摘要
为了确定大兴安岭北段中部温库吐地区玛尼吐组的形成时代、岩石成因及其地球动力学背景,对玛尼吐组火山岩进行岩相学、锆石SHRIMP U-Pb年代学与岩石地球化学研究。结果表明:玛尼吐组火山岩组成包括英安岩、粗安岩、玄武粗安岩与粗面玄武岩。锆石呈自形-半自形晶,韵律环带发育,Th/U为0.74~1.68,这一指标指示其岩浆成因。定年结果显示,玛尼吐组火山岩形成于141.3±1.7的早白垩世。岩石地球化学研究表明,玛尼吐组火山岩属高钾钙碱性系列。样品球粒陨石标准化稀土配分曲线均有相似特征,微量元素显示富集大离子亲石元素Rb、Ba、K,亏损高场强元素Nb、P、Ti为特征。其岩浆源区来源于地壳,形成于古太平洋板块向欧亚大陆板块俯冲的背景下。
This paper is intended to identify the age, petrogenesis and geodynamic setting of Manitu Formation volcanic rocks, located in the Wenkutu area of in the middle of northern part of the Greater Kh- ingan Mountains. The study works towards petrography observation, zircon SHRIMP U -Pb dating and a- nalysis of geochemistry. The results show that the Manitu Formation consists of a set of volcanicrocks, in- cluding dacite, trachyandensite, basaltic trachyandensite and trachybasalt, the zircon grains from Manitu Formation are mostly euhedral - subhedral, with oscillatory zones; Higher Th/U ratio （0.74 - 1.68） of zircon grains indicates magnmtic origin. The dating results show that the age of Manitou Formation volcanic rocks is 141.3± 1.7 Ma formed in the Early Cretaceous. The trace elements pattern are characterized by enrichment of Rb, Ba, K, depletion of Nb, P, Ti. The provenances of Manitu Formation volcanic rocks derive from the crust, formed on the background of ancient Pacific plate subduction to the Asian continent. Manitu Formation volcanic rocks are the product of the collision of Ergun block and Xing＇ an block.
出处
《黑龙江科技大学学报》
CAS
2017年第4期411-416,共6页
Journal of Heilongjiang University of Science And Technology
基金
黑龙江省地质勘查科研基金项目(201706)
内蒙古区域地质矿产调查基金项目(1212011220428)
关键词
锆石
地球化学
玛尼吐组
温库吐地区
大兴安岭
SHRIMP
geochemistry
Manitu Formation
Wenkutu area
Greater Khingan Mountains
