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| 西藏吉塘花岗岩地球化学特征及成因 | |
| 引用本文： | 陶琰,毕献武,李金高,朱飞霖,廖名扬,李玉帮.西藏吉塘花岗岩地球化学特征及成因[J].岩石学报,2011,27(9):2763-2774. |
| 作者姓名： | 陶琰 毕献武 李金高 朱飞霖 廖名扬 李玉帮 |
| 作者单位： | 1. 中国科学院地球化学研究所,矿床地球化学国家重点实验室,贵阳550002 2. 西藏自治区地质矿产局,拉萨,850000 3. 中国科学院地球化学研究所,矿床地球化学国家重点实验室,贵阳550002;中国科学院研究生院,北京100049 |
| 基金项目： | 本文受国家重点基础研究发展计划项目(2009CB421005)、中国科学院重要方向项目(KZCX2-YW-Q04-08)、国家自然科学基金项目(40973039)和矿床地球化学国家重点实验室开放基金(200905)联合资助 |
| 摘 要： | 沿澜沧江结合带发育一条长达1000余千米的印支期澜沧花岗岩带,吉塘岩体位于该带北段,产出在吉塘以西约3km,轴向NNW,侵位于古元古代吉塘群变质岩系中,长70km,宽2~10km、出露面积341km2。主要由花岗闪长岩和二长花岗岩组成,Rb-Sr等时线年龄值为220Ma。本文对吉塘岩体开展了系统的岩石地球化学特征分析。研究结果表明吉塘岩体为过铝质钙碱性S型花岗岩,吉塘岩体在岩石化学组成上,SiO2含量63%~71%,平均66.5%,Na2O含量2.8%~4.2%,K2O含量1.7%~3.4%,铝饱和指数A/CNK=1.09~1.48,CIPW标准矿物中刚玉1.5%~5.6％,微量元素组成类似于片麻岩质的中地壳。(87Sr/86Sr)i值为0.7280~0.7395,εNd(i)为-14.1~-16.2,指示岩浆源区为地壳物质,成因上与俯冲作用无关,Nd同位素亏损地幔模式年龄(tDM)在2.0Ga左右,与昌都陆块变质基底古元古代吉塘群的原始形成年代相当,岩体Sr、Nd同位素组成也与变质基底吉塘群片麻岩一致,综合分析认为,岩浆源岩为变质杂砂岩成分的古元古代吉塘群片麻岩,其原岩建造主要是火山弧成因的英安岩或英安质火山碎屑岩,微量元素组成指示为黑云母脱水熔融。分析认为岩浆形成于地壳加厚增温环境下的地壳深熔作用,构造上与板块碰撞后的环境相联系。支持澜沧江构造带为冈瓦纳与扬子大陆边缘多岛弧系统的边界即古特提斯主洋盆的观点。澜沧江洋的闭合时间早于澜沧花岗岩带的形成年龄220Ma,根据构造带上相关研究成果,倾向于认同碰撞时间在280Ma左右。 |
| 关 键 词： | 吉塘花岗岩 澜沧江 深熔作用 昌都 三江特提斯 |
| 收稿时间： | 4/2/2011 12:00:00 AM |
| 修稿时间： | 7/7/2011 12:00:00 AM |
Geochemistry and petrogenesis of the Jitang granitoids in Tibet, SW China |
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| TAO Yan,BI XianWu,LI JinGao,ZHU FeiLin,LIAO MingYang and LI YuBang.Geochemistry and petrogenesis of the Jitang granitoids in Tibet, SW China[J].Acta Petrologica Sinica,2011,27(9):2763-2774. | |
| Authors: | TAO Yan BI XianWu LI JinGao ZHU FeiLin LIAO MingYang and LI YuBang |
| Institution: | State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;Geological Bureau of Tibet Autonomous Region, Lhasa 850000, China;State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;Graduate School of Chinese Academy of Sciences, Beijing 100049, China;State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;Graduate School of Chinese Academy of Sciences, Beijing 100049, China;State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;Graduate School of Chinese Academy of Sciences, Beijing 100049, China |
| Abstract: | The Lancang River tectonic zone in southwestern Yunnan and eastern Tibet is important for the study of the evolution of the Paleotethys.The most important component of the Lancang River tectonic zone is the Triassic granitoids which occur over 1000km from Leiwuqi,Tibet in the north to Yunnan in the south.The Jitang granitoid intrusion is a representative body in the northern part of this granite belt.It consists of granodiorite and monzonitic biotite granite.The outcrop of this intrusion is 70km long and 2~... |
| Keywords: | Jitang granitoid intrusion Lancang River Anatexis Changdu Sanjiang Tethys |
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