藏南亚东地区片麻状含石榴子石黑云花岗闪长岩LA-ICP-MS锆石U-Pb测年及其地质意义.pdf

第29卷第12势
地质通报
Vol 29. No12
10)年12月
GEOLOGICAL BULLETIN OF CHINA
Dec.2010
藏南亚东地区片麻状含石榴子石黑云花岗闪长岩
LA-ICP-MS错石U-Pb测年及其地质意义
时超2,李荣社2,何世平2,王超2,潘术娟12,刘银1,辜平阳2
SHI Chao LI Rong-she', HE Shi-ping, WANG Chao
PAN Shu-juan", LIU Yin, GU Ping -yang
.中国地质大学(北京)地球科学与资源学院,北京100083;
2.中国地质调查局西安地质矿产研究所,陕西西安710054
1. China Uninersity of Geosciences, Beijing 10083, Chin
2. Kian Institute of Geology andd Mineral Resourees. China Geological Surey, ian 710054, Shaanxi, China
摘要:亚东岩组是高喜马拉雅地区重要的前寒式纪变质地层之一。利用LA-ICP-MS結石U-Pb浏年技术对侵入亚东岩组的片
麻状合石榴子石黑云花岗闪长岩进行了測年,获得岩浆结晶年龄为(499.2土3.9)Ma(中寒武世),提供了泛非构造一若浆事件的记
录。岩石地球化学分析表明,黑六花岗闪长岩SiO2含量为68.0)4%-68.92%,在(KO+NaO)-SiO2图解上样品点落入亚碱性系列
的花岗闪长岩区,A/CNK指最均大于1.1在 Shand指数图解上落入过铝质系列区。稀土元素配分模式属轻稀土元素富集的右
倾岫线,出现弱Eu负异常(Eu=0.62-0).79);後量元素表现出Ba、Nb、Ta、Sr亏损和Rb、Th、じ相对富集的特征。通过Rb-(Y+
Nb)和Rb-Hf-Ta图解判别,认为亚东地区片麻状含石榴子石黑云花岗闪长岩形成于后碰撞枸造阶段。
关键词:片麻状含石招予石黑云花岗闪长岩;亚东岩组:LA-ICPーMS結石UーPb同位素年龄;泛非运动;西藏亚东地区
中图分类号:P58.121;P5973
文献标志码:A
文章编号:1671-2552(2010)12-1745-(09
Shi C, Ii R S, He S P, Wang C, Pan S J, Liu Y, Gu P Y. LA-ICP-MS zircon U-pb dating for gneissic garnet-bearing bi
otite granodiorite in the Yadong area, southern Tibet, China and its geological significance. Geological Bulletin ofchina,
2010,29(12):1745-1753
Abstract: Yadong Fomnation-complex is an important precambrian metamorphic strata of the Yadong area in Tibet. LA-ICP-MS
method is used to determined the zircon U-pb isotope age for gneissic biotite granodiorite with garnet insert the Yadong Formation-
complex of the Yadong area, Tibet. It's magmatic crystallization age of(499.2*3.9)Ma (Middle Cambrian), provides a Pan-african
te tonic -magmatic event record. Geochemical analysis shows that io ontent of 68.04%68.92%, K N O-SIO2 diagram into
granodiorite region of the sub-alkaline series, A/CNK index greater than 1.1, Shand index diagram in the area fall into peraluminous
series. REE patters show light rare earth enrichment right-inclined curve, and slightly negative Eu anomalies(Eu=0.62-0.79);race
elements showed the teatures of Ba, Nb, Ta, Sr loss, and Rb, Th and U relative enrichment. It is considered that the gneissic biotite
granodiorite with armet insert the Yadong Formation-complex of the Yadong area formed in the post-collisional stage though Rb
(YーNh)adRbー-FHf-T: discriminant diagrams.
Key words: Gneissic garlet-bearing biotite granodiorite; Yadong Formation-complex; LA-ICP-MS
∠1rCOn
U-pb isotope age; Pan
African lavement: Yadong area of Tibet
收稿日期:21(1-07ー);修订日期:2010-(8-()5
地调项目:中国地质调査局土资源大査项目《青藏高源前寒武纪地质、古生代构造一声地理综合研究》(编号:1212010610102)资助
作者简介:时超(1986-),男,在读飯士.构造地质学专业、E-mail: fanboy88@163com
通讯作者:何世平(1963-),男,研究员,从事大地构造和地球化学研究。E-mai:xakeyif163.com