...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Contributions to Mineralogy and Petrology >Origins of cold-wet-oxidizing to hot-dry-reducing rhyolite magma cycles and distribution in the Taupo Volcanic Zone, New Zealand
【24h】

Origins of cold-wet-oxidizing to hot-dry-reducing rhyolite magma cycles and distribution in the Taupo Volcanic Zone, New Zealand

机译：新西兰陶波火山区冷-湿-氧化-热-减少流纹岩岩浆循环的起源和分布

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

Slab-derived aqueous fluid components (Ba, Cl) correlate well with oxygen fugacity, and other welldefined characteristics of silicic magmas in the Taupo Volcanic Zone (TVZ) between a cold-wet-oxidizing magma type [R1: amphibole ± biotite; high Sr, low Zr and FeO~*/MgO, depleted middle rare-earth elements (MREE)] and a hot-dry-reducing magma type (R2: orthopyroxene ± clinopyroxene; low Sr, high Zr, and FeO~*/MgO, less depleted MREE). Oxygen fugacity was obtained from analysis of Fe–Ti oxides and ranges between -0.04 and +2.1 log units (DQFM, where QFM = quartz + fayalite + magnetite buffer) and is positively correlated with the bulk-rock Ba/La ratio, indicating that slab-derived fluid is the oxidizing agent in the rhyolites. Chlorine contents in hornblende also correlate with the bulk-rock Ba/La ratio. Hence, high-fluid flux typically correlates with the R1 and low-fluid flux with R2 rhyolite magma types. A geochemical evolution and distribution can be tracked in time and space throughout the central region of the TVZ from 550 ka to present and has revealed two distinct magmatic cycles that vary in length. The first cycle included widespread R1 type magmatism across the central TVZ beginning ca. 550 ka nd was directly associated with previously unreported dome-building and ignimbrite-forming volcanism, and led to a voluminous (>3,000 km~3) ignimbrite ‘flare-up’ between ca. 340 and 240 ka. The second cycle began roughly 180 ka, erupting ca. 800 km~3 of magma, and continues to the present. The duration, rate, and composition of magma production within these cycles appears to be governed by the flux of fluid released from the subducting slab, while the distribution of magmas may be governed more by extension along the central rift axis. Shorter cycles have also been identified and are unrelated to subduction processes, but occur following large, calderaforming events.
机译：平板状含水流体成分（Ba，Cl）与氧逸度以及陶波火山带（TVZ）冷湿氧化岩浆类型[R1：闪石±黑云母;高Sr，低Zr和FeO〜* / MgO，贫化的中稀土元素（MREE）和热干还原岩浆类型（R2：邻苯二酚±斜py石;低Sr，高Zr和FeO〜* / MgO ，消耗较少的MREE）。氧气逸度是通过分析Fe-Ti氧化物获得的，其范围介于-0.04和+2.1 log单位之间（DQFM，其中QFM =石英+铁橄榄石+磁铁矿缓冲液），并且与块状岩石的Ba / La比值呈正相关，表明平板状流体是流纹岩中的氧化剂。角闪石中的氯含量还与块状岩石的Ba / La比相关。因此，高流体通量通常与R1相关，而低流体通量与R2流纹岩岩浆类型相关。从550 ka到现在，整个TVZ中心区域的时间和空间都可以追踪地球化学演化和分布，并揭示了两个不同的岩浆旋回，它们的长度各不相同。第一个周期包括大约从大约开始的整个中央TVZ的广泛的R1型岩浆作用。 550 kand与先前未报道的穹顶建设和形成火成岩的火山作用直接相关，并导致大约两千之间（> 3,000 km〜3）大量的火成岩“爆发”。 340和240 ka。第二个周期大约开始180 ka，爆发约800 km〜3的岩浆，并一直持续到现在。在这些周期内，岩浆产生的持续时间，速度和组成似乎受俯冲板释放的流体通量的控制，而岩浆的分布可能更多地由沿中央裂谷轴的伸展控制。还已经确定了更短的周期，并且与俯冲过程无关，但是发生在大型的火山口事件之后。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 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