Tracer test in the vadose zone of Praileaitz Cave (Deba, Guipúzcoa). Application for protection of karstic cavities

Se ha realizado un ensayo de trazador en la zona no saturada de la Cueva de Praileaitz (Bajo Deba, Guipúzcoa) para ayudar a la delimitación del área de protección de la cavidad. Dicho ensayo se ha efectuado con 14.000 L de agua desionizada y una masa de 500 gr de LiCl. El trazador analizado (Li+) ha permitido deducir un tránsito de entre 18 y 19 horas desde el momento de la inyección. Esta primera detección corresponde a una ve locidad de flujo no saturado de entre 4-5 m/h. La concentración máxima al canzada de litio fue de 11’28 µg/L.A tracer test has been performed in the vadose zone of the Cave of Praileaitz (Bajo Deba, Guipúzcoa) for helping in the delimitation of its protection area.The test was done with 14.000 L of deionized water and a mass of 500 gr of LiCl. The detection of the tracer substance (Li+) has allowed deducing a transit time between 18 and 19 hours since the injection. This first detection corresponds to a non-saturated flow between 4-5 m/h. The maximum lithium concentration was 11’28 µg/L

Colour and CaCO3 content in the Upper Maastrichtian and the Lower Eocene couplets at Sopelana (Basque Arc): palaeoenvironmental responses

The Sopelana sea-cliff exposes marl-limestone couplets from the Upper Maastrichtian (MS1 and MS2 sections) and the Lower Eocene (EI section), in the deep Basque Arc domain. The high-resolution analysis (% CaCO3) of the MS1 couplets confirms a complex behaviour with strong compositional contrast vs. a more regular MS2 couplets. This may be due to a drastic environmental change (long humid and rainy alternating to drier periods) towards dominant humid and rainy periods, with a minor seasonal nature and high sedimentation rate (72 cm/20 ky). The deep, cold, oxygenated marine water produces a change of coloration (grey to purple) during the sedimentation, in the Upper Maastrichtian couplets before diagenesis activity. It is the beginning of the Cretaceous oceanic red beds (CORB´s