...
  • 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 >The high PT stability of apatite and Cl partitioning between apatite and hydrous potassic phases in peridotite: an experimental study to 19 GPa with implications for the transport of P, Cl and K in the upper mantle
【24h】

The high PT stability of apatite and Cl partitioning between apatite and hydrous potassic phases in peridotite: an experimental study to 19 GPa with implications for the transport of P, Cl and K in the upper mantle

机译：橄榄岩中磷灰石的高PT稳定性和Cl在磷灰石和含水钾相之间的分配：对19 GPa的实验研究，对上地幔中P，Cl和K的迁移有影响

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

摘要

High PT experiments were performed in the range 2.5–19 GPa and 800–1,500°C using a synthetic peridotite doped with trace elements and OH-apatite or with Cl-apatite + phlogopite. The aim of the study was (1) to investigate the stability and phase relations of apatite and its high PT breakdown products, (2) to study the compositional evolution with P and T of phosphate and coexisting silicate phases and (3) to measure the Cl-OH partitioning between apatite and coexisting calcic amphibole, phlogopite and K-richterite. Apatite is stable in a garnet-lherzolite assemblage in the range 2.5–8.7 GPa and 800–1,100°C. The high-P breakdown product of apatite is tuite γ-Ca3 (PO4)2, which is stable in the range 8–15 GPa and 1,100–1,300°C. Coexisting apatite and tuite were observed at 8 GPa/1,050°C and 8.7 GPa/1,000°C. MgO in apatite increases with P from 0.8 wt% at 2.5 GPa to 3.2 wt% at 8.7 GPa. Both apatite and tuite may contain significant Na, Sr and REE with a correlation indicating 2 Ca2+=Na+ + REE3+. Tuite has always higher Sr and REE and lower Fe and Mg than apatite. Phosphorus in the peridotite phases decreases in the order Pmelt ≫ Pgrt ≫ PMg2SiO4 > Pcpx > Popx. The phosphate-saturated P2O5 content of garnet increases from 0.07 wt% at 2.5 GPa to 1.5 wt% at 12.8 GPa. Due to the low bulk Na content of the peridotite, [8]Na[4]P[8]M2+ −1 [4]Si−1 only plays a minor role in controlling the phosphorus content of garnet. Instead, element correlations indicate a major contribution of [6]M2+[4]P[6]M3+ −1 [4]Si−1. Pyroxenes contain ~200–500 ppm P and olivine has 0.14–0.23 wt% P2O5 in the P range 4–8.7 GPa without correlation with P, T or XMg. At ≥12.7 GPa, all Mg2SiO4 polymorphs have <200 ppm P. Coexisting olivine and wadsleyite show an equal preference for phosphorus. In case of coexisting wadsleyite and ringwoodite, the latter fractionates phosphorus. Although garnet shows by far the highest phosphorus concentrations of any peridotite silicate phase, olivine is no less important as phosphorus carrier and could store the entire bulk phosphorus budget of primitive mantle. In the Cl-apatite + phlogopite-doped peridotite, apatite contains 0.65–1.35 wt% Cl in the PT range 2.5–8.7 GPa/800–1,000°C. Apatite coexists with calcic amphibole at 2.5 GPa, phlogopite at 2.5–5 GPa and K-richterite at 7 GPa, and all silicates contain between 0.2 and 0.6 wt% Cl. No solid potassic phase is stable between 5 and 8.7 GPa. Cl strongly increases the solubility of K in hydrous fluids. This may lead to the breakdown of phlogopite and give rise to the local presence in the mantle of fluids strongly enriched in K, Cl, P and incompatible trace elements. Such fluids may get trapped as micro-inclusions in diamonds and provide bulk compositions suitable for the formation of unusual phases such as KCl or hypersilicic Cl-rich mica.
机译：使用掺杂有微量元素和OH-磷灰石或Cl-磷灰石+金云母的合成橄榄岩，在2.5-19 GPa和800-1,500°C的温度范围内进行了高PT实验。该研究的目的是（1）研究磷灰石及其高PT分解产物的稳定性和相关系，（2）研究磷酸盐和共存硅酸盐相的P和T的组成演变，（3）测量Cl-OH在磷灰石和共存的钙化角闪石，金云母和钾富钛矿之间分配。磷灰石在2.5–8.7 GPa和800–1,100°C的石榴石-锂铁矿组合中稳定。磷灰石的高P分解产物为tuiteγ-Ca 3 （PO 4 ） 2 ，稳定在8–15范围内GPa和1,100–1,300°C。在8 GPa / 1,050°C和8.7 GPa / 1,000°C下观察到磷灰石和土土并存。磷灰石中的MgO随着P从2.5 GPa时的0.8 wt％增加到8.7 GPa时的3.2 wt％。磷灰石和土石都可能含有大量的Na，Sr和REE，且相关性表明2 Ca 2 + = Na + + REE 3 + 。与磷灰石相比，Tuite始终具有较高的Sr和REE以及较低的Fe和Mg。橄榄岩相中的磷以P melt ≫ P grt ≫ P Mg2SiO4 cpx opx 。石榴石的磷酸盐饱和P 2 O 5 含量从2.5 GPa时的0.07 wt％增加到12.8 GPa时的1.5 wt％。由于橄榄岩的低钠含量， [8] Na [4] P [8] M 2+ < / sup> −1 [4] Si −1 仅在控制石榴石的磷含量中起较小的作用。相反，元素相关性表示 [6] M 2+ [4] P [6] M 3+ < / sup> -1 [4] Si -1 。辉石的P含量约为200-500 ppm，橄榄石的P 2 O 5 含量为0.14-0.23 wt％，P范围为4-8.7 GPa，与P，T或X不相关 Mg 。在≥12.7GPa时，所有Mg 2 SiO 4 多晶型物的P均<200 ppm。橄榄石和辉石岩共存对磷的偏好相同。如果同时存在沃兹利石和林伍德石，后者会分馏磷。尽管石榴石显示了橄榄岩硅酸盐相中最高的磷浓度，但橄榄石作为磷载体同样重要，并且可以存储原始地幔的全部磷预算。在掺有Cl-磷灰石+金云母的橄榄岩中，磷灰石在PT范围2.5-8.7 GPa / 800-1,000°C时含有0.65-1.35 wt％的Cl。磷灰石与钙闪石（2.5 GPa），金云母（2.5-5 GPa）和钾富钾石（7 GPa）共存，所有硅酸盐都含有0.2至0.6 wt％的Cl。在5至8.7 GPa之间，没有固态钾相稳定。 Cl大大增加了K在含水流体中的溶解度。这可能会导致金云母的分解，并在地幔中引起局部存在，其中富含K，Cl，P和不相容的痕量元素。这样的流体可能会以微夹杂物的形式被捕获在钻石中，并提供适合于形成不寻常相（例如KCl或富硅化高云母的云母）的本体组成。

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