关于“沉积成矿系列”的若干理论问题 |
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引用本文:宋天锐.1987.关于“沉积成矿系列”的若干理论问题[J].地球学报,9(2):83-93. |
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中文摘要:作者对“沉积成矿系列”的研究和划分,考虑到一系列因素,如岩相古地理环境、地球化学、生物地球化学、气候、水动力条件以及大地构造和岩浆作用的叠加等。沉积成矿系列中的矿床类型、矿床规模、富矿分布、成矿系列的完整性都受到上述因素综合制约。文章详述了“盆地外”和“盆地内”,还原和氧化对系列的影响不同,并着重强调“盆地内”“还原”环境的重要性。文中指出微生物在局部还原微环境中对造矿作用的意义;层控型沉积成矿系列中蒸发岩和白云岩所起的“封闭”作用大致可与石油-天然气的“生、储、盖”三条件类比。 |
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ON SOME THEORETICAL PROBLEMS OF“SEDIMENTO- MINEROGENETIC SERIES”OF MINERAL DEPOSITS |
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Abstract:The concept of minerogenetie series of mineral deposits was suggested by Professor Cheng Yuqi in the late 70s.The establishment and the classification of minerogenetie series (and series associations) are based on synthetic studies of the regional setting, in which the various types of mineral deposits concerned are formed, emphasis being put on their interrelationship in the light of the geological evolution of the specific minerogenetie epoch and region as an entity. Such a study serve as a scientific basis for the areal minerogenetie analysis and also as a guide to mineral prognostics. It is thus different to various schemes of classification of mineral deposits, which emphasize on the concrete characteristics and formation conditions of individual mineral deposits rather than the regional and collective features.Sedimento-minerogenetic series (series associations) is one of the three major groups of the minerogenetie series of mineral deposits, and six theoretical problems of its formation genesis are considered in this paper.In regard to the facies-paleogeographic or environmental features of the sedimentational epoch concerned, a distinction should be made between the specific deposits formed inside the depositionsl basin and those outside it (Fig. 1), with emphasis on the environment in the basin.As to the geochemical and biogeochemical factors which may influence the formation of relevant deposits, the difference between the reducing and oxidizing conditions is of great significance. Attention should also be paid to the possible existance of decomposition of organic remains (Fig. 2), including those of microorganisms, which may lead to a local reducing environment that is favourable to the formation of certain Cu-Pb-Zn and other relevant minerogenetie series.With regard to the climatic and hydrodynamic factors in the minerogenetie analysis of the sedimentogenetic deposits, the protolithic, vertical mine- rogenetic zoning, in the character of temporal variation of sedimentation, and the original, horizontal zonaation of deposits resulted from spatial difference in deposition, are two important subjects of study. The importance of direct water currents in the placer ore-accumulation should, however, not be neglected.And lastly, concerning the tactonic factors, the occurence of geosubsiden-ces, either within the continents or along their margins, are of paramount importance. They often serve as locations for the accumulation of Meso-Ceno-zoic oil and gas-and coal-bearing formations. |
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