作　　者： ; ;

机构地区： 东华理工大学

出　　处： 《大地构造与成矿学》 2019年第3期518-527,共10页

摘　　要： 先存断层的活化对许多热液矿床的形成起到至关重要的作用。加拿大阿萨巴斯卡盆地的不整合型铀矿是一个受活化断层控制矿床的典型例子。该铀矿产于基底与盆地砂岩之间的不整合面附近,并与根植于基底的断层密切相关。这些控矿基底断层切穿并错动了盆地的不整合面。一系列证据表明这些基底断层以韧性的方式形成于盆地之前,但在盆地形成之后又发生脆性活化,而正是这种断层活化作用控制铀矿的产出。先存断层作为完整岩石中的薄弱位置,在后期构造运动中,其活化比产生新断层更容易发生。数值模拟表明在后期挤压构造运动中,有先存基底断层的不整合面被显著错动,而无先存断层的不整合面并没有错动。基底断层的脆性活化,不仅在活化过程中为流体提供了驱动力,而且由于活化导致岩石渗透率的提高,为后期的流体流动提供了通道以及容矿场所,形成阿萨巴斯卡盆地的不整合型铀矿。 Reactivation of pre-existing faults plays an important role in the formation of many hydrothermal ore deposits. The unconformity-related uranium deposits in the Athabasca Basin (Canada) is a good example of controls of fault reactivation on hydrothermal mineralization. The unconformity-related uranium deposits in the Athabasca Basin are closely associated with basement faults, which have significantly displaced the unconformity surface between the basin and basement. These faults were initially formed before the basin but were reactivated after the formation of the basin;it is the reactivation of the basement faults that controlled the uranium mineralization. Pre-existing faults represent structural weakness, therefore, it is easier for fractures to form along pre-existing faults (i.e., fault reactivation) than to be created in the intact rocks. Numerical simulation demonstrates that during tectonic compression, the unconformity surface with pre-existing basement fault was displaced, whereas the unconformity without pre-existing basement fault was not displaced. The process of fault reactivation and the resultant enhancement of permeability facilitate fluid circulation and mineralization, and eventually control the uranium mineralization in the Athabasca Basin.

关 键 词： 断层活化 构造控矿 阿萨巴斯卡盆地 不整合型铀矿

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