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Título:
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Gypsum speleothems in lava tubes from Lanzarote (Canary Islands). Ion sources and pathways
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Autores:
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Huerta, Pedro ;
Martín Pérez, Andrea ;
Martín García, Rebeca ;
Rodríguez Berriguete, Álvaro ;
La Iglesia, Á. ;
Alonso-Zarza, Ana María
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Tipo de documento:
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texto impreso
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Editorial:
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Elsevier, 2019-04-01
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Dimensiones:
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application/pdf
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Nota general:
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info:eu-repo/semantics/restrictedAccess
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Idiomas:
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Palabras clave:
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Estado = Publicado
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Materia = Ciencias: Geología: Geoquímica
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Materia = Ciencias: Geología: Mineralogía
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Materia = Ciencias: Geología: Petrología
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Tipo = Artículo
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Resumen:
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Lava tubes from Lanzarote Island in the Canary Archipelago commonly show white speleothems that stand out from the black basaltic rock. Mineralogical analyses of the speleothems from El Covón and Chifletera lava tubes show that gypsum is the dominant mineral with minor amounts of halite. Speleothems composed of microcrystalline gypsum (up to 150??m long) are: coatings, globules, or extensive white powder accumulations covering the tube floor. Those composed of macrocrystalline gypsum with millimetric-size tabular and lenticular crystals are: crusts and stalactites. Uranium series dating of speleothems show ages ranging from 6217?±?1644?yr to 40,039?±?4748?yr. ?34S and the ?18O of gypsum speleothems (?34S is 20.97‰ V-CDT and ?18O is 9.78‰ V-SMOW) is similar to that of sulphate dissolved in seawater. 87Sr/86Sr from speleothems (0.708665–0.708976) suggests that the main source of Ca is seawater, but additional Ca contributions from aeolian dust have reduced the Sr isotope values. These data support the idea that gypsum precipitates in the lava tube by evaporation of marine spray or solutions derived from marine spray. Two probable vias for ions input into the lava tube are considered: 1) sea spray circulating through the lava tube; 2) low-frequency rain infiltration leaching the marine spray salts precipitated at the surface. The constant supply of ions from sea spray, air currents in the cave, and the fast, but partial, evaporation due to the high relative humidity in the lava tube favours accumulation of major amounts of gypsum and subordinately halite. Scarcity of precipitation in the western Canary Islands prevents dissolution of gypsum speleothems.
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En línea:
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https://eprints.ucm.es/id/eprint/51767/1/Gypsum%20speleothems%20in%20lava%20tubes%20from%20Lanzarote%20%28Canary%20Islands%29%20Ion%20sources%20and%20pathways.pdf
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