岩石矿物学杂志2025，Vol.44Issue(5)：1003-1027,25.DOI:10.20086/j.cnki.yskw.2025.4183
华北克拉通北缘沙峪口早白垩世埃达克质花岗岩成因
Petrogenesis of the Early Cretaceous adakitic granites in the Shayukou area of the northern margin of North China Craton:Geogchronologic and geochemical constraints
摘要
Abstract
Granites serve as critical indicators of crust-mantle material cycling.Their genetic evolution provides essential constraints for deciphering continental crustal accretion-differentiation processes,unraveling the dynamics of orogenic mechanisms,and elucidating the evolution of deep-seated geochemical reservoirs.To constrain the Late Mesozoic tectonic evolution of the Yanshan Fold Belt along the northern margin of the North China Craton,we con-ducted systematical investigations of the Shayukou granites in Beijing.These investigations included petrographic analysis,zircon U-Pb geochronology,whole-rock major and trace element geochemistry,and Lu-Hf isotopic analy-ses.Zircon U-Pb concordant ages from the Shayukou monzogranite yield 134±1,132±1,132±1,131±3,130±4 and 133±2 Ma,respectively,constraining the pluton emplacement to the Early Cretaceous.Geochemical analyses reveal the following characteristics:the Shayukou monzogranites possess high silica(SiO2=63.70％～69.13％),alkali enrichment(Na2O+K2O=9.48％～10.81％),and peraluminous composition(A/CNK=1.05～1.13 and A/NK=1.26～1.29),classified as high-K calc-alkaline Ⅰ-type granites.The rocks exhibit pronounced enrichment in large-ion lithophile elements(LILEs;e.g.,Rb,K,Ba)and light rare earth elements(LREEs),coupled with depletion in high-field-strength elements(HFSEs;e.g.,Nb,Ta,Ti).Diagnostic features,including elevated K2O,Sr,(La/Yb)N ratios,and suppressed MgO,Y,and Yb contents,collectively characterize them as C-type adakites.Zircons from the Shayukou monzogranites exhibit εHf(t)values ranging from-23.84 to-19.76,with two-stage Hf model ages(tCDM)of 3 768～3 408 Ma,indicating derivation from the partial melting of Paleoarchean crust.The low zircon saturation temperatures,ranging from 637℃ to 699℃,classify the monzogranite as a low-temperature granite,suggesting the generation of magma involved infiltration of external fluids.Integrated with regional tectonic evolution,the Shayukou granite formed in a setting associated with the subduction of the Paleo-Pacific Plate.The underplating of mantle-derived magma,along with fluid fluxing,initiated the partial melting of thickened Archean igneous lower crust.Subsequently,the magma underwent limited fractional crystallization and crystallized at low temperatures.关键词
沙峪口花岗岩/C型埃达克岩/锆石U-Pb定年/Lu-Hf同位素/岩石成因Key words
Shayukou granite/C-type adakites/zircon U-Pb dating/Lu-Hf isotope/petrogenesis分类
天文与地球科学引用本文复制引用
李壮,杨荣彬,秦明硕,朱鑫,华秋实,宋泽章..华北克拉通北缘沙峪口早白垩世埃达克质花岗岩成因[J].岩石矿物学杂志,2025,44(5):1003-1027,25.基金项目
国家自然科学基金项目(42002238,41804045,42272161) （42002238,41804045,42272161）
东北亚矿产资源评价重点实验室开放课题(DBY-KF-19-03) （DBY-KF-19-03）
中国石油天然气股份有限公司重大科技专项(2023ZZ16,2024D101-01-06) National Natural Science Foundation of China(42002238,41804045,42272161) （2023ZZ16,2024D101-01-06）
Open Fund Project of Key Laboratory of Mineral Resources Evaluation in Northeast Asia(DBY-KF-19-03) （DBY-KF-19-03）
PetroChina Compa-ny Limited Major Science and Technology Project(2023ZZ16,2024D101-01-06) （2023ZZ16,2024D101-01-06）
