关于鲕粒形成原因的相关研究综述

A Review of Related Studies on Oolitic Genesis

摘要: 鲕粒这种特殊的沉积颗粒，在地质学中具有重要的意义。它们广泛存在于古代和现代沉积环境中，常被用作反映古气候和古海洋学指标的依据，如海平面、氧化还原状态、水深、温度、盐度和水动力环境等。关于鲕粒的成因，主要有无机成因和有机成因两种说法。无机成因认为，鲕粒是在碳酸盐过饱和且扰动的水体环境中，由溶液中析出的碳酸钙围绕着被水扰动浮起的质点为核心沉淀而成的。这个过程需要满足一定的条件，如碳酸钙的过饱和、充足的核心以及动荡的水流等。而有机成因则主张鲕粒的形成与微生物的活动有关。一些学者认为，微生物的代谢活动可以改变溶液中的pH值，从而导致碳酸盐矿物的沉淀。此外，胞外聚合物还可以为碳酸盐矿物的生长提供成核位置。不过，也有学者通过实验和观察对有机成因提出了挑战，他们认为微生物活动并不是鲕粒形成的直接原因，而是强调了化学过程在鲕粒形成中的重要性。

Abstract: Oolitic is a special sedimentary particle, which is of great significance in geology. They exist widely in ancient and modern sedimentary environments, and are often used as the basis for reflecting paleoclimate and paleoceanographic indicators, such as sea level, REDOX state, water depth, temperature, salinity and hydrodynamic environment. There are two kinds of theories about the origin of oolith: inorganic origin and organic origin. According to the inorganic origin, the oolitic particles are precipitated by the calcium carbonate precipitated from the solution around the particles floated by the water disturbance in the supersaturated and disturbed water environment. This process requires certain conditions, such as supersaturation of calcium carbonate, an adequate core, and turbulent water flow. The organic origin suggests that the oolitic formation is related to the activity of microorganisms. Some scholars believe that the metabolic activity of microorganisms can change the pH in the solution, which leads to the precipitation of carbonate minerals. In addition, extracellular polymers can also provide nucleation sites for the growth of carbonate minerals. However, some scholars have challenged the organic origin through experiments and observations. They believe that microbial activities are not the direct cause of oolitic formation, but emphasize the importance of chemical processes in oolitic formation.