Abstract Aragonite and high-magnesium calcite are abundant constituents of modern shallow marine carbonate sediments, but are rare in ancient carbonate rocks. Because these minerals are metastable, they tend to stabilize to microcrystalline calcite which is ubiquitous in most Phanerozoic marine and lacustrine limestones. Calcite microcrystals exhibit a range of textures that have been classified in terms of crystal size, morphology, and contact geometry. These textures have the potential to reveal information about the precursor sediments as well as the diagenetic conditions of stabilization, and thus may serve as a proxy for paleoenvironmental conditions. However, despite their ubiquity and importance, the origin of these textures is controversial. Hypotheses regarding the origin of calcite microcrystal textures typically involve inferences regarding the precursor depositional sediments, diagenetic conditions of stabilization, or diagenetic processes. Here, hundreds of laboratory experiments were conducted in which metastable carbonate sediments were stabilized to calcite. The goal of these experiments was to investigate the depositional and diagenetic controls on calcite microcrystal textures. The depositional variables investigated were precursor mineralogy, type, and size, and the diagenetic variables were temperature, fluid chemical composition, and fluid:solid ratio. Our results show that experimental stabilization of carbonate sediments produces calcite with a wide variety of textures depending on the various depositional and diagenetic parameters. These textures are remarkably similar to those commonly observed in the rock record. Calcite microcrystal morphology is controlled by fluid chemistry, fluid:solid ratio, and reactant type. Calcite microcrystal size is controlled by temperature, fluid chemistry, fluid:solid ratio, and reactant size. The degree to which calcite microcrystals are fitted together is controlled by reactant size and reactant microstructure. Our findings challenge most of the existing hypotheses regarding the origin of calcite microcrystal textures. We specifically show that textures that have been interpreted to indicate late diagenetic processes such as dissolution and cementation, may be the result of the early diagenetic processes of stabilization.

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碳酸盐沉积物对方解石的实验稳定：深入了解方解石微晶结构的沉积和成岩控制

摘要 文石和高镁方解石是现代浅海相碳酸盐岩沉积物中的丰富成分，但在古代碳酸盐岩中很少见。由于这些矿物是亚稳态的，它们倾向于稳定为微晶方解石，这种方解石在大多数显生宙海相和湖相石灰岩中普遍存在。方解石微晶表现出一系列纹理，这些纹理已根据晶体尺寸、形态和接触几何形状进行分类。这些纹理有可能揭示有关前体沉积物的信息以及稳定的成岩条件，因此可以作为古环境条件的代表。然而，尽管它们无处不在且很重要，但这些纹理的起源是有争议的。关于方解石微晶结构起源的假设通常涉及关于前体沉积沉积物、稳定的成岩条件或成岩过程的推论。在这里，进行了数百次实验室实验，其中亚稳态碳酸盐沉积物稳定为方解石。这些实验的目的是研究方解石微晶结构的沉积和成岩控制。研究的沉积变量是前体矿物学、类型和大小，成岩变量是温度、流体化学成分和流体：固体比。我们的结果表明，碳酸盐沉积物的实验稳定产生了具有多种质地的方解石，这取决于各种沉积和成岩参数。这些纹理与岩石记录中常见的纹理非常相似。方解石微晶形态受流体化学、流体：固体比和反应物类型控制。方解石微晶尺寸受温度、流体化学、流体：固体比和反应物尺寸控制。方解石微晶装配在一起的程度由反应物尺寸和反应物微观结构控制。我们的发现挑战了大多数关于方解石微晶结构起源的现有假设。我们特别表明，已被解释为表明溶解和胶结等晚期成岩过程的纹理可能是早期成岩稳定过程的结果。固体比和反应物类型。方解石微晶尺寸受温度、流体化学、流体：固体比和反应物尺寸控制。方解石微晶装配在一起的程度由反应物尺寸和反应物微观结构控制。我们的发现挑战了大多数关于方解石微晶结构起源的现有假设。我们特别表明，已被解释为表明溶解和胶结等晚期成岩过程的纹理可能是早期成岩稳定过程的结果。固体比和反应物类型。方解石微晶尺寸受温度、流体化学、流体：固体比和反应物尺寸控制。方解石微晶装配在一起的程度由反应物尺寸和反应物微观结构控制。我们的发现挑战了大多数关于方解石微晶结构起源的现有假设。我们特别表明，已被解释为表明溶解和胶结等晚期成岩过程的纹理可能是早期成岩稳定过程的结果。我们的发现挑战了大多数关于方解石微晶结构起源的现有假设。我们特别表明，已被解释为表明溶解和胶结等晚期成岩过程的纹理可能是早期成岩稳定过程的结果。我们的发现挑战了大多数关于方解石微晶结构起源的现有假设。我们特别表明，已被解释为表明溶解和胶结等晚期成岩过程的纹理可能是早期成岩稳定过程的结果。