• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Nature >Water and its influence on the lithosphere asthenosphere boundary
【24h】

Water and its influence on the lithosphere asthenosphere boundary

机译：水及其对岩石圈软流圈边界的影响

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

The Earth has distinctive convective behaviour, described by the plate tectonics model, in which lateral motion of the oceanic lithosphere of basaltic crust and peridotitic uppermost mantle is decoupled from the underlying mechanically weaker upper mantle (asthenosphere). The reason for differentiation at the lithosphere-asthenosphere boundary is currently being debated with relevant observations from geophysics (including seismology) and geochemistry (including experimental petrology). Water is thought to have an important effect on mantle rheology, either by weakening the crystal structure of olivine and pyroxenes by dilute solid solution, or by causing low-temperature partial melting. Here we present a novel experimental approach to clarify the role of water in the uppermost mantle at pressures up to 6GPa, equivalent to a depth of 190 km. We found that for lherzolite in which a water-rich vapour is present, the temperature at which a silicate melt first appears (the vapour-saturated solidus) increases from a minimum of 970 ℃ at 1.5 GPa to 1,350 ℃ at 6GPa. We have measured the water content in lherzolite to be approximately 180 parts per million, retained in nominally anhydrous minerals at 2.5 and 4 GPa at temperatures above and below the vapour-saturated solidus. The hydrous mineral pargasite is the main water-storage site in the uppermost mantle, and the instability of pargasite at pressures greater than 3 GPa (equivalent to more than about 90 km depth) causes a sharp drop in both the water-storage capacity and the solidus temperature of fertile upper-mantle lherzolite. The presence of interstitial melt in mantle with more than 180 parts per million of water at pressures greater than 3 GPa alters mantle rheology and defines the lithosphere-asthenosphere boundary. Modern asthenospheric mantle acting as the source for mid-oceanic ridge basalts has a water content of 50-200 parts per million (refs 3-5). We show that this matches the water content of residual nominally anhydrous minerals after incipient melting of lherzolite at the vapour-saturated solidus at high pressure.
机译：地球具有独特的对流行为，这是板块构造模型所描述的，其中玄武岩壳和橄榄石最上层地幔的海洋岩石圈的横向运动与下层机械上较弱的上地幔（软流圈）解耦。目前正在与来自地球物理学（包括地震学）和地球化学（包括实验岩石学）的相关观测结果辩论岩石圈-软流圈边界差异的原因。人们认为，水对地幔流变性的重要影响是通过稀释固溶体来削弱橄榄石和辉石的晶体结构，或者是通过引起低温部分熔融。在这里，我们提出了一种新颖的实验方法，以阐明最高压力为6GPa（相当于190 km的深度）时水在最上层地幔中的作用。我们发现，对于其中存在富水蒸气的锂铁矿，硅酸盐熔体首次出现（蒸汽饱和固相线）的温度从1.5 GPa的最低970℃升高到6GPa的1,350℃。我们测量的水铁矿中的水含量约为百万分之180，在高于和低于蒸气饱和固相线的温度下，分别以2.5 GPa和4 GPa保留在名义上的无水矿物中。含水矿物辉石是最上层地幔的主要储水点，在压力大于3 GPa（相当于约90 km以上深度）的压力下，辉石的不稳定性会导致储水量和含水量急剧下降。肥沃的上地幔锂铁矿的固相线温度。在高于3 GPa的压力下，百万分之180的水中地幔融化的存在改变了地幔的流变性，并定义了岩石圈-软流圈的边界。现代的软流圈地幔是中洋脊玄武岩的来源，其水含量为百万分之50-200（参考3-5）。我们表明，这与高压下饱和气态固相线形锂铁矿的初次熔融后残留的名义上无水矿物的含水量相匹配。

著录项

  • 来源
    《Nature》 |2010年第7314期|P.448-451|共4页
  • 作者

    David H. Green; William O. Hibberson; Istvan Kovacs; Anja Rosenthal;

  • 作者单位

    School of Earth Sciences and Centre for Ore Deposit Studies, University of Tasmania, Hobart 7001, Tasmania, Australia Research School of Earth Sciences, The Australian National University, Mills Road, Canberra, Australian Capital Territory 0200, Australia;

    rnResearch School of Earth Sciences, The Australian National University, Mills Road, Canberra, Australian Capital Territory 0200, Australia;

    rnResearch School of Earth Sciences, The Australian National University, Mills Road, Canberra, Australian Capital Territory 0200, Australia Department of Data Management, Eoetvoes Lorand Geophysical Institute of Hungary, Columbus utca 17-23, H-1145 Budapest, Hungary;

    rnResearch School of Earth Sciences, The Australian National University, Mills Road, Canberra, Australian Capital Territory 0200, Australia;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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