从瞬变电磁电性剖面到拟地震剖面的转换

为实现瞬变电磁测深资料的精细解释,本文提出了回线源瞬变电磁拟地震剖面转换的思路。给出水平层状介质下的转换模型,并提出了转换方法及转换步骤;直接由野外实测的二次感应电压数据,经过傅氏交换,在频率域利用线性数字滤波求出地面波阻抗;再经过反傅氏变换,在时间域利用线性规划法求取瞬变电磁场反射系数序列q_m;最终以q_m为参数绘制拟地震剖面。结果表明该方法效果明显。

华容隆起及周缘电性结构地质认识

华容隆起的主要原因是发生在印支晚期的推覆构造运动和岩浆侵入(或岩体)上隆。由于推覆运动,高阻的元古代地层覆盖在中、古生代的沉积地层之上;燕山期构造运动,岩浆的侵入和混合岩化作用,使得该区上隆,上覆地层遭到剥蚀,在地表出露区表现为一隆起带。华容地区大地电磁测深获得的深部电性结构分析结果表明,在华容隆起及北缘地区存在中古生界的沉积地层,是进行海相油气勘探的有利区带。

伊通盆地西北缘断裂乐山南段电磁异常特征与地质单元

本文运用可控源音频大地电磁测深(CSAMT)方法对伊通盆地西北缘断褶带进行勘探。将所得的电性剖面与区域地质地球物理资料进行有机结合后,对研究区域进行了综合地质解释,发现研究区由大黑山隆起、西北缘断褶带及伊通盆地三个地质单元构成。通过电性剖面特征共划分出两条北东向的断裂(F_1,F_2),一条近东西向的断裂(F_3),确定了各地层结构,以及地层单元间的接触关系为构造接触。

Tide and Current Observations in the Central Chukchi Sea During the Summer of 2012

Current data from a moored Acoustic Doppler Current Profiler （ADCP） deployed at 69°30.155N, 169″00.654″W in the central Chukchi Sea during 2012 summertime is analyzed in the present paper. Characteristics of tidal and residual currents are obtained with Cosine-Lanczos filter and cross-spectral analyses. The main achievements are as follows： 1） Along with the local inertial frequency of 12.8 h, two other peaks at -12-h and -10-d dominate the time series of raw velocity; 2） The M2 dominates the 6 resolved tide constituents with significant amplitude variations over depth and the ratios of current speed of this constituent to that of the total tidal current are 54% and 47% for u and v components, respectively. All the resolved tidal constituents rotate clockwise at depth with the exception of MM and O1. The constituents of M2 and $2 with the largest major semi-axes are similar in eccentricity and orientation at deeper levels; 3） The maximum of residual currents varies in a range of 20-30 cm s-1 over depth and the current with lower velocities flow more true north with smaller magnitudes compared to the current in surface layer. The -10d fluctuation of residual current is found throughout the water column and attributed to the response of current to the local wind forcing, with an approximate 1.4 d lag-time at the surface level and occurring several hours later in the lower layer; 4） Mean residual currents flow toward the north with the magnitudes smaller than 7 cm s-1 in a general agreement with previous studies, which suggests a relatively weaker but stable northward flow indeed exists in the central Chukchi Sea.

The age measures and its layer sequence tratigraphy of Late Quaternary sediment in Lushan Dajiaochang of China

Through the scientific investigation on Lushan for a long time, detailed studies have been carried out on the geologic stratum section of Late Quaternary in Dajiaochang. The series age data of complete stratigraphic section and full time formation since 400 kaBP were based on the results of the analyses using the dating methods with various instruments such as the ancient geomagnetism, electronics spin resonance （ESR）, 36C1 and lumines- cence dating, etc. Corresponding to these data, it identified the paleomagnetic polarity events including Biwa- III event （320 kaBP）, Biwa- 1I event （260 kaBP）, Biwa- I event （180 kaBP, scarcity due to the disturbance of the iron dish）, Blake event （100 kaBP） and Laschamp event （20 kaBP, didn＇t grow due to the activities of the surface）, etc. Combined with the sequence stratigraphy, layer type characteristics and its sediment environment, the strati- graphic can be divided into 4 stages of development respectively ： Stage [ is the climate period of glacial epoch （200-400 kaBP）; stage 11 is the climate period of interglacial epoch （100-200 kaBP）; stage llI is the climate peri- od of periglacial epoch （10-100 kaBP）; stage IV is the climate period ofpostglacial epoch （0-10 kaBP）.

On Affine Connections Induced on the(1,1)-Tensor Bundle

Let M be an n-dimensional differentiable manifold with an affine connection without torsion and T_1~1(M) its(1, 1)-tensor bundle. In this paper, the authors define a new affine connection on T_1~1(M) called the intermediate lift connection, which lies somewhere between the complete lift connection and horizontal lift connection. Properties of this intermediate lift connection are studied. Finally, they consider an affine connection induced from this intermediate lift connection on a cross-section σ_ξ(M) of T_1~1(M) defined by a(1, 1)-tensor field ξ and present some of its properties.

Global characteristics of the second-order ionospheric delay error using inversion of electron density profiles from COSMIC occultation data

It is a well known fact that ionospheric delay error is a predominant factor which influences the positioning accuarcy of GNSS.Although the main part of the first-order ionospheric delay error can be removed by the frequency-dependent behaviors of the ionosphere,the second-order ionospheric delay error must be eliminated to achieve millimetre-scale positioning accuracy.Due to COSMIC occultation providing electron density profiles on the global scale,the paper presents the first-order and the second-order ionospheric delay error analysis on the global scale using the inversion of electron density profiles from COSMIC occultation data during 2009–2011.Firstly,because of the special geographical location of three ISR(incoherent scatter radar),the first-order and the second-order ionospheric delay errors are calculated and discussed;the paper also shows and analyzes the diurnal,seasonal,semi-annual variation of ionospheric delay error with respect to signal direction.Results show that for the L1 signal path,the first-order ionospheric delay error is the largest near the equator,which is circa 7 m;the maximum second-order ionospheric delay error are circa 0.6 cm,0.8 cm and 0.6 cm respectively for L1 signals coming from the zenith,the north and the south at 10 degree elevation angles.The second-order ionospheric delay error on the L1 signal path from zenith are the symmetry between 15°and 15°with respect to magnetic equator,and are nearly zero at the magnetic equator.For the first time,the second-order ionospheric delay error on the global scale is presented,so this research will greatly contribute to analysing the higher-order ionospheric delay error characteristics on the global scale.