Coupling textural and stable-isotope variations in fluvial stromatolites: Comparison of Pleistocene and recent records in NE Spain

Textural and stable isotopic features of two middle Pleistocene fluvial stromatolite profiles are compared to a recent stromatolite, both formed in the River Piedra system (NE Spain), to test the reliability of climatic, hydrologic and depositional information derived from ancient records. The Pleis...

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Autores: Arenas, C., Osácar, M.C., Auqué, L., Sancho, C.
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2019
País:España
Institución:Universidad de Zaragoza
Repositorio:Zaguán. Repositorio Digital de la Universidad de Zaragoza
OAI Identifier:oai:zaguan.unizar.es:78823
Acceso en línea:http://zaguan.unizar.es/record/78823
Access Level:acceso abierto
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spelling Coupling textural and stable-isotope variations in fluvial stromatolites: Comparison of Pleistocene and recent records in NE SpainArenas, C.Osácar, M.C.Auqué, L.Sancho, C.Textural and stable isotopic features of two middle Pleistocene fluvial stromatolite profiles are compared to a recent stromatolite, both formed in the River Piedra system (NE Spain), to test the reliability of climatic, hydrologic and depositional information derived from ancient records. The Pleistocene stromatolites formed in a multi-domed, highly-inclined cascade-barrage. The recent stromatolite also formed in a highly-inclined cascade of the River Piedra, the sedimentary conditions of which were periodically examined between the years 2000 and 2012. The Pleistocene stromatolites are formed of an alternation of 1) thin large-crystal laminae (type A), with elongated crystals up to 1 mm long, and 2) thick small-crystal laminae (type B), consisting of cyanobacterial fan- and bush-shaped bodies. The textural and isotopic comparison with the recent stromatolite shows that each A–B couplet corresponds to one year. The type-A laminae are comparable to the macrocrystalline laminae that occur in the cool-period deposits of the recent stromatolite, and the type-B laminae are comparable to the warm-period deposits of the recent stromatolite. Water temperatures (Tw), calculated from d 18 O calcite and present measures of d 18 O water , were similar in the Pleistocene and recent specimens, and close to the measured river Tw. Thus, the Pleistocene stromatolites formed not far from isotopic equilibrium, as did the recent stromatolite. The Pleistocene d 18 O calcite biannual oscillation is wider in amplitude than in the recent stromatolite, which suggests larger differences in Tw through the year in the Pleistocene than at present. The Pleistocene d 13 C calcite does not show any pattern; and the values are slightly higher than the recent ones. The co-evolution of d 18 O and d 13 C is parallel in the Pleistocene stromatolites, matching the recent stromatolite behavior. These results and their comparison with other ancient examples prove that textural and isotopic features in ancient stromatolites are useful tools to infer past depositional, climatic and hydrological conditions. Moreover, interpretations from recent fluvial stromatolites can be extrapolated to past environments to help decipher patterns of past processes, in cases where both recent and ancient stromatolites can be compared within one environmental setting. Such comparisons may be used to help interpretations of ancient stromatolites where the modern ones are not available to study.2019info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionapplication/pdfhttp://zaguan.unizar.es/record/78823reponame:Zaguán. Repositorio Digital de la Universidad de Zaragozainstname:Universidad de ZaragozaInglésinfo:eu-repo/grantAgreement/ES/DGA/E32-17Rinfo:eu-repo/grantAgreement/ES/MICINN/CGL2013-42867info:eu-repo/grantAgreement/ES/MINECO/CGL2009-09216-CLIinfo:eu-repo/semantics/openAccessoai:zaguan.unizar.es:788232026-05-29T13:59:51Z
dc.title.none.fl_str_mv Coupling textural and stable-isotope variations in fluvial stromatolites: Comparison of Pleistocene and recent records in NE Spain
title Coupling textural and stable-isotope variations in fluvial stromatolites: Comparison of Pleistocene and recent records in NE Spain
spellingShingle Coupling textural and stable-isotope variations in fluvial stromatolites: Comparison of Pleistocene and recent records in NE Spain
Arenas, C.
title_short Coupling textural and stable-isotope variations in fluvial stromatolites: Comparison of Pleistocene and recent records in NE Spain
title_full Coupling textural and stable-isotope variations in fluvial stromatolites: Comparison of Pleistocene and recent records in NE Spain
title_fullStr Coupling textural and stable-isotope variations in fluvial stromatolites: Comparison of Pleistocene and recent records in NE Spain
title_full_unstemmed Coupling textural and stable-isotope variations in fluvial stromatolites: Comparison of Pleistocene and recent records in NE Spain
title_sort Coupling textural and stable-isotope variations in fluvial stromatolites: Comparison of Pleistocene and recent records in NE Spain
dc.creator.none.fl_str_mv Arenas, C.
Osácar, M.C.
Auqué, L.
Sancho, C.
author Arenas, C.
author_facet Arenas, C.
Osácar, M.C.
Auqué, L.
Sancho, C.
author_role author
author2 Osácar, M.C.
Auqué, L.
Sancho, C.
author2_role author
author
author
description Textural and stable isotopic features of two middle Pleistocene fluvial stromatolite profiles are compared to a recent stromatolite, both formed in the River Piedra system (NE Spain), to test the reliability of climatic, hydrologic and depositional information derived from ancient records. The Pleistocene stromatolites formed in a multi-domed, highly-inclined cascade-barrage. The recent stromatolite also formed in a highly-inclined cascade of the River Piedra, the sedimentary conditions of which were periodically examined between the years 2000 and 2012. The Pleistocene stromatolites are formed of an alternation of 1) thin large-crystal laminae (type A), with elongated crystals up to 1 mm long, and 2) thick small-crystal laminae (type B), consisting of cyanobacterial fan- and bush-shaped bodies. The textural and isotopic comparison with the recent stromatolite shows that each A–B couplet corresponds to one year. The type-A laminae are comparable to the macrocrystalline laminae that occur in the cool-period deposits of the recent stromatolite, and the type-B laminae are comparable to the warm-period deposits of the recent stromatolite. Water temperatures (Tw), calculated from d 18 O calcite and present measures of d 18 O water , were similar in the Pleistocene and recent specimens, and close to the measured river Tw. Thus, the Pleistocene stromatolites formed not far from isotopic equilibrium, as did the recent stromatolite. The Pleistocene d 18 O calcite biannual oscillation is wider in amplitude than in the recent stromatolite, which suggests larger differences in Tw through the year in the Pleistocene than at present. The Pleistocene d 13 C calcite does not show any pattern; and the values are slightly higher than the recent ones. The co-evolution of d 18 O and d 13 C is parallel in the Pleistocene stromatolites, matching the recent stromatolite behavior. These results and their comparison with other ancient examples prove that textural and isotopic features in ancient stromatolites are useful tools to infer past depositional, climatic and hydrological conditions. Moreover, interpretations from recent fluvial stromatolites can be extrapolated to past environments to help decipher patterns of past processes, in cases where both recent and ancient stromatolites can be compared within one environmental setting. Such comparisons may be used to help interpretations of ancient stromatolites where the modern ones are not available to study.
publishDate 2019
dc.date.none.fl_str_mv 2019
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dc.language.none.fl_str_mv Inglés
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dc.relation.none.fl_str_mv info:eu-repo/grantAgreement/ES/DGA/E32-17R
info:eu-repo/grantAgreement/ES/MICINN/CGL2013-42867
info:eu-repo/grantAgreement/ES/MINECO/CGL2009-09216-CLI
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eu_rights_str_mv openAccess
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