滇西兰坪盆地白垩纪-早第三纪古地磁结果及其地质意义  

CRETACEOUS AND EARLY TERTIARY PALEOMAGNETIC RESULTS FROM THE LANPING BASIN AND ITS GEOLOGICAL IMPLICATIONS

作　　者：尹济云 孙知明[2] 杨振宇[2] 梁其中 

机构地区：[1]云南省地质矿产研究所,昆明650011 [2]中国地质科学院地质力学研究所,北京100081

出　　处：《地球物理学报》1999年第5期648-659,共12页Chinese Journal of Geophysics

基　　金：国家自然科学基金

摘　　要：通过对滇西兰坪盆地白垩系地层的古地磁采样和室内退磁研究，揭示出一组高温特征分量，９５％正倒转检验和９９％置信度下的正褶皱检验，说明这组高温分量很可能代表岩石形成时的原生剩磁．对比国际标准地磁极性年表，发现南新组与阿尔比期、赛诺曼期和土仑期相当，而虎头寺组则相当于晚白垩世的三冬期和康尼阿克期．与中国东部的白垩纪古地磁数据比较．进一步证实了晚白垩世华南与印度支那地块存在明显的纬度差，这一事实说明了印度支那地块在印度板块与欧亚板块的碰撞及进一步挤压下，印度支那地块在早第三纪沿红河大断裂走滑千余公里，并伴随着１５　－２０　的顺时针旋转．After detailed paleomagnetic sampling and thermal demagnetization for Cretaceousand Early Tertiary rocks from the Lanping basin, Western Yunnan, a group of highertemperature charasteristic components were revealed. The directions from both theJinxing and Yunlong formations pass reversal test at 95% confidence level, and apositive fold test is achieved at the 99% confidence for the Nanxin and Futoushiformations. It implies that mis group of direchons may represent a primarymagnetization formed during the formation of the rocks. Comparing with geologicalbine scale, we note that Nanxin formation can be correlated with Cretaleous Albian,Cenomanian and Turonian stages, Futuoshi formation matches with Coniacian andSantonian stages. In comparison with available lower-middle Cretaceous paleomagneticresults from Eastern China, a paleolatitude difference of 11.5 7.6 is confirmedbetween indochina and Easter China. It corresponds a significant southeastwarddisplacement ( 1000kin) and accompeded with clockwise rotation of 15-20 ofIndochina relative to Eastern China along the Red River fault since fare Crethceousbine, which resulted from the collision and Penetration of india into Asia.

关 键 词：兰坪盆地 白垩纪-第三纪 磁性地层 古地磁 

分 类 号：P318.4[天文地球—固体地球物理学] P534.53[天文地球—地球物理学]