Association of quartz, Cr-pyrope and Cr-diopside in mantle xenolith in V.Grib kimberlite pipe (northern East European Platform): genetic models
| Autor: | Elena V. Agasheva, Denis S. Mikhailenko, Andrei V. Korsakov |
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| Jazyk: | English<br />Russian |
| Rok vydání: | 2024 |
| Předmět: | |
| Zdroj: | Записки Горного института, Vol 268, Pp 503-519 (2024) |
| Druh dokumentu: | article |
| ISSN: | 2411-3336 2541-9404 |
| Popis: | The first results of mineralogical and geochemical studies of a unique xenolith of lithospheric mantle are presented illustrating the earlier non-described mineral association of quartz, Cr-pyrope and Cr-diopside. Structural and textural features of the sample suggest a joint formation of these minerals. The calculated P-T-parameters of the formation of Cr-diopside indicate the capture of xenolith from the depth interval ~ 95-105 km (31-35 kbar) corresponding to the stability field of coesite. This suggests that quartz in the studied xenolith can represent paramorphs after coesite. It was shown that quartz in this rock is not a product of postmagmatic processes. The transformation stage of the source lherzolite into garnet- and clinopyroxene-enriched rock/garnet pyroxenite as a result of exposure to a high-temperature silicate melt was reconstructed. Subsequent stages of the influence of metasomatic agents were identified by the presence of a negative Eu-anomaly in some garnet grains, which could result from the impact of subduction-related fluid and the enrichment of rock-forming minerals with light rare earth elements, Sr, Th, U, Nb and Ta as a consequence of fluid saturated with these incompatible elements. Several models for the formation of SiO2 phase (quartz/coesite) in association with high-chromium mantle minerals are considered including carbonatization of mantle peridotites/eclogites and melting of carbonate-containing eclogites at the stage of subduction and the impact of SiO2-enriched melt/fluid of subduction genesis with peridotites of the lithospheric mantle. |
| Databáze: | Directory of Open Access Journals |
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