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    基底卷入型构造:特征、样式、机制与形成环境

    Basement-involved structures: characteristics, styles, mechanism and tectonic settings

    • 摘要: 基底卷入型构造是厚皮构造的主要类型之一,该类型构造发育于多种构造环境中,并非仅仅局限在活动大陆边缘地区,部分发育在远离活动大陆边缘的内陆地区,还涉及到造山带的形成、前陆盆地的破碎、高原的形成以及克拉通的变形等。基底卷入型构造中,基底与盖层变形既有联系又存在明显区别。一般而言,盖层厚度、基底先存构造、应力场方向以及基底与盖层的流变学差异等是控制基底卷入型构造的重要因素。目前,有关基底卷入型构造的动力来源,尤其是深处内陆地区的变形动力机制还尚不清楚,大洋板块低角度俯冲被认为是导致应力远距离传递的主要途径。中国大陆在中、新生代经历了多期次的构造-热事件,有发育基底卷入型构造的先决条件,在华北中部、准噶尔盆地以及青藏高原北部等地区均发现了典型的基底卷入型构造,它们的形成代表着不同的大陆地壳变形状态,既有高原形成过程中的变形,也有克拉通的缩短变形,还有代表着造山带前陆地区逐渐破碎化的过程。我国基底卷入型构造的研究尚未得到足够的重视,还缺少对这些变形在大陆变形过程中意义的深刻认识。我国华南地区中生代也经历了显著的大陆变形,然而区别于华北地区,华南地区基底卷入型构造的报道和研究更少,这可能是未来的研究方向之一。

       

      Abstract: The basement-involved structure is predominant in the thick-skinned structure and developed in various tectonic settings, which is not constricted within the peripheral of the active continental margins but also involves the formation of orogenic belts, fragmentation of foreland basins, formation of plateaus, and deformation of cratons. Some of these structures are developed in intracontinental areas far away from active continental margins. There are both links and differences between basement deformation and caprocks deformation in the basement-involved structure, including the thickness of caprocks, pre-existing structures of basement, stress field, rheological differences between basement and caprocks, thickness of caprocks and so on. At present, the formation of basement-involved structures, especially the deformation mechanisms in intracontinental areas, are still unclear, low angle subduction of oceanic plates is considered to be the main pathway leading to long-distance stress transmission. During the Mesozoic and Cenozoic, the Chinese mainland has experienced multiple tectono-thermal events, which are prerequisites for the development of basement-involved structures. At present, typical basement-involved structures have been found in central North China Craton, the Junggar Basin, northern Qinghai-Tibetan Plateau and other regions. Their formation mechanism and setting represent different important continental crustal deformation, including the deformation in the process of plateau formation, the shortening deformation of craton, and the process of gradual fragmentation of foreland areas of orogenic belts. However, the study of basement-involved structures in China has not drawn enough attention, and there is also less profound understanding on the influence of these deformations in the process of continental deformation. Southern China has also undergone significant continental deformation during the Mesozoic. However, unlike Northern China, there are fewer reports and studies on basement-involved structures in Southern China, which may be one of the future research directions.

       

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