简介:Thispaperreportssiliconandoxygenisotopesof20kindsofigneousrocksandtheirmajorelementsfromtheeasternManusBasin.Combiningsiliconandoxygenisotopicdatafromotherstudies,wesupposethatbothδ30Siandδ18OvaluesincreasewiththeincreasingofSiO2content.Itmeansthatthefractionationofsiliconandoxygenisotopesareaffectedbythesilicacontent.ThepositivecorrelationbetweenCaO/Al2O3ratiosandMgOandthatbetweenSi/AlandSiO2contentindicatethatclinopyroxeneisthepredominantmineralphaseinoursamples.Wesupposethatthefractionationofsiliconandoxygenisotopesareinfluencedbymineralfractionalcrystallization.Probably,itisduetotheirdifferentsiliconandoxygenbridges.Inthisstudy,theδ30Simeanvalue=-0.17‰±0.17‰andδ18Omeanvalue=+6.07‰±0.57‰arehigherthannormalδ30Siandδ18Ovaluesofmantle,andweproposethattheseigneousrocksintheeasternManusBasinareaffectedbyhydrothermalalteration.
简介:对中间的熔岩的起源有许多最近的兴趣,几个假设是:1)在浸透水的条件下面的披风的直接融化,2)改变的外壳的部分融化,3)父母岩浆的部分结晶化,并且4)岩浆与dacitic/rhyolitic岩浆混合mafic岩浆。暴烈摇系列从东方手盆从玄武岩的安山岩到dacite(从53.8~63.0wt.%的SiO2范围)被检测为主修并且跟踪元素作文理解他们的起源。低H2O内容,2和Yb-SiO2,氧同位素数据和在斜长石斑晶的摆动的zoning的踪迹元素集中的模糊变化排除的La-SiO的积极关联硅的熔岩从含水的披风的直接融化导致的模型,改变的海洋的外壳或斑粝岩的部分融化,并且分别地混合的岩浆。除以外,geochemical数据完全摇并且融化包括显示部分结晶化在产生中介起一个主导的作用有subduction特征的熔岩。