Deep seismic reflection profiling revealing the complex crustal structure of the Tongling ore district

Deep seismic reflection profiling has been the dominant method for probing the deep structure of continental crust since the initiation of the COCORP in 1974[1,2]. Over the past few decades, this tool has been applied to diverse geologic features from the Appalachian area of the United States, to the Rhine-graben area in Western Europe and to the Tibetan Pla-teau[36]. In recent years, the Australian Geodynamic Cooperative Research Center ( AGCRC ) has applied this technique to the stu…     

邢台7.2级地震震源区的电磁阵列剖面法测量与电性特征研究

为了取得邢台地震区地壳细结构,对该区进行了综合地球物理方法探测,其中电磁阵列剖面法（EMAP）测量在我国尚属首次．EMAP剖面穿过邢台7．2级地震区,经过EMAP阻抗求取、空间滤波处理和二维反演解释,剖面显示出清晰的地壳电性细结构特征：4km以上电性简单,4-20km深度电性复杂;震源区电性复杂,非源区简单;发震深度变化复杂;震源区电性突变,显示隐伏高角度断裂,高寻层不连续部位为发震部位．其观测结果对于了解该区的构造背景、发震构造和深部构造的关系有重要意义．     

俄歇电子谱学在地球化学中的应用

俄歇电子谱（ＡＥＳ）在研究ｎｍ厚度表面层物质的主量和微量元素组成有广泛用途。ＡＥＳ可以观察到高放大倍率的表面组构和形貌,其极端表面灵敏度、极好的侧向分辨率使它能够在μｍ尺度上对矿物表面不同的晶畴进行化学分析,证明在矿物单个表面上存在侧向不均一性。ＡＥＳ不仅在扫描模式下可检测痕量的二次相,也可用来分析直径在μｍ尺度的几个ｎｍ厚度的产物,同样ＡＥＳ在测定热爆低盐度流体包裹体极薄的盐膜时也显示出独特的能力。ＡＥＳ最有潜力的地质应用是可以在侧向分辨率为μｍ级时得到ｎｍ尺度上的深度剖面。用ＡＥＳ得到的深度剖面对于研究化学风化作用是很重要的,因为它们直接提供了反应随深度的变化规律。俄歇谱结合ＸＰＳ研究提供对矿物流体界面输运机制的研究方法和矿物流体之间的反应机制。     

延庆─怀来地区地壳细结构──利用深地震反射剖面

１９９２年底在延庆－怀来地区实施了深地震反射剖面测量，目的是通过对该区地壳细结构的研究来探讨延庆－怀来盆地形成演化的机制和过程，以及与该区地震活动图像的关系．结果表明，研究区上部地壳总体上呈“透明”性质，厚２５－２６ｋｍ；下部地壳具有强烈的反射性质，厚约１４－１５ｋｍ．壳幔过渡带是由双程走时约２ｓ和厚约５－６ｋｍ的水平反射叠层所组成，莫霍界面具有深度深（约３９－４０ｋｍ）和平坦的特点。     

Environmental applications of magnetometry profiling

Environmental impact assessment is currently a standard procedure for assessing the possible consequences of any particular activity that may cause degradation of the environment. Magnetometry profiling, which involves accurate measurements of the Earth's magnetic field at closely spaced stations is a technique that has a large number of environmental applications that can greatly improve this assessment. The technique has been applied successfully for waste disposal site evaluation, toxic waste detection, assessment of the quality of roadstone before excavations and can provide information that allows subsurface water movement models to be refined. Magnetometry profiling is inexpensive, nondestructive, and a very costeffective method of acquiring useful information about the environment.     

从地震折射和反射剖面结果讨论唐山地震成因

通过唐山震中的地震测深以及深反射剖面,揭示了唐山震源区的浅部及深部构造图象,它与以往的推测很不相同。 唐山东面的开平向斜属中生代构造,探测的结果表明,向斜轴是一近于直立的地壳断裂。唐山地震时的水平地形变主要是由开平地壳断裂的位移引起的,它是北北东-南南西向右旋走滑断裂。开平地壳断裂西面的陡河断层是一自地表向南东方向下插的正断层,断层倾角为26°,延伸至5km深处。陡河正断层刚好插到唐山市震中区的正下方。唐山地震时的垂直地形变主要是由陡河正断层的滑动引起的。 野鸡坨-丰台断层通过震源区的西部边缘,断层以西的第四纪沉积层,在过去一百万年间曾经沿北北东方向水平滑移15km,表明它也是一个右旋的走滑断层。但是它在近代数百年间并无地震活动,唐山地震时该断层的滑动亦不明显。 开平地壳断裂和陡河正断层在唐山地震时同时滑动,说明地震的作用力除区域水平构造力外,地壳上方还存在一个附加的引张力。在开平断裂处,上部地壳的反射面倾角杂乱,而且在它的正下方,莫霍界面明显错断,因此,地幔顶部的热物质可能自开平地壳断裂中上升。热物质产生的热应力在地壳上方可表现为张应力,而在地壳下方却表现为压应力,这与反射地震剖面图的现象相符合。开平地壳断裂中热物质的上升对地震的产生有     

Study on Fine Crustal Structure of the Sanhe-Pinggu Earthquake （M8.0） Region by Deep Seismic Reflection Profiling

