RT Journal Article
T1 The Azuaje travertine: an example of aragonite deposition in a recent volcanicsetting, N Gran Canaria Island, Spain
A1 Rodríguez Berriguete, Álvaro
A1 Alonso-Zarza, Ana María
A1 Cabrera Santana, María del Carmen
A1 Rodríguez González, Alejandro
AB The Azuaje travertines in the north of Gran Canary Island crop out in the Azuaje Gorge, which is incised into Miocenevolcanic breccias of the Roque Nublo Formation. This travertine is interesting because of the scarcity of travertines inthe Canary Islands and its close relationship with recent volcanic events. Part of the travertine overlies a lava flow,dated at 2420±40 years BP. The travertine is composed mainly of aragonite in both perched systems on thegorge walls and in gorge bottom deposits parallel to the present stream. Perched systems include deposits fromthe feeder conduits within the Roque Nublo Formation that spilled out through waterfalls and over barriers. Thegorge (valley) bottom system includes barrier and pool deposits. The main laminated facies are composed mostlyof large fibrous aragonite crystals, while there are also common micritic and porous microfabrics. Shrubs, coatedgrains, coated bubbles and rafts are present in many of the deposits. Detailed study of the microfacies shows thepresence of sparsely distributed biogenic features. The δ13C values are between +4.0 and +11.0‰, and the δ18Ovalues range between −11.0 and −2.0‰ VPDB. These δ13C values lie within the range of those of thermogenetravertines fed by thermal waters that cooled downstream, as indicated by the increase of the carbon and oxygenisotope values in that direction. The common occurrence of fibrous radial fabrics is interpreted to be due to disequilibriumconditions during aragonite precipitation. Disequilibrium was likely caused by rapid CO2 degassing of thethermalwaters that led to a rapid increase in the degree of aragonite saturation. Thus, themorphology of the aragonitecrystals and the isotopic composition indicate that the formation of the Azuaje travertine was mostly due toabiogenic processes induced by rapid degassing of thermalwaters, linked to the presence of a recent lava flow withinthe Gorge. In short, the Azuaje travertine shows the important role of volcanic activity in travertine deposition, inthe facies distribution as well as in the geochemical signatures of the deposits, and so can be used as a recentanalogue for ancient travertine deposits in volcanic settings
PB Elsevier
SN 0037-0738
YR 2012
FD 2012
LK https://hdl.handle.net/20.500.14352/44164
UL https://hdl.handle.net/20.500.14352/44164
LA eng
DS Docta Complutense
RD 29 abr 2024