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@article{1696317,
author = {Čopjaková, Renata and Prokop, Jiří and Novák, Milan and Losos, Zdeněk and Gadas, Petr and Škoda, Radek and Holá, Markéta},
article_location = {Amsterdam},
article_number = {January},
doi = {http://dx.doi.org/10.1016/j.lithos.2020.105823},
keywords = {Tourmaline; Granitic pegmatite; Tourmaline replacement; Hydrothermal alteration; Nature of fluid; Fluid mixing},
language = {eng},
issn = {0024-4937},
journal = {Lithos},
title = {Hydrothermal alteration of tourmaline from pegmatitic rocks enclosed in serpentinites: Multistage processes with distinct fluid sources},
url = {https://doi.org/10.1016/j.lithos.2020.105823},
volume = {380-381},
year = {2021}
}
TY - JOUR
ID - 1696317
AU - Čopjaková, Renata - Prokop, Jiří - Novák, Milan - Losos, Zdeněk - Gadas, Petr - Škoda, Radek - Holá, Markéta
PY - 2021
TI - Hydrothermal alteration of tourmaline from pegmatitic rocks enclosed in serpentinites: Multistage processes with distinct fluid sources
JF - Lithos
VL - 380-381
IS - January
SP - "105823"
EP - "105823"
PB - Elsevier
SN - 00244937
KW - Tourmaline
KW - Granitic pegmatite
KW - Tourmaline replacement
KW - Hydrothermal alteration
KW - Nature of fluid
KW - Fluid mixing
UR - https://doi.org/10.1016/j.lithos.2020.105823
L2 - https://doi.org/10.1016/j.lithos.2020.105823
N2 - Hydrothermal alteration of primary tourmaline (dravite, oxy-dravite, fluor-dravite,” uvite“, schorl, oxy-schorl, fluor-schorl) and associated plagioclase and quartz is examined in coarse-grained pegmatitic plagioclase-tourmaline rocks, simple granitic pegmatites and zoned beryl-columbite pegmatites, all cutting serpentinite from the Moldanubian Zone, Czech Republic. Tourmaline is replaced by a wide spectrum of minerals—prehnite, pumpellyite-(Al), K-feldspar, chlorite, muscovite, natrolite, arfvedsonite, titanite, epididymite, and hydrous Mg-silicates—and idealized replacement reactions of tourmaline are presented. Secondary mineral assemblages replacing tourmaline and chlorite geothermometry suggest evolution of the PT conditions of tourmaline alteration from T ~ 400–350 °C to 200–100 °C and P < ~1–2 kbar. The replacement processes of tourmaline proceed from the early to late subsolidus stages, and the intensity of tourmaline replacement decreases with decreasing temperature. Alteration typically occurs in small bodies of primitive plagioclase-tourmaline rocks, whereas large, more evolved and locally Li-bearing crosscutting pegmatites exhibit less pronounced tourmaline alteration. Based on the secondary mineral assemblages and types of fluids, four distinct compositional/paragenetic types are defined: Ca,Mg-, Na,K,Mg-, K,Mg- and K,Na-dominant. Sources of fluids include (i) fluids exsolved from pegmatite melt (Na, K, Ca, ± Li), particularly in the more evolved pegmatites, and (ii) fluids infiltrated/diffused from host rocks (Mg, Ca, ± Ni, Cr) at all localities; however, mixing of the fluids is obvious. Boron released from the altered tourmalines into fluids escaped from the system, and the behavior of B in aqueous fluids from granitic pegmatites is discussed. The instability of quartz and tourmaline as well as common late K-feldspar, zeolites, arfvedsonite, and minor smectite suggests alkaline conditions. The alkaline character of fluids promoted by host serpentinite was very likely the main factor affecting tourmaline replacement and the instability of plagioclase, quartz, and other minerals.
ER -
ČOPJAKOVÁ, Renata, Jiří PROKOP, Milan NOVÁK, Zdeněk LOSOS, Petr GADAS, Radek ŠKODA and Markéta HOLÁ. Hydrothermal alteration of tourmaline from pegmatitic rocks enclosed in serpentinites: Multistage processes with distinct fluid sources. \textit{Lithos}. Amsterdam: Elsevier, 2021, 380-381, January, p.~''105823'', 19 pp. ISSN~0024-4937. Available from: https://dx.doi.org/10.1016/j.lithos.2020.105823.
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