The superficial emission arise from phisicist phenomena (conduction and convection) relating depht table-water warmed by a magma intrusion in a cooling phase.
The decrement of density (caused by heating and by the addition of magma origined volatiles) and the pression of the overhanging impermeable thickness support water-bearing to go up again along structural and stratigraphic discontinuity.
(low temperatur) and chemical (high salinity) caracteristics of waters make us
suppose there can be depht water circuits very long and slow as well as
dilutions with cold superficial-low saline tenor water-tables.