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1.
零磁空间对虎皮鹦鹉声行为的影响   总被引:5,自引:0,他引:5  
蒋锦昌  金海强 《地震学报》1998,20(4):421-426
零磁空间对虎皮鹦鹉(melopsittacus undulafus)声行为活动有明显影响.均匀和不均匀零磁空间中,叫声日频度比地磁场中平均下降44.710.0%.不均匀零磁空间中抗议叫声的占有率(OP)比地磁场中平均下降8.5%~20.3%,并呈适应性变化.均匀零磁空间中,75%的观察天数内的OP比地磁场中平均增高16.2~23.3%.零磁空间对虎皮鹦鹉节律习性的影响,仅仅终鸣时受到均匀零磁空间的一定影响,比地磁场中平均提前67 min.   相似文献   

2.
通过对阳江深井地磁观测系统所测到的地球磁场总场强度值数据与附近地面的流动地磁观测台、广东肇庆地磁基准台以及其它地磁台站的进行对比分析,结果表明:阳江深井地磁观测系统的地磁场总场强度记录数据与附近地面观测的相近。深井地磁观测技术和方法有效地过滤了附近的表面高频电磁干扰,并在一定程度上对远处的中国南方电网的"糯广线"的高压直流干扰也起到了压制作用。在磁扰弱时,深处地下200m的地磁观测受围岩的感应地磁场影响不大;但当磁扰剧烈时,会受一定程度的感应地磁场影响。广东阳江深井地磁观测技术和方法的实践为深井地磁观测技术发展做了有益的尝试。  相似文献   

3.
本文主要针对当前磁法勘探中高精度处理解释的需求,对强磁性体ΔT异常计算存在的误差进行分析研究.我们首先通过理论模型计算试验,证明常规计算采用的投影关系的ΔT与实际测量的模量差ΔT之间的误差E在磁异常幅值大时是明显存在的,其影响不容忽视.其次,当磁性强且剩磁存在时,投影ΔT曲线及其误差曲线在磁化方向与地磁场方向改变时具有一定的对称性;地磁场T0、磁性体形态(如二度水平圆柱体模型的半径r、柱体埋深R)和磁性参数(如磁化率κ)等参数确定的情况下,最大误差值出现在磁性体正上方,且其大小与磁性参数(κ)和模型体规模(如r/R)之间皆是指数关系;另外,研究还发现ΔT的计算误差曲线的一些其他规律特点,如在各纬度带上,ΔT计算误差的最大值Emax曲线的极值主要分布在中纬度地区;磁异常矢量Ta与地磁场T0的夹角θ逐渐变化时,随θ变化Emax曲线的极值分布在θ=90°~120°范围内;当磁异常幅值小于10000nT时,最大误差近似为磁异常矢量垂直于地磁场方向的测点附近的误差值;另外,磁性体(圆柱体为例)的半径(即尺度)与埋深的比值r/R超过0.5,且磁化率超过0.1SI时误差已达到3.9nT,磁化率增大与对应的Emax的值呈指数增长特点.因此,我们的研究表明,在强磁性体、磁异常幅值大的数据处理、反演及解释时,现有方法会产生较大的误差,应该基于严格的模量差ΔT,完善相应的处理以及反演方法.  相似文献   

4.
用二维可压缩的MHD模型模拟研究了北半球背阳面磁层顶区的瞬时重联过程.结果表明,当行星际磁场(IMF)具有南向Bz分量和背太阳向Bx分量时,IMF与地磁场联接,磁层顶向外扩张,在等离子体幔区可形成流体旋涡,磁力线被扭曲,但不易形成磁涡旋;当IMF具有北向Bz分量时,不论Bx分量是背向太阳或指向太阳,都可发生瞬时重联,而且当IMFBx分量与地磁场Bx分量反向时,在等离子体幔区更易形成磁涡旋.这两种情况,在磁层顶边界层区都能产生多层的电流片.  相似文献   

5.
运用2014年7月至2016年4月冀鲁豫交界区开展的流动地磁9期次测量资料,分析相邻期、半年期、一年期的地磁场变化特征。结果表明,除2015年11月、12月地磁场总强度相邻期异常变化较大外,其余期次的相邻期地磁场变化较小,在10nT左右;半年、一年尺度磁异常整体表现为上升。将范县附近8个测点磁异常变化与地震序列进行对比分析发现,磁异常变化梯度较大时,范县易发生小震群活动。  相似文献   

