QUARTZ REPLACEMENT BY KEROLITE IN GRAPHIC QUARTZ-FELDSPAR
INTERGROWTHS FROM THE VĚŽNÁ I PEGMATITE, CZECH REPUBLIC: A
COMPLEX DESILICIFICATION PROCESS RELATED TO EPISYENITIZATION

J 2012

QUARTZ REPLACEMENT BY KEROLITE IN GRAPHIC QUARTZ-FELDSPAR INTERGROWTHS FROM THE VĚŽNÁ I PEGMATITE, CZECH REPUBLIC: A COMPLEX DESILICIFICATION PROCESS RELATED TO EPISYENITIZATION

DOSBABA, Marek and Milan NOVÁK

Basic information

Original name

QUARTZ REPLACEMENT BY KEROLITE IN GRAPHIC QUARTZ-FELDSPAR INTERGROWTHS FROM THE VĚŽNÁ I PEGMATITE, CZECH REPUBLIC: A COMPLEX DESILICIFICATION PROCESS RELATED TO EPISYENITIZATION

Authors

DOSBABA, Marek (203 Czech Republic, belonging to the institution) and Milan NOVÁK (203 Czech Republic, guarantor, belonging to the institution)

Edition

Canadian Mineralogist, 2012, 0008-4476

Other information

Language

English

Type of outcome

Article in a journal

Field of Study

10500 1.5. Earth and related environmental sciences

Country of publisher

Canada

Confidentiality degree

is not subject to a state or trade secret

Impact factor

Impact factor: 1.180

RIV identification code

RIV/00216224:14310/12:00064363

Organization unit

Faculty of Science

DOI

http://dx.doi.org/10.3749/canmin.50.6.1609

UT WoS

000314295200012

Keywords in English

quartz kerolite replacement desilicification episyenitization contamination pegmatite serpentinite Věžná

Abstract

V originále

Quartz replacement by kerolite (variety of talc) was examined in coarse- to medium-grained graphic intergrowths of quartz + feldspars (oligoclase An13-15Or3/orthoclase Or95-99Ab5-1) from the desilicated granitic pegmatite hosted in serpentinized apoharzburgite, at the locality Věžná I, western Moravia, Czech Republic. Pale brownish to white kerolite (Mg2.77-2.79Al0.09-010 Fe0.04 Si 4.05-4.08O10(OH)2.1.98H2O) forms aggregates, up to 2 cm in size, varying from massive fine-grained (1-10 m) to radial (needles up to ~1 mm long). Diffraction patterns exhibit a very broad peak at ~ 10 A (001) and a sharp peak at ~ 1.52 A (060). Kerolite does not swell at ethylenglycol atmosphere; cation exchange capacity (CEC) was 31+2.3 meq/100 g. Kerolite is a product of interaction between quartz and Mg-rich fluids originating from the host rock by the simplified reaction: 4SiO2 + 3MgCl2 + 6H2O = Mg3Si4O10(OH)2.2H2O + 6HCl. The process of kerolitization was evidently associated with albitization of oligoclase producing minor to trace amounts of Ba-rich K-feldspar, pectolite, analcime, natrolite, celadonite, monazite-(Ce) and niobian titanite, and possibly with vermiculitization of phlogopite. The simplified reaction including oligoclase, SiO2 released during kerolitization, and assuming immobility of Al was calculated as: 20(Na0.85Ca0.10K 0.05)Al1.15Si2.85O8 + 14SiO2 + 4.5H2O + 6NaCl = 21NaAlSi3O8 + 1KAlSi3O8 + 1NaCa2Si3O8 (OH) + 1NaAlSi2O6.H2O + 6HCl. This process likely proceeded at T ~ 100-300 C and P lt; ~ 0.5-1 kbar, under high activity of alkalis and low tectonic stress. Pseudomorphs of kerolite locally with rare relics of quartz were later almost completely removed because of surface weathering, which produced empty cavities in the graphic unit. Similar processes such as kerolitization of quartz at Věžná occur not only in granitic pegmatites but may operate in episyenites, where a direct dissolution of quartz and consequential formation of open vugs typically occurs.

Cite

DOSBABA, Marek and Milan NOVÁK. QUARTZ REPLACEMENT BY KEROLITE IN GRAPHIC QUARTZ-FELDSPAR INTERGROWTHS FROM THE VĚŽNÁ I PEGMATITE, CZECH REPUBLIC: A COMPLEX DESILICIFICATION PROCESS RELATED TO EPISYENITIZATION. Canadian Mineralogist. 2012, vol. 50, No 6, p. 1609-1622. ISSN 0008-4476. Available from: https://dx.doi.org/10.3749/canmin.50.6.1609.

