Zircon solubility modulated by boron in hydrous granitic melts

IF 5 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Geochimica et Cosmochimica Acta Pub Date : 2025-08-10 DOI:10.1016/j.gca.2025.08.008

Jinhua Huang , Renzhi Zhu , Huaiwei Ni

{"title":"Zircon solubility modulated by boron in hydrous granitic melts","authors":"Jinhua Huang , Renzhi Zhu , Huaiwei Ni","doi":"10.1016/j.gca.2025.08.008","DOIUrl":null,"url":null,"abstract":"<div><div>Granitic rocks associated with zircon deposits often contain notable boron (B), suggesting a potentially crucial role of B in zircon mineralization. However, the influence of B on the solubility of zircon in granitic magma remains unclear. In this study, the solubility of zircon in three granitic melts (peralkaline, metaluminous, and peraluminous) with approximately 6 wt% H2O (i.e., water-saturated) and up to 7.7 wt% B2O3 was investigated at 800 °C and 2 kbar using a cold-seal vessel. As melt B2O3 content increased from 0 to 1 wt%, ZrO2 content always increased, from 2.10 to 2.60 wt% in the peralkaline melt (ASI = 0.63), from 0.20 to 0.26 wt% in the metaluminous melt (ASI = 0.98), and from 0.02 to 0.03 wt% in the peraluminous melt (ASI = 1.20). However, with a further increase of B2O3 to 7.7 wt%, the ZrO2 content in all of the three granitic melts steadily decreased to approximately one-sixth of the maximum value. Raman and nuclear magnetic resonance spectroscopic measurements suggest that the shift in zircon solubility behavior is related to structural change involving boron and oxygen. The turning point at 1 wt% B2O3 marks a transition from predominantly trigonally coordinated boron in low-boron melts, producing non-bridging oxygen favorable to zirconium (Zr) incorporation, to the prevalence of tetrahedrally coordinated boron in high-boron melts promoting bridging oxygen. The experimental results imply that the mechanism and behavior of zircon saturation can be different for different boron-bearing magmas. In granitic magma (usually with <1 wt% B2O3), B serves to promote the Zr-carrying capacity of magma, which is in favor of Zr mineralization. By contrast, in pegmatitic magma (mostly with >1 wt% B2O3), the Zr-carrying capacity of magma is low, and B is harmful to Zr mineralization.</div></div>","PeriodicalId":327,"journal":{"name":"Geochimica et Cosmochimica Acta","volume":"405 ","pages":"Pages 15-24"},"PeriodicalIF":5.0000,"publicationDate":"2025-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geochimica et Cosmochimica Acta","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0016703725004144","RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}

引用次数: 0

Abstract

Granitic rocks associated with zircon deposits often contain notable boron (B), suggesting a potentially crucial role of B in zircon mineralization. However, the influence of B on the solubility of zircon in granitic magma remains unclear. In this study, the solubility of zircon in three granitic melts (peralkaline, metaluminous, and peraluminous) with approximately 6 wt% H₂O (i.e., water-saturated) and up to 7.7 wt% B₂O₃ was investigated at 800 °C and 2 kbar using a cold-seal vessel. As melt B₂O₃ content increased from 0 to 1 wt%, ZrO₂ content always increased, from 2.10 to 2.60 wt% in the peralkaline melt (ASI = 0.63), from 0.20 to 0.26 wt% in the metaluminous melt (ASI = 0.98), and from 0.02 to 0.03 wt% in the peraluminous melt (ASI = 1.20). However, with a further increase of B₂O₃ to 7.7 wt%, the ZrO₂ content in all of the three granitic melts steadily decreased to approximately one-sixth of the maximum value. Raman and nuclear magnetic resonance spectroscopic measurements suggest that the shift in zircon solubility behavior is related to structural change involving boron and oxygen. The turning point at 1 wt% B₂O₃ marks a transition from predominantly trigonally coordinated boron in low-boron melts, producing non-bridging oxygen favorable to zirconium (Zr) incorporation, to the prevalence of tetrahedrally coordinated boron in high-boron melts promoting bridging oxygen. The experimental results imply that the mechanism and behavior of zircon saturation can be different for different boron-bearing magmas. In granitic magma (usually with <1 wt% B₂O₃), B serves to promote the Zr-carrying capacity of magma, which is in favor of Zr mineralization. By contrast, in pegmatitic magma (mostly with >1 wt% B₂O₃), the Zr-carrying capacity of magma is low, and B is harmful to Zr mineralization.

查看原文本刊更多论文

硼对含水花岗岩熔体中锆石溶解度的调节

与锆石矿床伴生的花岗质岩石通常含有显著的硼(B)，表明B在锆石成矿作用中可能起着关键作用。但B对锆石在花岗质岩浆中溶解度的影响尚不清楚。在这项研究中，使用冷密封容器，在800°C和2 kbar的温度下，研究了锆石在三种花岗岩熔体（过碱性、过铝质和过铝质）中的溶解度，这些熔体含有大约6 wt%的H2O（即水饱和）和高达7.7 wt%的B2O3。随着熔体B2O3含量从0 wt%增加到1 wt%， ZrO2含量不断增加，过碱性熔体（ASI = 0.63）从2.10 wt%增加到2.60 wt%，铝质熔体（ASI = 0.98）从0.20 wt%增加到0.26 wt%，过铝熔体（ASI = 1.20）从0.02 wt%增加到0.03 wt%。然而，当B2O3含量进一步增加到7.7 wt%时，3种花岗岩熔体中的ZrO2含量都稳定下降到最大值的六分之一左右。拉曼和核磁共振光谱测量表明，锆石溶解度的变化与含硼和氧的结构变化有关。1 wt% B2O3的转折点标志着低硼熔体中主要的三角配位硼，产生有利于锆（Zr）掺入的非桥氧，到高硼熔体中普遍存在的四面体配位硼，促进桥氧。实验结果表明，不同含硼岩浆的锆石饱和机制和行为可能不同。在花岗质岩浆中（通常B2O3含量为<；1 wt%）， B增强了岩浆携带Zr的能力，有利于Zr矿化。而在伟晶质岩浆中（B2O3含量多为>；1 wt%），岩浆携带Zr的能力较低，B不利于Zr成矿。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Geochimica et Cosmochimica Acta 地学-地球化学与地球物理

CiteScore

9.60

自引率

14.00%

发文量

437

审稿时长

6 months

期刊介绍： Geochimica et Cosmochimica Acta publishes research papers in a wide range of subjects in terrestrial geochemistry, meteoritics, and planetary geochemistry. The scope of the journal includes: 1). Physical chemistry of gases, aqueous solutions, glasses, and crystalline solids 2). Igneous and metamorphic petrology 3). Chemical processes in the atmosphere, hydrosphere, biosphere, and lithosphere of the Earth 4). Organic geochemistry 5). Isotope geochemistry 6). Meteoritics and meteorite impacts 7). Lunar science; and 8). Planetary geochemistry.