Facies character and depositional architecture of hydrothermal travertine slope aprons (Pleistocene, Acquasanta Terme, Central Italy)

Porta, Giovanna Della; Capezzuoli, Enrico; Bernardo, A. De

doi:10.1016/j.marpetgeo.2017.03.014

Cited by 44 publications

(87 citation statements)

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“…This conclusion would partly necessitate reconsidering the general interpretation of travertine fabrics; steeply inclined slopes and cascades with high flow velocity are characterized by the sparitic fabric due to more pronounced CO 2 degassing and consequent higher saturation state, leading to the prevalence of abiotic precipitation; while sub-horizontal pools and ponds with low flow velocity are characterized by the micritic fabric due to less pronounced CO 2 degassing and consequent lower saturation state, leading to the prevalence of microbially-influenced precipitation (e.g. Chafetz & Folk, 1984;Guo & Riding, 1998;Chafetz & Guidry, 1999;Rainey & Jones, 2009;Fouke, 2011;Capezzuoli et al, 2014;Della Porta, 2015;De Boever et al, 2017;Della Porta et al, 2017;Erthal et al, 2017). Although CO 2 degassing and a concomitant increase in the CaCO 3 saturation state is a fundamental driving force of travertine deposition, it cannot solely explain the difference between sparitic and micritic fabrics because the saturation state positively correlates with the rates of both crystal growth (leading to sparitic fabric) and crystal nucleation (leading to micritic fabric) (e.g.…”

Section: Influence Of the Flow Velocity On The Depositional Processesmentioning

confidence: 99%

“…Due to their microbial involvement, travertines are often investigated as analogues of stromatolites and laminated benthic microbial deposits; and their fabrics are compared with Precambrian examples to better understand the interaction between microbes and their environment (Walter & Des Marais, 1993;Riding, 2000;Okumura et al, 2011Okumura et al, , 2012Okumura et al, , 2013a. In addition, travertines have recently gained attention as analogues of Pre-Salt oil reservoirs found in the South Atlantic subsurface Cretaceous succession, which are potentially microbial carbonates and often described as stromatolites or shrub framestones/boundstones (Della Porta, 2015;De Boever et al, 2016Claes et al, 2017;Cook & Chafetz, 2017;Della Porta et al, 2017;Erthal et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Relative influence of biotic and abiotic processes on travertine fabrics, Satono‐yu hot spring, Japan

et al. 2018

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The relative influences of biotic and abiotic processes on travertine fabrics are still not well understood, despite increasing interest in the last decade to better understand the record of ancient microbial life and sedimentary fabrics in microbial hydrocarbon reservoirs. This study examines travertines at Satono‐yu hot spring in Japan (the temperature of water flowing over the travertine was ca 35°C), to better understand the interaction between depositional, hydrochemical and microbial parameters at different flow settings. Characteristics of the bulk hydrochemistry, mineralogy (exclusively aragonite) and the driving force for precipitation (primarily abiotic CO2 degassing with some photosynthetic microbial contribution) were similar among all of the flow settings. Conversely, the increase in flow velocity suppressed the influence of photosynthesis and enhanced the abiotic precipitation due to the thinner diffusive boundary layer at the travertine surface–water interface. Additionally, the increase in flow velocity changed the microbial composition and decreased the bacterial diversity by reflecting their adhesion efficiency on the travertine substrate. The acidity of the cyanobacterial sheaths controls the aragonite nucleation rate and the resulting calcification, even at significantly high equilibrium CO2 partial pressure (ca 22 to 28 matm), high dissolved inorganic carbon concentration (ca 35 to 38 mmol l−1), and elevated aragonite saturation state (ca 20‐fold to 34‐fold). Therefore, the increase in flow velocity suppresses the microbial influence with respect to the increase in the saturation state, the nucleation site supply and pore space generation. Overall, this results in the predominance of abiotic precipitation under high flow velocities. Consequently, a sparse‐micritic fabric with abundant interlamina porosity forms under lower flow velocity where the microbial influence is effective, while a dense‐sparitic fabric with little inter‐crystalline porosity forms under higher flow velocity where abiotic precipitation prevails. These findings provide an essential base for assessing the formation processes of ancient travertines and comparable deposits from petrological fabrics.

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Section: Influence Of the Flow Velocity On The Depositional Processesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Relative influence of biotic and abiotic processes on travertine fabrics, Satono‐yu hot spring, Japan

et al. 2018

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“…It is hard to avoid some mixing of the different carbonate phases, even during fabric selective micro-sampling within thin sections to selectively target different carbonate components (e.g. sparite cements, clotted peloidal micrite, crystalline dendrites) Della Porta et al, 2017). Nevertheless, in some cases, careful bulk sampling of homogenous parts of carbonate samples can be representative enough to answer the relevant scientific question Toker et al, 2015).…”

