Fig. 12
Conceptual model of the magmatic-hydrothermal system of Irazú and Turrialba volcanoes displayed in a sketch E–W cross section (not to scale). It is shown the location of magmatic-hydrothermal sub-systems (MHS) feeding the studied thermal springs along the north flank of Irazú–Turrialba (SC San Cayetano, ST Santa Teresita, OJA Ojo de Agua, BLP Bajo las Peñas) and summit crater lakes, together with their isothermal lines. The MHS related to Hervideros de Buenos Aires springs (HBA) is not included because located on the opposite side of Irazú. Measured and estimated T values for all the springs are displayed. Arrows indicate the interpreted relationships between different individual MHSs. A presumed location for the main magmatic chambers is given. Main conduits and vents feeding plume degassing and eruption from the summit crater area of Turrialba are shown ( boquete 1–2010 and 1–2012). The collapse fault (F) tapping Bajo Las Peñas springs accounts for an ascending peak of isothermal lines. A curved black arrow is the expression of fresh meteoric waters infiltrating from higher elevations and diluting Bajo Las Peñas springs. Average values of isotopic compositions (δD and δ18O) of thermal spring waters, fumaroles, rivers and meteoric waters are provided for Irazú and Turrialba volcanoes. The prevailing direction of provenance of Caribbean rains and winds from the northeast is outlined