黑龙江镜泊湖新生代火山岩成因机制研究  

STUDY OF THE GENETIC MECHANISM OF CENOZOIC VOLCANIC ROCKS IN THE JINGPOHU AREA, HEILONGJIANG PROVINCE

作　　者：李明涛 王婵 杜海涛[6] 陶瑞 任蕊 LI Mingtao;WANG Chan;DU Haitao;TAO Rui;REN Rui(School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;Ningia Institute of Geological and Mineral Resources Survey,Yinchuan,Ningria 750021,China;South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou,Guangdong 510301,China;Key Laboratory of Ocean and Marginal Sea Geology,Chinese Academy of Sciences,Guangzhou,Guangdong510301,China;Key Laboratory of Tectonic Controlled Mineralization and Oil Reservoir of Ministry of Natural Resources(ChengduUniversityof Technology),Chengdu,Sichuan 610059,China;Geosciences Research Institute of Heilongjiang,Harbin,Heilongjiang 150080,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]宁夏回族自治区矿产地质调查院,宁夏银川750021 [3]中国科学院南海海洋研究所,广东广州510301 [4]中国科学院边缘海与大洋地质重点实验室,广东广州510301 [5]自然资源部构造成矿成藏重点实验室成都理工大学,四川成都610059 [6]黑龙江省地质科学研究所,黑龙江哈尔滨150080

出　　处：《矿物岩石》2022年第4期44-59,共16页Mineralogy and Petrology

基　　金：自然资源部构造成矿成藏重点实验室开放基金(项目编号:gzck202101);中国博士后科学基金(项目编号:2021M703296);广东省基础与应用基础研究基金(项目编号:2021A1515110782)。

摘　　要：黑龙江镜泊湖新生代火山岩被认为是我国典型陆内碱性玄武岩研究圣地,其成因机制研究对约束东北地区新生代板内岩浆活动具有重要意义。本次研究选取黑龙江镜泊湖火山岩区3期(船底山期、杏山期、镜泊湖期)火山岩开展岩石学、元素地球化学及同位素地球化学研究,分析结果显示这3期火山岩岩性为低分异钠质碱性玄武岩系列,整体地球化学特征较一致,具有高的Na2O/K2O比值(平均值为1.82)、Mg~#值(平均值为77.67)、ΣREE值(平均值为162.55×10^(-6))和LREE/HREE比值(平均值为9.15),δCe负异常(平均值为0.75),相对富集不相容元素;REE标准化模式呈平缓右倾型,微量元素配分曲线呈轻微“凸”字型隆起(富集Ta,Nb和P而相对亏损Ce,Nd,Zr,Y和Yb);同位素地球化学特征表现为,较小的εNd(t)正值(平均值为1.6712),较低的87Sr/86Sr值(平均值为0.704487)和稍高的δ18O值(平均值为7.45‰)。综合区域资料,本次研究认为镜泊湖3期火山岩均属于起源于富集Ⅰ型地幔源区的OIB型板内碱性玄武岩,其成因与地幔柱背景下的石榴石二辉橄榄岩的部分熔融相关,而富集的地球化学特征则受控于古太平洋板片沉积物的再循环及大陆岩石圈地幔的加入。The Cenozoic volcanic rocks developed in Jingbohu area of Heilongjiang Province are considered to be typical intracontinental alkaline basalts in China. In this paper, three periods of volcanic rocks occurred in this area(Chuandishan period, Xingshan period and Jingbohu period) are selected as research target, and the study of their petrology, petrography, element geochemistry and isotope geochemistry is of great importance in exploring the genetic mechanism to the constraint on Cenozoic intra-plate magmatic activity in northeast China. The results show that the three stage volcanic rocks are low-differentiation sodium alkaline basalts series. Geochemical analusis indicates that these volcanic rocks display consistent geochemical characteristics. They have high Na_(2)O/K_(2)O ratio(mean 1.82), Mg^(#) value(mean 77.67), ΣREE value(mean 162.55×10^(-6)) and LREE/HREE ratio(mean 9.15). δCe shows a negative anomaly(mean value=0.75), relatively enriching incompatible elements. The REE normalized diagram shows a gentle right-leaning pattern, and the trace element partition curve shows a slight convex pattern(enriched in Ta, Nb and P, but depleted in Ce, Nd, Zr, Y and Yb). Analysis of isotope geochemistry shows low ε)*Nd((t) values(mean 1.671 2), low^(87)Sr/^(86)Sr values(mean 0.704 487), and slightly higher δ^(18)O values(mean 7.45‰). Based on the study in this paper, combined with the regional geological data, it is considered that these three periods of volcanic rocks were originated from the I-type enriched mantle(EMⅠ) source region and belong to OIB intraplate alkaline basalts. The origin of these volcanic rocks is related to the partial melting of garnet peridotite under the background of mantle plume, while the geochemical characteristics of enrichment are controlled by the recycling of paleo-Pacific plate sediments and the addition of continental lithospheric mantle.

关 键 词：新生代火山岩 地球化学 碱性玄武岩 地幔柱 黑龙江 

分 类 号：P579[天文地球—矿物学]