Skip to Main Content
Skip Nav Destination
GEOREF RECORD

Compositional and textural variations of columbite-group minerals from beryl-columbite pegmatites in the Marsikov District, Bohemian Massif, Czech Republic; magmatic versus hydrothermal evolution

Stepan Chladek, Pavel Uher and Milan Novak
Compositional and textural variations of columbite-group minerals from beryl-columbite pegmatites in the Marsikov District, Bohemian Massif, Czech Republic; magmatic versus hydrothermal evolution
The Canadian Mineralogist (November 2020) Pre-Issue Publication

Abstract

We studied compositional variations in columbite group minerals (CGM) from several granitic pegmatites of the beryl-columbite subtype in the Marsikov district, Silesian Domain of the Bohemian Massif, Czech Republic. The CGM are characterized by distinct zoned patterns in BSE images. Primary magmatic homogeneous to oscillatory zoning is preserved in corroded crystal cores, whereas the majority of the crystal volume is replaced by secondary complexly zoned domains formed via post-magmatic processes. The primary domains show relatively uniform evolutionary trends from core to rim, generally with steeply increasing Ta/(Ta + Nb) and negligible to slightly increasing Mn/(Mn + Fe). In contrast, the compositions of secondary CGM domains indicate a reversed evolution, with: (1) steeply decreasing Ta/(Ta + Nb) and relatively constant Mn/(Mn + Fe) characteristics for CGM in the Bienergraben and Scheibengraben pegmatites, and (2) insignificantly decreasing Ta/(Ta + Nb) and strongly decreasing Mn/(Mn + Fe) characteristics for CGM in the Schinderhuebel I and Lysa Hora pegmatites. Patchy zoning and secondary evolution in CGM result from metasomatic replacement processes related to fluids. These fluids are probably late-magmatic and exsolved from the residual melt and in later stages locally mixed with external Mg-enriched fluids derived from the host rocks. The presence of volatiles (mainly H2O, F) facilitated high mobility of the elements and replacement of the early CGM. Textural characteristics and compositional variations in CGM show the complex evolution of the pegmatite system from the magmatic stage to subsolidus-hydrothermal conditions.


ISSN: 0008-4476
EISSN: 1499-1276
Coden: CAMIA6
Serial Title: The Canadian Mineralogist
Serial Volume: Pre-Issue Publication
Title: Compositional and textural variations of columbite-group minerals from beryl-columbite pegmatites in the Marsikov District, Bohemian Massif, Czech Republic; magmatic versus hydrothermal evolution
Affiliation: Department of Geological Engineering, Technical University of Ostrava, Poruba-Ostrava, Czech Republic
Published: 20201124
Text Language: English
Publisher: Mineralogical Association of Canada, Ottawa, ON, Canada
References: 89
Accession Number: 2021-003296
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables, sketch map
N49°55'00" - N50°10'00", E16°49'60" - E17°15'00"
Secondary Affiliation: Comenius University, SVK, SlovakiaMasaryk University, CZE, Czech Republic
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2021, American Geosciences Institute. Abstract, copyright, Mineralogical Association of Canada. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 2021
Close Modal

or Create an Account

Close Modal
Close Modal