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普定县境内碳酸盐岩地层出露面积约占总面积的84.27％,厚度占地层总厚度的77％,岩溶十分发育,类型较多,特征各异。本文根据岩溶发育特征与碳酸盐岩的野外观察分析,室内镜下鉴定,结合岩石化学成分,物理性质和单层、多层碳酸盐岩层地下水的化学分析资料,来阐明碳酸盐岩沉积时的环境(相带)、成岩作用及其对岩溶发育的影响。研究结果表明:台地边缘浅滩相带中高能搅动水浅滩环境内沉积的生物碎屑,鲡粒亮晶灰岩;开阔海台地相带内沉积的生物碎屑泥晶灰岩,岩溶发育最为完美,是正向地形突出的裸露型岩溶,形态类型为残留峰林、岩溶丘陵以及密度较大的漏斗、洼地和岩溶谷地;局限海台地相带中低能环境内沉积的泥晶、粉晶灰岩,岩溶发育中等,主要是正向和负向地形的裸露型岩溶,形态以岩溶丘陵和漏斗洼地为主,个体形态较小;陆棚相带中含粘土较多的层纹泥灰岩,岩溶发育一般较差,但在古老的地面上,可以发育成隐伏型岩溶,隐伏于覆盖物之下的溶沟和石芽也相当可观,在工程上是一种十分有害的隐患;对于封闭的咸化海、泻湖及潮汐坪带内蒸发较强的环境中的细、粉晶白云岩、含膏白云岩、白云化白云岩岩溶发育较差,成为覆盖型岩溶,覆盖层较厚,但覆盖层予下的溶沟和石芽亦较发育,覆盖漏斗深度很大;在礁相带内发育的岩溶,形态多种,地下河上天窗密布,峰林典型。海底成岩作用、强烈的化学(生物)的和生物的活动可以容易地改变和破坏灰质质点,或胶结起来成为颗粒集合体;在大陆淡水环境成岩时,将发生强烈的溶解作用和矿物成分的变化,在蒸发卤水和其他后生水渗过碳酸盐沉积物时,可以产生生物腐蚀作用,溶解作用,转化为低镁方解石。粒间孔隙的胶结作用,晶体重排列作用和交代作用,可以改变和扩大孔隙空间。在压实成岩作用时,可压缩孔隙,也可以产生收缩裂罅,缝合线构造等。成岩作用既可以改变岩面的化学成分,也可以改变岩石的物理特性和生物组构,可以缩小孔隙率,也可以扩大渗透率,因而可以促进或滞缓岩溶发育进程,其影响程度如何,则应视具体条件而异。
The area of carbonate rock formation in Puding county accounts for 84.27% of the total area, and the thickness accounts for 77% of the total thickness of the formation. Karst is well developed with many types and different features. Based on the analysis of the karst development characteristics and the observation and analysis of carbonate rocks in the field, the laboratory microscopic identification, chemical composition of rocks, physical properties and chemical analysis data of single-layer and multi-layer carbonate groundwater to clarify the carbonate deposition Environment (facies belt), diagenesis and its impact on karst development. The results show that the bioclastic and granodiorite sediments in high-energy agitating shoal facies in the marginal shoal facies belt of platform platform are the most perfect, It is a bare type of karst with a positive terrain. The morphological types are residual peak forest, karst hills, dense funnels, depressions and karst valleys; mudstones, powdered limestones and karst Medium-sized, mainly in the positive and negative topography of the bare type of karst, the shape of the karst hills and funnel depressions, the individual shape is small; continental shelf facies with more clay layered karstification, karst development generally more Poor, but in the ancient ground, can develop into a concealed karst, hidden under the cover of the ditch and stone bud is also considerable, in engineering is a very harmful hazard; for closed salty sea, Fine lava dolomite, dolomite-bearing dolomite and dolomitic dolomite in the lagoons and tidal flat evanescent environments developed poorly in karst facies and became cover-type karsts with thick overburden but with overburden Ditch and stone bud also Development, covering the funnel great depth; development in karst reef facies, various forms, the underground river skylight clouds, typical peaks. Seabed diagenesis, intense chemical (biological) and biological activity can easily change and disrupt the gray matter, or become a collection of particles; in the continental diagenetic environment, strong dissolution and mineral composition changes , In the evaporation of brine and other water after infiltration carbonate sediments, can produce biological corrosion, dissolution, into low-magnesium calcite. Intergranular pore cementing, crystal rearrangement and account of the role, can change and expand the pore space. In the compaction of diagenesis, can compress the pores, can also produce shrinkage cracks, suture structure and so on. Diagenesis can not only change the chemical composition of the rock face, but also change the physical characteristics and biological structure of the rock. It can reduce the porosity and permeability, thus promoting or slowing the development of karst. What is the degree of influence? It should be different depending on the specific conditions.