地质力学学报2017，Vol.23Issue(3)：397-410,14.
内蒙古乌拉特后旗乌兰敖包地区二叠纪中-基性火山岩地球化学、年代学、Hf同位素特征及其地质意义
GEOCHEMISTRY, CHRONOLOGY AND HF ISOTOPE FEATURES OF THE PERMAIN INTERMEDIATE-BASIC VOLCANIC ROCKS IN WULANAOBAO AREA, URAD HOUQI, INNER MONGOLIA AND ITS GEOLOGICAL SIGNIFICANCE
摘要
Abstract
The Wulanaobao intermediate-basic volcanic rocks,distributed in Urad Houqi,Inner Mongolia,are located in the western north margin of the north China block.The outcropped lithologies mainly are grey black-spruce basalt,spruce basaltic andesite and greyish-green andesite.All samples show chemical signatures of calcalkaline series which are characterized by contents of SiO2 (49.33 ～65.84％),Na2O (0.53 ～5.49％) and K2O (0.25 ～6.40％).From basic to intermediate,the amount of rare earth elements,light rare earth elements enrichment degree and En negative anomaly degree show a trend of increase.The trace elements show subduction zone arc magmatite features which are characterized by wide depletion of Ta and Nb,and enrichment of the large ion lithophile elements (U,Ba,K).The zircon U-Pb dating results of the magma from volcanic rocks are 285.0 ± 2.3Ma and 265.0 ± 1.5Ma,which indicates that the volcanic rocks were formed at the early-middle Permian period.The age characteristics of captured zircons and the contact relations between volcanic rocks and underlying strata suggest that volcanic rocks from Wulanaobao were formed on the crust of the north China block.Zircon Hf isotopic information indicates that the magma was derived from the depleted mantle which was affected by the subducting plate and partly joined with crust-derived material during the rising stage.关键词
兴蒙造山带/中-基性火山岩/二叠纪/地球化学/大陆边缘弧Key words
Hinggan-Mongolia orogenic belt/intermediate-basic volcanic rocks/Permian period/geochemistry/continental marginal arc分类
天文与地球科学引用本文复制引用
郭硕,滕学建,刘洋,滕飞,何鹏,王文龙,田健,段霄龙..内蒙古乌拉特后旗乌兰敖包地区二叠纪中-基性火山岩地球化学、年代学、Hf同位素特征及其地质意义[J].地质力学学报,2017,23(3):397-410,14.基金项目
中国地质调查局地质调查项目(12120113056300,121201006000160902) （12120113056300,121201006000160902）