6.
地磁场变化的小波熵复杂度分析方法   总被引:4,自引:2,他引:2  
根据南极中山站地磁台2005年的地磁观测数据,运用小波分析方法---小波熵复杂度对地磁场观测数据进行了分析,其小波熵序列与时间序列的变化完全一致,表明小波熵序列能够表征地磁场变化程度及变化范围.进一步研究发现,小波熵序列具有阶段特性,反映了地磁场变化在不同的过程中具有不同的变化性质及内容;当地磁场观测数据的幅度整体削减时,小波熵值整幅增大,但小波熵序列的特征完全一致,说明小波熵非常好地反映了地磁场观测数据的幅度与频率的变化,能够揭示地磁场变化的内在规律.因此,可以借助地磁场观测数据的小波熵复杂度计算来反演地球及其外围空间的动力学特征.  相似文献   

7.
本文根据最新的国际地磁参考场模型(IGRF11),结合梯度法分析能够很好的表现细微变化部分特征的优点,计算和绘制了1900—2010年期间间隔5年的全球地磁场水平分量H的水平梯度和垂直梯度,分析其时空分布,各磁异常中心位置和强度的变化规律。结果表明,地磁场的各个异常中心位置在水平方向和垂直方向上都有变化,主要以西漂为主,南大西洋正磁异常区水平分量梯度异常中心点强度值变化最大。  相似文献   

8.
不考虑磁层顶磁重联的全球三维MHD模型   总被引:2,自引:1,他引:1       下载免费PDF全文
本文介绍了一个新的磁层全球三维MHD模型,该模型可通过把IMF和地球磁场分开处理的方法“关闭”磁层顶的磁重联,从而可直观地显示不同IMF条件下磁层顶的IMF与地磁场的反平行区域,即磁重联最可能发生的地方,结果表示,IMFBx分量对磁层顶磁重联有重要影响。由于可关闭磁重联,该模型还可有效地研究有无磁重联时,太阳风对磁层位形(如晨-昏不对称性)、粒子输运等重要问题的影响,有助于揭示磁层物理现象的基本特性。  相似文献   

9.
四川旺苍地区中三叠世雷口坡组重磁化机理初步研究   总被引:1,自引:0,他引:1  
对四川北部旺苍地区中三叠世雷口坡组进行了古地磁学和岩石磁学研究,结果表明,主要载磁矿物为多畴磁铁矿和磁赤铁矿,所携带的特征剩磁在地理坐标下与近代地磁场方向接近,可能是由于后期白云岩化作用和热粘滞剩磁引起的重磁化所致.  相似文献   

10.
本文根据最新的国际地磁参考场模型(IGRF11),结合梯度法分析能够很好的表现细微变化部分特征的优点,计算和绘制了1900—2010年期间间隔5年的全球地磁场水平分量H的水平梯度和垂直梯度,分析其时空分布,各磁异常中心位置和强度的变化规律。结果表明,地磁场的各个异常中心位置在水平方向和垂直方向上都有变化,主要以西漂为主,南大西洋正磁异常区水平分量梯度异常中心点强度值变化最大。  相似文献   

11.
磁异常揭示的峨眉山大火成岩省的深部结构   总被引:1,自引:0,他引:1       下载免费PDF全文
峨眉山大火成岩省位于中国西南部,在晚二叠纪约260 Ma喷发出巨量的大陆溢流型玄武岩.对于大火成岩省的岩浆喷发,在地下必定有一个相应的大规模岩浆聚集和运移系统.地球物理方法是探测岩石圈内部的有效方式.峨眉山大火成岩省为镁铁质岩浆喷发,由于镁铁质-超镁铁质岩石一般具有强磁性,因此,在喷发结束之后,地下岩浆系统如果被镁铁质岩浆填充,冷却固化成为岩石圈的一部分,很有可能会引起磁异常.本文使用区域磁异常数据来对峨眉山大火成岩省的深部构造进行研究.该区域的磁异常由一系列离散的异常组成,通过3D磁化率反演可以得到磁性体的空间分布.由于磁异常中具有明显的剩磁,直接使用经典的反演方法会有较大误差,我们首先将磁异常转换为弱敏感于磁化方向的磁异常模量,再使用模量数据进行3D反演,得到地下空间内磁异常源的分布.经过分析认为这些离散分布的磁异常源反映了岩石圈内部的镁铁质-超镁铁质侵入体.侵入体的位置可能反映了底侵和内侵的镁铁质岩浆固化形成的侵入体,代表镁铁质岩浆房位置或者岩浆运移的主要通道.  相似文献   

12.
基于二阶导数的磁源边界与顶部深度快速反演   总被引:5,自引:2,他引:3       下载免费PDF全文
为实现磁异常反演,首先提出了磁异常非参数快速反演的概念,即无需提供先验信息.在Nabighian提出的磁场通用梯度公式的基础上,推导实现了基于磁异常垂向二阶导数的非参数快速反演(V2D_depth).它不仅可以获取场源的边界信息,同时可以反演场源的埋深.通过与Tilt_depth方法对比,本文方法计算的场源边界更清晰,反演的深度也更接近真实深度,同时较大程度上克服了Tilt_depth方法受叠加异常的影响.理论模型验证了方法的有效性,并通过准噶尔盆地某区块磁异常数据的处理,提取了受强大的区域背景场掩盖的石炭系火成岩产生的弱异常,突出了构造分区、断裂分布等信息,获取了火成岩的位置及埋深参数,为该区的火成岩油气藏勘探提供了有效的处理途径.  相似文献   

