滇西一些新生代飞来峰的构造演化

在印度和欧亚大陆相互作用下,滇西三江造山带在新生代中期发生了强烈的东西向缩短,地壳物质的大规模推覆作用形成众多的飞来峰。野外调查发现:这些飞来峰中有的在就位后没有再发生过变形,如分布在兰坪——思茅盆地中段的无量山东北山麓一带的一系列上三叠统灰岩飞来峰;有的飞来峰在就位后再次遭受到强烈的变形,如分布在兰坪盆地金顶一带的上三叠统灰岩飞来峰,在渐新世时与下伏岩层一同卷入了强烈的褶皱变形;分布在大理地区鹤庆盆地西侧的中三叠统灰岩飞来峰因受到后期东西向伸展构造的破坏,已被改造成分选极差的重力滑塌沉积。这些古近纪飞来峰由于在就位后再次发生了变形,所以不应称之为飞来峰,应称为异地岩或者是外来岩块。

TECTONIC EVOLUTION OF SOME CENOZOIC KLIPPEN IN WESTERN YUNNAN

The Sanjiang (Three River) orogenic belt was experienced intensive E-W shortening, accommodated mainly by thrusting, in middle Tertiary time due to the interaction between the Indian and Eurasian continents, resulted in many klippen. Based on our field observation and structural study, some of these klippen have remained undeformed since they settled down, as those formed by Triassic limestone, distributed in the northeastern piedmont of the Wuliang Shan belt. Whereas those occurred within the Lanping Basin and the Dali Block have experienced strong deformation. The former, formed by the Late Triassic limestone, was shortened along a series of the N-trending folds and thrust faults, and the latter, consisting of Middle Triassic limestone, was experienced strong extensional deformation and broken into pieces with various size, suggestive of landslide deposits. These deformed Middle Cenozoic klippen have lost their original features of the klippen and should be termed as either allochthon or exotic blocks.