摘要
燕山期强过铝质侵入岩零星出露于冀晋辽地区。其岩石化学成分表现出高钾和超高钾质、低钠含量和高钾钠比值的特征。这些侵入岩被认为是燕山运动峰期地壳熔融的产物,Al2O3/TiO2比值变化于50～250之间,暗示其熔融温度在800～900℃之间;稀土元素配分形式指示其熔融源区的残留矿物组合中含有斜长石、单斜辉石、石榴子石和角闪石,表明这些强过铝质岩浆形成于0.9～1.7GPa的压力条件下。所以,这些强过铝质侵入岩的岩石化学数据提供了关于燕山运动峰期地壳发生部分熔融时的温压条件的信息。据此,对造山运动峰期的热结构进行了简单的模拟,结果并不支持整个岩石圈地幔均发生拆沉的动力学模型。
Yanshanian strongly peraluminous intrusive rocks occur sporadically in the Hebei-Shanxi-Liaon-ing area.Their petrochemical data exhibit high or ultrahigh potassium and lower sodium contents and a high K 2 O /Na 2 O ratio.They are considered as the product of crustal melting in the peak perio d of the Yanshanian orogeny.Their Al 2 O 3 /TiO 2 ratios vary from50to250.These values imply that the melting temperatures of the strongly peraluminous rocks are in range of 800to900℃.The REE pattern s of these rocks indicate that the residual mineral assemblage of the source includes plagioclase,clinopyroxene,garnet and hornblende which suggests that the strongly peraluminous magma originated at pressures of 0.9-1.7GPa.Therefore,the petrochemical data provide the P-T conditions of crustal melting in the peak period of the Yanshanian orogeny.Based on this information,the authors performed simple modeling on the ther-mal structure in the peak period of the orogeny,and the result does not support the geodynamic model of delamination occurring in the whole lithospheric mantle.
出处
《地质通报》
CAS
CSCD
北大核心
2002年第4期270-276,共7页
Geological Bulletin of China
基金
国家自然科学基金项目(编号40104003)
国土资源部科技发展计划"华南地区岩石圈三维结构及其演化"(20001010206)
"华北地区岩石圈三维结构及其演化"(20001010202)
中国博士后科学基金
中国地质调查局基础地质综合研究课题"燕山造山带花岗岩与大陆地壳改造和生
