Mantle Origin of CO2 and Carbonate Budget of Oceans and Travertine Deposits – Examples from Turkey and Szeklerland

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The Pamukkale Travertine was deposited along the Burdur-Fethye fault zone. The main source of the significant amount of CO2 converted into bicarbonate should be of mantle origin, as proven by the nearby presence of borate deposits in the Bigadiç borate Basin.

Carbonate budget in the oceans of the Earth and in continental domains, as well, basically depends on the availability of CO2 in aqueous solutions, which might be a function of the mantle CO2 release by oceanic floor volcanic activity, in a given geological period. Wilson includes the enrichment in volatiles, halogens and CO2, among the general characteristics of continental rift zone magmatism (Wilson, 1989). Solubility of CO2 in magmas increases with pressure and magma alkalinity (Lowenstern, 2001).

Mantle origin CO2 is commonly present in active strike-slip zones, either as bicarbonate ion in aqueous solutions, or as dry CO2, and may give birth to significant continental carbonate deposits in the form of travertines, like in Pamukkale, Turkey, or the Yellowstone carbonate travertines in the USA. For example, the Ol Doinyo Lengai volcano of the East African Rift, Tanzania, is producing natrocarbonatite lava, accompanied by a flux of 6000–7200 tonnes CO2 d−1 (Koepenick et al., 1996). It is very difficult to disproof the mantle origin of these enormous CO2 fluxes.

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Small size Holocene carbonate tufa dome at Tălișoara/ Olasztelek, Szeklerland, Romania

Distribution of massive CO2 occurrences and that of larger carbonate tufa domes is related to deep crustal faults, and thus surface carbonate tufa deposits can be used to trace deep seated crustal faults, hence we consider them as integral parts of the GSST mapping techniques. A minor carbonate tufa dome is above from Tălișoara/ Olasztelek, which together with the Bálványos carbonate tufa domes delineate a major W to E trending deeper crustal fault system in Szeklerland/ Romania. Another synthetic fault to the master is coming from the Racoș/ Alsórákos neovolcanic area via the Ozunca Băi/ Uzonkafürdő carbonate tufa dome.

Published in: Kovács, J.Sz., 2015 (in press), Elements of Global Strike-Slip Tectonics: a Quasi-Neotectonic Analysis, Journal of Global Strike-Slip Tectonics, v1., Szekler Academic Press, Sfintu Gheorghe.