@article{fdi:010053074,
  title = {{F}luid geochemistry of natural manifestations from the {S}outhern {P}oroto-{R}ungwe hydrothermal system ({T}anzania) : preliminary conceptual model},
  author = {{D}elalande, {M}. and {B}ergonzini, {L}. and {G}herardi, {F}. and {G}uidi, {M}. and {A}ndr{\'e}, {L}. and {A}bdallah, {I}. and {W}illiamson, {D}avid},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he {S}outh {P}oroto-{R}ungwe geothermal field, in the northern part of the {M}alawi rift, {T}anzania divides in two main areas. {T}he relatively high altitude northern area around the main {N}gozi, {R}ungwe, {T}ukuyu and {K}yejo volcanoes, is characterised by cold and gas-rich springs. {I}n contrast, hot springs occur in the southern and low-altitude area between the {K}yela and {L}ivingstone faults. {T}he isotopic signature of the almost stagnant, cold springs of the {N}orthern district is clearly influenced by {H}2{O}-{CO}2(g) exchange as evidenced from negative oxygen-shifts in the order of few deltas permil. {I}n contrast, the isotopic signature of waters discharged from the hot springs of the {S}outhern district is markedly less affected by the {H}2{O}-{CO}2(g) interaction. {T}his evidence is interpreted as an effect of the large, permanent outflow of these springs, which supports the hypothesis of a regional-scale recharge of the major thermal springs. {M}easurements of carbon isotope variations of the dissolved inorganic carbon of waters and {CO}2(g) from the {N}orthern and {S}outhern springs support a model of {CO}2(g)-driven reactivity all over the investigated area. {O}ur combined chemical and isotopic results show that the composition of hot springs is consistent with a mixing between (i) cold surface fresh ({SFW}) and (ii) {D}eep {H}ot {M}ineralised ({DHMW}) {W}ater, indicating that the deep-originated fluids also supply most of the aqueous species dissolved in the surface waters used as local potable water. {B}ased on geothermometric approaches, the temperature of the deep hydrothermal system has been estimated to be higher than 110 degrees {C} up to 185 degrees {C}, in agreement with the geological and thermal setting of the {M}alawi rift basin. {G}eochemical data point to (i) a major upflow zone of geothermal fluids mixed with shallow meteoric waters in the {S}outhern part of the province, and (ii) gas absorption phenomena in the small, perched aquifers of the {N}orthern volcanic highlands.},
  keywords = {{T}anzania ; {P}oroto-{R}ungwe ; thermal springs ; fluid geochemistry ; water and carbon isotope compositions},
  booktitle = {},
  journal = {{J}ournal of {V}olcanology and {G}eothermal {R}esearch},
  volume = {199},
  numero = {1-2},
  pages = {127--141},
  ISSN = {0377-0273},
  year = {2011},
  DOI = {10.1016/j.jvolgeores.2010.11.002},
  URL = {https://www.documentation.ird.fr/hor/fdi:010053074},
}