1,721,052 research outputs found
Comparison of carbon dioxide emissions with fluid upflow, chemistry, and geologic structures at the Rotorua geothermal system, New Zealand
No full textDuring 2002 and 2003, carbon dioxide fluxes were measured across the Rotorua geothermal system in the Taupo Volcanic Zone (TVZ), New Zealand. The results of a 956-measurement survey and of modeling studies show that CO2 fluxes could be used to determine the main hot fluid upflow areas in Rotorua, and perhaps in undeveloped geothermal regions. Elevated degassing was observed along inferred fault traces and structures, lending confidence to their existence at depth. Degassing was also observed along lineaments that were consistent with the alignment of basement faulting in the TVZ. Areas where elevated degassing was spatially extensive typically overlapped with known regions of hot ground; however, elevated CO2 fluxes were also observed in isolated patches of non-thermal ground. The total emission rate calculated from sequential Gaussian simulation modeling of CO2 fluxes across the geothermal system was 620t d(-1) from an 8.9-km(2) area. However, because approximately one-third of the geothermal system is known to extend beneath Lake Rotorua, we expect the emissions could be minimally on the order of 1000 t d(-1). Comparing the emission rate with geochemical analyses of geothermal fluids and estimated upflows suggests that the majority of deep carbon reaches the surface in the form of carbon dioxide gas, and that less than one tenth of the CO2 emissions is dissolved in, or released from, the fluids at depth. Thus, the geothermal reservoir exerts very little control on deep degassing of CO2. Carbon isotopic analyses of soil gases suggest a primarily magmatic source for the origin of the CO2. The total Rotorua emission rate is comparable to those from active volcanoes such as at White Island, New Zealand, and, when normalized by geothermal area, is comparable to other volcanic and hydrothermal regions worldwide
Triponzo: a thermal system in a cold area of the Apennines (Italy)
No full textThe Bagni di Triponzo thermal springs, characterised by a Ca-SO4 composition and temperatures up to 30 degrees C, are located in the eastern sector of Umbria region in the Umbria-Marche Apennine (central Italy). The region is characterised by a low geothermal gradient and low conductive heat flux and the composition of Triponzo thermal waters significantly differs with respect to the cold waters circulating in the surrounding areas. The origin of the heat transported by the waters of the Triponzo springs is mainly due to a deep component, characterised by high CO2 and He contents, coming from a deeper reservoir, rising along normal faults and mixing with infiltrating waters of meteoric origin. The total amount of thermal water discharged by the system is about 34 L s(-1). According to the ternary SO4-2-F--HCO3-geoindicator for carbonate-evaporite reservoirs, the fluids at reservoir condition are charcterised by a partial pressure of CO2 about 0.5 bar and a temperature between 70-75 degrees C whereas the silica geothermometers give a temperature about 62 degrees C. The computed thermal energy transported by advection and discharged at the surface by Triponzo springs is about 3.71x10(11) +/- 0.56x10(11) J/day
Microseismicity along low-angle normal faults triggered by fluid overpressure: an example from the Altotiberina fault (Central Italy).
No full textUsing fumarolic inert gas composition to investigate magma dynamics at Campi Flegrei (Italy)
No full textApplication of sthochastic simulation to carbon dioxide flux from soil: Mapping and quantification of gas release (2003). EGS-AGU-EUG Joint Assembly
No full textWater-gas-rock interactions in carbonate-evaporite aquifers sited in CO2 degassing areas
No full textCarbon dioxide degassing and energy thermal energy release at vesuvio (Italy). EGS-AGU-EUG Joint Assembly
No full text
- …
