分形求和法及其在地球化学数据分组中的应用

分形建模广泛地应用于具有自相似性不同尺度测量的地质现象空间分布特征。分形分布的特点要求大于等于某一尺度的数目,与物体大小之间存在幂函数关系,这种关系具有尺度不变性。这里提出的分形求和法可以确定地球化学数据分组界限。应用澳大利亚新南威尔士东北地区汇水沉积物地球化学数据,采用分形求和法确定其分组界限,并与传统的概率图模型结果进行比较。铜(Cu)元素数据划分二个部分,一部分是元素含量少于20 ppm的正态分布数据,另一部分是元素含量大于20 ppm的多个对数正态分布数据,能识别第三纪玄武岩区域和铜的主要矿化区。这一结论与使用传统的概率图模型方法得到的结论一致。该方法不仅适用于地球化学铜元素数据,而且还适用于其它元素和地质数据,具有普遍的意义。

Fractal summation methods and its application in geochemical element data for population limits

Fractal modelling has been applied extensively as a mean to the spatial distribution of geological phenomena that display self-similarity at differing scales of measurement.A fractal distribution exists where the number of objects exhibiting values is larger than a specified magnitude displays a power-law dependence on that magnitude,and where this relationship is scale-invariant.Population limits,derived from fractal modeling using a summation method,are compared with those derived from more conventional probability plot modeling of stream sediment geochemical data from north-eastern New South Wales.The dominant Cu population determined by fractal summation methods is similar to that from probability plots.The Cu data appears to divide into a normal distribution for values below the first population upper limit 20 ppm for the fractal plot and one or more lognormal distributions above 20 ppm thresholds,which can identifies both the regions of Tertiary basalts and main trend of Cu mineralization.The method can be not only applied to Cu data but also suited for other geochemical element data or geological data and has general meaning.