...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of African earth sciences >Different melt source regions for the volcanics of the Bushveld large igneous province: New observations from MELTS modeling of the Palaeoproterozoic Rooiberg Group (South Africa)
【24h】

Different melt source regions for the volcanics of the Bushveld large igneous province: New observations from MELTS modeling of the Palaeoproterozoic Rooiberg Group (South Africa)

机译：BUSHVELD大火省火山岩的不同熔体源区：古古典罗刀群（南非）熔体建模的新观察

获取原文
获取原文并翻译 | 示例
   

获取外文期刊封面封底 >>

       
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The volcanic Rooiberg Group represents the extrusive phase of the Bushveld Magmatic Province in South Africa, forming the roof as well as the floor of the mafic-ultramafic 2057 Ma Rustenburg Layered Suite. Typically, the volcanic rocks of the Rooiberg Group vary from mafic compositions in the oldest unit (the Dullstroom Formation) to felsic compositions in the younger overlying units (the Damwal, Kwaggasnek and Schrikkloof formations). The lower parts of the Dullstroom Formation (including a basal rhyolitic unit) occur beneath the Rustenburg Layered Suite (RLS) in the southeastern part of the Bushveld Province, whereas the remainder of the Rooiberg Group occurs above the RLS. In this study, petrographic descriptions, whole rock geochemistry and MELTS modeling are used to show that the Dullstroom rhyolite could have evolved from fractional crystallisation of a siliceous and magnesian mafic liquid such as the so-called B1 liquid, parental to the lower parts of the Rustenburg Layered Suite. Due to its unique position at the base of the otherwise andesitic to dacitic Dullstroom Formation, the focus of this contribution is on the Dullstroom rhyolite and a comparison thereof with the rhyolites of the upper formations. Consistent with previous studies, the new data generated in this study show that a clear distinction can be made between the rhyolite in the Dullstroom, and those of the Damwal, Kwaggasnek and Schrikkloof formations. The Dullstroom rhyolite exhibits higher MgO contents (1.41-1.87 wt%) compared to the distinctly ferroan rhyolites of the Damwal, Kwaggasnek and Schrikkloof formations (0.01-0.91 wt% MgO). Similarly, immobile trace elements such as Y and Nb range from 9.72 to 12.7 ppm and 4.43-4.53 ppm, respectively, for the Dullstroom rhyolite, and are significantly different to the upper rhyolites (Y - 12.6-87.2 ppm and Nb - 12.3-24.2 ppm) suggesting likely petrogenetic differences. MELTS modeling shows that the Dullstroom rhyolite could not have evolved from the same liquids that generated the rhyolites of the Damwal, Kwaggasnek and Schrikkloof formations. The modeling suggests that the Dullstroom rhyolite formed through -20% assimilation of upper continental crustal rocks during fractional crystallisation of the B1 composition, and not from the low-Ti basaltic andesite, as previously proposed for the overlying rhyolites. The modeling aspects of this study provide evidence for different sources and melting-fractionation pathways throughout the evolution of the Bushveld Magmatic Province, consistent with characteristics recorded by the volcanic edifice of this large igneous province.
机译：火山岩Rooiberg集团代表南非的Bushveld Magmatic省的外阶段，形成了屋顶以及Mafic-Ultramafic 2057 Ma Rustenburg分层套房的地板。通常，Rooiberg组的火山岩从最旧的单位（沉睡形成）中的MAFIC组合物变化到较年轻的覆盖单位（Damwal，Kwaggasnek和Schrikkloof Chormations）中的毛丝组合物。杜鹃省省东南部的杜鹃分层套件（RLS）下方发生了杜鹃层叠套房（RLS），而罗格伯格组的其余部分发生在RLS之上。在这项研究中，岩体描述，整个岩石地球化学和熔化建模旨在表明，杜鹃石可以从硅质和镁镁型液体的分数结晶，例如所谓的B1液体，父母到下部的父母Restenburg分层套房。由于其在否则所依赖的底座的独特位置到达石棺形成，因此在杜鹃花的杜松岩上的焦点和其比较与上层的菱形。本研究中生成的新数据一致地符合先前的研究表明，可以在杜鹃花中的杜鹃花和Damwal，Kwaggasnek和Schrikkloof形成之间进行清晰的区别。与Damwal，Kwaggasneks和Schrikkloof地层的明显菲尔坎流谷菌（0.01-0.91wt％MgO）相比，杜鹃石的杜鹃籽含量较高（1.41-1.87wt％）。类似地，不动态痕量元素，例如Y和Nb，分别为杜鹃花的9.72至12.7ppm和4.43-4.53ppm，并且与上脉灰岩有显着不同（Y - 12.6-87.2 ppm和Nb - 12.3-24.2 PPM）表明可能的细胞差异。熔化建模表明，杜鹃石无法从相同的液体中发展，这些液体产生了产生了达摩力，Kwaggasnek和Schrikkloof地层的流孔。该模型表明，在B1组合物的分数结晶期间，通过-20％的上大陆地壳岩体同化形成，而不是从低Ti玄武岩骨灰化，如前所述，如前所述，如前所述。本研究的建模方面为丛林型岩浆省省的进化中的不同来源和熔化分馏途径提供了据证明，这与这一大火火炬省火山大厦记录的特征一致。

著录项

  • 来源
    《Journal of African earth sciences》 |2020年第12期|103999.1-103999.13|共13页
  • 作者

    Jolayemi Olutola O.; Robb Laurence; Lenhardt Nils; Hughes Hannah S. R.;

  • 作者单位

    Univ Witwatersrand Sch Geosci Private Bag 3 ZA-2050 Johannesburg South Africa;

    Univ Witwatersrand Sch Geosci Private Bag 3 ZA-2050 Johannesburg South Africa|Univ Oxford Dept Earth Sci South Park Rd Oxford OX1 3AN England|Univ Johannesburg DSI NRF CIMERA Johannesburg South Africa;

    Univ Pretoria Dept Geol Private Bag X20 ZA-0028 Pretoria South Africa|Univ Johannesburg DSI NRF CIMERA Johannesburg South Africa;

    Univ Witwatersrand Sch Geosci Private Bag 3 ZA-2050 Johannesburg South Africa|Univ Exeter Coll Engn Math & Phys Sci Camborne Sch Mines Penryn TR10 9FE England;

  • 收录信息
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Bushveld magmatic province; Rhyolite; MELTS modeling; Geochemistry; South Africa; Kaapvaal craton;

    机译：Bushveld Magmatic Province;流石;融化模型;地球化学;南非;Kaapvaal Craton;

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