Geochemistry and Tectonic Significance of the Volcanic Rocks of Baiyingaolao Formation in Huolinhe Area
In order to study the formation age,magma source and tectonic setting of volcanic rocks the Baiyingaolao formation in Huolinhe area,central part of the Greater Khingan Mountains,Zircon U-Pb dat-ing and geochemical analysis of the Baoyinggaolao Formation volcanic rocks in the area.The six zircon U-Pb dating samples are 141.7±1.3,140.5±3.5,137.3±2.0,136.4±1.7,135.8±1.6,and 128.6±1.4 Ma,re-spectively,which belong to the Early Cretaceous.Geochemistry show that the volcanic rocks of the Baiyin-gaolao formation in the study area are characterized by high silicon,rich alkali aluminum and poor calcium magnesium iron,and are a set of quasi-aluminium-weak peraluminous high potassium calc-alkaline series volcanic rocks.The total amount of rare earth is high with different degrees of light and heavy rare earth frac-tionation characteristics and negative europium anomaly.Compared with the original mantle,large ion litho-phile elements(Rb,K,Ba,K)and light rare earth elements(LREE)are mainly enriched,while high field strength elements(Nb,Ta,P,Ti)and heavy rare earth elements(HREE)are depleted.According to the analysis,the volcanic magma in this area mainly originates from the partial melting of crustal rocks under high temperature and low pressure environment,and is accompanied by the separation crystallization pro-cess of plagioclase and apatite.Based on the geochronology,geochemistry,and regional geological data,it is widely believed that the volcanic rocks of the Baoyinggaolao Formation originated in a post-subduction ex-tensional setting,subsequent to the subduction of the Paleo-Pacific plate.
NETL
NSTL
万方数据
