磁东线GSM-R网络优化技术分析与总结

随着近年来中国高速铁路的蓬勃发展以及普速铁路的升级换代,GSM-R在中国铁路通信系统中发挥着越来越重要的作用。网络优化作为GSM-R工程建设的重要环节,直接影响网络覆盖合格与否。文章以磁东线铁路工程施工为例,对GSM-R网络测试中发现的典型问题进行了梳理分析,给出了相应的解决对策,并对网络优化技术经验进行了归纳总结,为类似的工程问题解决提供相关参考。

辛泰、磁东、东莱线限坡改造方案研究

结合既有辛泰、磁东、东莱线现状坡度、自然条件、运输特点及能力适应性，对因该线限制坡度改造从路网协调性、经济性、行车安全性及运输质量等方面进行综合分析比选，得出该线的限坡改造推荐方案，对其他既有线路限坡改造方案研究具有一定的借鉴作用．

The 3D magnetic structure beneath the continental margin of the northeastern South China Sea

Understanding the continental margin of the Northeastern South China Sea is critical to the study of deep structures, tectonic evolution, and dynamics of the region. One set of important data for this endeavor is the total-field magnetic data. Given the challenges associated with the magnetic data at low latitudes and with remanent magnetism in this area, we combine the equivalent-source technique and magnetic amplitude inversion to recover 3D subsurface magnetic structures. The inversion results show that this area is characterized by a north-south block division and east-west zonation. Magnetic regions strike in EW, NE and NW direction and are consistent with major tectonic trends in the region. The highly magnetic zone recovered from inversion in the continental margin differs visibly from that of the magnetically quiet zones to the south. The magnetic anomaly zone strikes in NE direction, covering an area of about 500 km × 60 km, and extending downward to a depth of 25 km or more. In combination with other geophysical data, we suggest that this strongly magnetic zone was produced by deep underplating of magma associated with plate subduction in Mesozoic period. The magnetically quiet zone in the south is an EW trending unit underlain by broad and gentle magnetic layers of lower crust. Its magnetic structure bears a clear resemblance to oceanic crust, assumed to be related to the presence of ancient oceanic crust there.

Application of wide-field electromagnetic method in shale gas survey in Eastern Kunlun,Qinghai province,China

In order to study the distribution of shale gas reservoir in the Babaoshan Basin of Eastern Kunlun,the wide-field electromagnetic(WFEM)survey was carried out to obtain the spatial distribution characteristics of the underground electrical volume resistivity based on the delineation of the scope of the Babaoshan Basin by regional gravity data.The basic characteristics of the basement,basin framework,and extension,vertical change,burial depth of dark mud shale in this area were identified,and the electrical distribution of the Babaoshan mud shale horizon was revealed,which has been proved to be a good geological effect by drilling.The exploration results show that the WFEM has significant effects on the exploration of shale gas occurrence strata,which meets the needs of investigation and evaluation of multi-layered and large-scale shale gas,and plays a good demonstration role in the follow-up shale gas exploration.

Magnetic Characteristics of Surface Sediments of Liaodong Bay, China

Analysis of magnetic properties of marine surface sediments has been gradually proved to be one of the effective means for researching the source of marine sediments. In this paper, samples from 39 sites in Liaodong Bay were collected to analyze the magnetic characteristics of the surface sediments. Magnetic study indicated that the surface sediments of the Liaodong Bay are char- acterized by magnetite. In the middle and eastern part and the southwest comer of the Bay, the main magnetic grains were coarse multi- domain and pseudo-single-domain particles, while in other areas single-domain and pseudo-single-domain particles constitute the majority. Based on grain size and environmental magnetism data, the content of magnetic minerals has a positive correlation with the hydrodynamic environment when the magnetic mineral domain is finer. However, the content of magnetic minerals is in a complex relationship with the hydrodynamic environment in the coarse magnetic domain of magnetic minerals found in central Liaodong Bay and places outside the Fuzhou Bay, implying that the strong hydrodynamic environment accelerates the sedimentation of coarse magnetic minerals. Based on geographic pattern of magnetic properties, it can be inferred that the main provenance of the surface sediments of the Liaodong Bay is the surrounding rivers, and the comparative analysis indicates that Yellow River substances maybe also exist in the bay.

