A. A. Bendeliani, A. V. Bobrov, L. Bindi, N. N. Eremin
{"title":"Ti and Cr in High-Pressure Mica: Experimental Study and Application to the Mantle Assemblages","authors":"A. A. Bendeliani, A. V. Bobrov, L. Bindi, N. N. Eremin","doi":"10.1134/S0869591123010113","DOIUrl":null,"url":null,"abstract":"<p>Experiments aimed at the synthesis of Cr- and Ti-bearing phlogopite in the silicate-carbonate systems peridotite—K<sub>2</sub>CO<sub>3</sub> + H<sub>2</sub>O and basalt—K<sub>2</sub>CO<sub>3</sub> + H<sub>2</sub>O at 7 GPa and 900–1200°С were carried out. It is shown that the crystallization of titanium-bearing phlogopite requires subducted crustal material at mantle depths. However, the mantle peridotite should predominate over basalt for Ti-phlogopite crystallization; otherwise, dioctahedral mica (aluminoceladonite) with (Mg + Fe)/<sup>VI</sup>Al > 1 is formed via the scheme 2<sup>VI</sup>Al = <sup>VI</sup>Ti<sup>4+</sup> + <sup>VI</sup>(Mg + Fe). The competitive behavior of Ti and Cr upon incorporation into phlogopite is considered. It is shown that the presence of >1.3 wt % TiO<sub>2</sub> introduces a limitation on the high concentrations of Cr<sub>2</sub>O<sub>3</sub> via the scheme <sup>VI</sup>(Mg<sup>2+</sup>) + <sup>IV</sup>(Si<sup>4+</sup>) = <sup>VI</sup>(Cr<sup>3+</sup>) + <sup>IV</sup>(Al<sup>3+</sup>). This can explain the compositional patterns of phlogopite from inclusions in natural diamonds, in which the Ti content is much higher than that of Cr. The results obtained support the original idea that the composition of phlogopite may be applied to distinguish the paragenetic associations of diamond.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":null,"pages":null},"PeriodicalIF":1.0000,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Petrology","FirstCategoryId":"89","ListUrlMain":"https://link.springer.com/article/10.1134/S0869591123010113","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
Experiments aimed at the synthesis of Cr- and Ti-bearing phlogopite in the silicate-carbonate systems peridotite—K2CO3 + H2O and basalt—K2CO3 + H2O at 7 GPa and 900–1200°С were carried out. It is shown that the crystallization of titanium-bearing phlogopite requires subducted crustal material at mantle depths. However, the mantle peridotite should predominate over basalt for Ti-phlogopite crystallization; otherwise, dioctahedral mica (aluminoceladonite) with (Mg + Fe)/VIAl > 1 is formed via the scheme 2VIAl = VITi4+ + VI(Mg + Fe). The competitive behavior of Ti and Cr upon incorporation into phlogopite is considered. It is shown that the presence of >1.3 wt % TiO2 introduces a limitation on the high concentrations of Cr2O3 via the scheme VI(Mg2+) + IV(Si4+) = VI(Cr3+) + IV(Al3+). This can explain the compositional patterns of phlogopite from inclusions in natural diamonds, in which the Ti content is much higher than that of Cr. The results obtained support the original idea that the composition of phlogopite may be applied to distinguish the paragenetic associations of diamond.
期刊介绍:
Petrology is a journal of magmatic, metamorphic, and experimental petrology, mineralogy, and geochemistry. The journal offers comprehensive information on all multidisciplinary aspects of theoretical, experimental, and applied petrology. By giving special consideration to studies on the petrography of different regions of the former Soviet Union, Petrology provides readers with a unique opportunity to refine their understanding of the geology of the vast territory of the Eurasian continent. The journal welcomes manuscripts from all countries in the English or Russian language.