Affiliation:
1. Istituto di Geologia Ambientale e Geoingegneria (IGAG), Consiglio Nazionale delle Ricerche (CNR), Area della Ricerca di Roma 1, Via Salaria km 29,300, Monterotondo Street, 00015 Rome, Italy
Abstract
A database consisting of 163 data on the uranium content and 234U/238U initial activity ratio of 15 Italian travertine and calcareous tufa sites was created using data from the relevant literature. Using a graphical method, data were interpreted considering the U geochemistry in natural environments as well as the geological, hydrogeological and hydrogeochemical settings of each site. The U content and 234U/238U initial activity ratio in travertine and tufa appear to be affected by different factors, such as the availability of U in the aquifer rocks, the redox state of the waters, and the alpha-active radionuclide recoil phenomenon. The data allow the identification of four groups of travertines/tufas: (i) those precipitated from circulating groundwater, with a short/fast flow path, in volcanic rocks with a high radionuclide content; (ii) those precipitated from circulating groundwater, with a long, deep flow path in carbonate/evaporite formations with a relatively low radionuclide content; and (iii) those precipitated from cold waters associated with riverine systems, which are characterized by oxidizing conditions and fed by high-discharge springs recharged by carbonate aquifers. The fourth group represents the intermediate situations frequently occurring due to the mixing of waters from different aquifers. The results suggest an interpretative model that might contribute to the paleo-environmental reconstruction of fossil travertine and calcareous tufa depositing systems.
Subject
Geology,Geotechnical Engineering and Engineering Geology
Reference76 articles.
1. Panichi, C., and Tongiorgi, E. (1975, January 20–29). Carbon isotopic composition of CO2 from springs, fumaroles, mofettes and travertines of central and southern Italy: A preliminary prospection method of geothermal area. Proceedings of the 2nd UN Symposium on the Development and Use of Geothermal Energy, San Francisco, CA, USA.
2. Origin, transport and discharge of CO2 in central Italy;Minissale;Earth-Sci. Rev.,2004
3. Late Pleistocene depositional cycles of the lapis Tiburtinus travertine (Tivoli, Central Italy): Possible influence of climate and fault activity;Faccenna;Glob. Planet. Change,2008
4. Palaeoclimatic records from stable isotopes in riverine tufas: Synthesis and review;Andrews;Earth-Sci. Rev.,2006
5. Decoding tufa and travertine (freshwater carbonates) in the sedimentary record: The state of the art;Capezzuoli;Sedimentology,2014