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,将其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内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 Spatial Fault Distribution in the Southern South China Sea

Fractal geometry can effectively quantify naturally nonlinear or much complicated phenomena, and fractal dimension is the quantitative parameter. In this paper, we applied fractal geometry to analyze spatial fault distribution of the southern South China Sea. Calculation results indicate that the spatial fault distribution of this area have remarkable fractal features in a non-scale interval of 25 - 250 km, with fractal dimensions of 1.660 1, 1.387 5, and 1.269 3 for all faults, NE-trending faults and NW-trending faults, respectively. These dimensions (capacity dimensions), obtained by box-counting method, represent well the characteristics of spatial fault distribution. Displayed by isoline-maps of fractal dimensions, faults in the study area arrange symmetrically along the spreading axis of the Southwest Sub-basin, and density of the NE-trending faults supplements to that of the NW-trending faults, revealing a property of mutual restriction between these two groups of faults. At last, by correlating the fractal features of spatial fault distribution with the evolution of the South China Sea and the distribution of oil or gas basins, we tried to reveal their relationships.