13.
郑敏  余钦范 《地震地质》1993,15(2):167-173
通过确定河北迁安矿区宫店子向形的岩石磁组构,分析了褶皱的磁组构特征,并用磁组构对向形构造做了一些简单的地质解释  相似文献   

14.
核磁共振测井在火成岩地层应用的适应性分析   总被引:1,自引:0,他引:1  
火成岩岩石具有高磁化率特征,与沉积岩差别明显,岩石的高磁化率会对核磁共振信号产生显著影响,开展核磁共振测井在火成岩地层应用的适应性分析研究,为广泛使用核磁共振测井用于火成岩储层评价提供参考.采用理论模拟、实验分析及实际测井资料相结合的方法,分析了高磁化率岩石的核磁共振响应特征.分析结果表明,火成岩岩石具有很高的磁化率,从酸性火成岩到基性火城岩,岩石的磁化率一般是逐渐增大的.高磁化率岩石孔隙内部会产生强梯度磁场,孔隙内部的磁场梯度越强,核磁共振的T2谱前移越明显,核磁信号衰减幅度也越大,核磁分析孔隙度与常规分析的孔隙度误差也越大;相同岩石磁化率情况下,岩石孔径越小,岩石孔隙内部磁场梯度越强,核磁信号衰减越大,核磁共振测井计算的孔隙度也越低.因此,核磁共振测井与岩性有关系,核磁共振测井会受到高磁化率岩石的显著影响.核磁共振测井在部分火成岩,尤其在中基性火成岩和小孔径火成岩储层中应用具有很大的局限性.  相似文献   

15.
To determine the magma flow direction of the giant, 179 Ma Okavango dyke swarm of northern Botswana, we measured the anisotropy of magnetic susceptibility (AMS) of 23 dykes. Dykes are located in two sections (Shashe and Thune Rivers), which are about 300 km and 400 km from the presumed magma source respectively; the Nuanetsi triple point. We collected samples from the margins of the dykes in order to use the imbrication of magnetic foliation to determine magma flow direction. About half of the magnetic fabric in the dykes is inverse, i.e. with the magnetic foliation perpendicular to the dyke plane. Lateral flow to the west and vertical flow is in evidence in the Shashe section. However, the overall analysis of normal and inverse magnetic fabric data supports that lateral flow to the west was dominant in the Shashe section. Across the Thune section, a poorly defined imbricated magnetic foliation also suggests lateral flow to the west.  相似文献   

16.
岩石的磁化率张量的统计处理,传统的处理方法是用费歇尔法,但对于火成岩等磁化率各向异性较弱的岩石,这种方法存在着局限性。本文介绍了“自益再采样法”,并与传统的方法进行了对比,指出,自益再采样法不仅有助于消除测量过程中的误差,而且它是建立在数据的实际分布之上的,能更准确地反映磁化率轴的实际分布方位以及方位的分散程度。;  相似文献   

17.
Experimental control in the classical igneous petrology is based on determination of the equilibrium conditions of simple — mostly 1–4 component — system. The statements based on such experiments are valid for rock products chemically not influenced by active environments. For elucidation of processes between geochemically active volatile-rich country rocks, high pressure and high temperature experiments oncomplex systems containing such active rock samples, too were performed. High pressure bombs were constructed with long and narrow container, allowing to investigate the selective migration of elements between different rock samples, even by temperature slope within the container. In these bombs different igneous, sedimentary and metamorphic rocks in contact at different temperatures and pressures were investigated. P-t relations and stability fields of different mineral facies cannot be exactly determined by phase diagrams of simple uni- or multicomponent systems, because they depend on other components and on the environments, too. The new complex experiments, however permit to assess directly the stability fields of the mineral facies. The data obtained proves that an intense selective migration of the volatiles take place even in solid samples at 550° C, in some rock associations already at 250° C, if there is a concentration gradient of volatiles between the samples. Selective migration proceeds following the principle of transvaporization, i.e. towards the partial pressures — chemical activities — of the mobile components and following the sequence of their ionic potentials. In this way, different hypomagmatic and metamorphic rocks are produced. The new kind of experiments shows that — opposite to the approaches of the classical igneous petrology — a high grade contamination of the ascending magma is possible. Contamination proceeds by transvaporization. Assimilation — Einschmelzung — mostly plays an insignificant role. Gravitative crystallization differentiation operates intensely only in the higher sections of volcanic pathways, characterized by relatively low pressures and thus by low viscosity of the magma. Contamination is intense if the ascension of magma is relatively slow as it is presumable along the oblique circumpacifique or innercarpathian andesitic structural lines. In this way, basaltic magma produces andesitic to rhyolitic rocks partly abundant in volatiles. However contamination is restricted and consequently basaltic rocks are formed if magma ascends rapidly through vertical channels as it is presumably the case with the young peripherical basalt volcanics, e.g. the innercarpathian basin system. These experiments also evidence the activation process of magma by transvaporization. Selective migration of volatiles even through solid rocks is introduced by structural pressure minimum zones towards these zones, which results in the melting of neighbouring rocks and their lifting as liquid magma until volatile supply is sufficient.  相似文献   

