Crater lake evolution at Santa Ana Volcano (El Salvador) following the 2005 eruption

Geochemistry of REE, Zr and Hf in a wide range of pH and water composition: The Nevado del Ruiz volcano-hydrothermal system (Colombia)

“…8) are characterized by strong LREE depletion. A similar shape of pattern with LREE depletion was already observed in other acid-sulphate waters from Waiotapu (New Zealand), Copahue volcano (Argentina), Santa Ana (El Salvador), Kawah Ihen Crater Lake (Indonesia) and Kutomintar and Sinarka volcanoes (Kawah Ijen) (Takano et al, 2004;Wood et al, 2006;Varekamp et al, 2009;Colvin et al, 2013;Kalacheva et al, 2015). Strong REE fractionation occurs during the hydrothermal alteration in very low pH waters with high SO 4 2− contents, showing higher LREE contents in alunitic advanced argillic alterated rocks compared to the unalterated volcanic rocks (Hikov, 2011).…”

“…This diagram allows to evaluate if the chemical composition of waters is a reflection of the rocks (nearcongruent dissolution, under hyperacid conditions) and the possible removal of elements by precipitation of secondary minerals (Taran et al, 2008;Colvin et al, 2013;Varekamp, 2015 and references therein). The hyperacid waters of Group 2 fall between the isosol lines indicating the dissolution of about 5 to 10 g of rock (Fig.…”

“…Strong depletions of Fe, Al, K and minor depletion of Na (Fig. 5) suggest the precipitation of alunite [(K,Na)Al 3 (SO 4 ) 2 (OH) 6 )] and jarosite [(K, Na)Fe 3 (SO4) 2 (OH) 6 ], typical minerals precipitating in hyperacid hydrothermal systems (Taran et al, 2008;Varekamp et al, 2009;Colvin et al, 2013). The waters of Group 1 don't reflect the composition of the average local rock, showing the strong depletions in Fe and Al (Fig.…”

Geochemical characterisation of Taal volcano-hydrothermal system and temporal evolution during continued phases of unrest (1991–2017)

“…The alteration mineral assemblage found in the Main Crater of Taal volcano corresponds to alunite-rich advanced argillic alteration and the current MCL fluids correspond to the associated fluids, so REE fractionation at Taal is likely related to intensive interaction of fluids with mature rocks that have been heavily leached and altered. A similar REE pattern has been seen before in other volcanic lakes and hot springs, including Maly Semiachik, Russia; Kusatsu-Shirane, Japan; Keli Mutu, Indonesia; Santa Ana, El Salvador; Nevado del Ruiz, Colombia; Kutomintar and Sinarka volcanoes, Kuril Islands and Azufral, Colombia (Takano et al, 2004;Colvin et al, 2013;Inguaggiato et al, 2015;Kalacheva et al, 2015;Varekamp, 2015;Inguaggiato et al, 2017).…”

A Polyextreme Hydrothermal System Controlled by Iron: The Case of Dallol at the Afar Triangle

“…Hyperacidic values have been reported as well for several volcanic crater lakes and hot springs, among them the Kawah Ijen crater lake in Indonesia (pH ∼ 0.3), 16 the Poas crater in Costa Rica (pH ∼ −0.89), 17,18 the Ebeco Volcano in Kuril Islands (pH ∼ 0.2) 19 the Copahue in Argentina (pH ∼ 0.2), 20−22 the Ruapehu in New Zealand (pH ∼ 0.6), 23 the Nevado del Ruiz, Colombia (pH ∼ 1), 24 and the Santa Ana Volcano, El Salvador (pH ∼ 0.5). 25 Concerning acid mine effluents, hyper-acidic to acidic pH values (0.9–3) have been measured in Rio Tinto in Spain, 26 while 27 reporting a bizarre much lower value of pH, −3.6, from the Richmond Mine of the Iron Mt in California. Thus, to the best of our knowledge, the hydrothermal system of Dallol is the most acidic natural system.…”