La sedimentación tobácea actual en el Parque del Monasterio de Piedra (provincia de Zaragoza)

• C. Arenas ^[1] ; C. Sancho ^[1] ; M.Cinta Osácar ^[1] ; M. Vázquez ^[1] ; L.F. Auqué ^[1]
  1. [1] Universidad de Zaragoza

     Universidad de Zaragoza

     Zaragoza, España

     
• Localización: Geotemas (Madrid), ISSN 1576-5172, Nº. 6, 2, 2004 (Ejemplar dedicado a: IV Congreso Geológico de España), págs. 27-30
• Idioma: español
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• Resumen

  • This contribution shows the most significant results of modern tufa sedimentation at the Piedra river in the Monasterio de Piedra (northeast Spain) from several sites in which some parameters and characteristics were measured from 1999 through 2003. Based on morphodynamic features and flora associations several environments of tufa formation primarily related to calcite precipitation on biological sustrates can be differentiated. Water is of calcium bicarbonate type, with mean pH~8.4, conductivity between 630 and 670 pS/cm and is always oversaturated in calcite. The sediment;

    sampled in summer and winter; consists mainly of low Mg calcite. Its mean isotopic composition is ö 13C=-8%o PDB and S'80=-8.3 %oPDB, with S180 lower in summer (-8.9%o) than in winter (- 7.7%o). The mean Si80 of water is -8.4 %0 SMOW in summer and -8.7%o SMOW in winter. Sedimentation rates were measured biannually (March and September) on limestone tablets (25x15x2cm). Data from some selected tablets installed in different environments indicate that the highest rates (-9-10 mm/year) are linked to intense mechanical C 0 2 outgassing within fast flow areas of the channel and to flora associations in waterfalls. The lowest values are found in slow flow and splash areas. For the whole system there is a marked difference between the warm (-5 mm/semester) and cool (-1.8 mm/semester) periods that is related to temperature effects and plant growth.