New insights into the nature of glauconite

Glauconite must be assessed as mica-rich mica-smectite R3 interstratified mineral, with the pure end-member mica also having intrinsic K-deficient chemical characteristics (K ~ 0.8 apfu). This assertion is in accordance with our X‑ray diffraction (XRD) and high-resolution tranmission electron micros...

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Autores: López-Quirós, Adrián, Sánchez Navas, Antonio, Nieto, F., Escutia, Carlota
Tipo de recurso: artículo
Estado:Versión aceptada para publicación
Fecha de publicación:2020
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/216430
Acceso en línea:http://hdl.handle.net/10261/216430
Access Level:acceso abierto
Palabra clave:Glauconite
Glaucony
HRTE
Minter stratified
Glauconite-smectite
XRD
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spelling New insights into the nature of glauconiteLópez-Quirós, AdriánSánchez Navas, AntonioNieto, F.Escutia, CarlotaGlauconiteGlauconyHRTEMinter stratifiedGlauconite-smectiteXRDGlauconite must be assessed as mica-rich mica-smectite R3 interstratified mineral, with the pure end-member mica also having intrinsic K-deficient chemical characteristics (K ~ 0.8 apfu). This assertion is in accordance with our X‑ray diffraction (XRD) and high-resolution tranmission electron microscopy (HRTEM) studies and chemical analyses by electron probe microanalysis (EPMA) of mature glauconites in Cenozoic Antarctic sediments that indicate that: (1) It consists of a glauconite-smectite (R3 ordered) mixed-layer silicate, composed mainly of mica-type layers (>90%), but displaying slightly different proportions of Fe(III)-smectite layers (<10%). (2) More mature glaucony grains are characterized by major K and Fe (mica layers) and minor Fe (smectite layers) content in the interstratified glauconite-smectite. (3) Potassium is stabilized at the interlayer site by the octahedrally coordinated Fe. (4) Microtexture of the glauconite crystals are comparable with those of other micas and illite minerals, with straight, defect-free lattice fringes of ~10 Å spacings glauconite packets characteristic of mica with minor interstratified poorly crystalline smectite layers. In addition, our new findings give insights into the glauconitization process and at the same time investigate the potassium-deficient character of the dioctahedral mica "glauconite." These findings show that glauconite crystallizes by a layer-growth mechanism at the expense of a poorly crystalline smectite precursor and that smectite-to-glauconite transformations are accompanied by a gradually higher octahedral charge deficiency (Fe/Fe) stabilized by K uptake into the interlayer sheet.Walter de GruyterConsejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]2020202020202020info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Postprintinfo:eu-repo/semantics/acceptedVersionhttp://hdl.handle.net/10261/216430reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Ingléshttp://dx.doi.org/10.2138/am-2020-7341Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/2164302026-05-22T06:33:51Z
dc.title.none.fl_str_mv New insights into the nature of glauconite
title New insights into the nature of glauconite
spellingShingle New insights into the nature of glauconite
López-Quirós, Adrián
Glauconite
Glaucony
HRTE
Minter stratified
Glauconite-smectite
XRD
title_short New insights into the nature of glauconite
title_full New insights into the nature of glauconite
title_fullStr New insights into the nature of glauconite
title_full_unstemmed New insights into the nature of glauconite
title_sort New insights into the nature of glauconite
dc.creator.none.fl_str_mv López-Quirós, Adrián
Sánchez Navas, Antonio
Nieto, F.
Escutia, Carlota
author López-Quirós, Adrián
author_facet López-Quirós, Adrián
Sánchez Navas, Antonio
Nieto, F.
Escutia, Carlota
author_role author
author2 Sánchez Navas, Antonio
Nieto, F.
Escutia, Carlota
author2_role author
author
author
dc.contributor.none.fl_str_mv Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
dc.subject.none.fl_str_mv Glauconite
Glaucony
HRTE
Minter stratified
Glauconite-smectite
XRD
topic Glauconite
Glaucony
HRTE
Minter stratified
Glauconite-smectite
XRD
description Glauconite must be assessed as mica-rich mica-smectite R3 interstratified mineral, with the pure end-member mica also having intrinsic K-deficient chemical characteristics (K ~ 0.8 apfu). This assertion is in accordance with our X‑ray diffraction (XRD) and high-resolution tranmission electron microscopy (HRTEM) studies and chemical analyses by electron probe microanalysis (EPMA) of mature glauconites in Cenozoic Antarctic sediments that indicate that: (1) It consists of a glauconite-smectite (R3 ordered) mixed-layer silicate, composed mainly of mica-type layers (>90%), but displaying slightly different proportions of Fe(III)-smectite layers (<10%). (2) More mature glaucony grains are characterized by major K and Fe (mica layers) and minor Fe (smectite layers) content in the interstratified glauconite-smectite. (3) Potassium is stabilized at the interlayer site by the octahedrally coordinated Fe. (4) Microtexture of the glauconite crystals are comparable with those of other micas and illite minerals, with straight, defect-free lattice fringes of ~10 Å spacings glauconite packets characteristic of mica with minor interstratified poorly crystalline smectite layers. In addition, our new findings give insights into the glauconitization process and at the same time investigate the potassium-deficient character of the dioctahedral mica "glauconite." These findings show that glauconite crystallizes by a layer-growth mechanism at the expense of a poorly crystalline smectite precursor and that smectite-to-glauconite transformations are accompanied by a gradually higher octahedral charge deficiency (Fe/Fe) stabilized by K uptake into the interlayer sheet.
publishDate 2020
dc.date.none.fl_str_mv 2020
2020
2020
2020
dc.type.none.fl_str_mv info:eu-repo/semantics/article
http://purl.org/coar/resource_type/c_6501
Postprint
info:eu-repo/semantics/acceptedVersion
format article
status_str acceptedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/216430
url http://hdl.handle.net/10261/216430
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv http://dx.doi.org/10.2138/am-2020-7341

dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv Walter de Gruyter
publisher.none.fl_str_mv Walter de Gruyter
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
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repository.mail.fl_str_mv
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