湘中锑矿带断裂构造信息维特征及其意义

THE INFORMATION DIMENSION OF FRACTURE SYSTEM AND ITS SIGNIFICANCE IN THE ANTIMONY MINERALIZED ZONES OF CENTRAL HUNAN

运用信息维的原理与方法对湘中锑矿带断裂构造体系的二维平面分布特征进行了研究。结果表明，信息维较之容量维更能反映断裂体系的结构特征，各矿带信息维值的差异定量地刻画了断裂的相对发育程度及分布特点。结合各矿带内锑矿床的分布特征，可发现信息维值的大小对成矿流体的运移和矿床定位有一定的指示作用，锑矿（点）产出较多、矿床储量较大的地区，其信息维值较大。

Formation of fractures is an important geological phenomenon which produced break and displacement of rocks by crust stress. From the mathematical viewpoint the observed spatial distribution of fractures is a series of irregular line shaped and plane shaped geometric body set. Regarding the irregular shaped geometric body set as a fractal body, the fractal dimension of spatial distribution characteristics of fractal body can be quantitatively calculated by using fractal geometric method. The NE and NNE fracture systems of antimony mineralized zones in central Hunan control the migration of ore forming fluid and location of antimony deposits in the region. In present paper,the principles and methods of information dimension are applied to the study of fractal characteristics of the two dimensional distribution of fracture system in the antimony mineralized zones,central Hunan. The research of the information dimension (D1) of fracture system considers the contribution of each fracture to information,reflects the characteristics of spatial distribution of fractures from a new point of view, and avoids the shortcomings of the fractal dimension of capacity(D0). The results of calculation show that the information dimension of fractures in three antimony mineralized zones are 1.706, 1.810 and 1.593 for Simingshan zone, Xikuangshan Longshan zone and Dashenshan zone respectively. The difference in information dimensions of fracture system in antimony mineralized zones quantitatively describes the fracture intensity and fracture distribution. It also shows that these three antimony mineralized zones of central Hunan belong to three self-similar systems with different information dimensions. Integrating with the characteristics of antimony deposit distribution of all zones, it can be noted that the numerical value of information dimensions for fractures can trace the migration of ore-forming fluid and indicate the location of antimony deposits. The more the antimony deposits and the larger the ore reserves, the higher the information dimension values.