基于分形理论的板块形态重建

Plate reconstruction based on fractal theory

全球板块重建的精细化和区域化是当前研究的热点领域之一。值得注意的是,针对重建板块形态分布规律的研究,尚未充分展开。在大数据背景下,本文根据已有板块重建模型,对中生代以来的重建板块的形态,进行了分形维数分析,并结合斑岩型铜矿床的频数分布规律,讨论了分形维数和斑岩型矿床频数对板块重建整体性评估的意义。研究结果表明,自250 Ma以来的地质历史时期,全球重建板块形态的分形维数具有先下降后上升的特点,在65 Ma达到最小,可能代表了由Pangea超大陆向未来超大陆Amasia的转换。此外,全球斑岩型铜矿床的频数异常与板块重建形态的分形维数异常具有良好的对应关系,表明板块运动过程中产生的快速形变与斑岩型铜矿床形成之间具有密切的联系。该结果可能将为整体性评估重建板块形态的真实性提供一个全新的方法,特别是对约束古老板块的形态方面,具有一定的科学价值;同时,也能为斑岩型铜矿床的成因,提供对照参考的数据基础。

The refinement and regionalization of global plate reconstruction is currently a hot topic in geological study.However,determination of shape distribution of reconstruction plates has not been fully carried out.Based on the existing plate reconstruction models,we analyzed the relationship between fractal dimensions of the reconstruction plates and frequency of global porphyry copper deposits since the Mesozoic.The results showed that the fractal dimensions of 250-65 Ma plates has a minimum at 65 Ma,which reflects the switching process from Pangea breakup to Amasia assembly.Moreover,the frequency anomalies of global porphyry copper deposits correspond well with the fractal dimension anomalies of reconstruction plates since 250 Ma,which suggests that the rapid change of plate morphology may affect the formation of porphyry copper deposits.Our findings provide new insights into evaluating authenticities of reconstruction plates and restricting morphology of ancient plates.Meanwhile,they can also provide reference data for the genesis of porphyry copper deposits.