| 小兴安岭平顶山一带早侏罗世花岗岩类年代学、地球化学特征及其地质意义 |
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| 引用本文： | 尹志刚,宫兆民,王春生,刘松杰,张圣听,王冠群,周小刚,张志浩.小兴安岭平顶山一带早侏罗世花岗岩类年代学、地球化学特征及其地质意义[J].吉林大学学报(地球科学版),2021,51(1):107-125. |
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| 作者姓名： | 尹志刚 宫兆民 王春生 刘松杰 张圣听 王冠群 周小刚 张志浩 |
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| 作者单位： | 1. 辽宁工程技术大学矿业学院, 辽宁 阜新 123000;2. 黑龙江省生态地质调查研究总院, 哈尔滨 150036 |
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| 基金项目： | 中国地质调查局项目（1212011220435）；辽宁工程技术大学学科创新团队资助项目（LNTU20TD-14） |
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| 摘 要： | 小兴安岭平顶山大地构造位于兴蒙造山带东段，隶属松嫩地块。本文对小兴安岭平顶山一带碱长花岗岩和正长花岗岩进行了锆石U-Pb年代学和岩石地球化学研究，以确定其形成时代、岩石成因及大地构造背景。结果显示：碱长花岗岩形成于（189±3） Ma，正长花岗岩形成于（191±3） Ma，同为早侏罗世岩浆事件演化的产物；岩石具有高硅（w（SiO2）为75.00%~77.60%）、富碱（w（K2O+Na2O）为7.13%~9.00%）、贫镁（w（MgO）为0.05%~0.45%）、贫钙（w（CaO）为0.17%~1.10%）、低磷钛（w（P2O5）为0.01%~0.07%，w（TiO2）为0.09%~0.23%）的特点，A/CNK值为0.94~1.17，属于准铝质-弱过铝质、高钾钙碱性系列岩石；亏损高场强元素Nb、P、Ti、Ta和大离子亲石元素Ba、Sr，Rb、K、Th、Hf等元素具有明显的正异常；稀土元素总量（w（ΣREE））为（38.76~297.13）×10-6，稀土配分曲线显示为轻稀土略微富集、重稀土较为平坦缓向倾斜的右倾型，具明显的负Eu异常。锆石饱和温度值及地球化学特征等多种证据显示，岩石为高分异的I型花岗岩。结合小兴安岭区域构造演化特征分析，研究区早侏罗世花岗岩类为松嫩地块与佳木斯地块沿嘉荫—牡丹江缝合带碰撞拼合后伸展环境下的产物，岩浆起源于下地壳火成岩物质的部分熔融。
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| 关 键 词： | 花岗岩类 I型花岗岩 锆石U-Pb年代学 岩石地球化学 小兴安岭 |
| 收稿时间： | 2019-12-05 |
Chronological,Geochemical Characteristics and Geological Significance of Early Jurassic Granites in Pingdingshan Area of Lesser Xing'an Range |
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| Yin Zhigang,Gong Zhaomin,Wang Chunsheng,Liu Songjie,Zhang Shengting,Wang Guanqun,Zhou Xiaogang,Zhang Zhihao.Chronological,Geochemical Characteristics and Geological Significance of Early Jurassic Granites in Pingdingshan Area of Lesser Xing'an Range[J].Journal of Jilin Unviersity:Earth Science Edition,2021,51(1):107-125. |
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| Authors: | Yin Zhigang Gong Zhaomin Wang Chunsheng Liu Songjie Zhang Shengting Wang Guanqun Zhou Xiaogang Zhang Zhihao |
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| Institution: | 1. College of Mining Engineering, Liaoning Technical University, Fuxin 123000, Liaoning, China;2. Heilongjiang General Institute of Ecological Geological Survey and Research, Harbin 150036, China |
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| Abstract: | Lesser Xing'an Range is located in the eastern section of Xing-Meng orogenic belt, and belongs to Songnen block. The zircon U-Pb geochronology and rock geochemistry of the alkali feldspar granite and syenite granite in Pingdingshan area of Lesser Xing'an Range were studied to determine their formation age, rock genesis, and tectonic setting. The dating data show that the alkali feldspar granite was formed in (189±3) Ma,and the syenite granite was formed in (191±3) Ma, which is the product of the evolution of the Early Jurassic magmatic event. The geochemical results show that the rocks are characterized by high silicon (75.00%-77.60%), rich alkali(7.13%-9.00%), poor magnesium (0.05%-0.45%), poor calcium (0.17%-1.10%), low phosphorus (0.01%-0.07%) and titanium (0.09%-0.23%), and A/CNK (0.94-1.17), belonging to metal aluminous-weak peraluminous high-K calcium-alkaline series. The rocks are poor in high field strength elements Nb, P, Ti, Ta and large ion-lithophile elements Ba, Sr, while rich in Rb, K, Th, Hf and other elements. The total amount of rare earth elements is (38.76-297.13)×10-6. The REEs distribution curve shows that the light rare earth elements are slightly enriched, and the heavy rare earth elements are gently inclined to the right with obvious negative Eu anomaly. The zircon saturation temperature and geochemical characteristics show that the rocks are highly differentiated Type I granites. Based on the tectonic evolution characteristics of Lesser Xing'an Range, the Early Jurassic granites in the study area are the products the collision and amalgamation of Songnen block and Jiamusi block along the Jiayin-Mudanjiang suture zone, and the magma was originated from the partial melting of igneous material in the lower crust. |
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| Keywords: | granite rock Type I granite zircon U-Pb chronology rock geochemistry Lesser Xing’an Range |
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