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


The origin ofBe in island-arc volcanic rocks
Authors:Marc C Monaghan  Jeffrey Klein  Chris I Measures
Abstract:The presence of cosmogenic10Be (t1/2 = 1.5 × 106 y) in island-arc volcanic rocks has been interpreted as indicating that sediments are subducted to the depths of island-arc magma genesis 1,2]. We have measured10Be and9Be (the stable common isotope) in phenocryst and groundmass fractions separated from four Aleutian volcanic rocks.10Be and9Be covary linearly in three of the rocks proving that the10Be was incorporated prior to the formation of phenocrysts. In the other rock10Be and9Be do not covary; the lack of covariation indicates either that the rock incorporated10Be during weathering or that9Be-rich xenocrysts were incorporated by mechanical mixing. Our results strongly support the hypothesis of Brown et al. 1] and Tera et al. 2] that sediments containing10Be are an integral part of island-arc magmatic systems. As we cannot identify the depth at which the10Be was incorporated we still cannot completely rule out the possibility of assimilation of sediments or altered crust near the Earth's surface as a source of10Be.
Keywords:
本文献已被 ScienceDirect 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