Pyrolytical evidence of the abiotic origin of moonmilk formations from Castañar cave (Cáceres, Spain)

Pyrolytical evidence of the abiotic origin of moonmilk formations from Castañar cave (Cáceres, Spain)

Póster presentado en EGU 2019, Viena (Austria) 7 al 12 de abril de 2019. Puede ver el Abstract en https://meetingorganizer.copernicus.org/EGU2019/EGU2019-17244.pdf

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Main Authors: González-Pérez, José Antonio, San Emeterio, Layla M., Martín-Pérez, Andrea, Iglesia, A. la, Alonso-Zarza, Ana María, Almendros Martín, Gonzalo
Other Authors: González-Pérez, José Antonio [0000-0001-7607-1444]
Format: póster de congreso biblioteca
Language:English
Published: European Geosciences Union 2019
Online Access:http://hdl.handle.net/10261/183777
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spelling dig-irnas-es-10261-1837772020-06-01T09:24:33Z Pyrolytical evidence of the abiotic origin of moonmilk formations from Castañar cave (Cáceres, Spain) González-Pérez, José Antonio San Emeterio, Layla M. Martín-Pérez, Andrea Iglesia, A. la Alonso-Zarza, Ana María Almendros Martín, Gonzalo González-Pérez, José Antonio [0000-0001-7607-1444] San Emeterio, Layla M. [0000-0002-0919-1283] Alonso-Zarza, Ana María [0000-0002-3957-1092] Almendros Martín, Gonzalo [0000-0001-6794-9825] Póster presentado en EGU 2019, Viena (Austria) 7 al 12 de abril de 2019. Puede ver el Abstract en https://meetingorganizer.copernicus.org/EGU2019/EGU2019-17244.pdf Castañar cave (Cáceres, Spain) characteristically contains a series of Mg-Si phases forming fibres and films associated to aragonite, magnesite, huntite and spheroidal dolomite in moonmilk, which form coatings and crust speleothems. These Mg-Si phases consist of kerolite, sepiolite and its admixtures. Under scanning electron microscope kerolite appears as colloform, smooth masses or films. Sepiolite mostly occurs as isolated fibres 50 to 200 nm thick and up to 50 µm long and mats of interwoven fibres of several shapes, which often look like jelly, flexible-like films. Both minerals are highly hydrated and with low crystallinity. In order to evaluate a possible role of organic matter in the biogeochemical formation of these minerals, two samples of moonmilk and 4 controls were analyzed by analytical pyrolysis (Py-GC/MS). The pyrolizate of the samples consisted mainly of a) methoxyl-lacking benzenes, b) unsaturated and saturated hydrocarbons, c) polycyclic aromatic and d) hydroaromatic hydrocarbons. This chemical assemblage is not compatible with a recent biogenic origin of the organic matter in the moonmilk. This is suggested by the small proportions of fatty acids in addition to the lack of nitrogen- and carbohydrate-derived compounds. In fact, most of the aromatic compounds (e.g., phenols and catechols) which would be expected from plant or microbial biomass were in negligible proportions whereas methoxyphenols (typical lignin-derived compounds) were completely absent, suggesting no contribution from biomass of vascular plants. Conversely, the signature of alkyl compounds found in these samples (homologous series) is compatible with that in coals, kerogens or other forms of fossil organic matter. In particular, the whole pyrograms resembled the control shale from the host rock, which suggests that the organic matter was in fact inherited from the host rocks. Concerning the mineral phase, the low crystallinity and textures of kerolite and sepiolite indicate formation by direct precipitation in the cave waters via recrystallization of a gel precursor, under specific local conditions of high alkalinity and activity of Mg and Si. In conclusion, the low amount of organic matter content and its molecular composition, in addition to the lack of clear organic features and the general context indicates that kerolite and sepiolite precipitation in Castañar cave was most probably abiotic. Peer reviewed 2019-06-11T08:22:45Z 2019-06-11T08:22:45Z 2019 póster de congreso http://purl.org/coar/resource_type/c_6670 Geophysical Research Abstracts Vol. 21, EGU2019-17244 (2019) http://hdl.handle.net/10261/183777 en Sí open European Geosciences Union
institution IRNAS ES
collection DSpace
country España
countrycode ES
component Bibliográfico
access En linea
databasecode dig-irnas-es
tag biblioteca
region Europa del Sur
libraryname Biblioteca del IRNAS España
language English
description Póster presentado en EGU 2019, Viena (Austria) 7 al 12 de abril de 2019. Puede ver el Abstract en https://meetingorganizer.copernicus.org/EGU2019/EGU2019-17244.pdf
author2 González-Pérez, José Antonio [0000-0001-7607-1444]
author_facet González-Pérez, José Antonio [0000-0001-7607-1444]
González-Pérez, José Antonio
San Emeterio, Layla M.
Martín-Pérez, Andrea
Iglesia, A. la
Alonso-Zarza, Ana María
Almendros Martín, Gonzalo
format póster de congreso
author González-Pérez, José Antonio
San Emeterio, Layla M.
Martín-Pérez, Andrea
Iglesia, A. la
Alonso-Zarza, Ana María
Almendros Martín, Gonzalo
spellingShingle González-Pérez, José Antonio
San Emeterio, Layla M.
Martín-Pérez, Andrea
Iglesia, A. la
Alonso-Zarza, Ana María
Almendros Martín, Gonzalo
Pyrolytical evidence of the abiotic origin of moonmilk formations from Castañar cave (Cáceres, Spain)
author_sort González-Pérez, José Antonio
title Pyrolytical evidence of the abiotic origin of moonmilk formations from Castañar cave (Cáceres, Spain)
title_short Pyrolytical evidence of the abiotic origin of moonmilk formations from Castañar cave (Cáceres, Spain)
title_full Pyrolytical evidence of the abiotic origin of moonmilk formations from Castañar cave (Cáceres, Spain)
title_fullStr Pyrolytical evidence of the abiotic origin of moonmilk formations from Castañar cave (Cáceres, Spain)
title_full_unstemmed Pyrolytical evidence of the abiotic origin of moonmilk formations from Castañar cave (Cáceres, Spain)
title_sort pyrolytical evidence of the abiotic origin of moonmilk formations from castañar cave (cáceres, spain)
publisher European Geosciences Union
publishDate 2019
url http://hdl.handle.net/10261/183777
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