Fluxes of high- versus low-temperature water rock interactions in aerial volcanic areas: Example from the Kamchatka Peninsula, Russia

• Published in: Geochimica et Cosmochimica Acta
• Main Authors: Dessert, Céline, Gaillardet, Jérôme, Dupre, Bernard, Schott, Jacques, Pokrovsky, Oleg S.
• Other Authors: Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Géosciences Environnement Toulouse (GET), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2009
• Subjects: [SDU]Sciences of the Universe [physics]; Carbonic acid; Kamchatka; Kamchatka Peninsula
• Online Access: https://insu.hal.science/insu-03633442; https://doi.org/10.1016/j.gca.2008.09.012

International audience Volcanic areas play a key role in the input of elements into the ocean and in the regulation of the geological carbon cycle. The aim of this study is to investigate the budget of silicate weathering in an active volcanic area. We compared the fluxes of the two major weathering regimes occurring at low temperature in soils and at high temperature in the active volcanic arc of Kamchatka, respectively. The volcanic activity, by inducing geothermal circulation and releasing gases to the surface, produces extreme conditions in which intense water-rock interactions occur and may have a strong impact on the weathering budgets. Our results show that the chemical composition of the Kamchatka river water is controlled by surface low-temperature weathering, atmospheric input and, in some limited cases, strongly imprinted by high-temperature water-rock reactions. We have determined the contribution of each source and calculated the rates of CO 2 consumption and chemical weathering resulting from low and high-temperature water/rock interactions. The weathering rates (between 7 and 13.7 t/km 2 /yr for cations only) and atmospheric CO 2 consumption rates (∼0.33-0.46 × 10 6 mol/km 2 /yr for Kamchatka River) due to rock weathering in soils (low-temperature) are entirely consistent with the previously published global weathering laws relating weathering rates of basalts with runoff and temperature. In the Kamchatka River, CO 2 consumption derived from hydrothermal activity represents about 11% of the total HCO 3 flux exported by the river. The high-temperature weathering process explains 25% of the total cationic weathering rate in the Kamchatka River. Although in the rivers non-affected by hydrothermal activity, the main weathering agent is carbonic acid (reflected in the abundance of HCO3- in rivers), in the region most impacted by hydrothermalism, the protons responsible for minerals dissolution are provided not only by carbonic acid, but also by sulphuric and hydrochloric acid. A clear increase of ...