Fissure Ridges: A Reappraisal of Faulting and Travertine Deposition (Travitonics)

Abstract

The mechanical discontinuities in the upper crust (i.e., faults and related fractures) lead to the uprising of geothermal fluids to the Earth’s surface. If fluids are enriched in Ca2+ and HCO3-, masses of CaCO3 (i.e., travertine deposits) can form mainly due to the CO2 leakage from the thermal waters. Among other things, fissure-ridge-type deposits are peculiar travertine bodies made of bedded carbonate that gently to steeply dip away from the apical part where a central fissure is located, corresponding to the fracture trace intersecting the substratum; these morpho-tectonic features are the most useful deposits for tectonic and paleoseismological investigation, as their development is contemporaneous with the activity of faults leading to the enhancement of permeability that serves to guarantee the circulation of fluids and their emergence. Therefore, the fissure ridge architecture sheds light on the interplay among fault activity, travertine deposition, and ridge evolution, providing key geo-chronologic constraints due to the fact that travertine can be dated by different radiometric methods. In recent years, studies dealing with travertine fissure ridges have been considerably improved to provide a large amount of information. In this paper, we report the state of the art of knowledge on this topic refining the literature data as well as adding original data, mainly focusing on the fissure ridge morphology, internal architecture, depositional facies, growth mechanisms, tectonic setting in which the fissure ridges develop, and advantages of using the fissure ridges for neotectonic and seismotectonic studies.

Tectonically induced travertine deposition in the Middle Miocene Levač intramountain basin (Central Serbia)

“…This implies that Mn‐minerals were precipitating from the fluid flow phase post‐dating calcite precipitation. Similar manganese accumulations are observed in Ouarzazate depression (Morocco), Belin (north–central New Mexico) and Iano (southern Tuscany), and have been described to result from microbially mediated manganese–mineral precipitation (Chafetz et al ., 1998; Chafetz & Guidry, 1999; Matera et al ., 2021; Brogi et al ., 2021a). There, precipitation likely occurs due to elevated pH and Eh in the area inhabited by bacteria where oxidizing and alkaline conditions promote the precipitation of Mn (Rankama & Sahama, 1960; Chafetz et al ., 1998).…”

“…mixing between thermally generated and meteoric CO 2 enriched waters supplying the spring, as also observed in the case of Iano travertine site (southern Tuscany, Matera et al ., 2021). In such conditions, low‐temperature meteoric water‐dominated fluids depleted in CO 2 allowed bacteria to thrive and locally change pH values leading to manganese accumulations (Chafetz et al ., 1998; Matera et al ., 2021; Brogi et al ., 2021a). Therefore, the alternation between the light and dark crystalline crust travertine represents events of active thermally generated CO 2 enriched fluid flow associated with fast CO 2 degassing and events of stasis allowing the mixing of deep thermal and shallow cooler meteoric waters.…”

Factors controlling the geometry of travertine mounds: Insights from Heinitang (China)

“…3). These assumptions are acceptable for small mounds, as shown by many active mounds, like those from Yellowstone National Park (USA) (Brogi et al ., 2021). However, flow paths on large mounds are more irregular: fan‐shaped discharge areas, channels and terraced slopes might be formed (e.g.…”

“…Isolated travertine mounds have been generally considered to be genetically linked to fault activity and unconsolidated substrate (Hancock et al ., 1999; Capezzuoli et al ., 2014; Mohammadi et al ., 2019; Brogi et al ., 2021) and have been widely documented around the world (Bargar, 1978; Pentecost, 2005; Fouke, 2011; Guido & Campbell, 2012; Liu et al ., 2012; Sugihara et al ., 2016; Jones & Peng, 2017; Özkul et al ., 2019). However, their geometries are highly variable: they can extend over ten metres high (for example, Liberty Cap, USA, ca 14 m high; Bargar, 1978; Chafetz & Guidry, 2003; Fouke, 2011) and up to several hundred metres wide (for example, Bullicame mound, Italy, ca 220 m wide) (Della Porta et al ., 2021) or may only limitedly develop as metre‐scale mounds, like those from Shiqiang, China (Jones & Peng, 2017).…”

Factors governing travertine deposition in fluvial systems: The Bagni San Filippo (central Italy) case study

“…With respect to these spring-constructed carbonates, multiple depositional models have been built based on their morphologies, lithofacies and facies associations: tufa depositional models are generally divided into perched springline model, fluvial model, paludal model, lacustrine model, and cascade model, while the classification of travertine depositional models is much different, encompassing fissure ridge model, terraces and range front sheet model, slope model, depression model, and mound model (e.g. Pedley, 1990;Ford and Pedley, 1996;Pedley, 2009;Capezzuoli et al, 2014;Della Porta, 2015;Toker et al, 2015;Mancini et al, 2019;Brogi et al, 2021;Kandemir et al, 2021). All the classifications considered "rivers/streams" as potential depositional areas for spring-constructed carbonates, but only for tufa (e.g.…”