地质与资源2025，Vol.34Issue(6)：679-688,10.DOI:10.13686/j.cnki.dzyzy.2025.06.001
大兴安岭富林林场晚侏罗世埃达克质火山岩特征及其地质意义
Characteristics of Late Jurassic adakitic volcanic rocks in Fulin Forest Farm,Daxinganling Mountains:Geological implication
摘要
Abstract
In the Fulin Forest Farm area of northern Daxinganling Mountains,a suite of intermediate volcanic rocks is exposed,primarily composed of trachyandesite and trachyte.The LA-ICP-MS zircon U-Pb dating yields an age of 145.8±1.7 Ma,indicating a Late Jurassic emplacement age.Geochemically,these volcanic rocks belong to a high-K calc-alkaline,metaluminous to weakly peraluminous series,characterized by SiO2＞56％,high Al(Al2O3＞15％),low Ca and Mg,high Sr(averaging 676.58×10-6),and low Yb(averaging 1.42×10-6)and Y(averaging 15.00 ×10-6).The rocks show significant fractionation between light and heavy rare earth elements,with(La/Yb)N ratios of 12.50-26.55,and show weak negative Eu anomalies(δEu=0.74-1.02).Trace element patterns are marked by enrichment in LILEs(K,Rb,Ba,and Sr)and depletion in HFSEs(Nb,Ta,Ti,and P),consistent with the characteristics of"C-type"high-K calc-alkaline adakitic rocks.Integrated studies suggest that the Late Jurassic adakitic volcanic rocks in the Fulin Forest Farm area were derived from low-degree partial melting of K-rich basaltic metamorphic rocks within thickened lower crust.They formed during the late stage of the closure and collisional orogeny of the Mongol-Okhotsk Ocean,under a transitional tectonic regime shifting from compression to extension.The presence of these rocks indicates that crustal thickening occurred in this region no later than the Late Jurassic,implying that the eastern segment of the Mongol-Okhotsk Ocean had already closed by that time.关键词
埃达克岩/地球化学/晚侏罗世/大兴安岭Key words
adakite/geochemistry/Late Jurassic/Daxinganling Mountains分类
天文与地球科学引用本文复制引用
乔牡冬,韩燕东,袁帅,徐磊,毛琛,项磊..大兴安岭富林林场晚侏罗世埃达克质火山岩特征及其地质意义[J].地质与资源,2025,34(6):679-688,10.基金项目
中国地质调查局项目"松嫩平原松原地区黑土地地表基质调查"(DD20220861) （DD20220861）
"黑龙江省大兴安岭富西里地区地质矿产调查"(1212011120684). （1212011120684）
