盐源—丽江构造带是新生代陆内造山带

Yanyuan-Lijiang Tectonic Zone: A Cenozoic Intracontinental Orogenic Belt

盐源-丽江构造带处于扬子大陆与青藏特提斯的结合部,其造山时代的确定,不仅对正确认识该区的构造性质与发展历史及指导矿产勘查有重要意义,而且有助于判定印度-欧亚板块碰撞事件对欧亚板块内部影响的广度和深度。通过系列构造-成矿测年,结合地层、构造、岩浆活动、成矿作用的综合研究,证实盐源-丽江构造带是新生代陆内造山带,而不是印支造山带。其造山作用主要发生于中-晚始新世之交的喜马拉雅期,与欧亚-印度板块碰撞触发的扬子大陆岩石圈向青藏特提斯岩石圈俯冲有关,表现为地壳多层次拆离、剪切和沉积盖层的滑脱、褶皱和推覆,属陆内造山,系印度-欧亚板块碰撞事件的一种远程效应。

The Yanyuan—Lijiang Tectonic Zone acts as the junction zone between the Qinghai—Tibet Tethys and Yangtze continent. Dating its orogenic age is very important, not only for defining its tectonic nature and evolution and prospecting of mineral deposits in the zone, but also for judging the effects within the Eurasian plate of the collision event between India and Eurasia in depth and area. By combining the tectonic and metallogenetic dating of a series of samples with a comprehensive study on stratigraphy, tectonics, magmatism and metallogenesis, we confirmed that the Yanyuan—Lijiang tectonic zone is a Cenozoic intracontinental orogenic belt rather than an Indosinian orogenic zone. Its orogeny mainly occurred in the second episode of the Himalayan orogeny between the middle Eocene and late Eocene. The orogeny is bound up with the subduction of the Yangtze lithosphere beneath the Qinghai—Tibet Tethyan lithosphere, resulting from the collision between the Eurasian and Indian plates. And it shows multiple-layer detachment and shearing of the crust, and gliding, folding and napping of the sedimentary cover. It is an intracontinental orogeny as the distant effects of the collision between the Eurasian and Indian plates.