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991.
泥炭沼泽的演化及其机制 总被引:2,自引:1,他引:1
泥炭沼泽的演化普遍存在,演化的实质是在成因因素有利的配合下,沼泽植物群落发生了变化乃至更替。根据泥炭植物残体分析和煤层的煤岩、煤化学研究,可以了解泥炭沼泽的演化和形成煤层的原始泥炭沼泽的演化。 相似文献
992.
冀西北张全庄金矿石英的矿物学特征 总被引:1,自引:0,他引:1
本文较为详尽地研究了张全庄金矿两种主要含矿石英(乳白色和烟灰色石英)的成分特征、气液包裹体成分特征及晶胞参数特征等,对比了两种石英含金性的差异及与上述各特征间的内在联系,在此基础上得出;烟灰色石英与乳白色石英具有不同的矿物学特征;张全庄金矿的成矿溶液为一种弱碱性、Na+-Ca2+-SO型,属中(深)成、中(高)温热液型矿床. 相似文献
993.
“复合条分法”一文并不是想寻求一种精确的方法,仅仅是对工程界习惯采用的改良圆弧法,即土坝设计规范和有些土力字教课书中介绍的方法,作一些讨论,并提出改进的意见。较精确的方法,如摩根斯坦法已提出多年,但工程中还是习惯于用瑞典法或简化毕肖普法,遇有软弱夹层则用改良圆弧法。原因在于精确的方法形式上复杂,反而不如简单的方法易于推广。从这一点出发,该文仍以改良圆弧法为基础,稍加改进。 相似文献
994.
唐古拉山侏罗系沉积的若干特征及沉积盆地背景条件的探讨 总被引:1,自引:0,他引:1
对于唐古拉山侏罗系沉积类型的不同认识由来已久,然而无论是将其视为地槽型沉积,还是地台型沉积,均难以令人满意地解释该区侏罗纪沉积的特点和性质。 作者在野外工作和室内研究的基础上,从地球化学因素、古生态分析、沉积岩沉积构造和矿物结构成熟度等综合考虑,对该区侏罗纪沉积的特点和性质提出下列证据: (1)含盐度值一般均低于广海的平均盐度值。 (2)发育了海相一半咸水相一陆相的双壳类动物群序列,并以半咸水双壳类属占优势。 (3)沉积构造多为浅水成因的小型波痕,交错层理沉积组合。 (4)沉积岩粒度分析表现了近岸环境的概率曲线特征。 (5)沉积岩矿物结构,成熟度较高,未见海相成因的粒级层理。 结论是唐古拉山区侏罗系应为近岸局限海环境下的沉积产物,在海退时期还发育了滨岸湖相沉积。 根据羌塘地区侏罗纪沉积相空间展布的特点,可以认为唐古拉山区侏罗系仅仅是大西洋型大陆边缘沉积的一个组成部分,是陆架大幅度坳陷所承受的巨厚陆源碎屑沉积,整个羌塘地区侏罗纪沉积在空间上的演替关系及其巨大厚度可借助于大西洋型大陆边缘特有的大陆堤前展沉积模式得到较好的解释。 相似文献
995.
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997.
A dual-ship-towed marine electromagnetic (EM) system is a new marine exploration technology recently being developed in China. Compared with traditional marine EM systems, the new system tows the transmitters and receivers using two ships, rendering it unnecessary to position EM receivers at the seafloor in advance. This makes the system more flexible, allowing for different configurations (e.g., in-line, broadside, and azimuthal and concentric scanning) that can produce more detailed underwater structural information. We develop a three-dimensional goal-oriented adaptive forward modeling method for the new marine EM system and analyze the responses for four survey configurations. Oceanbottom topography has a strong effect on the marine EM responses; thus, we develop a forward modeling algorithm based on the finite-element method and unstructured grids. To satisfy the requirements for modeling the moving transmitters of a dual-ship-towed EM system, we use a single mesh for each of the transmitter locations. This mitigates the mesh complexity by refining the grids near the transmitters and minimizes the computational cost. To generate a rational mesh while maintaining the accuracy for single transmitter, we develop a goal-oriented adaptive method with separate mesh refinements for areas around the transmitting source and those far away. To test the modeling algorithm and accuracy, we compare the EM responses calculated by the proposed algorithm and semi-analytical results and from published sources. Furthermore, by analyzing the EM responses for four survey configurations, we are confirm that compared with traditional marine EM systems with only in-line array, a dual-ship-towed marine system can collect more data. 相似文献
998.
