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Minerály vybraných kritických prvků (REE, Zr, Nb) zjištěné v roztockém intruzivním komplexu v Českém středohoří.

Authors :
MYSLIVEČEK, JAKUB
VÁCHA, JAKUB
RAPPRICH, VLADISLAV
POUR, ONDŘEJ
RACEK, MARTIN
Source :
Geoscience Research Reports / Zprávy o Geologických Výzkumech v Roce; 2020, Vol. 53 Issue 2, p161-169, 9p
Publication Year :
2020

Abstract

Strongly carbonatized alkaline rocks and a carbonatite s. s. (xenolith) were discovered in the R-2 drillcore in the Roztoky Intrusive Complex (Figs 1, 2, 7; Rapprich et al. 2017). Both carbonate-rich rock types contain minerals of critical elements reported for the first time in the alkaline volcanic rocks of the České středohoří Mts. These include (Ca)-REE fluorocarbonates, minerals of Zr (zircon, baddeleyite; Fig. 3) and columbite. Chemical composition of these minerals was determined using SEM and EMP and the crystalchemical formulae were calculated. Columbite was classified as columbite-(Mn) (Tab. 3). (Ca)-REE fluorocarbonates were detected in two different samples and rock types. Ca-poor bastnäsite-(Ce) represents the only REE mineral present in carbonatized trachyte at the depth of 156.5 m. Synchysite-(Ce), bastnäsite-(Ce) and parisite-(Ce) were found in dolomite carbonatite at 286.5 m. These minerals form epitactic intergrowths up to 30 µm in size (Fig. 5, 8), which is, according to Armbrustmacher (1979), typical for primary (magmatic) REE minerals. (Ca)-REE fluorocarbonates are Ce-dominant (0.5 apfu), containing significant amounts of La (0.3 apfu) and Nd (0.2 apfu) (Tab. 1). The REE minerals show a typical Y3+?REE3+ substitution, which is especially significant in Ce-poor phases represented by analyses e3 and e4, where Ce is substituted by Y (0.1 apfu) and minor Sm, Eu, Gd and Th (Tab. 1). [ABSTRACT FROM AUTHOR]

Details

Language :
Czech
ISSN :
05148057
Volume :
53
Issue :
2
Database :
Complementary Index
Journal :
Geoscience Research Reports / Zprávy o Geologických Výzkumech v Roce
Publication Type :
Academic Journal
Accession number :
147850679
Full Text :
https://doi.org/10.3140/zpravy.geol.2020.18