岩石矿物学杂志2018，Vol.37Issue(1)：47-60,14.
西藏新嘎果地区典中组火山岩年代学、Hf同位素及地球化学特征
Zircon U-Pb ages, Hf isotopes and geochemistry of the volcanic rocks in Dianzhong Formation from Xingaguo area, Tibet
摘要
Abstract
The volcanic rocks in Linzizong Group are developed in the Gangdise belt of Tibet,and can reflect the important information of Neo-Tethys from its subduction to the India-Asia collision.The Xingaguo area is located in the northern middle part of south Gangdise,Tibet,lying to the south of Luobadui-Milashan Fault.The volcanic rocks in Dianzhong Formation consist of rhyolitic detritus crystal tuff,and are distributed in a limited area in the north of the ore district.The volcanic rocks in Dianzhong Formation from Xingaguo are composed of rhyolitic detritus crystal tuff and are distributed in the northern area,with the exposed area being small.Chemical analyses show that the volcanic rocks in Dianzhong Formation have high SiO2(SiO2 =75.09 ％ ～ 78.10 ％),low alkali (K2O + Na2O =4.84 ％ ～ 6.52 ％),and low Mg (MgO =0.24 ％ ～ 0.37 ％),with peraluminous nature (A/CNK =1.02～1.75);they are characterized by LREE enrichment and obvious REE differentiation [(La/Yb)y =9.49～ 11.30],with weak positive and negative Eu anomalies (δEu =0.76～1.15);they are enriched in LILEs (Rb,Th,U and K),depleted in HFSEs (Nb,Ta,P and Ti),and obviously depleted in Ba and Sr,thus belonging to calc-alkalic and peraluminous series and having the characteristics of continental margin arc volcanic rocks.The LA-MC-ICP-MS zircon U-Pb chronology indicates that the volcanic rocks in Dianzhong Formation were emplaced at 70.89 ± 0.31 Ma,which is the oldest age for the volcanic rocks in Dianzhong Formation,and has 176Hf/177Hf values in the range of 0.282 820～0.282 939,εHf(t) values in the range of + 3.2～ + 7.4 and single-stage model ages (tDM) between 662 and 930 Ma.The volcanic rocks in Dianzhong Formation from Xingaguo area were formed in a tectonic environment of ocean subduction,mainly derived their materials from the mantle components,and contaminated crustal material in the process of magma rising.关键词
典中组火山岩/地球化学/LA-ICP-MS锆石U-Pb定年/Hf同位素/冈底斯/西藏Key words
Dianzhong Formation volcanic rocks/geochemistry/LA-ICP-MS U-Pb zircon dating/Hf isotope/Gangdise/Tibet分类
天文与地球科学引用本文复制引用
唐攀,唐菊兴,郑文宝,冷秋锋,林彬,唐晓倩,王豪..西藏新嘎果地区典中组火山岩年代学、Hf同位素及地球化学特征[J].岩石矿物学杂志,2018,37(1):47-60,14.基金项目
Public Science and Technology Research Funds Projects (201511022-05,201511017) （201511022-05,201511017）
National Natural Science Foundation of China (41302060) （41302060）
The Basal Research Fund of Chinese Academy of Geological Sciences(YYWF201608)公益性行业专项(201511022-05,201511017) （YYWF201608）
国家自然科学基金项目(41302060) （41302060）
中国地质科学院基本科研业务费(YYWF201608) （YYWF201608）
