Decoding tufa and travertine (fresh water carbonates) in the sedimentary record: The state of the art

Abstract

Traditionally, fresh water carbonate research has focused on the sedimentology and palaeontology of ancient lacustrine deposits. Lithofacies in such low-energy deposits are typically fine-grained, developed uniformly in a generally concentric distribution ('bulls-eye' pattern) and are predictable even when preserved imperfectly. In contrast, because of their local lithofacies and palaeontological complexities, fluvial carbonates were either delegated to a status of 'minor geomorphological features' or barely considered prior to the 1970s. This viewpoint was based on the depositional record of fluvial and spring-fed fresh water carbonates, which were considered to be restricted generally to localized karstic areas. Such deposits are often preserved as scattered patches of ambient temperature tufa. Occasionally, however, in active tectonic areas, localized travertine deposits are also developed from deeply circulating hydrothermal waters. With a few exceptions (for example, basins with high subsidence rates or in arid climate zones), these fresh water carbonates are prone to erosion from continuing river incision and thus may not be preserved in the geological record. A partial record of fluvial and springdeposited carbonates is often preserved in Quaternary deposits, but the record in older deposits is typically fragmentary and often diagenetically modified. Yet once their unique facies architecture (and specialized nomenclature) is understood, these carbonates provide an important record of past sedimentological cycles of great value in palaeoenvironmental landscape modelling. The emphasis of modern research is to acquire information that explains how active systems function. In this respect, tufas reveal much of how carbonate precipitation is a shared product of physico-chemical and microbiological biomediation processes. Likewise, travertines not only show an intimate interrelation with active tectonism but also hold great potential as monitors of past volcanic carbon dioxide emissions. In addition, both tufas and travertines contain palynological records that can be used as proxy indicators of climate change. Perhaps no other field of sedimentology has witnessed more developments and applications over such a brief period of study.

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

“…The deposition of travertine results from the interplay of abiotic processes (CO 2 degassing, heat dispersion, flow turbulence) and the presence and activity of (micro)biota (Andrews and Brasier, 2005;Pentecost, 2005;Takashima and Kano, 2008;Brasier, 2011;Pedley, 2014) and may thus contain preserved "biomarkers" that make it an important target for reconstructing ancient life on the early Earth and potentially other planets (Russell and Hall, 1999;Allen et al, 2000; National Research Council of the National Academies, 2007). Furthermore, typical, finely laminated calcareous, continental spring deposits and their isotopic and elemental geochemistry have long been recognized as important records of environmental, climatic and tectonic information throughout the Quaternary (Kano et al, 2003;Andrews and Brasier, 2005;Brasier et al, 2010;Sierralta et al, 2010;Pazzaglia et al, 2013;Capezzuoli et al, 2014;Dabkowski et al, 2015;Frery et al, 2015). More recently, offshore discoveries suggest that ancient continental carbonate deposits may contribute to economically important subsurface reservoirs (Garland et al, 2012;Ronchi and Cruciani, 2015;Schroeder et al, 2016).…”

“…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). Furthermore, a continuum exists between cool and warmer springs in terms of water temperature, water chemistry, rock facies, fabrics and microbial or biological signatures (Jones and Renaut, 2010;Lopez et al, in press), which hampers a strict discrimination between ambient and warm water ancient carbonate spring deposits.…”

“…Despite different reviews about continental carbonate spring facies and fabrics (Guo and Riding, 1998;Chafetz and Guidry, 2003;Pentecost, 2005;De Filippis et al, 2012;Capezzuoli et al, 2014;Della Porta, 2015), some of the most extensive sites of modern and ancient travertine deposition have never been compared. Hence, an integrated and comparative travertine depositional facies model based on spatial and quantitative mapping (at meter to kilometer length scales) of different, key travertine systems does not exist.…”

“…Different travertine depositional facies models of modern spring systems have been proposed to describe the complex textural and geometric variations of ancient spring deposits (Guo and Riding, 1998;Fouke et al, 2000;Capezzuoli et al, 2014;Claes et al, 2015;Della Porta, 2015) and to accurately reconstruct the environmental conditions under which ancient deposits originally formed and evolved (Chafetz and Folk, 1984;Veysey et al, 2008;Fouke, 2011;Gandin and Capezzuoli, 2014;Sotohian and Ranjbaran, 2015). A facies, as summarized by James and Dalrymple (2010), is a 'body of (sedimentary) rock characterized by a particular combination of lithology and physical and biological structures that bestow an aspect that is different from the bodies of rock adjacent.…”

Travertine occurrences along major strike-slip fault zones: structural, depositional and geochemical constraints from the Eastern Anatolian Fault System (EAFS), Turkey

“…Andrews, 2006;Hancock, Chalmers, Altunel, & Çakir, 1999;Jones & Renaut, 2010;Mesci, 2004Mesci, , 2013Özkul, Gökgöz, & Horvatinčić, 2010;Özkul et al, 2013, 2014Pedley, 2009;Uysal et al, 2007Uysal et al, , 2009). Although there is little consensus on the use of the terms travertine and tufa (Capezzuoli, Gandin, & Pedley, 2014;Jones & Renaut, 2010), tufa is herein considered to be a product of CaCO 3 precipitation from cool (near ambient temperature) water regimes that typically contain remains of micro-and macrophytes, invertebrates and bacteria. In contrast, the term travertine is used for the spring carbonates that form from hydrothermal waters (Ford & Pedley, 1996;Jones & Renaut, 2010;Kele et al, 2011).…”