桂林理工大学学报2023，Vol.43Issue(4)：535-546,12.DOI:10.3969/j.issn.1674-9057.2023.04.001
桂东南云开地区南渡钾玄质侵入岩的年代学、地球化学及其地质意义
Chronology,geochemistry and its geological significance of Nandu shoshonitic pluton in Yunkai area,southeastern Guangxi
摘要
Abstract
In order to constrain the tectonic enviromment of Early Yanshan in southeastern Guangxi,the petrog-raphy,petrogeochemistry and LA-ICP-MS zircon U-Pb geochronology of Nandu pluton were studied.The Nandu pluton is composed of four lithologic units,including Tanfu,Liulin,Xincun and Shihe,of which main rock types are quartz monzonite,monzonite,syenite,quartz monzonite porphyry and hornblende syenite porphy-ry and so on.The LA-ICP-MS zircon U-Pb ages of two samples are 155.2±1.7 Ma and 155.9±1.8 Ma,re-spectively,indicating that the Nandu pluton was formed in the Late Jurassic of Early Yanshanian period.The major elements of Nandu pluton are characterized by high silicon and aluminum,low iron and magnesium,rich alkali,with Rietmann index ranging from 3.56 to 6.77,the total alkali content ranging from 6.33％to 11.59％,and K2 O/Na2O value ranging from 1.02 to 1.63.The Nandu pluton has a right-leaning chondrite standardized distribution pattern which is enriched in light rare earth elements and the negative Eu anomaly is not obvious.It is enriched in large ion lithophile elements,Zr and Hf,with moderate depletion of Sr,P and Ti,and no obvious Nb and Ta anomalies.In the Harker diagrams,TiO2,TFe2O3,MgO,CaO,MnO and P2O5 are negatively correlated with SiO2,while Al2O3 and Na2O are not significantly correlated with SiO2.Combined with the depletion of Sr,P and Ti,and no negative Eu anomaly,it is suggested that there might be separation crys-tallization of apatite,ilmenite and clinopyroxene,but no fractional crystallization of plagioclase.The petrograph-ic and geochemical characteristics of Nandu pluton indicate that it is the typical intraplate shoshonite rocks that formed in an intraplate extensional tectonic environment,and maybe it is related to the asthenosphere of mantle upwelling,lithospheric extension and rifting in the Early Yanshan period in South China continent.关键词
LA-ICP-MS锆石定年/钾玄质侵入岩/伸展构造环境/南渡杂岩体/桂东南Key words
LA-ICP-MS zircon dating/shoshonitic pluton rock/extensional tectonic setting/Nandu pluton/southeastern Guangxi分类
地质学引用本文复制引用
周鹏程,秦亚,杨启军,马强分,林炫名,钟宁军,邓伟强..桂东南云开地区南渡钾玄质侵入岩的年代学、地球化学及其地质意义[J].桂林理工大学学报,2023,43(4):535-546,12.基金项目
广西自然科学基金项目(2022GXNSFAA035570) （2022GXNSFAA035570）
广西科技基地和人才专项(桂科AD20159027) （桂科AD20159027）
国家自然科学基金项目(42162018) （42162018）
广西地质找矿突破战略行动勘查项目(桂自然资函[2018]104号) （桂自然资函[2018]104号）
