• 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 >Vanadium and niobium behavior in rutile as a function of oxygen fugacity: evidence from natural samples
【24h】

Vanadium and niobium behavior in rutile as a function of oxygen fugacity: evidence from natural samples

机译：金红石中钒和铌的行为与氧逸度的关系：自然样品的证据

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

Vanadium occurs in multiple valence states in nature, whereas Nb is exclusively pentavalent. Both are compatible in rutile, but the relationship of V-Nb partitioning and dependence on oxygen fugacity (expressed as fO_2) has not yet been systematically investigated. We acquired trace-element concentrations on rutile grains (n = 86) in nine eclogitic samples from the Dabie-Sulu orogenic belt by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and combined them with published results in order to assess the direct and indirect effects of oxygen fugacity on the partitioning of V and Nb into rutile. A well-defined negative correlation between Nb (7-1,200 ppm) and V concentrations (50-3,200 ppm) was found, documenting a competitive relationship in the rutile crystal that does not appear to be controlled by bulk rock or mineral compositions. Based on the published relationship of ~(Rt)D_v and V valence with AQFM, we suggest that the priority order of V incorporation into rutile is V~(4+)>V~(3+)>V~(5+) The inferred Nb-V competitive relationship in rutile from the Dabie-Sulu orogenic belt could be explained by decreasing fO_2 due to dehydration reactions involving loss of oxidizing fluids during continental subduction: The increased proportion of V~(3+) (expressed as V~(3+)/ΣV) and attendant decrease in ~(Rt)D_v is suggested to lead to an increase in rutile lattice sites available for Nb~(5+). A similar effect may be observed under more oxidizing conditions. When V~(5+)/ΣV increases, ~(Rt)D_v shows a dramatic decline and Nb concentration increases considerably. This is possibly documented by rutile in highly metaso-matized and oxidized MARID-type (MARID: mica-amphibole-rutile-ilmenite-diopside) mantle xenoliths from the Kaapvaal craton, which also show a negative V-Nb covariation. In addition, their Nb/Ta covaries with V concentrations: For V concentrations 1,250 ppm, Nb/Ta is considerably lower (5-15). This relationship is mainly controlled by a change in Nb concentrations, suggesting that the indirect dependence of ~(Rt)D_(Nb), on fO_2, which is not mirrored in ~(Rt)D_(Ta), can exert considerable influence on rutile Nb-Ta fractionation.
机译：钒在自然界中以多种价态存在，而Nb仅是五价的。两者在金红石中都相容，但尚未系统地研究V-Nb分配与氧逸度（表示为fO_2）之间的关系。我们通过激光烧蚀-电感耦合等离子体质谱法（LA-ICP-MS）从大​​别-苏鲁造山带获得了9个洋矿样样品中金红石颗粒（n = 86）上的痕量元素浓度，并将其与已发表的结果结合起来以进行评估氧逸度对V和Nb分配为金红石的直接和间接影响。在Nb（7-1,200 ppm）和V浓度（50-3,200 ppm）之间发现了明确定义的负相关关系，这证明了金红石晶体中的竞争关系似乎不受散装岩石或矿物成分的控制。根据〜（Rt）D_v和V价与AQFM的已公开关系，我们建议将V掺入金红石的优先顺序为V〜（4 +）> V〜（3 +）> V〜（5+）。推断大别-苏鲁造山带金红石中的Nb-V竞争关系可以通过大陆俯冲过程中涉及氧化液损失的脱水反应引起的fO_2降低而降低：V〜（3+）的比例增加（表示为V〜（ 3 +）/ΣV）和随之而来的〜（Rt）D_v的降低被认为会导致可用于Nb〜（5+）的金红石晶格位点的增加。在更多的氧化条件下可以观察到类似的效果。当V〜（5 +）/ΣV增大时，〜（Rt）D_v急剧下降，Nb浓度显着增加。这可能是由Kaapvaal克拉通中高度交代化和氧化的MARID型（MARID：云母-安瓿-金红石-钛铁矿-透辉石）地幔异种岩中的金红石所证实的，V-Nb协变也为负。此外，它们的Nb / Ta与V浓度呈协变量：对于V浓度<1,250 ppm，Nb / Ta介于35至45之间，而对于V> 1,250 ppm，Nb / Ta则相对较低（5-15）。这种关系主要受Nb浓度变化的控制，表明〜（Rt）D_（Nb）对fO_2的间接依赖性（未反映在〜（Rt）D_（Ta）中）可以对金红石有相当大的影响。 Nb-Ta分馏。

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