不同成岩期泥质岩非构造裂缝发育规律、形成机理及其地质意义

通过野外剖面踏勘、井下岩芯观测、镜下微区扫描等，初步探讨了泥质岩非构造裂缝（泥裂）的发育期次、空间展布形态、裂缝开裂模式及影响因素等。研究表明:（1）泥裂发育可以分为3个期次，依次为同生成岩期、埋藏成岩期（早成岩期和中-晚成岩期）和表生成岩期，各期泥裂发育数量与面孔率表现为∑同生期＞∑表生期＞∑埋藏期；（2）泥裂开裂方式主要包括3大类7种模式； （3）现代泥裂发育通常经历四个阶段，其中砂-泥旋回地层中砂层的润滑作用有助于泥裂的形成，并为早期裂缝填充提供了物质保障，同时，此类地层也有利于异常高压缝的发育；（4）泥裂单边延展开裂后期通常产生分叉，分叉角度多为120°，其次为90°，主要与沉积物颗粒均质性和能量释放有关；（5）影响泥裂发育的因素有多个方面，其中粘土含量和盐度决定着泥裂的发育程度，地形坡度控制着泥裂的空间组合形态，沉积旋回影响着泥裂的开裂方式、位置及裂缝内填充模式等;（6）构造裂缝的存在对泥裂的发育与保存具有一定的积极作用，二者互相影响。

The Growth Patterns and Mechanisms of Mud Cracks at Different Diagenetic Stages and Its Geological Significance

This paper discusses the growth stages, spatial structures, quantitative fitting relationships among various parameters, growth patterns and influencing factors of mud cracks by field survey, core observation and SEM analysis. The study shows that: (1) Mud crack growth can go through three stages, i.e. syndiagenetic stage, burial diagenetic stage (including early diagenetic stage, middle late diagenetic stage) and epidiagenetic stage in turn. The number of mud cracks in different stages is represented as Σ syndiagenesis > Σ epidiagenesis > Σ burial diagenesis. (2) Mud crack growth has three models, such as unilateral growth model including linear growth pattern, curvilineal growth pattern and bifurcation growth pattern, multilateral growth model including intersectional growth pattern, join growth pattern and dispersed growth pattern, and mixed growth model including the combination of any patterns listed above. (3) Modern mud crack growth usually undergoes four stages, among which, sand beds in sand mud rhythmic strata can play a lubricative role on crack growth, and provide enough sandy sediments for filling cracks. (4) Mud crack growth usually produces bifurcation and bifurcation angle is mostly 120,  then 90, mainly related to sediment heterogeneity and released energy. (5) Factors affecting mud crack growth cover many aspects, that is to say, clay content and salinity can control the number of mud cracks in different areas, terrain can control mud crack morphology, and different sedimentary cycle can control the growth patterns and filling models of mud cracks. (6) Structure fractures can contribute to the growth and preservation of mud cracks, and they affect each other at different diagenetic stages. 