中国西南思茅地体中部白垩纪古地磁结果及陆内地壳变形特征

对我国西南地区思茅地体中部巍山和五印地区白垩纪地层进行了详细的岩石磁学和古地磁研究，获得了两个地区的高温剩磁分量并通过了褶皱检验.巍山剖面特征剩磁方向为Ds=64.3°，Is=48.5°，k=54.6，α95=4.7°；五印剖面特征剩磁方向为Ds=15.4°，Is=44.8°，k=212.0，α95=4.6°.通过思茅地体磁偏角变化与兰坪—思茅褶皱带构造线迹变化的相关性分析，确定思茅地体内部差异性旋转变形受控于思茅地体弧形构造带的形成和演化.通过青藏高原东南缘走滑断裂带活动年代分析，确定兰坪—思茅褶皱带蜂腰构造部位形成于两期构造事件，早期构造变形与东喜马拉雅构造结北北东向挤压缩进有关，后期构造变形与川滇微地块发生顺时针旋转时南向挤出运动有关.以华南板块稳定区白垩纪古地磁极为参考极，计算得出巍山和五印相对于华南板块分别发生了10.5°±6.0°和3.8°±4.9°的南向运移量.通过选取思茅地体内部构造形态较稳定的巍山和普洱地区白垩纪古地磁极为参考极，计算得出五印相对于巍山和普洱分别发生了3.4°±5.0°和3.1°±5.4°的北向纬向运移，表明五印和和巍山之间自印亚碰撞以来经历了较大规模的北向地壳缩短变形作用.

The Creatceous paleomagnetic results from the central part of the Simao Terrane in the southwest part of China and its tectonic implications

Detailed paleomagnetic and rock magnetic studies were carried out on the Cretaceous red beds at the Weishan and Wuyin area in the middle part of Simao Tarrane . High-temperature magnetic components were isolated from the two study areas and the positive fold test shows its primary nature of magnetization. The tilt corrected site-mean direction of the Upper Cretaceous from the Weishan section and the Lower Cretaceous from the Wuyin section is Ds=64.3°, Is=48.5°, k=54.6, α95=4.7° and Ds=15.4°, Is=44.8°, k=212.0, α95=4.6°, respectively. The correlation analysis between the declination changing and the tectonic line changing of Simao Terrane shows that the different rotational deformation of Simao Terrane was controlled by the formation of arcuate structure zone of Simao terrane. According to the active history of the huge strike-slip fault zones in the southeast edge of Tibet plateau, the wasp waist structure of the middle part of Simao Terrane was formed in two tectonic deformation stages. The early stage was related to the NNE stress between the Indian Plate and the Eurasia Plate. The later stage was induced by the southward rotational extrusion movement of Chuandian Terrane. The Weishan and Wuyin area moved about 10.5°±6.0° and 3.8°±4.9° southward respectively relative to the stable area of South China Block. The analysis of the inclination shows that the Wuyin sampling area displaced about 3.4°±5.0° and 3.1°±5.4° northward relative to the Weishan area and Pu'er area, respectively, indicating large crustal shorting occurred between the Wuyin area and the the Weishan area since the collision of India/Eurasia.