Textural and compositional zoning in plagioclase phenocrysts:implications for magma chamber processes in the Emeishan large Igneous Province,SW China

作     者：Qi Chen Song-Yue Yu Lie-Meng Chen Sheng-Hua Zhou Jian Kang Qi Chen;Song-Yue Yu;Lie-Meng Chen;Sheng-Hua Zhou;Jian Kang

作者机构：State Key Laboratory of Ore Deposit GeochemistryInstitute of GeochemistryChinese Academy of SciencesGuiyang 550081China University of Chinese Academy of SciencesBeijing 100049China 

出 版 物：《Acta Geochimica》 (地球化学学报（英文）)

年 卷 期：2023年第42卷第3期

页      面：453-470页

核心收录：

学科分类：0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学] 

基　　金：funded by the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(XDB41000000) the NSFC(41573009,41873026,and 42173020) the‘‘Western Light Young scholar’’program of the Chinese Academy of Sciences to Prof.Lie-Meng Chen 

主　　题：Emeishan large Igneous Province Plagioclase-phyric basalt Compositional zoning Plagioclase phenocryst Magma replenishment 

摘      要：Textural and compositional zoning within plagioclase phenocrysts records the magma chamber processes,such as magma differentiation,magma recharge and mixing,and crustal *** plagioclase phenocrysts in the Daqiao and Qiaojia plagioclase-phyric basalts from the Emeishan Large Igneous Province(LIP)show complex textural and compositional zoning patterns,e.g.,normal,reverse,oscillatory,and patchy zoning *** plagioclase phenocrysts exhibit a core–rim normal zoning pattern(Pl-A)with euhedral high-An cores(An=76–78%,in mole fraction)and low-An rims(An=68–72%),indicative of the crystal regrowth processes caused by recharge of relatively evolved magmas after the formation of high-An *** phenocrysts have a core–rim reverse zoning pattern(Pl-B)with irregular ovaloid cores,characterized by extremely low An(60–61 mol%)and Ba(84–88 ppm)contents and extremely high87Sr/86Sr ratios(0.7120–0.7130).The rims of the Pl-B have relatively high An(69–72%),Ba(~160 ppm)contents,and low87Sr/86Sri(~0.7056).These Pl-B plagioclase phenocrysts preserve the information about the interaction between the crustal xenocrysts and the transporting *** plagioclase phenocrysts show a core–mantle–rim oscillatory zoning pattern(Pl-C)with multiple oscillations of An(70–80%),Ba(88–147ppm)from core to rim,revealing replenishment and mixing of multiple batches of basaltic melts with diverse compositions.87Sr/86Sr ratios of the Pl-C do not vary significantly(0.7050–0.7054).A small portion of phenocrysts has patchy patterns in the cores(Pl-D),where the low-An patches(72–75%)in form of elliptical or irregular elongated shapes were enclosed by the high-An domains(80–87%).These features can be attributed to crystal dissolution and regrowth processes during the reaction between earlyformed low-Cumulates and recharged hot primitive *** cores,mantles,and rims of different types of plagioclase phenocrysts(except the core of Pl-B)commonly display nearly constant Sr isotopic comp