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本文通过分析滇南地区不同时代的沉积物发育特征和构造形变,揭露区内构造发育面貌,并以大的岩石圈板块(包括古板块)边界的活动和迁移来解释不同时期的构造发育。 作者依据断层运动与相关地貌发育的关系确定了滇南地区第四纪活动断层;根据第四纪地表形变资料探讨曲江断裂的运动与相关的曲溪盆地的发育机制,确定了区内构造应力分布与断层运动特征。指出本区自第四纪以来,构造应力场较以前有明显的改变,主要在近南北向的挤压应力作用支配下,导致区内块断运动,其运动形式表现为北西向高角度走滑断层运动,造成一些部位引张发育成盆地,同时使另一些部位挤压抬升和地壳增厚,形成涡漩状重力负异常。这种高角度走滑断层运动和盆地发育相匹配的图案与板块边界的裂谷和转换断层之间的发育关系颇为相似。 作者指出滇南地区的历史强震主要发生在这些走滑型断层上,通海大地震就是一例;并强调指出评价大震危险区时应对这些走滑型断层给予充分的重视。
In this paper, by analyzing the sedimentary development and tectonic deformation in different ages in southern Yunnan, the tectonic development of the area is revealed and the tectonic development in different periods is explained by the activity and migration of the large lithospheric plate (including the old slab). Based on the relationship between fault movement and related landform development, the authors determined the Quaternary active faults in southern Yunnan. Based on the Quaternary surface deformation data, the authors discuss the movement of the Qujiang fault and the related Qu Xi basin development mechanism, and determine the tectonic stress Distribution and fault movement characteristics. It is pointed out that since the Quaternary, the tectonic stress field has changed obviously from the past, mainly under the compressional stress near the north-south direction, leading to block motion in the area. Fault movement, resulting in the extension of some parts of the development of the basin, while other parts of the crustal uplift and crustal thickening, the formation of swirling gravity negative anomaly. The pattern of this high-angle strike-slip faulting and basin development is quite similar to the developmental relationship between rift and transition faults at plate boundaries. The author points out that the historical strong earthquakes in southern Yunnan mainly occur on these strike-slip faults, and the Tonghai Earthquake is an example. It is also emphasized that sufficient attention should be paid to these strike-slip faults in the assessment of the danger zone of large earthquakes.