现策略及2D实际地震数据试算结果,证明方法的有效性,为进一步实用化奠定理论和方法基础. 相似文献
17.
Common‐conversion‐point binning associated with converted‐wave (C‐wave) processing complicates the task of parameter estimation, especially in anisotropic media. To overcome this problem, we derive new expressions for converted‐wave prestack time migration (PSTM) in anisotropic media and illustrate their applications using both 2D and 3D data examples. The converted‐wave kinematic response in inhomogeneous media with vertical transverse isotropy is separated into two parts: the response in horizontally layered vertical transverse isotrophy media and the response from a point‐scatterer. The former controls the stacking process and the latter controls the process of PSTM. The C‐wave traveltime in horizontally layered vertical transverse isotrophy media is determined by four parameters: the C‐wave stacking velocity VC2, the vertical and effective velocity ratios γ0 and γeff, and the C‐wave anisotropic parameter χeff. These four parameters are referred to as the C‐wave stacking velocity model. In contrast, the C‐wave diffraction time from a point‐scatterer is determined by five parameters: γ0, VP2, VS2, ηeff and ζeff, where ηeff and ζeff are, respectively, the P‐ and S‐wave anisotropic parameters, and VP2 and VS2 are the corresponding stacking velocities. VP2, VS2, ηeff and ζeff are referred to as the C‐wave PSTM velocity model. There is a one‐to‐one analytical link between the stacking velocity model and the PSTM velocity model. There is also a simple analytical link between the C‐wave stacking velocities VC2 and the migration velocity VCmig, which is in turn linked to VP2 and VS2. Based on the above, we have developed an interactive processing scheme to build the stacking and PSTM velocity models and to perform 2D and 3D C‐wave anisotropic PSTM. Real data applications show that the PSTM scheme substantially improves the quality of C‐wave imaging compared with the dip‐moveout scheme, and these improvements have been confirmed by drilling. 相似文献
18.
《Astronomy& Geophysics》2008,49(4):4.16-4.18
The 2008 Rishbeth Prize for the best poster displayed at the National Astronomy Meeting in Belfast was awarded jointly to "A superposed epoch analysis of auroral evolution during substorm growth, onset, and recovery" by S E Milan, A Grocott, C Forsyth, S M Imber, P D Boakes and B Hubert. Steve Milan summarizes. 相似文献
19.
为了说明在物理空间中空间差分精度和空间分辨率对Arakawa A-D网格性能的影响程度,将线性浅水方程组采用二阶中央差和四阶中央差格距分别取100 km、10 km和1 km在Arakawa A-D网格上进行离散和120 min的模拟预报,模拟结果和解析解进行比较,结果表明：当网格距是1 km时,不论采用二阶中央差分方案还是四阶中央差分方案,重力惯性波在4种网格上模拟的结果相同,即变量配置的影响是可以忽略的;当网格距增加到10 km或100 km时,不同的变量配置模拟的结果是不同的.但是,不论对二阶中央差还是四阶中央差,当网格距相同的情况下,在C网格上模拟得到的结果均方根误差最小,在D网格上模拟得到的结果均方根误差最大.同时也表明：当差分精度从二阶增加到四阶后,模拟结果的误差并非一致减少,并和群速相对误差的变化一致,因此对于初值为混合波的多变量方程组而言,增加差分精度不能改进模拟的结果.并且缩小网格距比增加差分精度对减少在Arakawa A-D 网格上离散产生的误差更明显. 相似文献
20.
本研究利用国家地震台网131个地震台站2009—2016年记录的1 749次近震的初至P波和S波走时数据,与采用快速行进方法正演计算得到的华北地区4个三维地壳速度模型对应的走时数据进行对比,通过统计分析的方法,评价这4个速度模型与真实地下结构的近似程度。结果表明:4个速度模型在大范围内存在较高的一致性,在整个研究区内（111°E—119.5°E,37°N—42°N）,Shen等的模型（简称“S模型”）相对优于Fang等的模型（简称“F模型”）和Duan等的模型（简称“D模型”）,Laske等的Crust1.0模型（简称“C模型”）相对较差。我们认为该结果与上述几个模型所使用的数据及其分辨率有关。对于研究区域内的构造单元,D模型在燕山褶皱带西南部、太行山山前构造带西北部和沧县隆起区表现较好,F模型在太行山隆起区中部、沧县隆起北部、黄骅凹陷区和燕山褶皱带表现较好,S模型在西部地块、山西凹陷区、太行山山前构造带和冀中凹陷区表现较好,C模型无明显连片表现较好区域。 相似文献