首页 | 本学科首页   官方微博 | 高级检索  
     检索      


Formation of cordierite-bearing lavas during anatexis in the lower crust beneath Lipari Island (Aeolian arc,Italy)
Authors:Corrado Di Martino  Francesca Forni  Maria Luce Frezzotti  Rosaria Palmeri  James D Webster  Robert A Ayuso  Federico Lucchi  Claudio A Tranne
Institution:1.Dipartimento di Scienze della Terra e Geologico-Ambientali,Università di Bologna,Bologna,Italy;2.Dipartimento di Scienze della Terra,Università di Siena,Siena,Italy;3.Museo Nazionale Antartide-Sezione di Scienze della Terra,Siena,Italy;4.Department of Earth and Planetary Sciences,AMNH,New York,USA;5.U.S. Geological Survey, 954 National Center,Reston,USA
Abstract:Cordierite-bearing lavas (CBL;~105 ka) erupted from the Mt. S. Angelo volcano at Lipari (Aeolian arc, Italy) are high-K andesites, displaying a range in the geochemical and isotopic compositions that reflect heterogeneity in the source and/or processes. CBL consist of megacrysts of Ca-plagioclase and clinopyroxene, euhedral crystals of cordierite and garnet, microphenocrysts of orthopyroxene and plagioclase, set in a heterogeneous rhyodacitic-rhyolitic groundmass containing abundant metamorphic and gabbroic xenoliths. New petrographic, chemical and isotopic data indicate formation of CBL by mixing of basaltic-andesitic magmas and high-K peraluminous rhyolitic magmas of anatectic origin and characterize partial melting processes in the lower continental crust of Lipari. Crustal anatectic melts generated through two main dehydration-melting peritectic reactions of metasedimentary rocks: (1) Biotite + Aluminosilicate + Quartz + Albite = Garnet + Cordierite + K-feldspar + Melt; (2) Biotite + Garnet + Quartz = Orthopyroxene + Cordierite + K-feldspar + Melt. Their position into the petrogenetic grid suggests that heating and consequent melting of metasedimentary rocks occurred at temperatures of 725 < T < 900°C and pressures of 0.4–0.45 GPa. Anatexis in the lower crust of Lipari was induced by protracted emplacement of basic magmas in the lower crust (~130 Ky). Crustal melting of the lower crust at 105 ka affected the volcano evolution, impeding frequent mafic-magma eruptions, and promoting magma stagnation and fractional crystallization processes.
Keywords:
本文献已被 SpringerLink 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号