红河断裂两侧早第三纪古地磁研究及其地质意义

通过在红河两侧（大姚、景谷、江城、勐腊剖面）的早第三纪古地磁样品的研究，进一步证实了红河两侧由白垩纪古地磁研究所揭示的印支地块相对于华南地块存在的左旋相对运动。这一结果说明了印度支那地块在印度板块的挤压下，于早第三纪至中新世沿红河大断裂发生向南侧向滑移达1000km左右，它不仅使青藏高原的巨大构造缩短得到调整，而且在北部湾地区形成伸展构造，并引起南中国海的张开。印度支那地块北部各地区的差异性旋转和红河断裂共轭的剪切断裂系的发育，以及红河大断裂早第三纪至中新世左旋剪切作用密切相关。

Palaeomagnetic Study of the Early Tertiary on both Sides of the Red River Fault and Its Geological Implications

Palaeomagnetic study was carried out in four Early Tertiary sections in the eastern (Dayao area) and western (Jinggu, Jiangcheng and Mengla areas) parts of the Red River fault. The study further confirms the post-Cretaceous clockwise rotation and sinistral motion of the Indochian block relative to the South China block (SCB). The results revealed a 1000 km-sinistral motion of the Indochina block along the Red River fault due to the penetraction of the Indian plate into Asia from the Early Tertiary to Miocene. This sinistral motion not only accommodated the huge crustal shortening of the Tibetan plateau, but also led to the extension tectonics in the Beibu Gulf and the opening of the South China Sea. The differential rotations of different parts in the northern Indochina block and the development of the shear zones conjugated with the Red River fault are closely related to the sinistral shearing of the Red River fault from the Early Tertiary to Miocene. These results show that extrusion is one of the main mechanism which accommodates crustal shortening during the India - Asia collision.