| 大兴安岭南段小乌兰沟正长花岗岩成因:锆石LA?ICP?MS U?Pb年代学、地球化学及Hf同位素的制约 |
| |
| 引用本文： | 章培春,彭勃,赵金忠,王鑫,贺吉,张爱,双龙.大兴安岭南段小乌兰沟正长花岗岩成因:锆石LA?ICP?MS U?Pb年代学、地球化学及Hf同位素的制约[J].地球科学,2022,47(8):2889-2901. |
| |
| 作者姓名： | 章培春 彭勃 赵金忠 王鑫 贺吉 张爱 双龙 |
| |
| 作者单位： | 1.中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室, 北京 100037 |
| |
| 基金项目： | 中央级公益性科研院所基本科研业务费专项基金KK2017中央级公益性科研院所基本科研业务费专项基金KK2018国家自然科学基金项目41802103内蒙古自治区地质勘查基金项目NMKD2015-40 |
| |
| 摘 要： | 大兴安岭南段西坡发育有大量晚侏罗世-早白垩世花岗岩，深入讨论岩石成因对该地区中生代地球动力学背景及其构造演化的研究具有重要地质意义.报道了小乌兰沟正长花岗岩的锆石LA?ICP?MS U?Pb年龄，全岩地球化学及锆石Hf同位素数据.小乌兰沟正长花岗岩的锆石206Pb/238U加权平均年龄为139.4±0.7 Ma，属早白垩世. 样品主量元素表现为富硅、富钾的高钾钙碱性系列岩石，A/CNK值介于1.00~1.11之间，属弱过铝质. 微量元素富集Rb、Th、U等大离子亲石元素（LILE）和轻稀土元素（LREE），强烈亏损Ba、Sr、P、Ti等高场强元素（HFSE），Eu负异常明显（δEu=0.007~0.009），Zr+Nb+Ce+Y值基本小于350×10-6，含磁铁矿，未见原生白云母和碱性暗色矿物，属高分异I型花岗岩. 小乌兰沟正长花岗岩εHf（t）值介于+5.5~+8.9之间，Hf同位素模式年龄tDM2变化于700~947 Ma之间.结合区域研究，小乌兰沟正长花岗岩为上元古界变基性岩与中奥陶统变中性岩在低压、高温条件下发生部分熔融作用形成，是蒙古-鄂霍茨克洋闭合后伸展作用的产物.
|
| 关 键 词： | 大兴安岭南段西坡 蒙古?鄂霍茨克洋 小乌兰沟 LA?ICP?MS U?Pb年代学 Hf同位素 地球化学 |
| 收稿时间： | 2021-05-24 |
Petrogenesis of the Syenogranite in the Xiaowulangou Area of Southern Great Xing'an Range: Constraints from Zircon LA?ICP?MS U?Pb Geochronology,Geochemistry and Hf Isotopes |
| |
| Abstract: | TheLate Jurassic?Early Cretaceous granites are widely developed in the west slop of Southern Great Xing'an Range, and an in?depth study of the petrogenesis is of great geological significance to reveal the Mesozoic geodynamic background and tectonic evolution. In this paper, we report for the zircon LA?ICP?MS U?Pb age and Hf isotopic data, whole?rock major and trace element composition data from Xiaowulangousyeno granite. LA?ICP?MS U?Pb dating yields a weighted mean of 139.4±0.7 Ma, indicating that Xiaowulangousyeno granite formed in the Early Cretaceous. Geochemically, the syenogranite belongs to Si?K?rich calc?alkaline series, A/CNK=1.00~1.11 and are weak peraluminous. The syenogranite enriched in Rb, Th, U(LILE) and light rare earth elements(LREE), relatively depleted in Ba, Sr, P, Ti(HFSE), withobvious Eu negative anomaly(δEu=0.007~0.009). In addition, the (Zr+Nb+Ce+Y) values of syenograniteis less than 350×10?6. The syenogranite contains magnetite, and no primary muscovite and alkaline mafic minerals. All these features above suggest that Xiaowulangousyenogranite belongs to highly fractionated Ⅰ?type granite. The zircons εHf(t) values of syenogranite are +5.5~+8.9, and the two stage model ages (tDM2) range 700 Ma to 947 Ma. Combined with the reginoal geological background, we conclude that the Xiaowulangousyenograniteoriginated from the partial melting of upper Proterozoic meta?mafic rocks and middle Ordovician meta?andesite rocks under low pressure and high temperature, and the syenogranitewas the product of extension after the closure of Mongol?Okhotsk Ocean. |
| |
| Keywords: | |
|
| 点击此处可从《地球科学》浏览原始摘要信息 |
|
点击此处可从《地球科学》下载全文 |
|
