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621.
Fault Characteristics in Longmen Mountain Thrust Belt,Western Sichuan Foreland Basin,China 总被引:1,自引:0,他引:1
Through field geological survey,the authors found that abundant thrust faults developed in the Longmen (龙门) Mountain thrust belt.These faults can be divided into thrust faults and strike-slip faults according to their formation mechanisms and characteristics.Furthermore,these faults can be graded into primary fault,secondary fault,third-level fault,and fourth-level fault according to their scale and role in the tectonic evolution of Longmen Mountain thrust belt.Each thrust fault is composed of several secondary faults,such as Qingchuan (青川)-Maowen (茂汶) fault zone is composed of Qiaozhuang (乔庄) fault,Qingxi (青溪) fault,Maowen fault,Ganyanggou (赶羊沟) fault,etc..The Longmen Mountain thrust belt experienced early Indosinian movement,Anxian (安县) movement,Yanshan (燕山)movement,and Himalayan movement,and the faults formed gradually from north to south. 相似文献
622.
顶管具有不可比拟的优越性,在市政项目中应用越来越广泛,但施工技术难度较大,长距离顶管是顶管工程中施工工艺最复杂课题之一。本文讨论了长距离顶管中易出现的技术问题及处理措施,指出顶管技术通过与精心细致、信息化施工相结合,可以广泛地应用于城市的基础建设中。 相似文献
623.
Calcimicrobialites across the Permian-Triassic boundary in Huayingshan (华蓥山) region were investigated using the fluorescence microscopic measurements to understand the occurrence of organic matter. The microbialites are composed of micrite matrix and coarse spar cement. Abundant rhombic or magnetic needle-like carbonate minerals were observed adrift within the cement. The fluorescence microscopic measurement indicates the micrite matrix in microbialites shows the most abundant organic matter, with the rhombic or magnetic needle-like carbonate minerals and coarse spar cement coming to the 2nd and the 3rd, respectively. Organic matter is mainly preserved in the space between the grains of the micrite minerals but almost evenly distributed in the rhombic or magnetic needle-like carbonate minerals. As one of the common diagenesis types, dolomitization is observed to occur in the microbialites in Huayingshan. However, the carbonate cement in microbialites still has high content of element Sr as shown by the microprobe analysis, reflecting that the dolomitization might have happened in a restricted environment. Observation under the fluorescence microscope shows that dolomitization just led to the redistribution of organic matter in the grain space of dolomite minerals, inferring that the diagenesis has a slight effect on the preservation, and thus on the content of organic matter in the microbialites. 相似文献
624.
多点地质统计学在河流相储层建模中的应用 总被引:6,自引:1,他引:5
多点地质统计学综合了基于象元方法以及基于目标方法两者的优点,对于河流相等具有复杂地质形态的储层精确建模具有较强的优势.在对传统建模方法综合分析的基础上,介绍了多点地质统计学的基本理论及SNESIM算法,并应用该技术对大牛地气田某开发井区的辫状分流河道相进行了实际建模.研究结果表明,在河流相储层建模中,该方法比传统的建模方法更具优越性.最后,进一步综合讨论了多点地质统计学目前面临的主要问题(包括训练图像、目标体连续性、数据样板选择、综合地震信息等方面)的改进方法. 相似文献
625.
The characteristics and sources of natural gases from Ordovician weathered crust reservoirs in the Central Gas Field in the Ordos Basin 总被引:2,自引:2,他引:0
Xianqing Li Guoyi Hu Jian Li Dujie Hou Peng Dong Zhihong Song Yunfeng Yang 《中国地球化学学报》2008,27(2):109-120
The Central Gas Field is a famous large-sized gas field in the Ordos Basin of China. However, identification of main gas sources of the Ordovician reservoirs in this gas field remains puzzling. On the basis of a lot of geochemical data and geological research on natural gases, the characteristics and sources of natural gases from Ordovician weathered crust reservoirs in the Central Gas Field in the Ordos Basin were studied. The results indicated that natural gases from Ordovician weathered crust reservoirs in the Central Gas Field in the Ordos Basin have similar chemical and isotopic compositions to highly mature and over-mature dry gases. Both coal-derived gases and oil-type gases coexist in the Central Gas Field in the Ordos Basin. The former was derived mainly from Carboniferous-Permian coal measures and the latter from Lower Paleozoic marine carbonates. It is suggested that coal-derived gases occur in the eastern part of the Central Gas Field while oil-type gases may be produced mainly in the northern, western and southern parts of the Central Gas Field in the Ordos Basin. 相似文献
626.
