南海南部断裂的分形研究

分形几何作为定量描述自然界中复杂非线性现象的强有力工具被应用于南海南部断裂体系的研究中,通过数盒子法计算了断裂分布的分维值.研究结果表明这种方法是可行的,断裂分布的分维值能有效地描述断裂的空间分布特征.南海南部断裂体系在标度区间25~250km具有很好的统计自相似性,全部断裂的分维值为1.6601,北东向断裂的为1.3875,北西向断裂的为1.2693.根据断裂分维等值线,沿西南海盆扩张轴,两侧断裂呈对称展布;北东向的与北西向的在空间上有一定的互补性,这反映了两组断裂在发育过程中的相互制约性.结合南海的构造演化及南海南部油气盆地的分布,初步探讨了断裂分形特征与南海的构造演化及断裂分形特征与油气盆地分布之间的关系.

Fractal analysis of faults in the southern part of the South China Sea

Fractal geometry is a good method to describe the natural nonlinear phenomena quantitatively,and fractal dimension is a quantitative parameter.The fractal geometry is applied to studying the fault systems in the southern part of the South China Sea.Results indicate that the spatial distribution of all faults in the southern part of the South China Sea is a distinct fractal set with self-similarity in the non-scale range of 25~250 km,and the fractal dimension(capacity dimensions),obtained by a box-counting method,interprets well the characteristics of the spatial distribution of faults.The fractal dimension of all faults in the study area is 1.660 1,that of the NE-trending faults 1.387 5 and that of the NW-trending faults 1.269 3.Showed by isoline maps of fractal dimensions,faults arrange symmetrically on two sides along the spreading axis of the Southwest Subbasin;the densities of spatial distribution of the NE-trending faults and the NW-trending faults supplement to each other,indicating the inter-restraint properties of these two groups of faults.At last,correlating the fractal characteristics of the spatial distribution of faults with the evolution of the South China Sea and the distribution of basins bearing oil or gas,it is tried to find out the relationship between the fractal characteristics and evolution of the South China Sea and that between the fractal characteristics and distribution of basins bearing oil or gas.