摘要
滇东南老君山地区是我国重要的锡多金属成矿区之一 ,区内中—深变质岩系的时代归属尚存在不同认识。通过对其中的花岗片麻岩类的铅同位素研究 ,获得全岩 长石铅 铅等时线年龄为 598±84Ma,( 2 0 7Pb/ 2 0 4 Pb) 0 =1 4 .52 3± 0 .2 3 5,γ =0 .97898,MSWD =1 4。这一年龄值代表了花岗片麻岩遭受混合岩化作用的年龄 ,相当于晚震旦世晚期。结合前人研究成果 ,本文认为该中—深变质岩系的时代归属于前寒武纪。
The Laojunshan district located in southeastern Yunnan is an important tin polymetallic metallogenic district in China. A debatable problem is the age assignment of the moderate\| to high\|grade metamorphic rock series in this district. Based on studies on the lead isotopic characteristics of the granite\|gneiss, a lead\|lead isochron has been established for the whole rock and feldspar, giving the age (598±410)×10\+6 a, (\{\}\+\{207\}Pb/\+\{204\}Pb)\-0=14.523±0.235, γ=0.97898 and MSWD=14. It is suggested that the lead isotopic systematics of these samples had been homogenized during migmatization at Late Sinian. Combining with previous studies, the authors agreed with the opinion that the age of the metamorphic rock series should be assigned to the pre\|Cambrian.
出处
《矿物学报》
CAS
CSCD
北大核心
2000年第3期228-232,共5页
Acta Mineralogica Sinica
基金
国家自然科学基金!(批准号 :4963 3 110 )资助
关键词
深变质岩
铅-铅等时线
时代
滇东南
铅同位素
moderate\| to high\|grade metamorphic rock series
lead\|lead isochron
age assignment
Laojunshan
southeastern Yunnan