Qian Liu Xianghui Guo Zhiqiang Yin Kuanbo Zhou Elliott Gareth Roberts Minhan Dai 《中国科学:地球科学(英文版)》2018,61(11):1564-1582
This paper aims to provide an overview of regional carbon fluxes and budgets in the marginal seas adjacent to China.The "China Seas" includes primarily the South China Sea, East China Sea, Yellow Sea, and the Bohai Sea. Emphasis is given to CO_2 fluxes across the air-sea interface and their controls. The net flux of CO_2 degassing from the China Seas is estimated to be9.5±53 Tg C yr~(-1). The total riverine carbon flux through estuaries to the China Seas is estimated as 59.6±6.4 Tg C yr~(-1). Chinese estuaries annually emit 0.74±0.02 Tg C as CO_2 to the atmosphere. Additionally, there is a very large net carbon influx from the Western Pacific to the China Seas, amounting to ~2.5 Pg C yr~(-1). As a first-order estimate, the total export flux of particulate organic carbon from the upper ocean of the China Seas is 240±80 Tg C yr~(-1). This review also attempts to examine current knowledge gaps to promote a better understanding of the carbon cycle in this important region. 相似文献
999.
Seismic Rock physics plays a bridge role between the rock moduli and physical properties of the hydrocarbon reservoirs. Prestack seismic inversion is an important method for the quantitative characterization of elasticity, physical properties, lithology and fluid properties of subsurface reservoirs. In this paper, a high order approximation of rock physics model for clastic rocks is established and one seismic AVO reflection equation characterized by the high order approximation(Jacobian and Hessian matrix) of rock moduli is derived. Besides, the contribution of porosity, shale content and fluid saturation to AVO reflectivity is analyzed. The feasibility of the proposed AVO equation is discussed in the direct estimation of rock physical properties. On the basis of this, one probabilistic AVO inversion based on differential evolution-Markov chain Monte Carlo stochastic model is proposed on the premise that the model parameters obey Gaussian mixture probability prior model. The stochastic model has both the global optimization characteristics of the differential evolution algorithm and the uncertainty analysis ability of Markov chain Monte Carlo model. Through the cross parallel of multiple Markov chains, multiple stochastic solutions of the model parameters can be obtained simultaneously, and the posterior probability density distribution of the model parameters can be simulated effectively. The posterior mean is treated as the optimal solution of the model to be inverted.Besides, the variance and confidence interval are utilized to evaluate the uncertainties of the estimated results, so as to realize the simultaneous estimation of reservoir elasticity, physical properties, discrete lithofacies and dry rock skeleton. The validity of the proposed approach is verified by theoretical tests and one real application case in eastern China. 相似文献
1000.
Yue Tianxiang Zhao Na Liu Yu Wang Yifu Zhang Bin Du Zhengping Fan Zemeng Shi Wenjiao Chen Chuanfa Zhao Mingwei Song Dunjiang Wang Shihai Song Yinjun Yan Changqing Li Qiquan Sun Xiaofang Zhang Lili Tian Yongzhong Wang Wei Wang Ying’an Ma Shengnan Huang Hongsheng Lu Yimin Wang Qing Wang Chenliang Wang Yuzhu Lu Ming Zhou Wei Liu Yi Yin Xiaozhe Wang Zong Bao Zhengyi Zhao Miaomiao Zhao Yapeng Jiao Yimeng Naseer Ufra Fan Bin Li Saibo Yang Yang Wilson John P. 《中国科学:地球科学(英文版)》2020,63(8):1092-1112
We propose a fundamental theorem for eco-environmental surface modelling(FTEEM) in order to apply it into the fields of ecology and environmental science more easily after the fundamental theorem for Earth's surface system modeling(FTESM). The Beijing-Tianjin-Hebei(BTH) region is taken as a case area to conduct empirical studies of algorithms for spatial upscaling, spatial downscaling, spatial interpolation, data fusion and model-data assimilation, which are based on high accuracy surface modelling(HASM), corresponding with corollaries of FTEEM. The case studies demonstrate how eco-environmental surface modelling is substantially improved when both extrinsic and intrinsic information are used along with an appropriate method of HASM. Compared with classic algorithms, the HASM-based algorithm for spatial upscaling reduced the root-meansquare error of the BTH elevation surface by 9 m. The HASM-based algorithm for spatial downscaling reduced the relative error of future scenarios of annual mean temperature by 16%. The HASM-based algorithm for spatial interpolation reduced the relative error of change trend of annual mean precipitation by 0.2%. The HASM-based algorithm for data fusion reduced the relative error of change trend of annual mean temperature by 70%. The HASM-based algorithm for model-data assimilation reduced the relative error of carbon stocks by 40%. We propose five theoretical challenges and three application problems of HASM that need to be addressed to improve FTEEM. 相似文献