摘要
拉脊山造山带是在晋宁期基底上 ,由于断裂作用而形成的。拉脊山南北各有一条边界断裂 ,两断裂在早古生代由张性转化为压性具有重大意义 ,它们直接控制了火山岩和蛇绿岩套的时空分布 ,并影响火山岩和蛇绿岩套具有的一系列特征。按照“开”“合”观点对火山岩的岩石和岩石地球化学进行时序分析 ,证实了拉脊山造山带经历了一个完整的“开”“合”旋回 ,还可进一步划分为 3个次级“开”“合”旋回。拉脊山的蛇绿岩套仅限于∈ 3地层中 ,并有本身的一些特征 ,是一种新类型的蛇绿岩套 ,代表了小洋盆的基本特征。
The Laji orogenic belt has a basement of Jinning epoch.After a stable stage of cover rocks from Sinian to Early Cambrian,the orogenic belt began its “activation”.During the activation since Middle Cambrian,the faulting played an important role,respectively a boundary fault at south and north side of the Laji orogenic belt.They all strike NWW-SEE and have similar characters.Both faults show extension in Early Caledonian and compression in Late Caledonian.During Mesozoic they are high-angle reverse faults change to thrusting during Cenozoic.The changes of the kinematic characters of these two faults directly controlled the distribution and characters of the Early Palaeozoic volcanic rocks and ophiolites.Based on the analysis of petrology and geochemistry of different periods of volcanic rocks and the “opening” and “closing” theory,we prove that the Laji orogenic belt comes through full of “opening” and “closing” cycle.This full of “opening” and “closing” cycle can be separated into three sub-cycles.The ophiolites are limited in the Late Cambrian strata and belong to a new-type of ophiolite,expressing a small ocean basin.
出处
《地质科技情报》
EI
CAS
CSCD
北大核心
2000年第2期5-11,共7页
Geological Science and Technology Information
基金
高等学校博士点专项科研基金资助课题! (970 49119)
关键词
拉脊山造山带
断裂作用
火山岩
蛇绿岩套
Laji orogenic belt
faulting
volcanic rock
ophiolite
“opening” and “closing”