@article{1091369,
   author = {Dosbaba, Marek and Novák, Milan},
   article_number = {6},
   doi = {http://dx.doi.org/10.3749/canmin.50.6.1609},
   keywords = {quartz kerolite replacement desilicification episyenitization contamination pegmatite serpentinite Věžná},
   language = {eng},
   issn = {0008-4476},
   journal = {Canadian Mineralogist},
   title = {QUARTZ REPLACEMENT BY KEROLITE IN GRAPHIC QUARTZ-FELDSPAR INTERGROWTHS FROM THE VĚŽNÁ I PEGMATITE, CZECH REPUBLIC: A COMPLEX DESILICIFICATION PROCESS RELATED TO EPISYENITIZATION},
   volume = {50},
   year = {2012}
}

TY  - JOUR
ID  - 1091369
AU  - Dosbaba, Marek - Novák, Milan
PY  - 2012
TI  - QUARTZ REPLACEMENT BY KEROLITE IN GRAPHIC QUARTZ-FELDSPAR INTERGROWTHS FROM THE VĚŽNÁ I PEGMATITE, CZECH REPUBLIC: A COMPLEX DESILICIFICATION PROCESS RELATED TO EPISYENITIZATION
JF  - Canadian Mineralogist
VL  - 50
IS  - 6
SP  - 1609-1622
EP  - 1609-1622
SN  - 00084476
KW  - quartz kerolite replacement desilicification episyenitization contamination pegmatite serpentinite Věžná
N2  - Quartz replacement by kerolite (variety of talc) was examined in coarse- to medium-grained graphic intergrowths of quartz + feldspars (oligoclase An13-15Or3/orthoclase Or95-99Ab5-1) from the desilicated granitic pegmatite hosted in serpentinized apoharzburgite, at the locality Věžná I, western Moravia, Czech Republic. Pale brownish to white kerolite (Mg2.77-2.79Al0.09-010 Fe0.04 Si 4.05-4.08O10(OH)2.1.98H2O) forms aggregates, up to 2 cm in size, varying from massive fine-grained (1-10 m) to radial (needles up to ~1 mm long). Diffraction patterns exhibit a very broad peak at ~ 10 A (001) and a sharp peak at ~ 1.52 A (060). Kerolite does not swell at ethylenglycol atmosphere; cation exchange capacity (CEC) was 31+2.3 meq/100 g. Kerolite is a product of interaction between quartz and Mg-rich fluids originating from the host rock by the simplified reaction: 4SiO2 + 3MgCl2 + 6H2O = Mg3Si4O10(OH)2.2H2O + 6HCl. The process of kerolitization was evidently associated with albitization of oligoclase producing minor to trace amounts of Ba-rich K-feldspar, pectolite, analcime, natrolite, celadonite, monazite-(Ce) and niobian titanite, and possibly with vermiculitization of phlogopite. The simplified reaction including oligoclase, SiO2 released during kerolitization, and assuming immobility of Al was calculated as: 20(Na0.85Ca0.10K 0.05)Al1.15Si2.85O8 + 14SiO2 + 4.5H2O + 6NaCl = 21NaAlSi3O8 + 1KAlSi3O8 + 1NaCa2Si3O8 (OH) + 1NaAlSi2O6.H2O + 6HCl. This process likely proceeded at T ~ 100-300 C and P lt; ~ 0.5-1 kbar, under high activity of alkalis and low tectonic stress. Pseudomorphs of kerolite locally with rare relics of quartz were later almost completely removed because of surface weathering, which produced empty cavities in the graphic unit. Similar processes such as kerolitization of quartz at Věžná occur not only in granitic pegmatites but may operate in episyenites, where a direct dissolution of quartz and consequential formation of open vugs typically occurs.
ER  -

DOSBABA, Marek and Milan NOVÁK. QUARTZ REPLACEMENT BY KEROLITE IN GRAPHIC QUARTZ-FELDSPAR INTERGROWTHS FROM THE VĚŽNÁ I PEGMATITE, CZECH REPUBLIC: A COMPLEX DESILICIFICATION PROCESS RELATED TO EPISYENITIZATION. \textit{Canadian Mineralogist}. 2012, vol.~50, No~6, p.~1609-1622. ISSN~0008-4476. Available from: https://dx.doi.org/10.3749/canmin.50.6.1609.

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