<abstract xmlns="http://www.w3.org/1999/xhtml">

Previously unknown exposures of silicified serpentinites have been documented within the Szklary Massif, which is a fragment of the tectonically dismembered Central Sudetic Ophiolite (NE Bohemian Massif). On the basis of textural, mineralogical and chemical differences, two types of silicified serpentinites have been distinguished in this study (Type I and Type II). Type I is characterized by well-preserved primary minerals cut by numerous veinlets filled with microscale euhedral quartz crystals. Studied samples of Type I are enriched in silica (from 62 to 69 wt.% SiO2) and depleted in magnesium (from 10 to 19 wt.% MgO) in comparison to serpentinized peridotites from the Szklary Massif. Type II is almost exclusively composed of amorphous or poorly crystalline silica, with microquartz aggregates being the most abundant form. Silicified serpentinites of Type II show extremely high values of silica (from 83 to 90 wt.% SiO2) and low magnesium concentrations (from 4 to 8 wt.% MgO). Both types of silicified serpentinites have elevated content of REE and many other trace elements generally regarded as incompatible. We infer that the earlier silicification event was caused by the percolation of Si-rich hydrothermal fluids derived from igneous rocks, which intruded this area from ca. 380 to 330 Ma. A subsequent silicification event is the result of silica remobilization during intense chemical weathering under tropical conditions, which could have occurred between Late Cretaceous and Miocene.
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Previously unknown exposures of silicified serpentinites have been documented within the Szklary Massif, which is a fragment of the tectonically dismembered Central Sudetic Ophiolite (NE Bohemian Massif). On the basis of textural, mineralogical and chemical differences, two types of silicified serpentinites have been distinguished in this study (Type I and Type II). Type I is characterized by well-preserved primary minerals cut by numerous veinlets filled with microscale euhedral quartz crystals. Studied samples of Type I are enriched in silica (from 62 to 69 wt.% SiO2) and depleted in magnesium (from 10 to 19 wt.% MgO) in comparison to serpentinized peridotites from the Szklary Massif. Type II is almost exclusively composed of amorphous or poorly crystalline silica, with microquartz aggregates being the most abundant form. Silicified serpentinites of Type II show extremely high values of silica (from 83 to 90 wt.% SiO2) and low magnesium concentrations (from 4 to 8 wt.% MgO). Both types of silicified serpentinites have elevated content of REE and many other trace elements generally regarded as incompatible. We infer that the earlier silicification event was caused by the percolation of Si-rich hydrothermal fluids derived from igneous rocks, which intruded this area from ca. 380 to 330 Ma. A subsequent silicification event is the result of silica remobilization during intense chemical weathering under tropical conditions, which could have occurred between Late Cretaceous and Miocene.

Mineralogical and geochemical evidence for two-stage silicification of serpentinized peridotites from the Szklary Massif (NE Bohemian Massif)

Mineralogia

This work is licensed under the Creative Commons Attribution 4.0 International License.

Previously unknown exposures of silicified serpentinites have been documented within the Szklary Massif, which is a fragment of the tectonically dismembered...

Mineralogical and geochemical evidence for two-stage silicification of serpentinized peridotites from the Szklary Massif (NE Bohemian Massif)

Publicado en línea: 15 jun 2022

Páginas: 20 - 35

Recibido: 25 ene 2022

Aceptado: 17 may 2022

DOI: https://doi.org/10.2478/mipo-2022-0003

Palabras clave
silicified serpentinites, silicification, serpentinized peridotites, cathodoluminescence imaging, Szklary Massif

© 2022 Błażej Cieślik et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Mineralogical and geochemical evidence for two-stage silicification of serpentinized peridotites from the Szklary Massif (NE Bohemian Massif)

Publicado en línea: 15 jun 2022

Páginas: 20 - 35

Recibido: 25 ene 2022

Aceptado: 17 may 2022

DOI: https://doi.org/10.2478/mipo-2022-0003

Palabras clavesilicified serpentinites, silicification, serpentinized peridotites, cathodoluminescence imaging, Szklary Massif

© 2022 Błażej Cieślik et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Palabras clave
silicified serpentinites, silicification, serpentinized peridotites, cathodoluminescence imaging, Szklary Massif