18.
In a number of AMS studies, the presence and deciphering of composite magnetic fabrics is of major importance for a correct interpretation of the data. On the basis of several examples from intrusive rocks (diorites and dolerites) we show that the use of laboratory heatings can help to extract at least one component of the composite magnetic fabrics usually present. The procedure includes comparison of the fabrics measured after stepwise laboratory heating with the fabrics determined by tensor difference and by linear regression analysis. In the diorite samples, the measured AMS results from the superimposition of different component fabrics and does not correspond exactly to any of these fabrics. In these dykes, isolated magnetic fabric during thermal treatment corresponds to that of the main magnetic mineral (Ti-poor titanomaghemite) and reveals an unknown structure. In volcanic flow or doleritic dykes, a “parasitic” fabric related to late or post-magmatic evolution superimposed to the flow fabric can produce important scattering of the AMS principal directions. Decomposition of magnetic fabric during thermal treatment allows isolation of the flow fabric.  相似文献   

19.
韩玉林  谈晓冬 《地球物理学报》2009,52(10):2588-2594
一般认为磁组构能有效地反映岩石所经历的应变特征.为了研究不同类型的磁组构和不同期次应变之间的关系,对来自华南地块两个地区的早三叠世灰岩样品进行了岩石磁学、磁组构以及应变特征的对比分析.来自湖北通山县的样品经历了三期构造变形,这为解析磁组构和多期次应变提供了理想的机会.岩石磁学结果显示携磁矿物主要为磁铁矿.磁化率各向异性(AMS)和非磁滞剩磁各向异性(AAR)结果显示其最小轴与层面垂直,最大轴和中间轴分布于层面内,反映了沉积和压实作用产生的应变,而后期构造应变在磁组构中没有体现.来自广东连县的样品发育有渗透性压溶缝面理和方解石脉,说明经历了构造应变.AMS结果没有显示占优势的组构方向.AAR结果显示三轴组构,其最大轴分布于最大应力方位,与构造应变特征吻合,最初的压实组构被构造应变组构所代替.上述结果表明:(1)AAR可以很好地反映渗透性应变的特征,而AMS有时会失效;(2)应变的尺度要小于样品的尺度,磁组构才能有效地反映应变.  相似文献   

20.
There is an aggregate outcrop of 12,000 square miles of Permian-Triassic acid igneous rocks inland from Cairns and Townsville, North Queensland. The rocks consist of ignimbrite and rhyolite, which are structurally and magmatically related to three high-level intrusions the Herbert River, Esmeralda, and Elizabeth Creek Granites. Most of the igneous rocks intrude the Precambrian Georgetown Inlier, but some of them intrude along a fractured zone on the junction of the Inlier and the shelf zone of the adjacent Palaeozoic Tasman Geosyncline. The Upper Palaeozoic — Triassic igneous period consists of two main epochs, both consisting of granite, ignimbrite, and rhyolite. In both epochs granite intrudes the comagmatic and coeval ignimbrite and rhyolite. Rapid horizontal movement of granitic magma through the epizone and major fracturing of the crust are postulated to explain the widespread intrusion of the granite. The granitic magma was probably initially generated 5 miles below the surface of the crust by partial melting of the sediments at the base of the Tasman Geosyncline. Epeirogenic movement in the Precambrian Inlier area formed sheet-like fractures, which provided channels for rapid horizontal movement of the granitic magma. This magma was emplaced along the fractured marginal zone of the Inlier to form a thick sill-like body of granite — the Herbert River Granite — in the first epoch. Magma for the second epoch was derived from melting of the lower part of the granite of the first epoch. Renewed fracturing of the Inlier area formed cauldron subsidence areas and rift, which were quicly filled with rhyolite and ignimbrite. In these collapsed areas the granitic magma crystallized as the Elizabeth Creek and Esmeralda Granites under an insulating cover of about 1,000 feet of rhyolite and ignimbrite.  相似文献   

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