...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Volcanology and Geothermal Research >The petrologic history of the Sanganguey volcanic field, Nayarit, Mexico: Comparisons in a suite of crystal-rich and crystal-poor lavas
【24h】

The petrologic history of the Sanganguey volcanic field, Nayarit, Mexico: Comparisons in a suite of crystal-rich and crystal-poor lavas

机译：墨西哥纳亚里特市Sanganguey火山场的岩石学历史：一套富含晶体和缺乏晶体的熔岩的比较

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

To evaluate if intermediate magmas erupting from Volcan Sanganguey (Mexico) and the surrounding volcanic field are formed by mixing of basalts and rhyolites or if they initially exist as intermediate liquids, a detailed petrological study is presented for eight andesite and dacite magmas. Six of the samples erupted from the central edifice (four andesites and two dacites) are crystal-rich (<= 50 vol%), whereas the remaining two samples (one andesite and one dacite) erupted from monogenetic vents in the peripheral volcanic field and are crystal poor vol%). Despite the variation in crystallinity, all samples are multiply saturated in five to seven mineral phases (plagioclase + orthopyroxene + titanomagnetite + ilmenite + apatite +/- clinopyroxene +/- hornblende). In all samples, plagioclase spans a 30-40 mol% An range in composition and orthopyroxene spans a range in Mg# of 5-10. Pre-eruptive temperatures and oxygen fugacites (relative to the NNO buffer) range from 853 (+/- 24) to 1085 (+/- 16) degrees C and-0.1 (+/- 0.1) to 0.9 (+/- 0.1) ONNO, on the basis of Fe-Ti two oxide thermometry. Application of the plagioclase-liquid hygrometer to the samples reveals maximum H2O contents that range from 1.7-6.2 wt%. Comparison with phase equilibrium experiments demonstrates that all plagioclase and orthopyroxene compositions in the crystal-poor samples could have grown from their respective whole rock compositions. Comparison of crystal rich samples with phase equilibrium experiments reveals the presence of sodic xenocrysts which reflect resorption textures and an estimated excess plagioclase crystal cargo of >6 vol%. The excess plagioclase crystal cargo is not distinguishable from phenocrystic plagioclase based on composition or texture, suggesting that they were also grown in intermediate melts, and are therefore described as antecrystic. No calcic plagioclase xenocrysts (>An(79)) typical of hydrous arc basalts are observed, thus it is likely that the excess plagioclase in the crystal-rich samples were originally formed in intermediate magmas.
机译：为了评估是否通过混合玄武岩和流纹岩形成了从火山Sanganguey（墨西哥）喷发的中间岩浆和周围的火山场，或者它们最初以中间液体的形式存在，针对八种安山岩和闪锌矿岩浆进行了详细的岩石学研究。从中心大厦喷出的样品中有六个（四个安山岩和两个钠铁矿）富含晶体（<= 50 vol％），而其余两个样品（一个安山岩和一个钠铁矿）是从外围火山场的单相喷口中喷出的。晶体含量低）。尽管结晶度有所不同，但所有样品都在五到七个矿相（斜长石+邻辉石+钛磁铁矿+钛铁矿+磷灰石+/-斜py +/-角闪石）中被多个饱和。在所有样品中，斜长石的跨度为30-40摩尔％，邻位邻苯二酚的跨度为Mg＃（5-10）。爆发前的温度和氧逸度（相对于NNO缓冲液）的范围为853（+/- 24）至1085（+/- 16）摄氏度和-0.1（+/- 0.1）至0.9（+/- 0.1） ONNO，基于铁钛二氧化物测温法。将斜长石液体湿度计应用于样品显示最大H2O含量为1.7-6.2 wt％。与相平衡实验的比较表明，在晶体贫乏的样品中，所有斜长石和邻苯二酚的成分都可以由它们各自的完整岩石成分生长而成。将富含晶体的样品与相平衡实验进行比较，发现存在反映吸收结构的钠异晶晶硅，并且估计的斜长石晶体过量物> 6 vol％。基于组成或质地，过量的斜长石晶体货​​物与单晶斜长石没有区别，这表明它们也生长在中间熔体中，因此被描述为过晶体。没有观察到含水弧形玄武岩典型的钙化斜长石异晶（> An（79）），因此，富含晶体的样品中过量的斜长石可能最初形成于中间岩浆中。

著录项

相似文献

  • 外文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号