...
  • 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 >Trace element distribution between orthopyroxene and clinopyroxene in peridotites from the Gakkel Ridge: a SIMS and NanoSIMS study
【24h】

Trace element distribution between orthopyroxene and clinopyroxene in peridotites from the Gakkel Ridge: a SIMS and NanoSIMS study

机译：Gakkel山脊橄榄石中邻位和次生环戊烯和次生环戊烯之间的痕量元素分布：SIMS和NanoSIMS研究

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

Clinopyroxenes (cpx) in abyssal and ophiolitic peridotites are commonly analyzed for lithophile trace element abundances in order to estimate degrees of melting and porosity conditions during melt extraction, assuming that these data reflect near-solidus conditions. During cooling, however, cpxs always exsolve into parallel lamellae of low-Ca enstatite and high-Ca diopside. This may potentially lead to redistribution of the initial trace element budget. Since orthopyroxene (opx) cannot significantly host most incompatible trace elements, exsolution will lead to an enrichment in the cpx lamellae. In order to address a possibly exsolution-controlled partitioning between cpx and opx, we have obtained major and trace element mineral compositions on 14 plagioclase-free ocean floor mantle rocks. They cover the entire abyssal peridotite compositional spectrum from very fertile to highly depleted compositions. The mean volume proportion of opx lamellae in cpx por-phyroclasts lies around 15 percent of the original cpx. For the light to middle rare earth elements, the enrichment in the measured cpx exsolution is exclusively controlled by these phase proportions. Relative to these highly incompatible trace elements, solely Ti and Yb partition significantly into opx. Lamellar interpyroxene partition coefficients, estimated from NanoSIMS analyses, are around three times as high as the ones for near-solidus bulk pyroxene. The equilibration temperatures for the exsolution lamella are slightly higher than 800°C. The bulk cpx can be reconstructed using the lamellar proportions and their relative partitioning. The implication of such a reconstruction is that the cpx rare earth element patterns shift almost in parallel to lower values. These shifts, however, do not affect mantle melting models proposed thus far for mid-ocean ridges.
机译：假设这些数据反映了接近固相线的条件，通常对深海和乳橄榄岩橄榄岩中的斜辉石（cpx）进行亲石性痕量元素丰度分析，以估算熔体萃取过程中的熔融程度和孔隙度条件。但是，在冷却过程中，cpxs始终会分解成低钙顽辉石和高钙透辉石的平行薄片。这可能会导致重新分配初始跟踪元素预算。由于邻苯二酚（opx）不能显着容纳大多数不相容的痕量元素，因此洗脱将导致cpx薄片富集。为了解决cpx和opx之间可能由浓度控制的分区，我们在14个无斜长石的海底地幔岩石上获得了主要元素和微量元素矿物成分。它们涵盖了从深部肥沃到极度贫化的整个深海橄榄岩成分光谱。 cpx por-phyroclasts中opx薄片的平均体积比例约为原始cpx的15％。对于轻稀土元素至中等稀土元素，所测cpx浓缩物中的富集仅受这些相比例的控制。相对于这些高度不兼容的痕量元素，仅Ti和Yb显着分配为opx。通过NanoSIMS分析估计，层状py间环的分配系数约为近固相块状辉石的三倍。溶解薄片的平衡温度略高于800°C。可以使用层状比例及其相对分区来重建整体cpx。这种重建意味着cpx稀土元素图案几乎平行于较低值移动。但是，这些变化不会影响迄今为止为中海脊提出的地幔融化模型。

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