Diagenetic control of magnetic susceptibility variation in Core MD98-2172 from the Eastern Timor Sea

Detailed mineral magnetic measurements, integrated with grain-size distribution and X-ray diffraction （XRD） analyses, were made on the marine sediments of Core MD98-2172, retrieved from the Eastern Timor Sea. Values of magnetic susceptibility in this core drop sharply down-core from -3.85 m deep below sediment/water interface and are very low at -5.35 m. However, both XRD and grain-size distribution results show no sudden change in terrigenous input during sedimentation. Mineral magnetic results indicate that the depth of -3.85 m may be an oxic/anoxic boundary. Therefore, the sediments below -3.85 m have been subjected to intense reductive diagenesis, whereas the sediments above -3.85 m are seldom affected. The magnetic properties of the sediments shallower than 3.85 m are dominated by pseudo-single domain （PSD） magnetite, with little down-core variation in its content and grain size. Below -3.85 m, the magnetic mineral assemblages that have survived in the sediments may record different stages of the reductive diagenesis： （1） the sediments from the 3.85-5.35 m interval are at the stage of iron oxide reduction; t＇SD magnetite is the major magnetic contributor, but it becomes less abundant and coarser down-core; （2） the sediments below -5.35 m are at the stage of sulphate reduction; ferrimagnetie minerals almost vanish and paramagnetic minerals contribute to down-core susceptibility variations, including pyrite as evidenced by high-temperature magnetic susceptibility measurements. However, the susceptibility variations below -5.35 m of Core MD98-2172 show obvious periodicity, despite the intense effect of reduetive diagenesis. Furthermore, the down-core susceptibility variations are coincident with fluctuations in the quantity of fine detrital particles （〈8 μm）, which may come mainly from the advection of the Indonesia Throughflow （ITF） and/or river input from Timor. Therefore, for Core MD98-2172, susceptibility variation below -5.35 m, which potentially correspond to fluctuations in the quantity of fine particles, may record the histories of the development of the ITF and precipitation on Timor.

Re-Os dating of magnetite from the Shaquanzi Fe-Cu deposit,eastern Tianshan,NW China

Magnetite separates from the Shaquanzi Fe-Cu deposit in the eastern Tianshan are used for Re-Os geochronological study. Re-Os data show that magnetite separates contain ca. 0.7 to 50.9 ppb Re and ca. 16 to 63 ppt Os. Eight samples yield a model 3 isochron age of （303 ±12） Ma （2or）, which is within uncertainty consistent with of the Re-Os date （295±7 Ma） of associated pyrite. Tectonic evolution shows that the Late Carboniferous Aqishan-Yamansu belt was a back-arc rift. Therefore, the Re-Os age of ca. 300 Ma indicates that the Shaquanzi Fe-Cu deposit may have formed in a back-arc extensional environment and was closely related to mantle-derived magmatism. The successful application of Re-Os magnetite geochronology in the Shaquanzi Fe-Cu deposit suggests that the purity of magnetite, relatively high Re and Os contents, and the closure of Re-Os systematic are base factors for a successful Re-Os geochronology. There would be a good prospect for Re-Os geochronology for magnet- ite.

Paleomagnetic data from the Late Carboniferous-Late Permian rocks in eastern Tibet and their implications for tectonic evolution of the northern Qiangtang-Qamdo block

We report paleomagnetic results from the Late Carboniferous-Late Permian strata in eastern Tibet (China), and aim to clarify the tectonic and paleogeographic evolution of the northern Qiangtang-Qamdo block, which is the key to the study of plate boundary between the Gondwanaland and the Eurasia during the late Paleozoic. Two hundred and nineteen samples-including limestone, muddy siltstone, basalt, lava, and tuff-were collected at 24 sites in the Upper Carboniferous and Middle-Upper Permian successions. A systematic study of rock magnetism and paleomagnetism yields three reliable paleomagnetic pole positions. Both hematite and magnetite occurred in the Late Carboniferous limestone samples. The demagnetization curve shows a characteristic double-component, with the remanent magnetization (ChRM) exhibiting a positive polarity (negative inclination). In the Late Permian limestone, tuff, and basalt, magnetic information were recorded primarily in magnetite, although a small fraction of them was found in hematite in basalt. The demagnetization curve illustrates a double or single component, with the ChRM showing a negative polarity (positive inclination), which has passed the classic fold test successfully. The single polarity features of the ChRM directions of the Late Carboniferous and Middle-Late Permian rocks are respectively related to the Kiaman positive and reversed polarities under the stratigraphic coordinates. This, in turn, indicates that both ChRMs directions represent the original remanence directions. By comparison with the previously published paleomagnetic results from the late Paleozoic rocks in the northern Qiangtang Range, we suggest that: (1) Qamdo and northern Qiangtang block were independent of each other during the Late Carboniferous to the Early Permian periods. The north Lancangjiang ocean basin between the two blocks may have closed before the Middle Permian and been involved in the continent-continent collision stage in the Late Permian-Early Triassic periods. (2) The northern Qiangtang-Qamdo Block paleogeographically was situated at low to intermediate latitudes in the Southern Hemisphere in the Late Carboniferous-Late Permian periods, and began to displace northward in the Early Triassic, with an amount of more than 5000 km northward transport from its current location.