The building stone of the Roman city of Lixus (NW Morocco): provenance, petrography and petrophysical characterization

The characterization of building materials is a key tool to assess deterioration processes and improve potential restoration works of archaeological sites. The aim of this paper is to identify and characterize the most important building stones used in the construction of the Roman city of Lixus (La...

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Main Authors: T. Ajanaf, D. Gómez-Gras, A. Navarro, J.D. Martín-Martín, J.R. Rosell, A. Maate
Format: Article
Language:English
Published: Universitat de Barcelona (UB), Geociències Barcelona (Geo3BCN), Institut de Diagnosi Ambiental i Estudis de l'Aigua (IDAEA), Universitat Autònoma de Barcelona (UAB) 2020-08-01
Series:Geologica Acta
Subjects:
Online Access:https://revistes.ub.edu/index.php/GEOACTA/article/view/GeologicaActa2020.18.13/32292
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author T. Ajanaf
D. Gómez-Gras
A. Navarro
J.D. Martín-Martín
J.R. Rosell
A. Maate
author_facet T. Ajanaf
D. Gómez-Gras
A. Navarro
J.D. Martín-Martín
J.R. Rosell
A. Maate
author_sort T. Ajanaf
collection DOAJ
description The characterization of building materials is a key tool to assess deterioration processes and improve potential restoration works of archaeological sites. The aim of this paper is to identify and characterize the most important building stones used in the construction of the Roman city of Lixus (Larache, Morocco) by means of petrographic and petrophysical techniques. Based on the visual analysis of the monuments, three major building stones (i.e. lithotypes) have been identified: i) Oligocene sandstones, ii) Quaternary sandstones and iii) Quaternary conglomerates. Based on the analysis of the regional geology and exploitation marks, these three lithotypes have been recognised to crop out in the surroundings of Lixus and the quarries, presumably Roman in origin, recognized. The Oligocene sandstone is the primary building stone in Lixus as it forms and crops out extensively in the Tchemmis hill, at the top of which the city is settled. The Quaternary sandstones and conglomerates, which represent nearshore deposits and eolianites, crop out along the Atlantic coast where they form part of the cliffs next to Larache. Petrographic results indicate that lithotypes differ notably in grain size, ratio of detrital to allochemical components, and the configuration of their porous system. Mechanical analysis shows that the Oligocene sandstones are more resistant to compression than the Quaternary sandstones and conglomerates, the latter exhibiting relatively low compressive strength. The Oligocene sandstones, which display scarce porosity and permeability, show a hydric behaviour characterized by a very low degree of absorption and desorption water, likely resulting from a poor connectivity of the pore network. Contrary to the latter lithotype, the Quaternary sandstones, which exhibit very high porosity and permeability, display a hydric behaviour characterized by high degree of both absorption and desorption of water. This is attributed to the low degree of cementation compared to porosity of this lithotype and the excellent connectivity of the porous network. Finally, Oligocene and Quaternary sandstones do not show a significant weight loss after the accelerated artificial aging test, indicating that both are slightly affected by salt crystallization and presumably ice formation. Results indicate that the relatively fine state of conservation of the building rocks of Lixus is linked to intrinsic factors such as mineralogy and petrophysical characteristics together with the favourable effect of the climatic condition of the study area.
