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大兴安岭北部诺敏河地区早石炭世A型花岗岩的年代学、地球化学及Hf同位素研究
投稿时间:2019-07-08  修订日期:2019-10-10  点此下载全文
引用本文:
DOI:10.19762/j.cnki.dizhixuebao.2020033
摘要点击次数: 57
全文下载次数: 48
作者单位E-mail
吴子杰 中国石油大学(华东)地球科学与技术学院 midnight29@163.com 
汪洋 中国地质大学(北京)地球科学与资源学院 allen_thalassa@sina.com 
邱隆伟 中国石油大学地球科学与技术学院  
崔培龙 辽宁省冶金地质勘查院有限责任公司  
仲米山 辽宁省地质勘查院有限责任公司  
王海鹏 辽宁省地质勘查院有限责任公司  
基金项目:本文得到了中国地质调查局项目(项目编号:DD20160047—03)的资助。
中文摘要:大兴安岭北部诺敏河地区碱长花岗岩锆石呈自形-半自形短柱状-板状,具有结构清晰的振荡生长环带和较高的Th/U比值(1.10 ~ 2.18),指示其为典型岩浆成因锆石。LA-ICP-MS U-Pb年代学研究显示岩石形成于早石炭世杜内期(352.9 ± 3.3 Ma)。岩石地球化学研究显示,岩石属于准铝质-弱过铝质高钾钙碱性岩石,富硅(SiO2 = 73.25% ~ 77.01%)、富碱(Na2O+K2O = 7.72% ~ 9.48%)、富铁(Fe2O3 = 2.06% ~ 2.97%,Fe2O3+FeO = 2.32% ~ 3.33%),贫镁(MgO = 0.08% ~ 0.26%)。根据强烈亏损Sr、Eu、Ba、Ti、P等元素,REE分布曲线为右倾式海鸥型和明显的Eu负异常(δEu=0.26 ~ 0.31)的岩石地球化学特征,判断碱长花岗岩属于A型花岗岩。锆石176Yb/177Hf值为0.03778 ~ 0.133612,176Lu/177Hf值为0.001095 ~ 0.004155,176Hf/177Hf值为0.282824 ~ 0.282863。对应的锆石U-Pb年龄计算出锆石εHf(t) = 8.9 ~ 10.6,一阶段Hf模式年龄为tDM1 = 560 ~ 658 Ma,两阶段Hf模式年龄tDM2 = 815 ~ 974 Ma,指示其源于新元古代源岩的部分熔融。与额尔古纳地块早石炭世A型花岗岩的对比表明,在兴蒙造山带东北部古亚洲洋盆的闭合发生在早石炭世;结合内蒙古中部地区古亚洲洋盆闭合时代为晚石炭世,表明古亚洲洋盆的闭合是东早西晚的“剪刀状”发展过程。
中文关键词:兴蒙造山带,古亚洲洋,A型花岗岩,早石炭世,诺敏河
 
The Early Carboniferous A-type Granite in Nuominhe area, northern Great Xing’an Mountain: geochronology, geochemistry and Hf isotope studies
Author NameAffiliationE-mail
Wu Zijie China Petroleum University midnight29@163.com 
Wang Yang School of Earth Science and Resources, China University of Geosciences allen_thalassa@sina.com 
Qiu Longwei School of Earth Scicence and Technology, China Petroleum University  
Cui PEILONG Liaoning Metallurgy Geological Exploration Institute Ltd.  
Zhong Mishan Liaoning Geological Survey Ltd.  
Wang Hhaipeng Liaoning Provincial Institute of Geological Exploration Co., Ltd  
Abstract:The zircons of alkali-long granites in the Nomin River area in the northern Daxinganling are self-shaped-semi-self-shaped short column-plate-like, with a well-structured oscillation growth zone and a high Th/U ratio (1.10 ~ 2.18). It is a typical magma-forming zircon. The LA-ICP-MS U-Pb geochronology study showed that the rock was formed in the Early Carboniferous Duinian period (352.9 ± 3.3 Ma). Rock geochemical studies show that the rock belongs to quasi-aluminum-weak aluminous high-potassium-calcium-alkaline rock, rich in silicon (SiO2=73.25% ~ 77.01%), alkali-rich (Na2O+K2O=7.72% ~ 9.48%), rich Iron (Fe2O3 = 2.06% ~ 2.97%, Fe2O3 + FeO = 2.32% ~ 3.33%), magnesium deficiency (MgO = 0.08% ~ 0.26%). Strongly depleted Sr, Eu, Ba, Ti, P and other elements, the REE distribution curve is right-winged seagull type and obvious Eu negative anomaly (δEu=0.26 ~ 0.31), and the rock is judged to be A-type granite. Lu-Hf isotope analysis based on zircon U-Pb isotopic dating. The sample 176Yb/177Hf value was 0.03778 ~ 0.133612, the 176Lu/177Hf value was 0.001095 ~ 0.004155, and the 176Hf/177Hf value was 0.282824 ~ 0.282863. The corresponding zircon U-Pb age calculated zirconεHf(t) = 8.9 ~ 10.6, the first-stage Hf mode age was tDM1 = 560 ~ 658 Ma, and the two-stage Hf mode age tDM2 = 815 ~ 974 Ma, indicating that it originated from Partial melting of the Neoproterozoic source rocks. Our study and the development of the Early Carboniferous A-type granite in the Erguna block indicate that the closure of the Paleo-Asian ocean basin in the northeastern part of the Xingmeng orogenic belt occurred in the Early Carboniferous. Combined with the closure of the Paleo-Asian Ocean basin in the central part of Inner Mongolia, it is the Late Carboniferous, indicating that the closure of the ancient Asian ocean basin is a "scissor-like" development process in the east, west and west.
keywords:Xing’an-Mongolian  orogenic belt, Paleo-asian  ocean, A-type  granite, early  Carboniferous, Nuominhe  area
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