Water solubility in coesite at realistic temperatures of subduction zones
文献类型：期刊论文
| 作者 | Yan, Wei4,5,6; Lv, Mingda4,5; Wu, Dan3; Sun, Weidong2; Li, Xiaohu6; He, Mingyue1; Liu, Xi4,5 |
| 刊名 | Chemical Geology
 |
| 出版日期 | 2023 |
| 卷号 | 625页码:121412 |
| ISSN号 | 0009-2541 |
| DOI | 10.1016/j.chemgeo.2023.121412 |
| 英文摘要 | To constrain the water solubility of coesite (Coe) at typical temperatures of subduction zones, a series of Coe coexisting with an aqueous fluid was synthesized at 3–6 GPa and at 600–800 °C. Most experiments were performed in the system SiO2-H2O, and some were performed with small amounts of boron addition. With very long heating durations (120–336 h), all these experiments successfully produced Coe crystals of large grain size, ranging from ?100 to 1300 μm. For every experimental product, multiple unpolarized FTIR spectra were collected on randomly-selected Coe crystals. We have found that type-I hydrogarnet substitution (Si4+(Si2) + 4O2? = [4](Si2) + 4OH?) is the major water-incorporation mechanism whereas B-related defect (H+ + B3+ ? Si4+) makes no much contribution. The water solubility of Coe, ranging from 3(1) to 47(12) wt ppm, positively correlates with both P and T. It can be well described by the empirical equation cH2O = ?49(17) + 6.0(21) × P + 0.06(2) × T (cH2O representing water content in wt ppm, P pressure in GPa and T temperature in °C) and by the thermodynamic expression [Formula presented] (cOH representing water content in H/106 Si, fH2O water fugacity in GPa, R the gas constant, P pressure in GPa, T temperature in K, ?S1 bar reaction entropy as 18.5(509) J/mol/K, ?H1 bar reaction enthalpy as ?10.7(516) kJ/mol, and ?Vsolid the volume change of Coe during hydroxylation as 23.6(42) cm3/mol). Consequently, the water solubility of Coe in subduction zones should be ?0–123 wt ppm. When Coe with deep origin becomes metastable (i.e., approaching the P-T locus of the Coe-quartz (Qz) reaction), its water content is likely less than ?10 wt ppm. This trace water may be quickly lost along with further exhumation process, and metastable Coe becomes completely dry, as observed in the Coe discovered in all exhumed ultrahigh-pressure (UHP) metamorphic rocks. Since structurally-bonded water substantially speeds up the Coe-to-Qz phase transition, zero water in metastable Coe may be the key to the preservation of Coe in the UHP metamorphic rocks. ? 2023 Elsevier B.V. |
| 语种 | 英语 |
| 源URL | [http://ir.gig.ac.cn/handle/344008/80245]  |
| 专题 | 中国科学院矿物学与成矿学重点实验室 |
| 作者单位 | 1.School of Gemmology, China University of Geosciences (Beijing), Beijing; 100083, China 2.Center of Deep Sea Research, Institute of Oceanography, Chinese Academy of Sciences, Qingdao; 266071, China 3.Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou; 510640, China 4.Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education of China, Beijing; 100871, China 5.School of Earth and Space Sciences, Peking University, Beijing; 100871, China 6.Key Laboratory of Submarine Geosciences, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou; 310012, China |
| 推荐引用方式 GB/T 7714 | Yan, Wei,Lv, Mingda,Wu, Dan,et al. Water solubility in coesite at realistic temperatures of subduction zones[J]. Chemical Geology,2023,625:121412. |
| APA | Yan, Wei.,Lv, Mingda.,Wu, Dan.,Sun, Weidong.,Li, Xiaohu.,...&Liu, Xi.(2023).Water solubility in coesite at realistic temperatures of subduction zones.Chemical Geology,625,121412. |
| MLA | Yan, Wei,et al."Water solubility in coesite at realistic temperatures of subduction zones".Chemical Geology 625(2023):121412. |
入库方式： OAI收割
来源：广州地球化学研究所
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