现代地质2018，Vol.32Issue(2)：305-315,11.DOI:10.19657/j.geoscience.1000-8527.2018.02.09
冀北五凤楼煌斑岩年代学、地球化学特征及其成因
Chronology, Geochemistry Characteristics and Petrogenesis of Wufenglou Lamprophyres in Northern Hebei, China
摘要
Abstract
Mesozoic lamprophyres with lithological minette are developed as dykes near Shouwangfen-Wufenglou in Yanshan region,North China Craton.Chemically,the lamprophyres are basic (SiO2 from 48.25％ to 51.47％),have high values of sodium (Na2O/K2O values from 1.13 to 2.31),alkali (K2O + Na2O values from 6.61％ to 7.40％),Mg#(67.84 to 71.34) and TiO2(1.31％ to 1.65％),belonging to high-Ti,Na-rich calc-alkaline lamprophyres.The rock is enriched in LREE,LILE and P,depleted in HREE and HFSE (Nb,Zr,Ta),and has no Eu anomalies.LA-ICP-MS zircon U-Pb dating got an age of (135.2 ± 1.3) Ma,indicating that the lamprophyres were intruded at the same period of magmatic activity with the nearby granitic complex at Shouwangfen area in the Early Cretaceous.The εHf(t) values of lamprophyres are ranging from-19.3 to -13.3,the two stage Hf model ages are nuch older than the age of diagenesis,indicating an enriched mantle source.The high values of Ba/Th (123.09 to 436.34) and Sr (915.4 × 10-6 to 1 257 × 10-6) imply the magma formation was effected by the subduction-zone fluids.The low values of Rb/Sr(0.02 to 0.11) and the high values of Ba/Rb(10.8 to 80.9) showed that the source contained amphibole.It is concluded that the lamprophyres were derived from partial melting (0.5％ to 1.5％) of garnet-amphibole lherzolite of enriched mantle that formed by the interaction between sodium rich subduction fluid and mantle wedge,and the origin depth is 75 km to 100 km.关键词
煌斑岩/年代学/地球化学/五凤楼/冀北Key words
lamprophyre/chronology/geochemical characteristic/Wufenglou/Northern Hebei分类
天文与地球科学引用本文复制引用
董朋生,董国臣,孙转荣,李华伟,王树树,翟天雷,王伟清,耿建珍..冀北五凤楼煌斑岩年代学、地球化学特征及其成因[J].现代地质,2018,32(2):305-315,11.基金项目
中国地质大学(北京)燕山地质实践教学后备基地建设项目(2015-ms129) （北京）
国家重点研发计划项目(2016YFC0600502). （2016YFC0600502）
