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<title lang=en>Magnetic fingerprint of southern Portuguese speleothems and implications for paleomagnetism and environmental magnetism</title>
<creator>Font, Eric</creator>
<creator>Veiga-Pires, Cristina</creator>
<creator>Pozo, Manuel</creator>
<creator>Carvallo, Claire</creator>
<creator>De siqueira neto, Antonio carlos</creator>
<creator>Camps, Pierre</creator>
<creator>Fabre, Sebastien</creator>
<creator>Mirao, Jose</creator>
<contributor>Faculdade de Ciências, Universidade de Lisboa</contributor>
<contributor>Universidade do Algarve, Faro</contributor>
<contributor>Universidad Autonoma de Madrid (UAM)</contributor>
<contributor>Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC) ; Institut de recherche pour le développement [IRD] : UR206 - Centre National de la Recherche Scientifique (CNRS) - Muséum National d'Histoire Naturelle (MNHN) - Université Pierre et Marie Curie - Paris 6 (UPMC)</contributor>
<contributor>Universidade de São Paulo (USP)</contributor>
<contributor>Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS)</contributor>
<contributor>Institut de recherche en astrophysique et planétologie (IRAP) ; Université Paul Sabatier - Toulouse 3 (UPS) - Observatoire Midi-Pyrénées (OMP) - Centre National de la Recherche Scientifique (CNRS)</contributor>
<contributor>University of Évora [Portugal]</contributor>
<description>International audience</description>
<source>ISSN: 0148-0227</source>
<source>EISSN: 2156-2202</source>
<source>Journal of Geophysical Research</source>
<publisher>American Geophysical Union (AGU)</publisher>
<publisher>American Geophysical Union</publisher>
<identifier>hal-01114953</identifier>
<identifier>https://hal.archives-ouvertes.fr/hal-01114953</identifier>
<source>https://hal.archives-ouvertes.fr/hal-01114953</source>
<source>Journal of Geophysical Research, American Geophysical Union, 2014, 119 (11), pp.7993-8020. 〈10.1002/2014JB011381〉</source>
<identifier>DOI : 10.1002/2014JB011381</identifier>
<relation>info:eu-repo/semantics/altIdentifier/doi/10.1002/2014JB011381</relation>
<language>en</language>
<subject lang=en>Portugal</subject>
<subject lang=en>SEM</subject>
<subject lang=en>fungi</subject>
<subject lang=en>environment</subject>
<subject lang=en>magnetism</subject>
<subject lang=en>speleothem</subject>
<subject>[SDU.STU.GP] Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]</subject>
<type>info:eu-repo/semantics/article</type>
<type>Journal articles</type>
<description lang=en>Environmental magnetism of speleothems is still in its early stage of development. Here we report on our investigation of the environmental and paleomagnetic information that has been recorded in speleothems, and what are the factors that control its preservation and reliability. To address these issues, we used a multidisciplinary approach, including rock magnetism, petrography, scanning electron microscopy, stable carbon and oxygen isotope compositions, and major and trace element concentrations. We applied this to a set of samples from different stages of speleothem evolution: present-day dripwater (glass plates), a weathered stalactite, a fresh stalagmite, cave sediments, and terra rossa soils. These samples come from the Penico and Excentricas caves, located in two distinct aquifers of the Algarve region, South Portugal. Our results show that the main magnetic carriers of the speleothems under study are primary (detrital) and consist of maghemite (and magnetite?). Similarities in coercivity and temperature dependence of the studied set of samples suggest that iron oxides are inherited from the terra rossa soils that cap the cave and were transported to the speleothems by dripwater. Hence, they represent a regional environmental signature. Interestingly, a stable and probably detrital remanent magnetization could be isolated in the fresh stalagmite, whereas the weathered stalactite yielded chaotic magnetic directions and very low remanent intensities. We propose that these low intensities can be the result from (i) different remanence acquisition mechanisms between stalagmite and stalactite and/or (ii) iron dissolution by fungal activity. We also suggest that magnetic properties and color and the content in detrital elements in the fresh speleothem inform about environmental processes acting on the interface of rock (soil)-atmosphere, while oxygen isotope composition and alkaline-earth element concentrations inform about calcite-water interaction processes. These results provide a better understanding of how environmental information is recorded in speleothems and what the factors are that control the reliability of the paleomagnetic and paleo-environmental signal.</description>
<date>2014-11</date>
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