海洋科学2023，Vol.47Issue(9)：1-11,11.DOI:10.11759/hykx20200527001
马努斯海盆东部裂谷岩浆演化过程——火山岩中斜长石斑晶的启示
Magma evolution process in the East Rift,Manus Basin:evi-dence from plagioclase phenocrysts in lavas
摘要
Abstract
The structure and composition of plagioclase in volcanic rocks provide important information regarding magmatic evolution.In this study,we systematically analyzed the mineralogy of plagioclase phenocrysts in lavas from the East Rift(ER),Manus Basin.Results show that the plagioclase phenocrysts in basaltic andesites have normal zoning,the An values for the core-mantle(An=80-87)of plagioclase belong to high-An plagioclase,and the An values decrease sharply for the rim.In dacites,the composition of plagioclase phenocrysts slightly changes from the core to the rim,most plagioclases have normal zoning with the An value decreasing gradually,and few plagio-clases have oscillatory zoning.The calculation results of crystallizing temperature and pressure for phenocrysts show that the magma evolution process in ER involved the following phenomena:1)Magma originated via partial melting of the mantle at～1300℃;2)In the early age,magma had a high ascend rate owing to the large magma sup-ply.3)After a small degree of fractional crystallization,magma eventually ejected at a high velocity and tempera-ture and formed basalt-basaltic andesites.In the late stage of the ER lavas,the magma underwent strong fractional crystallization owing to the low supply rate of magma and long stay of magma in the chamber(3-10 km;960℃-1020℃)and finally formed acidic lavas.Moreover,we argue that magma mixing did not play an important role in the magmatic evolution process.关键词
马努斯海盆/东部裂谷/斜长石/矿物学特征/岩浆演化Key words
Manus Basin/East Rift/plagioclase/mineralogical characteristics/magmatic evolution process分类
海洋科学引用本文复制引用
王雄,黄朋,黄海军,胡宁静..马努斯海盆东部裂谷岩浆演化过程——火山岩中斜长石斑晶的启示[J].海洋科学,2023,47(9):1-11,11.基金项目
中国科学院战略性科技先导专项(XDB42020303,XDA1103030204) （XDB42020303,XDA1103030204）
国家重点基础研究发展计划(2013CB429702) （2013CB429702）
国家自然科学基金(41576055)Strategic Priority Research Program of the Chinese Academy of Sciences,Nos.XDB42020303,XDA1103030204 （41576055）
National Key Basic Research Programme of China,No.2013CB429702 （）
National Natural Science Foundation of China,No.41576055 （）
