【摘要】 <正> 引言碳酸盐岩是沉积岩中非常重要的岩石类型。近二十年来,碳酸盐岩的成岩作用是国际上讨论得最热烈的问题之一。不同的人根据各自的观察和研究,对碳酸盐岩的成因提出了许多不同的模式。福克(Folk,1959)等人,根据当时研究得比较深入的碎屑岩的沉积原理认为,碳酸盐岩不是纯化学形成的,而是与碎屑岩碎屑的机械沉积方式相同,是一定的水动力条件的产物。据此,提出了以异化颗粒和泥晶灰泥为两个端元组分对碳酸盐岩进行结构分类。这一研究成果对于碳酸盐岩的研究起了巨大的推动作用。近二十年来,大多数研究者大都是基于福克的分类原则来划分碳酸盐岩的岩石类型,并据此来推断它们的沉积环境。在地质实践过程中发现,以异化颗粒和泥晶灰泥为两个端元组分来划分岩石更多还原

【Abstract】 Based on the diagenetic experiment of the modern carbonate sand sampled from Xisha Archipelago, this paper studis in detail the diagenetic changes of the texture, construction and mineral composition of carbonate in higher temperature and higher pressure. The results of the experiment show that the sand grains of carbonate are micritized in three ways during the diagenetic process; (1) fractured micri-tization, under higher pressure coarse carbonate grains are fractured into fine micri-tic grains with closely mosaic texture. (2) pressolutional micritization, along the contact zone between carbonate grains a micro-mudband is formed because of mutual squeeze and the band width is generally not large. (3) solution micritization. The carbonate dissolved under various actions is deposited and forms micritic-muddy grains in pores and cracks of rocks. In which the most important one is the fractured micritization in the experiment, but the other two may be very important factors in the practical diagenetic process.With the increase of the experimental temperature and pressure the compacting ratios of the sand columns and the micritization of carbonate grains gradually increase. The strong or weak micritization somewhat depends on the grain size and composition of the fragments. Coral and shall fragments are more easely micritized than other fragments.The arrangement of carbonate grains, in which the longer axis is perpendicular to the direction of the pressure force, shows a certain orientation under higher pressure.There are two cement types in the rock samples of the experiment: (1) open-filled cementation and (2) touched cementation,with the increase of temperature and pressure, the porosity of rocks samples rapidly decreases.The mineral composition of rock samples shows a distinct change during the dia-genesis, aragonate of some rocks samples changes gradually into calcite. This change mainly related to the properties of the fluid involved in the diagenesis as well as the temperature and pressure. Among these factors the most important one is the property of the fluid. If the fluid used in the experiment is fresh or rainwater, aragonate quickly changes into calcite under the same pressure and temperature; if the fluid is normal marine water or other saline water, the change is more difficult. Therefore, fresh water, higher temperature and pressure are favourable to the mineral change.更多还原