低频数字电磁测深仪器系统及其在攀-西地区的应用          下载免费PDF全文

刘士杰  卢军 《地球物理学报》1989,32(4):417-422

本文介绍了在CTM-302型三分量磁通门磁力仪的基础上,研制的低频数字化大地电磁测深仪器系统;并根据该系统的功能和在攀-西地区的应用情况,对其发展前景进行了探索。  相似文献   

电离层声重波扰动的高频无线电诊断   总被引：1，自引：1，他引：1  

万卫星  李钧 《地球物理学报》1989,32(6):609-620

为了充分发挥现代数字式电离层探测仪在电离层结构与优动研究中的潜力,必须在传统的频高图真高换算的基础上,发展新的反演理论和算法.本文介绍了随时空缓变的各向异性电离层介质中无线电波包传播的广义射线方程组,讨论了计算波包射线几何路径以及计算波包参数,如频移、波矢、群时延等沿射线路径变化的传播正问题,并详细讨论了根据波包参量的测定值反演介质结构和扰动伏态的传播反问题.文中若干实验实例表明,这种反演理论和算法可用于数字式电离层探测仪记录的分析,它使高频无线电波探测技术成为研究全球电离层声重波一类扰动的有力工具。  相似文献   

高频多普勒台阵中的若干技术问题   总被引：2，自引：0，他引：2       下载免费PDF全文

李利斌  吴振华  宁百齐  李钧 《地球物理学报》1987,30(6):560-565

为了研究电离层动力学特性,1985年9月在武汉建成了一个由三个台站组成的高频多普勒台阵和卫星信标法拉第台阵。文中介绍了这个台阵的布局和多普勒接收系统中的一些技术细节。这些技术措施保证了在多普勒图中清晰地显示多径现象和有效地消除小不均匀体的影响。最后还简单地介绍了这个台阵一年来的实测情况。  相似文献   

Source-controlled carbonates in a small Eocene half-graben lake basin (Shulu Sag) in central Hebei Province, North China     

ZAIXING JIANG  DAIZHAO CHEN†  LONGWEI QIU‡  HONGBIN LIANG§  JUN MA§ 《Sedimentology》2007,54(2):265-292

Carbonate deposits, which unconformably overlie the Palaeozoic bedrocks, extensively occur in the base of the Tertiary lake succession in the half‐graben Shulu Sag, central Hebei Province, North China. This study focuses on the basal carbonate successions on the hinged western slope. Based on seismic, borehole and core data, nine facies are identified in the carbonate successions, and are further grouped into five facies associations: mid‐proximal alluvial fan, distal alluvial fan, fan fringe, moderately deep lake and deep lake. The first two facies associations constitute alluvial fans formed by debrisflows at the edge of lake and are dominated by mounded‐ to lobate‐shaped, matrix‐ to clast‐supported carbonate rudstones with minor calcretes in the lowermost rudstone units and basinward increase in interfingering with lacustrine carbonate facies. The fan fringe, moderately deep lake and deep lake associations are dominated by pebbly carbonate arenites (or rare carbonate arenites), calcisiltite‐calcilutites, and varve‐like calcilutites, calcareous shales and oil shales, respectively. Widespread occurrences of fine‐grained limestone packages containing varve‐like organic‐rich laminations, minor authigenic glauconite and pyrite, and planktonic and plant fossils suggest a meromictic, anoxic deep lake under a semi‐humid to humid climate, probably with a connection to marine basins. Similarities in lithology and fossil assemblages (e.g. trilobites) of lithoclasts with those of the Mid‐Upper Cambro‐Ordovician bedrock carbonates suggest that the clastic and dissolved carbonate loads were sourced from this Lower Palaeozoic catchment, and shed off the surrounding highlands into the basin. These carbonate facies associations represent the lake lowstand and transgressive deposits of the basal third‐order sequence (Ia) in which the highstand deposits are composed of lacustrine siliciclastics. During the lake lowstand stage (or initiation of basin‐filling) under an intermediate climate, carbonate alluvial fans occurred mostly subaerially at the bottom of the hinged slope with a narrow, shallow lake zone basinwards, and locally were perched within the palaeovalley on the mid‐upper slope. During the transgressive (deepening) stage under a semi‐humid to humid climate, carbonate alluvial fans became smaller in size and episodically stepped backwards upon the slope, with greatly expanded and deepened lake. Nevertheless, the carbonate system was switched to an exclusively siliciclastic system during the highstand stage. The exhumation and erosion of the Mid‐Lower Cambrian bedrock dominated by siliciclastics was probably the cause due to further uplift of the drainage basin. All these facts indicate that the carbonate deposition in the Shulu Sag was mostly controlled by the interactions of tectonics, climate and provenance.  相似文献   

中层耗散大气中Rossby波包的非线性相互作用理论          下载免费PDF全文

熊建刚  易帆 《地球物理学报》1994,37(4):415-421

采用弱非线性近似得出中层耗散大气连续谱Ｒｏｓｓｂｙ波包的非线性时空演化方程，讨论了Ｒｏｓｓｂｙ波包的三波相互作用问题．数值计算表明，耗散和非线性的共同效应决定了Ｒｏｓｓｂｙ波包的演变．当一个Ｒｏｓｓｂｙ波包通过大气传播时，它的振幅若超过某个阈值，空间尺度分别比它大和比它小的两个次级Ｒｏｓｓｂｙ波包的振幅会随时间增长．特别当这两个次级波包同时随时空变化时，仅当主波的振幅超过一个更大的阈值，且其群速度介于两次级波包的群速度之间时，两次级波包的振幅才会随时空同时增长，即出现绝对不稳定现象，耗散和３个波包的频率失配都会增大不稳定的阈值．  相似文献   

