摘要
最近通过对康定-红河南北向构造带的研究,作者认为它不是扬子地台的边缘隆起带,而是特提斯型碰撞构造带。该带地壳上地幔构造可分三层。最上层为脆性上地壳,其主要运动形式为逆掩叠瓦。第二层为塑性下地壳及部分上地幔,表现为挤压缩短。其速度结构与青藏地区相似。认为是从青藏挤过来的异地体。第三层为上地幔。从岩石圈厚度来判断,应属扬子地台。
The nearly N-S-trending tectonic belt from Kangding in Sichuan province to the Red River in Yunnan province constitutes an important tectonic unit in Southwest China. Most geologists assume that this is a marginal uplift zone of the Yangtze Platform.Based on recent geophysical investigations, the author deduces that this region is a Tethyan type collision belt. The crust and the upper mantle in this tectonic belt may be divided into three structural layers. The top layer is the brittle upper crust, and its main structural features are represented by overthrusting and imbrication. The second structural layer is the plastic lower crust and part of the upper mantle, which structurally is marked chiefly by compression and shortening. Owing to the fact that its velocity structure is similar to that of the Qinghai-Tibet Plateau, it might be an allochthone from the Qinghai-Tibet region. The third structural layer is the upper mantle; judging from the thickness of the lithosphere, it might belong to the Yangtze Platform.This Tethyan type collision belt has several geophysical characteristics. For example, overthrusting imbrication in the upper crust took place simultaneously with compressive folding in the lower crust; the décollement surface displacement of brittle structure tends to Coincide with the low-velocity layer and shallow-focus earthouakes; the lower surface of ductile Structural displacement often appears as the ductile shear zone; at the front of the deplaced block there might also exist intermediate-focus earthquakes. At the Moho there are compressive folds. There may appear such geophysical anomalies as high resistivity, high density and high velocity in the whole compressional mobile belt.
出处
《地质学报》
EI
CAS
CSCD
北大核心
1989年第1期1-13,共13页
Acta Geologica Sinica