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confidence: 99%

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

Boever

Brasier

Foubert

et al. 2017

Sedimentary Geology

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Non-marine carbonate rocks including cave, spring, stream, calcrete and lacustrine-palustrine sediments, are susceptible to early diagenetic processes. These can profoundly alter the carbonate fabric and affect paleoclimatic proxies. This review integrates recent insights into diagenesis of non-marine carbonates and in particular the variety of early diagenetic processes, and presents a conceptual framework to address them. With ability to study at smaller and smaller scales, down to nanometers, one can now observe diagenesis taking place the moment initial precipitates have formed, and continuing thereafter. Diagenesis may affect whole rocks, but it typically starts in nano-and micro-environments. The potential for diagenetic alteration depends on the reactivity of the initial precipitate, commonly being metastable phases like vaterite, Ca-oxalates, hydrous Mg-carbonates and aragonite with regard to the ambient fluid. Furthermore, organic compounds commonly play a crucial role in hosting these early transformations. Processes like neomorphism (inversion and recrystallization), cementation and replacement generally result in an overall coarsening of the fabric and homogenization of the wide range of complex, primary microtextures. If early diagenetic modifications are completed in a short time span compared to the (annual to millennial) time scale of interest, then recorded paleoenvironmental signals and trends could still acceptably reflect original, depositional conditions. However, even compact, non-marine carbonate deposits may behave locally and temporarily as open systems to crystal-fluid exchange and overprinting of one or more geochemical proxies is not unexpected. Looking to the future, relatively few studies have examined the behaviour of promising geochemical records, such as clumped isotope thermometry and (non-conventional) stable isotopes, in well-constrained diagenetic settings. Ongoing and future in-vitro and in-situ experimental approaches will help to investigate and detangle sequences of intermediate, diagenetic products, processes and controls, and to quantify rates of early diagenesis, bridging a gap between nanoscale, molecular lab studies and the fossil field rock record of non-marine carbonates.

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“…Thus, crystalline crusts are formed as a variety of calcite/aragonite crystals (feather, fan, dendrites; see Jones and Renaut, 1995; 2010 for a review; Jones et al, 2000Jones et al, , 2005. Furthermore, this clarifies the definition of travertine as a primary bedded thermogene deposit A C C E P T E D M A N U S C R I P T (Chafetz and Folk, 1984;Renaut, 1995, 2008;Jones et al, 1996Jones et al, , 2000Jones et al, , 2005Guo and Riding, 1998;Renaut, 1995, 2008;Jones et al, 1996Jones et al, , 2000Jones et al, , 2005Rainy and Jones, 2009;Gandin and Capezzuoli 2014;Della Porta, 2005;Croci et al, 2016;Della Porta et al, 2017) where the intercalation of porous ( Fig. 2) and crystalline deposits is a characteristics of travertine spring deposits (Riding, 1991;Pedley, 1990;Flügel, 2004;Pentecost, 2005;Pedley, 2009;Brogi et al, 2010;Capezzuoli et al, 2014;Pola et al 2013;Gandin and Capezzuoli, 2014;Gradzinski et al, 2014).…”

Section: Calcite Veins Versus Travertine Beds/layers (Crystalline Crumentioning

confidence: 84%

Comment on “First records of syn-diagenetic non-tectonic folding in Quaternary thermogene travertines caused by hydrothermal incremental veining” by Billi et al. Tectonophysics 700–701 (2017) 60–79

Alçiçek

Altunel

et al. 2017

Tectonophysics

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Billi et al. (2017) proposed a new interpretation for the origin and internal structure of thermogene travertine deposits. On the basis of evidence from two quarries located in southern Tuscany (Italy), they interpreted some travertine beds as calcite veins and argued that undulating travertine beds formed by syn-diagenetic (i.e. non-tectonic) folding that was caused by laterally-confined volume expansion caused by incremental veining. They assumed that such a process causes changes to the rock properties, including porosity reduction, rock strengthening, and age rejuvenation. The interpretations by Billi et al. (2017) challenge and question the current understanding and interpretation of thermogene travertine deposits. This understanding, based on numerous studies since the 1980s, is that these deposits form from thermal water flowing downslope, and precipitating calcium carbonate. Here, we explain how the comparison with active depositional systems is essential for the understanding the origin of structures in older, inactive travertine deposits, such as those studied by Billi et al. (2017). We further argue that the three-dimensional setting of travertine deposits should be taken into account in order to discuss the possible development of secondary structures. Indeed travertine deposition on slopes typically leads to the formation of terraced morphologies with pools bordered by rounded rims and separated from each other by steep walls. The resulting three-dimensional structures can be misinterpreted as asymmetric folds in two-dimensional views (i.e., in saw-cut walls of quarry). In this paper we debate the interpretations offered by Billi et al. (2017) and their criteria to recognise syn-diagenetic, non-tectonic folds in travertine deposits, and explain why many of their ideas are questionable.

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Facies character and depositional architecture of hydrothermal travertine slope aprons (Pleistocene, Acquasanta Terme, Central Italy)

Cited by 44 publications

References 54 publications

Relative influence of biotic and abiotic processes on travertine fabrics, Satono‐yu hot spring, Japan

Relative influence of biotic and abiotic processes on travertine fabrics, Satono‐yu hot spring, Japan

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

Comment on “First records of syn-diagenetic non-tectonic folding in Quaternary thermogene travertines caused by hydrothermal incremental veining” by Billi et al. Tectonophysics 700–701 (2017) 60–79

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