湖北大冶铁山地区缝合线三维形态模拟及其成因分析

Forming and Simulation of Three-Dimensional Morphology of Stylolites in Tieshan,Hubei Province,South China

广泛发育于碳酸盐岩中的缝合线构造可以用来分析构造应力方位、计算岩层的有限应变和恢复原始地层厚度;同时,缝合线可以是石油、天然气和地下水的储积场所和运移通道。湖北大冶铁山地区发育有大量的缝合线构造。通过影像云纹法和GIS技术恢复了采自该地区的数枚缝合线标本的三维数字形态。利用该模型对缝合线的尺度、坡角、粗糙度、谷底点分布、二维剖面形态和压溶量等进行了定量分析,完善了缝合线的几何形态学研究并在此基础上对其成因进行了解释,认为铁山地区的缝合线主要由成岩压实作用和压溶作用形成,缝合线在从初始到各种复杂形态的发展过程中主要受两个因素控制:一是岩石的力学性质;二是由主压应力引起的局部应力集中而产生的溶解释放。

Stylolite, which is identified in the limestone, is widely used to determine stress direction, calculate the finite strain and estimate the original thickness of strata. In addition, stylolites are also the storage spaces and transportation channels of oil, natural gas and underground water. Stylolites commonly developed in Tieshan formation are suitable for the simulation. Using the Shadow Moire method and GIS technique, this study analyzed several samples collected from Tieshan area for their three-dimensional digital morphology, which proved quantitative scale, slope, roughness, distribution of troughs, two-dimensional sections view, and amount of pressure solution of stylolites. Further we promoted the morphology of the stylolites. This paper concluded that stylolites in Tieshan area were produced by compaction and pressure solution in limestone. The forming of the stylolites depends on both factors, i. e. , the nature of rock mechanics and the solution-release mechanism created by the local stress concentration.