Tufas and travertines of the Mediterranean region: a testing ground for freshwater carbonate concepts and developments

Abstract

Actively forming travertine and tufa sites are widespread in temperate and warm climates, such as the Mediterranean region, but also develop in other climatic regimes from the Arctic to equatorial latitudes. The terms travertine and tufa are sometimes applied indiscriminately today; however, each has a specific definition. Most studied deposits are active or of Quaternary (especially Holocene) age. There are fewer Tertiary and even less late Mesozoic examples on record. In part, this is because of a recognition problem as these deposits commonly preserve as fragmentary erosional remnants. Physico-chemical precipitation of calcium carbonate is commonly considered to be the main mechanism contributing to tufa and travertine deposition. Rapid cooling of waters further aids the process in thermal (travertine) sites. However, biomediation of calcium carbonate, associated with prokaryote-microphyte biofilms, is now recognized to be equally important in slow flowing and near static sites. Much of this precipitation occurs in close association with cyanobacterial, heterotrophic bacterial and diatoms. The Mediterranean region figures significantly in the development of travertine and tufa research. Consequently, this article employs key literature on Mediterranean examples to illustrate developments and concepts in freshwater carbonate research. Modern work started in the 1950s and defined many previously unknown outcrops. Many such sites became the targets for early radiocarbon dating studies. Since the late 1970s, a number of laboratory-based and field-based classification schemes have been proposed. Some schemes were based on associated macrovegetation types; others were based on petrological characteristics or on geometry and sedimentary facies characteristics. Of late, the sedimentological modelling has benefited greatly from the use of shallow geophysical techniques in order to better define the internal geometries of the deposits. Two distinct research strands were developed during the 1990s, both aimed at a better understanding of environmental change. The first considered biocomponents. The research was multifaceted and ranged from exploring the role of micro-organisms in cement and lime mud precipitation to biostratigraphic analysis of contained pollen and invertebrate remains; these provided proxy environmental information which has helped to define past climate variability in the region. The second research strand focussed on geochemical signatures as a proxy tool for defining environmental change. This definition was made possible by new petrological studies which have greatly aided the recognition of primary depositional fabrics. This improved knowledge has reduced the sampling dangers of diagenetic contamination inherent in earlier geochemical studies. Lithofacies modelling has also brought to light important early postdepositional neomorphic changes, which obscure primary fabrics, and complex diagenetic histories have been revealed. 221 carbon and oxygen have also been used to define palaeo-water temperatu...

What do we really know about early diagenesis of non-marine carbonates?

“…), dissolution Lopez et al (2017), Westaway (1993), Pentecost et al (1997), Kele et al (2011), De Filippis et al (2012, Özkul et al (2013), Van Noten et al (2013), Lebatard et al (2014), Claes et al (2015Claes et al ( , 2017aClaes et al ( , 2017b Sorey and Colvard (1997), Fouke et al (2000Fouke et al ( , 2003, Kharaka et al (2000), Chafetz and Guidry (2003), Kandianis et al (2008), Veysey et al (2008) Cipriani et al (1977), Barazzuoli et al (1988), Guo and Riding (1992, Pentecost (1995), Minissale et al (2002), Brogi et al (2007), Brogi and Capezzuoli (2008), Pedley (2009), Gandin and Capezzuoli (2014) Arp et al (2001Arp et al ( , 2010, Shiraishi et al (2008aShiraishi et al ( , 2008b, Brinkmann et al (2015) (continued on next page) et al, 2012; Nielsen et al, 2014). Lab and field studies report ACC phases found in close association with crystalline CaCO 3 (Jones and Peng, 2012a;Pedley, 2014) and/or organisms (cyanobacteria) or organic substances (Couradeau et al, 2012;Benzerara et al, 2014;Martignier et al, 2017).…”

Comparative study of the Pleistocene Cakmak quarry (Denizli Basin, Turkey) and modern Mammoth Hot Springs deposits (Yellowstone National Park, USA)

“…Often, a distinction has been made between cool water 'tufa' and warm or hot water 'travertine' deposits (Ford and Pedley, 1996;Pedley, 2009). Such classification, however, proves difficult when mapping ancient travertine in the field (Brasier, 2011;Capezzuoli et al, 2014;Cantonati et al, 2016).…”

Holocene tufa in the Slovak Karst: facies, sedimentary environments and depositional history

“…The term tufa is used to de note such de pos its if they com prise macro-or microphyte moulds or im prints (Pedley, 2009). How ever, some au thors ex tend the mean ing of the term "trav er tine" to such depos its (see Gandin and Cappezuoli, 2008 as well as Jones and Renaut, 2010, for ter mi no log i cal dis cus sion).…”