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1kbar、800℃下REE在富磷过铝质熔体/流体相间分配的实验研究
  • ISSN号:1005-2321
  • 期刊名称:《地学前缘》
  • 时间:0
  • 分类:P579[天文地球—矿物学;天文地球—地质学]
  • 作者机构:[1]中国科学院地球化学研究所地球深部物质与流体作用地球化学研究室,贵州贵阳550002, [2]中国科学院研究生院,北京100049
  • 相关基金:国家重点基础研究发展计划“973”项目(2007CB411303);科学技术部支撑计划“305”项目(2007BAB25B01);国家自然科学基金项目(40673052,40273030)
中文摘要:

利用“RQV-快速内冷淬火”(或称之为“外加热冷封式”)高温高压实验装置,实验研究了1kbar、800℃条件下12个REE+Y在富磷过铝质熔体/含水流体相间的分配,并利用EMP、LA-ICPMS和ICP-MS分析技术分别测定了实验初始物、实验产物玻璃中主要化学组成以及熔体相和流体相中REE含量。实验结果表明,REE元素(La,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb和Lu)在流体/熔体相间的分配系数(D^fluid/melt)在(0.1~19.9)×10^-4范围,DY^fluid/melt在(0.2~7.8)×10^-4范围,指示REE和Y强烈趋向于在熔体中富集。REE在流体/熔体相间的分配系数(D^fluid/melt)与体系中P2O5含量变化呈近抛物线状分布,其最大值对应于残余熔体中w(P2O5)为1.44%处。REE在流体/熔体相间的分配系数(D^fluid/melt)随REE的原子序数增大而逐渐降低,构成右倾的平滑曲线,总体上显示出DLREE〉DMREE〉DHREE的趋势。Y与Ho在流体/熔体相间分配系数的比值(DY/DHo)约为1(0.91~1.28),不随体系中P2O5变化而变化的特征。上述特征表明熔体-流体作用不会导致Y-Ho及REE间的分异,因此,可推断熔体-流体作用过程不可能是过铝质岩浆体系中产生稀土“四重效应”机制。

英文摘要:

Fluid-saturated experiments were conducted to investigate the partitioning of 12 REE and Y between the phosphorus-rich peraluminous melt and coexisting aqueous fluid at 1 kbar and 800 ℃. All runs were conducted in cold-seal Rapid-Quench pressure Vessels (RQV, a kind of "externally heated cold-seal pressure vessels") using water as a pressure medium for durations of 144 hours. The major chemical compositions of the initial and run-product glasses were determined by EMPA; REE contents of the initial and run-product glasses were determined by LA-ICPMS; REE contents of aqueous fluids were analyzed by ICP-MS. It shows that the partitioning coefficients of REE (including La, Nd, Sin, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) between aqueous fluid and hydrous melt (D^fluid/melt) vary from 0. 1 × 10^-4 to 19.9 × 10^-4 , and DY^fluid/melt range from 0.2× 10^-4 to 7.8× 10^-4 , indicating that REE and Y are preferentially partitioned into the hydrous melts. The relationship of the fluid-melt partitioning coefficients of REEs to the phosphorus contents in the run-product glasses shows a near-normal distribution as the contents of P2O5 increasing from 0.19 wt% to 6.09 wt %, with the maximum D^fluid/melt corresponding to 1.44 wt/00 of P2O5. The fluid-melt REE partitioning coefficients decrease as increasing the atomic numbers of REE from La to Lu, showing DLREE〉 DMREE〉DHREE generally. The ratios of DY to DHo show no obvious variations with increasing P2 O5 contents in the run-product glasses from 0.19 wt% to 6.09 wt%, keeping a nearly constant value of -1 (in the range of 0. 91-1.28). The experimental results demonstrate that the interaction of phosphorus-rich peraluminous melt with coexisting aqueous fluid could not result in the fractionation between Y and Ho, and among the REEs. Therefore, it is implied that the melt-fluid interaction cannot be a candidate for the mechanism of REE tetrad effect during the evolution of peraluminous magmatic system.

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期刊信息
  • 《地学前缘》
  • 中国科技核心期刊
  • 主管单位:教育部
  • 主办单位:中国地质大学(北京) 北京大学
  • 主编:王成善
  • 地址:北京市学院路29号
  • 邮编:100083
  • 邮箱:frontier@cugb.edu.cn
  • 电话:010-82322973
  • 国际标准刊号:ISSN:1005-2321
  • 国内统一刊号:ISSN:11-3370/P
  • 邮发代号:
  • 获奖情况:
  • 荣获第五、六届"百种中国杰出学术期刊","首届中国高校精品科技期刊"称号
  • 国内外数据库收录:
  • 俄罗斯文摘杂志,美国化学文摘(网络版),荷兰文摘与引文数据库,美国工程索引,美国地质文献预评数据库,英国动物学记录,日本日本科学技术振兴机构数据库,中国中国科技核心期刊,中国北大核心期刊(2004版),中国北大核心期刊(2008版),中国北大核心期刊(2011版),中国北大核心期刊(2014版)
  • 被引量:34961