Chevkinite-group minerals in selected intrusions of the Mazury Complex, North-Eastern Poland: insights into the formation of a titanite-like phase by hydrothermal alteration

Abstract

Chevkinite-group minerals forming large and common (up to 0.03 vol%) accessory phases in monzodiorites and granodiorites from the Mesoproterozoic anorthosite-mangerite-charnockite-granite (AMCG) suite intrusions, Mazury Complex, north-eastern Poland, range from pristine magmatic types to hydrothermally altered varieties. The unaltered phase is perrierite-(Ce), with the uncommon feature of having Al dominant in the C site. Hydrothermal alteration of the perrierite-(Ce) followed two main trends: one shows depletion in Ca, Fe, Si, Al and Mg, and increasing Ti contents; the other shows increases in Si, Ti and Ca and decreases in light rare-earth elements (LREE), Y and Mg, at about constant Fe content. The second trend resulted in the formation of a phase compositionally similar to titanite. Result of chemical analyses show that the transition from perrierite-(Ce) to the titanite-like phase is sharp; an electron back-scatter diffraction (EBSD) study shows the titanite- like material to be amorphous. The hydrothermal alteration of a chevkinite-group mineral to titanite has commonly been reported in natural sequences but this is the first record of the identification of a titanite-like phase made on the basis of a structural analysis.

The REE-Zr-U-Th Minerals of the Maronia Monzodiorite, N. Greece: Implications on the Saturation and Segregation Mechanisms of Critical Metals in Intermediate–Mafic Compositions

“…Compositionally, the Maronia chevkinite-like phases, most closely, resemble magmatic chevkinite, as shown in Figure 8 [80]. In the literature, the association of chevkinite and Ti-minerals has been generally described as a hydrothermal alteration, converting chevkinite to either ilmenite, rutile or titanite [64,72,81]. However, in Maronia monzodiorite, the textural evidence suggests otherwise.…”

“…The presence of zirconolite, baddeleyite, uraninite-thorianite and huttonitic monazite as accessory minerals in phlogopite-bearing peridotites has been considered to be the result of an anomalous magmatic enrichment in LREE and Zr by slab-derived, mantle metasomatism [98,103]. In those cases, the dominance of Th and U over REE, Nb and Ta, and of Fe over Mg, in the composition of zirconolite, is taken to reflect the presence of a Si-undersaturated, carbonatitic or meta-carbonate-derived melt in the source, presumably derived by slab melting [81,98,103]. Similar chemical affinities have been observed in the Maronia zirconolites (Figure 10), and together with the whole-rock shoshonitic affinity and isotopic characteristics of the parent melts, indicate that the enrichment in critical metals in Maronia monzodiorite could be the result of the partial melting of a hydrous mantle source, which was enriched with incompatible elements from phosphate and carbonate material by a subducting slab.…”

Hydrothermal alteration of chevkinite: insights from natural rocks and experiments

“…Material for these studies comes mainly from two sources. First, as part of our own field and petrological studies, e.g., UK Palaeogene granites (Macdonald et al 2013), high-K trachyandesites from Moravia (Macdonald et al 2017), the Kłodzko-Złoty Stok intrusion, Sudetes (Nejbert et al 2020), the Joe Lott Tuff, Utah (Galanciak et al 2020), the Gold Flat Tuff, Nevada (Macdonald et al 2021) and the Krasnopol intrusion, Mazury Complex (Domańska-Siuda et al 2022). Second, through ongoing collaborations with other organizations, e.g., the U.S. Geological Survey, GFZ Potsdam, the Russian Academy of Sciences (Mos cow and Apatity), the Polish Academy of Sciences (Kraków), and the Universities of Edin burgh and Milan.…”