...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Economic geology and the bulletin of the Society of Economic Geologists >Petrogenesis of the Lower Zone Olivine-Rich Cumulates Beneath the Platreef and Their Correlation with Recognized Occurrences in the Bushveld Complex
【24h】

Petrogenesis of the Lower Zone Olivine-Rich Cumulates Beneath the Platreef and Their Correlation with Recognized Occurrences in the Bushveld Complex

机译：布什维尔德（Pushveld）复杂体中下部橄榄石富集的成岩作用积聚在平原下，并且与公认的发生率相关

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

Previously unknown Lower zone ultramafic sequences are described beneath the Platreef in the northern limb of the Bushveld Complex (South Africa). The Lower zone is separated from the overlying mineralized Platreef sequence by intervals of country rocks, which are represented by granofels (agmatites) and shales and include dim sills of fine-grained Marginal zone norite and pyroxenite. The chemical compositions of olivine and orthopyroxene in the Lower zone of the northern limb are more primitive than those established for the western and eastern limb and indicate that the Bushveld parental magma should be more Mg rich tiran previously suggested and therefore may have been able to dissolve more Cr than indicated by known Marginal chilled rock compositions. Olivine and orthopyroxene compositions show multiple reversals within the Lower zone sections which are accompanied by coherent reversals in the Cu/Pd ratio. The style of reversals is consistent with a gradual mixing of fresh magma with more evolved resident liquid in the chamber. Olivine and orthopyroxene contain higher Ni in sulfide-poor Lower zone sequences and are Ni depleted in mineralized rocks, whereas the degree of sulfide mineralization correlates with the S content in the country rock. Assimilation of sedimentary sulfur resulted in sulfide saturation and formation of Ni-depleted silicates in ultramafic rocks. The extremely high Ni content in olivine (up to 0.66 wt % NiO at Mg # = 88) from S-poor ultramafic rocks is attributed to Ni enrichment in residual melt after massive crystallization of Ni-poor orthopyroxene adcumulates. Trace element compositions of the most primitive cumulates and minerals confirm that the enrichment of primary melt of the Bushveld Complex in some incompatible elements is an initial feature of its anomalous mantle source.
机译：在Bushveld Complex（南非）北肢的Platreef下描述了以前未知的下层超镁铁质岩层。下层区域与上覆的矿化的Platreef层序隔开一定距离的乡村岩石，这些岩石以颗粒岩（ag石）和页岩为代表，并且包括细粒边缘区的红土和辉石的暗基石。北部肢体下部区域的橄榄石和邻二甲苯的化学成分比为西部和东部肢体确定的化学成分更原始，这表明Bushveld父母的岩浆应富含先前建议的富含Mg的钛，因此可能已经能够溶解铬比已知的边缘冷硬岩石成分所表明的要多。橄榄石和邻苯二酚组合物在下部区域内显示出多次反转，同时伴随着Cu / Pd比的连贯反转。反转的方式与新鲜岩浆和室内更多的残留液体的逐渐混合相一致。橄榄石和邻苯二茂在较差硫化物的下部区域序列中含有较高的Ni，在矿化岩石中贫化了Ni，而硫化物矿化的程度与乡村岩石中的S含量相关。沉积硫的同化导致硫化物饱和，并在超镁铁质岩石中形成贫镍的硅酸盐。 S贫超镁铁质岩石中橄榄石中的Ni含量极高（在Mg＃= 88时，高达0.66 wt％NiO）归因于贫Ni的邻位邻位邻苯二酚大量结晶后残余熔体中的Ni富集。最原始堆积物和矿物质的微量元素组成证实，Bushveld配合物中某些不相容元素的初熔体富集是其异常地幔源的初始特征。

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