摘要
托赖岩群是浪士当沟地区变质基底的重要组成部分,其泥质、长英质变质岩大多为铝过饱和型和Si O2过饱和的岩石,轻重稀土间分馏较强,Eu亏损明显;铁镁质变质岩石以高钛、高碱、低硅为特征,大部分岩石Si O2不饱和,稀土配分图上显示较弱的分异模式。通过原岩恢复认为托赖岩群的原岩建造为一套以泥质、泥砂岩沉积碎屑岩类为主,夹碳酸盐岩和中基性火山岩的岩石组合;沉积构造环境应为活动陆缘伸展型裂陷盆地。采用LA-ICPMS锆石U-Pb定年法,获得托赖岩群黑云斜长片麻岩的年龄为1537.0±5.3Ma,表明托赖岩群的成岩年龄可能下沿至中元古代。
Tuolai Group is an important part of the regional metamorphic basement in Langshidanggou area. the mud, quartzofeldspathic rocks are mostly aluminum saturation and supersaturation of SiO2 rock, fractionation between LREE and HREE is stronger, Eu losses significantly; mafic metamorphic rocks features high titanium, high alkali and low silicon , with most of the rock SiO2 unsaturated, REE fractionation patterns shown weak fractionation. The original rock recovery suggested that the protoliths of the Tuolai Group consists of a set of mud, mud sandstone sedimentary clastic rock ,clip carbonate rocks and basic volcanic rocks in the rock combination ; sedimentary tectonic environment was an active continental margin extensional rift basin. LA-ICP-MS zircon U-Pb dating method was used, to obtain biotite plagioclase gneiss age of Tuolaiduo group was 1537 ＋ 5.3Ma, showing that the diagenetic age of the Tuolai Group may be sretched to mesoproterozoic.
出处
《甘肃冶金》
2015年第4期96-102,共7页
Gansu Metallurgy
