| 沉积模拟的基本数学模型及其在第四纪研究中的应用 |
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| 引用本文： | 刘素华,刘承祚.沉积模拟的基本数学模型及其在第四纪研究中的应用[J].第四纪研究,1993,13(2):142-156. |
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| 作者姓名： | 刘素华 刘承祚 |
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| 作者单位： | 中国科学院地质研究所，中国科学院地质研究所 |
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| 摘 要： | 内容提要本文扼要介绍了沉积模拟的基本数学模型,其中包括十种随机模拟数学模型和十种确定模拟数学模型,阐明其简要原理和应用范围,并讨论它们在第四纪研究中的应用现状和前景。本文涉及的应用范围主要为:第四纪沉积环境、第四纪沉积物特征和成因类型。最后讨论了地质过程数学模拟的特点和意义、第四纪沉积过程数学模拟对提高第四纪地质学研究定量化水平的作用,以及进一步开展工作的方向。
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| 关 键 词： | 沉积过程 随机模型 确定模型 第四纪地质应用 |
BASIC MATHEMATICAL MODELS FOR SEDIMENTARY PROCESS SIMULATION AND THEIR APPLICATIONS IN .QUATERNARY GEOLOGY |
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| Institution: | Institute of Geology, Chinese Academy of Sciences |
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| Abstract: | Quaternary geology is a dicipline which studies historic law of development of Quaternary geological processes. Among numerous Quaternary processes, sedimentary processes are the most important ones. Therefore, physical and mathematical modeling of sedimentary processes is of important significance for Quaternary research. This paper deals with basic mathematical models for sedimentary process simulation and their applications in Quaternary geology. Models of mathematical simulation of geological processes may be divided into stochastic models and deterministic models. Ten stochastic models and ten deterministic models are introduced in this paper. Ten stochastic models of sedimentary processes may be described as follows: (1) Markov process model Markov process is one kind of random processes. Markov chain is one form of Markov process and it is often used in simulation of sedimentary processes. Markov chain may be regarded as a sequence or chain of discrete states in time (or space), in which the probability of transition from one state to a given state in the next step in the chain depends on the previous state. Markov chains are successfully used in modeling of stratigraphic succession consisting of alternating beds of different lithologics. (2) Semi-Markov process model The often used form of Semi-Markov process model is Semi-Markov chain which is a method for studies of comprehensive law of alternative of stratigraphic succession and bed thickness distribution. Semi-Markov chain is an ideal model for simulation of some kinds of sedimentary processes. (3) Poisson process model Poisson process is one kind of random processes available for stochastic modeling of turbidity current sedimentation. If the duration of bed formation equals the waiting duation between turbidity currents, Poisson process may be used for simulating the distribution of bed thickness. Some results were obtained. (4) Random walk process model Random walk process is another kind of random processes and they are often used in simulation of bed thickness distribution and sedimentary bed formation. (5) Kolmogorov model During period of intensive activity of erosion, new sedimentary beds may be formated due to erosion and accumulation. Kolmogorov model is available for simulating these processes, utilizing successive random variables instead of discreate random walk processes. From (6) to (10) renewal process model, stationary random process model, multivariate model, maximum likelihood model and replacement analysis model are introduced respectively. All of them are useful mathematical tools for simulation of sedimentary processes. Ten deterministic models of sedimentary processes may be introduced as follows: (1) Constant-mass model Constant-mass model is one of basic math ematical model for simulation of sedimentary processes. It assumes that during a finite time interval the mass of sediment deposited is equal to the mass eroded from older sedimentary rocks, plus the mass eroded from igneous rocks. During the same time interval the mass of old sediments is reduced by obliteration, partly by erosion and partly by melting. It is assumed that the mass obliterated by melting equals the sediment mass recently derived from the erosion of igneous rocks. Thus the sediment mass deposited during any time interval equals the sediment mass obliterated. Therefore, during any time interval the amount of sediment deposited is constant and equal to some fixed fraction of the total sedimentary mass. This model is available for simulating processes quantitatively. (2) Linear-accumulation model Linear-accumulation model assumes that the total mass of sediment has accumulated linearly through time. Certain equation of linear-accumulation model is given and this equation states that the mass deposited during a time increment equals the amount derived from the erosion of the total sedimentary mass during another time increment plus the fraction derived from the erosion of igneous rock and newly added to the mass of sedimentary rock. This model is another model available for simulation of sedimentary processes. (3) Sedimentary-basin model The basic concepts of this model can be described as follows: The shape of a body of sedimentary rocks varies as a function of the quantity of material supplied to the depositional site, the rate of subsidence at the site, the rate of dispersal and the nature of the material supplied. The basic concepts of the model may be realized by mathematical formula and computer. Thus a simulation can be done. From (4) to (7) erosion-sedimentatlon model, model of sedimentation in depressed basin, model for sedimentation controlled by ckanges of base levels and model for sedimentation in epicontinental sea are introduced respectively. (8) Evaporite-basin model An evaporite-basin model emphasizes materials balance and the model is set up based on the mass-conservation principles. This model is available for modeling formation of evaporite beds. In (9) and (10) delta and spit simulation models are introduced. Applications of the above-mentioned 20 mathematical models in studies of Quaternary sedimentary environment, characteristics and genetic types of Quaternary sediments are discussed in detail. |
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