摘要
大兴安岭北部新林地区战备村一带新发现早侏罗世酸性火山岩.共测试2个锆石LA-ICP-MS U-Pb年龄.第一个测年样品为绢英岩化流纹岩,谐和图上测点偏离谐和线右侧为典型的不谐和年龄,与谐和线相交年龄为192.0±1 Ma,MSWD=1.2,为流纹岩喷出后的冷却结晶年龄;第二个测试样品为弱硅化流纹岩,谐和年龄为178.0±1 Ma,系微量放射性Pb丢失的结果,其成岩时代为应与绢英岩化流纹岩时代相近.岩石化学及地球化学具有高Ti流纹岩和Ⅰ型流纹岩特征.流纹岩的Mg#值(0.43~0.73)及CIWP标准矿物中紫苏辉石含量(0.25%~0.96%)佐证了流纹岩是由基性岩浆的结晶-分异演化而来.
The Early Jurassic acid volcanic rocks are newly discovered in Zhanbeicun Formation of Xinlin area in northern Daxinganling Mountains,from which two samples of zircon LA-ICP-MS U-Pb ages are determined.The first is sericitized rhyolite,with the testing point deviating to the right side of concordant curve on the concordia diagram—a typical discordant age,yielding the intersecting age with concordant curve of 192.0±1 Ma(MSWD=1.2),which is the cooling crystallization age of rhyolites after extrusion.The second one is weakly silicified rhyolite with a concordant age of 178.0±1 Ma,which is the result of the loss of radioactive trace element Pb,and the rock-forming age should be close to that of the sericitized rhyolite.The volcanic rocks are petrochemically and geochemically characterized by high Ti rhyolite and I-type rhyolite.The Mg^(#)value of the rhyolite(0.43-0.73)and content of hypersthene in CIWP norm minerals(0.25%-0.96%)support that the rhyolite is derived from crystallization-differentiation of basic magma.
作者
刘涛
吉峰
王文东
王久懿
赵喜东
LIU Tao;JI Feng;WANG Wen-dong;WANG Jiu-yi;ZHAO Xi-dong(Harbin Center of Comprehensive Natural Resources Survey,CGS,Harbin 150086,China;No.3 Oil Production Plant Geological Institute of Daqing Oilfield Ltd.,Co.,Daqing 163000,Heilongjiang Province,China)
出处
《地质与资源》
CAS
2022年第1期1-12,共12页
Geology and Resources
基金
中国地质调查局项目“黑龙江大兴安岭战备村(M51E001017)、二中队幅(M51E001018)1∶5万区域地质矿产调查”(编号12120113072400).
关键词
早侏罗世
流纹岩
锆石年龄
地球化学
大兴安岭
Early Jurassic
rhyolite
zircon age
geochemistry
Daxinganling Mountains
