大陆板内构造变形及其动力学机制

典型大陆板内变形发生在克拉通化的大陆岩石圈内部,距离同变形期活动板块构造边界数百至2000km以上。收缩变形主要表现为区域尺度的盆地构造反转、结晶基底与上覆盖层共同卷入变形的厚皮式逆冲构造,具有变形局部化特征。因为流变学分层特征不同,大陆板内变形可以发生在中上部地壳、整个地壳乃至岩石圈尺度上,表现为不同波长的地壳或岩石圈尺度纵弯弯曲。大陆岩石圈板块内部物质组成与结构的不均一性、流体活动、热作用、克拉通内盆地巨厚沉积产生的覆盖效应、地壳加厚等导致的岩石圈强度的局部降低等,是导致大陆板内变形以及应变局部化的原因。构造活化是大陆板内变形的重要方式。板块俯冲或碰撞远程效应被认为是大陆板内变形的主导动力学模型,但是放射性元素积累导致的岩石圈强度热弱化,或大陆冰川消退触发板内应力状态变化等导致大陆板内变形的动力学模型也应该引起关注。

A review on the continental intraplate deformation and its dynamics.

Typical continental intraplate deformations developed within the craton interior where are several hundreds to more than 2 000 km away from the synchronous active plate boundaries. Intraplate contractional deformations are characterized by the inversion of former extensional basins and the basement-involved thick-skinned block upthrusting with strain localization, as well as the whole crustal or lithospheric buckling folds with varied wavelength depending on the rheological stratification of the lithosphere. The heterogeneities of the lithospheric composition and structure act as the fundamental bases for the continental intraplate deformation. The continental intraplate deformation and the strain localization are inferred to be controlled by the lithospheric weakening resulting from the thermal and fluid activities, thermal blanketing effect of the huge accumulation of sediments within the cratonic basins, and the thickening of the crust and lithosphere as well. Tectonic reactivation serves as a dominant deformation process in the continental intraplate deformation. Far-field effects of plate subduction and collision are invoked as the major dynamic model for the continental intraplate deformations so far. However, new developed dynamic models independent of plate interactions, such as the lithospheric weakening induced by the regional enrichment of radioactive elements and the large-scale isostatic disequilibrium of the lithosphere-asthenosphere system caused by deglaciation, deserve much more attention.