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spelling doaj.art-b414340d0b7f4ffaa83c63357406ce042023-10-13T10:45:07ZengUniversitat de Barcelona (UB), Geociències Barcelona (Geo3BCN), Institut de Diagnosi Ambiental i Estudis de l'Aigua (IDAEA), Universitat Autònoma de Barcelona (UAB)Geologica Acta1696-57282020-08-01181311610.1344/GeologicaActa2020.18.13The building stone of the Roman city of Lixus (NW Morocco): provenance, petrography and petrophysical characterizationT. Ajanaf0D. Gómez-Gras1A. Navarro2J.D. Martín-Martín3https://orcid.org/0000-0002-6530-6196J.R. Rosell4https://orcid.org/0000-0001-5034-8388A. Maate5Département de Géologie, Faculté des Sciences-Tétouan, Université Abdelmalek Essaadi MarocDepartament de Geologia, Universitat Autònoma de BarcelonaDepartament de Tecnologia de l’Arquitectura, Escola Politècnica Superior d’Edificació de Barcelona, UPCDepartament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona (UB)Departament de Tecnologia de l’Arquitectura, Escola Politècnica Superior d’Edificació de Barcelona, UPCDépartement de Géologie, Faculté des Sciences-Tétouan, Université Abdelmalek Essaadi MarocThe characterization of building materials is a key tool to assess deterioration processes and improve potential restoration works of archaeological sites. The aim of this paper is to identify and characterize the most important building stones used in the construction of the Roman city of Lixus (Larache, Morocco) by means of petrographic and petrophysical techniques. Based on the visual analysis of the monuments, three major building stones (i.e. lithotypes) have been identified: i) Oligocene sandstones, ii) Quaternary sandstones and iii) Quaternary conglomerates. Based on the analysis of the regional geology and exploitation marks, these three lithotypes have been recognised to crop out in the surroundings of Lixus and the quarries, presumably Roman in origin, recognized. The Oligocene sandstone is the primary building stone in Lixus as it forms and crops out extensively in the Tchemmis hill, at the top of which the city is settled. The Quaternary sandstones and conglomerates, which represent nearshore deposits and eolianites, crop out along the Atlantic coast where they form part of the cliffs next to Larache. Petrographic results indicate that lithotypes differ notably in grain size, ratio of detrital to allochemical components, and the configuration of their porous system. Mechanical analysis shows that the Oligocene sandstones are more resistant to compression than the Quaternary sandstones and conglomerates, the latter exhibiting relatively low compressive strength. The Oligocene sandstones, which display scarce porosity and permeability, show a hydric behaviour characterized by a very low degree of absorption and desorption water, likely resulting from a poor connectivity of the pore network. Contrary to the latter lithotype, the Quaternary sandstones, which exhibit very high porosity and permeability, display a hydric behaviour characterized by high degree of both absorption and desorption of water. This is attributed to the low degree of cementation compared to porosity of this lithotype and the excellent connectivity of the porous network. Finally, Oligocene and Quaternary sandstones do not show a significant weight loss after the accelerated artificial aging test, indicating that both are slightly affected by salt crystallization and presumably ice formation. Results indicate that the relatively fine state of conservation of the building rocks of Lixus is linked to intrinsic factors such as mineralogy and petrophysical characteristics together with the favourable effect of the climatic condition of the study area.https://revistes.ub.edu/index.php/GEOACTA/article/view/GeologicaActa2020.18.13/32292building stonelixuspetrographypetrophysicsdurability
spellingShingle T. Ajanaf
D. Gómez-Gras
A. Navarro
J.D. Martín-Martín
J.R. Rosell
A. Maate
The building stone of the Roman city of Lixus (NW Morocco): provenance, petrography and petrophysical characterization
Geologica Acta
building stone
lixus
petrography
petrophysics
durability
title The building stone of the Roman city of Lixus (NW Morocco): provenance, petrography and petrophysical characterization
title_full The building stone of the Roman city of Lixus (NW Morocco): provenance, petrography and petrophysical characterization
title_fullStr The building stone of the Roman city of Lixus (NW Morocco): provenance, petrography and petrophysical characterization
title_full_unstemmed The building stone of the Roman city of Lixus (NW Morocco): provenance, petrography and petrophysical characterization
title_short The building stone of the Roman city of Lixus (NW Morocco): provenance, petrography and petrophysical characterization
title_sort building stone of the roman city of lixus nw morocco provenance petrography and petrophysical characterization
topic building stone
lixus
petrography
petrophysics
durability
url https://revistes.ub.edu/index.php/GEOACTA/article/view/GeologicaActa2020.18.13/32292
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