摘要
商城岩体大体具有埃达克岩(adakite)的地球化学特征,其SiO267.72%～71.26%,Al2O313.70%～15.47%(平均15.0%),MgO=0.76%～1.88%,Na2O/K2O=0.9～1.4,Sr=(346～897)×10-6,Sr/Y=42～127,Sr/Yb=509～1533,球粒陨石标准化的REE分布以LREE富集((La/Yb)N=21～56)、强烈亏损HREE(Yb<1.77×10-6)和Eu异常不明显(δEu=0.85～0.94)为特征,这些均与埃达克岩的特征类似。商城岩体的Cr、Ni含量低于典型埃达克岩,在微量元素蛛网图上,Sr既有正异常,又有负异常,具有"C型"埃达克岩地球化学特征,可能为增厚下地壳底部底侵的玄武质岩石部分熔融的产物。
The Shangcheng granites are more or less alike to adakite in petrological and geochemical features:SiO_2=67.72%～71.26%;Al_2O_3 =13.70%～15.47%(averaging 15.0%);MgO=0.76 %～1.88%;Na_2O/K_2O= 0.9～1.4;Sr=(346～897)×10^(-6);Sr/Y=42～127;Sr/Yb=509～1533;rich in LREE( (La/Yb)_N=21～56 ) and heavy depletion in HREE(Yb<1.77×10^(-6)) with unobvious Eu anomaly ( δEu=0.85～0.94).However,the content of Cr and Ni in the Shangcheng granites are lower than those of typical adakite and has both positive and negative Sr anomaly in the trace element spider diagram,showing the geochemical features of C-type adakite and being probably resulted from partial melting of basalts underplated in the base of thicked lower crustal layer.
出处
《华南地质与矿产》
CAS
2003年第4期17-23,共7页
Geology and Mineral Resources of South China
基金
中国地质调查局项目(20011300013)子课题.
关键词
商城岩体
地球化学
C型埃达克岩
河南
Shangcheng granie body
geochemistery
C-type adakite
Henan