Extensive organic-matter (OM) rich facies (black shales) occur in the Ordo-Silurian boundary successions in the Yangtze area, South China. To investigate the redox changes of the Yangtze Sea during the Ordo-Silurian transition, two OM sections (Wangjiawan in Yichang, Hubei Province, and Sanjiaguan in Zhangjiajie, Hunan Province) straddling the Ordo-Silurian boundary are studied. The measurements finished in this study include contents of the total organic carbon (TOC), pyrite sulphur, and different species of Fe, including dithionite-extractable Fe (FED), pyrite Fe (FeP), HCl-extractable Fe (FeH), and total Fe (FeT), in black shales, as well as other redox proxies, such as the SIC ratio, the ratio between highly reactive Fe (FeHR = FeD + FeP) and FeT, and the FeP/(FeP + FeH) ratio, known as the degree of pyritization (DOP). In the Wangjiawan section, the Middle Ashgill sediments have high FeHR/FeT ratios (0.20-0.77; avg. 0.45), high DOP values (0.21-0.72; avg. 0.54), and a relatively constant sulfur content independent of the organic carbon content. By the contrast, the mid-early Hirnantian deposits generally have low FeHR/FeT ratios (0.10-0.35; avg. 0.21), low DOP values (0.11- 0.40; avg. 0.28), and SIC values are clustering on the normal marine value (SIC = 0.36). The late Hirnantian and early Rhuddanian deposits, similar to those of the Middle Ashgill deposits, are characterized by high FeHR/FeT ratios (0.32-0.49; avg. 0.41), high DOP values (0.46-0.68; avg. 0.53) and fairly constant sulfur contents. These data suggest the occurrences of marine anoxia on the Yangtze Sea shelf during intervals of the Mid Ashgill, Late Hirnantian and Early Rhuddanian, and ventilated and oxygenated marine conditions during the mid-early Hirnantian time. The mid-early Hirnantian ventilated event was concomitant with the global glacial period, likely resulted from the glacio-eustatic sea-level fall and subsequent circulation of cold, dense oxygenated waters 相似文献
627.
628.
A data-driven approach to local gravity field modelling using spherical radial basis functions 总被引:3,自引:0,他引:3
We propose a methodology for local gravity field modelling from gravity data using spherical radial basis functions. The methodology
comprises two steps: in step 1, gravity data (gravity anomalies and/or gravity disturbances) are used to estimate the disturbing
potential using least-squares techniques. The latter is represented as a linear combination of spherical radial basis functions
(SRBFs). A data-adaptive strategy is used to select the optimal number, location, and depths of the SRBFs using generalized
cross validation. Variance component estimation is used to determine the optimal regularization parameter and to properly
weight the different data sets. In the second step, the gravimetric height anomalies are combined with observed differences
between global positioning system (GPS) ellipsoidal heights and normal heights. The data combination is written as the solution
of a Cauchy boundary-value problem for the Laplace equation. This allows removal of the non-uniqueness of the problem of local
gravity field modelling from terrestrial gravity data. At the same time, existing systematic distortions in the gravimetric
and geometric height anomalies are also absorbed into the combination. The approach is used to compute a height reference
surface for the Netherlands. The solution is compared with NLGEO2004, the official Dutch height reference surface, which has
been computed using the same data but a Stokes-based approach with kernel modification and a geometric six-parameter “corrector
surface” to fit the gravimetric solution to the GPS-levelling points. A direct comparison of both height reference surfaces
shows an RMS difference of 0.6 cm; the maximum difference is 2.1 cm. A test at independent GPS-levelling control points, confirms
that our solution is in no way inferior to NLGEO2004. 相似文献
629.
630.