Two near-vertical deep seismic reflection profiles (140km-long, 24-fold) were completed in the 1679 Sanhe-Pinggu earthquake (M8.0) region. The profiles ran through the Xiadian fault and the Ershilichangshan fault. The profiling result shows that the crust in this region is divided into the upper crust, the lower crust and the crust-mantle transitional zone by two powerful laminated reflectors: one at the two-way travel-time of about 7.0s (21 km), the other at about11.0～12.5s (33～37km). Crustal structure varies significantly in vertical direction. The shallow part is characterized by obvious stratification, multilayers and complexity. The upper crust on the whole features reflection “transparency“, while the lower crust features distinct reflectivity. Crustal structure also varies a lot in the lateral direction. The main fracture in this region is the deep fault under the Xiadian fault. This deep fault is steeply inclined (nearly vertical), and is supposed to be the causative fault of the Sanhe-Pinggu MS.0 earthquake. The two profiles respectively reveal the existence of local strong reflectivity in the lower crust and the lower part of the upper crust, which is assumed to be a dike or rock mass formed by the upwelling and cooling down of materials from the upper mantle. Magmatic activity in this part brought about differences in regional stress distribution, which then gave rise to the formation of the deep fault. That is supposed to be the deep structural setting for the Sanhe-Pinggu M8.0 earthquake.     

太原市汾河断裂浅层高分辩率地震探测

通过浅层高分辩率地震探测，结合钻孔资料，获得了测线处汾河断裂的准确位置，几何结构，活动性质、时代和速率等参数，并对其动力学属性进行了初步的讨论。地震探测揭露出汾河断裂的西支断层，为高角度东倾的斜滑断层，切割了第四系下部，上断点位于地下约70m处。据钻孔剖面推断有2条高角度相向而倾的斜滑断层，东支位于汾河东岸，断至全新统-上更新统，其底界面垂直错距约8m。断裂北段另一个钻孔剖面表明，西支断层切割了全新统-上更新统，底界面垂直错距约6m。汾河断裂晚更新世以来的平均垂直滑动速率为0.06-0.08mm/a，大震平均重复间隔为5.0-6.7ka。     

THE FINE CRUSTAL STRUCTURE OF THE SOUTHERN MARGIN OF NORTH CHINA BLOCK REVEALED BY DEEP SEISMIC REFLECTION PROFILE

The study area is located at the junction of the northern margin of the Qinling orogenic belt and the southern margin of the North China Block. In order to study the fine crustal structure and the deep-shallow structural features of faults in this area, we conducted deep seismic reflection profiling with the seismic profile of 100km long, directing NE-SW in Zhumadian City, Henan Province, and got clear lithospheric structure images along the profile. As regards the data acquisition, we applied the geometry of 25m group interval, 1000 recording channels and more than 60 folds. Seismic wave exploding applies the 30kg shots of dynamite source with the borehole depth of 25m. The shot interval is 200m. In data processing, we focused on improving the signal-to-noise ratio. Data processing methods mainly include first break removal, tomographic static correction, abnormal amplitude elimination, amplitude compensation, pre-stack denoising, surface consistent deconvolution, velocity analysis, several iterations of the residual static correction, dip moveout, post-stack time migration and post-stack denoising, etc. The profile with high signal-to-noise ratio was obtained. The reflection wave group characteristics is obvious in the crust, which reflects abundant information about geological structure. Along the profile, the crust is characterized by double-layer reflection structure, and the Moho surface is composed of a series of laminated arc-shaped strong reflections. The thickness of the upper crust is about 14.8~20.7km, and the total thickness of the crust is about 32.0~35.1km. The upper crust is dominated by the inclined, densely stratified or arc-shaped reflections. The lower crust is dominated by arc-shaped and inclined reflection, and there is a reflective transparent zone under the Moho surface. The reflection sequences with different directions and shapes in the upper crust constitute the nappe structure in southwest segment and the structural model of two concaves with one uplift in NE segment, which correspond to the north Qinling nappe, Zhumadian-Huaibin depression, Pingyu-Xiping uplift and a secondary depression, respectively. There are abundant arc-shaped reflection sequences in the lower crust, which may represent multi-stage magmatic activities. The deep seismic reflection profile shows that faults in the upper crust are well developed. According to the characteristics of reflected wave field in the profile, four groups of fault structure which contain ten faults with different scales are interpreted. Among them, faults F_P1, F_P2 and F_P3 constitute the thrust fault system in the northern margin of Qinling Mountains, and F_P5 and F_P7 are boundary faults of Zhumadian-Huaibin depression. These faults are all developed within the upper crust. In addition, the Fault F_PM is a large fault that cuts through the lower crust and Moho surface. The deep seismic reflection profile reveals the crustal structure and deep-shallow structural features of faults at the junction of the northern margin of the Qinling orogenic belt and the southern margin of the North China block, which provides seismological evidence for the analysis of structural differences, the deep earth's interior processes and deep-shallow structural relationships between the Qinling-Dabie orogenic belt and the southern margin of the North China block. The lower crust of the study area is divided into two parts by deep faults that dislocate the Moho surface. These two parts have distinct reflective structures, suggesting that the area has experienced intense complex tectonic movements. The faults in the upper crust control the formation of basin-mountain structure and stratigraphic deposition of this area. And deep faults in the crust that disrupt Moho surface create conditions for the upwelling and energy exchange of deep materials. All of these have regulated the composition of material and the distribution of energy in the crust. The deep faults cutting through the lower crust and Moho surface and the south-dipping arc-shaped and inclined strong reflection sequences developed in the lower crust should indicate the large-scale subduction of the southern margin of the North China block towards the south-trending Qinling orogenic belt.     

电法在地下热水勘探中的应用

为进一步开发和利用热水镇的地热资源,运用物探联合剖面法,结合区域地质和构造特征,分析、推断地下热水形成和运移的水文地质条件;推测出隐伏的断裂带;证实张性断裂对地下热水的控制作用;查明该区第四系中视电阻率<40 Ω·m的地层为含热水砂砾石层,圈定联剖曲线低阻带中视电阻率<100 Ω·m的范围为断裂构造脉状地下热水的中心部位。