Correlation assessment and monitoring of the potential pollutants in the surface sediments of Pyeongchang River, Korea   总被引：1，自引：0，他引：1  

Md.Imran KABIR  Hosik LEE  Geonha KIM  Taesung JUN 《国际泥沙研究》2011,26(2):152-162

The study provides a baseline for the assessment of the organic and inorganic pollution specially, heavy metal contamination in the surface sediments of Pyeongchang River,South Korea.The assessment of the study areas was done with respect to metal pollution load,ecological risk and geoaccumulated risk.Based upon the used indices,a priority index(P_index) was used to rank the utmost contaminated sites.Though the concentrations of mercury in all sediments were below the guideline, the significant enriched contamination was observed by all applied indices.As expected,the values of pollution load index（PLI）,ecological risk index（RI） and geoaccumulation risk index(I_geo) demonstrated lower heavy metal contamination in upstream areas compared to the downstream. Admittedly,sediments were unpolluted to slightly-polluted according to PLI while high to extremely high ecological risks were observed in several sediment samples.Furthermore,all the samples were uncontaminated as per I_geo.After simplification of I_geo,the P_index,showed the utmost contaminated sediments with a value of 2.537.Notably,protective measures should be taken to the highly contaminated areas which are prioritized by P_index Admittedly,the maximum concentrations of total organic carbon,total nitrogen,inorganic nitrogen,total phosphorous,inorganic phosphorous,calcium, magnesium,sodium and potassium were significantly observed as 7.8×10⁴,3,185,36,1,032,3.7, 1,5163,2,881,669 and 4,076mg/kg accordingly.  相似文献   

应用CT扫描研究非饱和砂土中污染物的迁移规律          下载免费PDF全文

周念清  宋玮  大谷顺  江思珉 《水文地质工程地质》2010,37(6):97-101

应用CT扫描技术对两种稳定非饱和状态的砂土试样分层进行扫描,得到不同深度CT扫描层图像,采用Image J图像处理软件将CT图像转化为CT数均值,然后在稳定非饱和试样中分别间断性连续注入污染物KI溶液,测定不同时间间隔CT扫描图像,计算注入污染物先后扫描图像结果的差值,建立CT数均值和污染物迁移之间的关系,研究污染物在非饱和砂土中的运移特征,得出非饱和砂土中污染物浓度随时间和深度的变化规律,对研究其他介质中污染物的迁移具有重要的指导作用。  相似文献   

塔里木地块库车坳陷早白垩世古地磁结果及磁倾角偏低的成因探讨   总被引：3，自引：1，他引：3       下载免费PDF全文

方大钧  沈忠悦  谈晓冬 《地球物理学报》2001,44(1):72-82

运用主成分分离及线性区段等方法 ,使早白垩世样品明显分离出二组磁组分 .叠加剩磁为喜山期重磁化 ,特征剩磁明显偏离现代地磁场方向 ,经倾斜校正后 ,有很好的一致性并通过了倒转检验 ,给出塔里木地块库车坳陷早白垩世巴西盖组古地磁新数据 .综合已有的古地磁结果 ,获得了塔里木地块早白垩世平均剩磁方向及平均古地磁极 ,阐明了塔里木地块早白垩世磁倾角明显偏低这一现象 .分析导致磁倾角偏低的诸多因素 ,认为压实作用可能是导致磁倾角偏低的重要因素之一 .  相似文献   

三门峡盆地晚新生代沉积物磁性载体类型   总被引：3，自引：2，他引：3       下载免费PDF全文

李万伦  陈杰  范俊喜  卢演俦 《地球物理学报》2001,44(4):520-527

对三门峡盆地晚新生代沉积岩样品进行岩石磁学研究,通过三轴饱和等温剩磁和剩磁矫顽力实验、交变退磁和热退磁实验及磁化率测定,发现黄土-古土壤、河湖相灰绿层和冲洪积层3种不同岩性的磁载体存在显著差异.即黄土-古土壤以磁铁矿为主,赤铁矿和磁赤铁矿很少;河湖相灰绿色沉积磁性矿物含量较低,主要为赤铁矿和磁铁矿,但磁铁矿较多,此外还有一些不稳定磁性矿物(如针铁矿、菱铁矿等);冲洪积物以磁铁矿和赤铁矿为主,磁铁矿相对较多.  相似文献   

相关分析法在研究电离层不均匀結构中的应用          下载免费PDF全文

李钧 《地球物理学报》1962,11(2):105-122

本文詳細地介紹了武汉采用的交点相关法和十点相关法的理論基础和具体計算方法,并与Philtips和spcncer的相关法（PS法）及Yerg的六点相关法进行了比較。正如理論上所預期到的,武汉的实驗表明:交点法提供的参量最多,也最精确可靠,但計算量与PS法的差不多;十点法提供的参量与交点法的一样多,精确性不此PS法的低,然而計算量比PS法的少得多,与六点法的差不多。文中还討論了利用时移图上曲直线,以进一步提高十点法的精确性,以及在相关分析中采用結构函数和后效函数,以进一步簡化計算的可能性。本文还初步討論了各种相关分析法的誤差間題;并提出了相关函数值在时空上的預报方法,以及根据相关函数的預报值与实測值的对此等,判别在記录分析中有无反常現象,和甄別所求出的参量值是否可疑的方法。最后还特別指出了电离层混乱运动变化速度出現虛数值的可能性,并介紹了消除这种虛数值的方法。  相似文献