地质与资源2025，Vol.34Issue(3)：277-290,14.DOI:10.13686/j.cnki.dzyzy.2025.03.002
桂东南燕山早期岩浆岩年代学、地球化学特征及地质意义
Geochronology and geochemistry of the Early Yanshanian magmatic rocks in southeastern Guangxi:Geological implication
摘要
Abstract
The paper studies the petrography,geochronology,whole-rock geochemistry,and Sr-Nd isotope of the intermediate-basic magmatic rocks in Nandu and Tanrong areas of southeastern Guangxi.The results show that the main rock types of Nandu and Tanrong intermediate-basic magmatic rocks are monzonite and aegirine-augite syenite,with the zircon U-Pb ages of 159.8 Ma and 156.8 Ma,respectively,indicating both formed during the Late Jurassic.The Nandu monzonite is more basic,while the Tanrong syenite is relatively intermediate.In the SiO2-K2O diagram,all samples plot within the shoshonitic series.The LREEs are significantly enriched relative to HREEs,exhibiting an overall right-dipping pattern.The Nandu samples show obvious negative Ba anomalies,while Tanrong samples distinct negative Sr and Ti anomalies.The isotope characteristics reveal that the ISr values of Nandu samples range from 0.70554 to 0.70959,with the εNd(t)values from-10.58 to-0.75,mostly falling within the enriched mantle and close to the Bulk Silicate Earth(BSE)area.The ISr values of Tanrong samples are 0.69033-0.69615,with the εNd(t)value of 0.36,mainly plotting between depleted mantle and enriched mantle fields.In summary,the study area was in a back-arc extensional tectonic setting associated with the westward subduction of Paleo-Pacific Plate during the Late Mesozoic.The Nandu monzonite samples were likely formed by partial melting of enriched mantle material,with the mantle-derived magma contaminated by crustal material during ascent,accompanied by a certain degree of plagioclase fractional crystallization,while the Tanrong aegirine-augite syenite was probably generated by partial melting of newly formed lower crust,induced by heat under the influence of partial melting of enriched mantle.关键词
侏罗纪/岩浆岩/锆石U-Pb定年/地球化学/广西Key words
Jurassic period/magmatic rock/Zircon U-Pb dating/geochemistry/Southeastern Guangxi分类
天文与地球科学引用本文复制引用
申妍菲,康志强,杨锋,吴玲玲,穆洎仲,周璐..桂东南燕山早期岩浆岩年代学、地球化学特征及地质意义[J].地质与资源,2025,34(3):277-290,14.基金项目
国家重点研发计划项目"难熔元素和同位素分析技术的综合应用研究"(2020YFA0714804) （2020YFA0714804）
国家自然科学基金项目"特提斯喜马拉雅带中、东段镁铁质岩石成因及其对新特提斯洋早期演化历史的约束"(42173048) （42173048）
广西硕士研究生创新项目"山东微山郗山碱性杂岩体地球化学特征及其地质意义"(YCSW2022313). （YCSW2022313）
