克拉通演化的超大陆背景与克拉通盆地的成因机制

Supercontinent background of the evolution of cratons and the genetic mechanism of the cratonic basins

研究表明克拉通的形成与超大陆的汇聚和裂解有着重要关系。本文对近年来超大陆重建的研究进行了分析对比,对克拉通发展与超大陆事件的关系做出了总结。前人对超大陆的研究表明,其形成与地幔动力有直接联系,地幔柱重组的旋回导致了超大陆的旋回。Phillips and Bunge(2007)在前人三维球体地幔对流模型的基础上加入大陆进行了模拟实验,结果显示周期性的超大陆旋回只发生在理想模型中,而Senshu et al.(2009)对代表陆壳的英云闪长岩一奥长花岗岩—花岗岩(TTG)地壳进行了研究,提出随着俯冲的TTG地壳产热速率的下降,超大陆旋回的周期随之变长;更有许多学者指出,历史上哥伦比亚超大陆存在时间明显较长,因此超大陆的旋回并不具有周期性。对近年来不同学者提出的哥伦比亚、罗迪尼亚、冈瓦纳、潘基亚4个超大陆新的重建证据进行分析,大致确定出上述4个超大陆的形成时间、格局及演化过程。此外,对华北、东欧、西伯利亚、亚马孙、刚果、西非6个克拉通各自的演化进行分析,也显示出克拉通演化与超大陆汇聚及裂解在时间与空间上有对应关系。通过分析得出克拉通演化与超大陆旋回有关,且确定出克拉通演化的4个超大陆旋回。本文最后讨论了克拉通盆地的成因机制以及3种端元类型,并将盆地的发育与超大陆演化的巨旋回相联系。

Previous research shows that the formation of cratonic basins and the assembly and breakup of supercontinents have important connection.This paper analyse and compare the recent research of the reconstructions of supercontinents as well as the relationship between evolution of cratons and supercontinents event.According to previous research,the supercontinents formation is directly related to forces from mantle,and the cycle of the reassemble of the plume results in the supercontinent cycles.Phillips and Bunge （2007） coupled multiple continents with the former three-dimensional spherical mantle convection model,and the results suggest that periodic supercontinent cycles only occur in idealized models.Senshu et al.（2009） studied on the TTG （tonalite-trondhjemite-granite）crust which indicating the continental crust,and they proposed that the heat producing rate of the subducted TTG crust will decrease,thus the supercontinent cycle will become longer,then many researchers pointed out that the Columbia supercontinent existed longer than other supercontinents,thus the cycle of supercontinent shows no periodic characteristics.Analysing and making comparison to the recent new evidence of the reconstructions of the Columbia,Rodinia,Gondwana and Pangea supercontinent proposed by different researchers,we generally obtained the fomation time,configuration and evolution progress of the four supercontinents.Our summary of the evolution of North China,East Europe,Siberia,Amazon,Congo and West Africa craton reflects the spatial and temporal relationship between the evolution of cratons and the assembly and breakup of supercontinents,for instance,some parts of the Columbia splited and rotated and then collided with the remnants at 1.25～ 1.0 Ga,thus the Rodinia assembled,while the Congo craton experienced compression at 1.02 Ga is suspected connecting with the assemble of the Rodinia,according to above,we believe that craton evolution is related to supercontinent cycles,and we also present the four supercontinent cycles of the evolution of craton.At the end of this paper,we discussed the genetic mechanism of cratonic basins and their three end-member types,at the same time,we coupled the growth of the basins with the super cycles of the evolution of supercontinents.