Pedogenic carbonates: Forms and formation processes

Zamanian, Kazem; Pustovoytov, Konstantin; Kuzyakov, Yakov

doi:10.1016/j.earscirev.2016.03.003

Cited by 440 publications

(279 citation statements)

References 168 publications

(178 reference statements)

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“…Summary of (primary) non-marine carbonate fabrics, mineralogy and processes of crystal formation 2.1.1. Primary fabrics and mineralogy Presumed primary, depositional fabrics of non-marine carbonates have been rather extensively covered in several recent reviews (Alonso-Zarza, 2003;Fairchild et al, 2006;Brasier, 2011;Gandin and Capezzuoli, 2014;Della Porta, 2015;Frisia, 2015;Zamanian et al, 2016) and volumes (Pentecost, 2005;Alonso-Zarza and Tanner, 2010a;Pedley and Rogerson, 2010;Fairchild and Baker, 2012), as well as in an increasing number of individual case studies. Table A1 therefore summarizes a number of these micro-to macrofabrics as observed in the field and under transmitted light microscopy, plus key literature that offers an overview of the range of commonly reported 'primary ', not yet diagenetically altered, carbonate products.…”

Section: Introduction: Non-marine Carbonates and Early Diagenesis?mentioning

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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Section: Introduction: Non-marine Carbonates and Early Diagenesis?mentioning

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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“…Radiocarbon ages of recrystallized nodules tend to show younger ages on the reprecipitated surfaces, with older ages on the nonaffected surfaces. This is because the quantities of inorganic 13 C are artificially lower with respect to the organic (includes 14 C) constituents due to loss of carbon in the older portions of the nodules (Amundson et al 1994;Chappell and Polach 1972;Chen and Polach 1986;Zamanian et al 2016). Whether (re)precipitates are older or younger than the non-or primary precipitates in a sample depends on parent material weathering, and whether the precipitates are authigenic (formed in situ) or allogenic (formed ex situ) in origin.…”

Section: Dolomitization and Recrystallizationmentioning

confidence: 99%

Accuracy vs. Precision: Understanding Potential Errors from Radiocarbon Dating on African Landscapes

Wright¹

2017

Afr Archaeol Rev

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The application of radiocarbon dating to determine the geochronology of archaeological sites is ubiquitous across the African continent. Accelerator mass spectrometry has made radiocarbon dating the most precise method to determine the death of living organisms that occurred within the last 50,000 years. However, the method is not without limitations and this review article provides Africanist archaeologists with cautionary insights as to when, where, and how to utilize radiocarbon dates. Specifically, the review will concentrate on the potential of carbon reservoirs and recycled organic remains to inflate apparent age estimates, diagenesis of carbon isotopes in variable pH ecologies, and hot-humid climates and non-climate-controlled archives that can compromise the efficacy of samples. Legacy radiocarbon ages must be critically examined for what method was used to generate the age, and calibration radiocarbon ages from critical periods of African prehistory lack precision to resolve significant debates. A multipronged dating strategy and careful selection of radiocarbon sample materials are advocated from the earliest stages of research design.Résumé L'application de la datation par le carbone 14 pour déterminer la géochronologie des sites archéologiques est. omniprésente à travers le continent africain. La spectrométrie de masse a rendu la datation par le carbone 14 la méthode la plus précise pour déter-miner la mort d'organismes vivants ayant eux lieux au cours des 50,000 dernières années. Cependant, la méthode n'est. pas sans limites. Cette revue fournit les archéologues africanistes avec des appréciations et des mises en garde sur l'utilisation des âges radiocarbone. Plus précisément, cette revue se concentrera sur la possibilité que les estimations d'âge apparentes soient exagérées par la présence de réservoirs de carbone et de restes organiques recyclées, sur la diagenèse d'isotopes de carbone dans les écologies de pH variables, et sur les climats chauds et humides ainsi que les archives sans température contrôlée qui peuvent compromettre l'efficacité des échantillons. Les âges radiocarbone basés sur des données anciennes doivent être rigoureusement examinés pour en déduire la méthode employée dans la détermination d'âge. Egalement, les âges radiocarbone de calibration, issue de périodes critiques de la préhistoire africaine, manque la précision nécessaire pour résoudre des débats importants. Une stratégie de datation multiple et une sélection rigoureuse des matériaux d'échantillons de radiocarbone sont conseillées dès les premières étapes de la conception de la recherche.

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“…Higher amounts of SOC and SIC have always been recognized as a major sink of the global 256 C pool (Lal & Kimble, 2000;Schlesinger, 2002;Mi et al, 2008;Zamanian et al, 2016). In arid 257 and semiarid regions that cover as much as one-third of the surface of the planet, the SIC pool is 258 approximately two to ten times larger than the SOC stock (Post et al, 1982;Schlesinger, 1982; 259 Eswaran et al, 2000).…”

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confidence: 99%

“…Our findings highlight that SOC and SIC should be simultaneously 45 included in the computation of soil carbon budgets to avoid false estimation of carbon changes as 46 a result of using either SOC or SIC alone. Although a better estimate of regional and global soil organic carbon (SOC) stocks is now 52 becoming available (Lal, 2004, Lorenz et al, 2011, this is not the case for soil inorganic carbon 53 (SIC) (Mi et al, 2008;Zamanian et al, 2016). In China, soils with SIC cover about 3.44 x 10 6 km 2 54 of China (Mi et al, 2008;Wu et al, 2009).…”

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confidence: 99%

Empirical model predictions and field measurements manifested divergent changes of SOC and SIC in calcareous soils in China

Wang

2017

Preprint

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Background. Considerable amounts of calcareous soils exist in China and various management practices are used for improving their productivity; however, no holistic view is currently available of their effects on soil organic carbon (SOC) and soil inorganic carbon (SIC) pools. Our study aims to define co-current changes of SOC and SIC by using empirical model predictions and reviewing analysis of actual field data. Methods. Three datasets were compiled for the present study; the first was obtained from 9 soil survey reports from China and included data for SOC and SIC concentrations and various soil fertility parameters of soil N and available N; soil P and available P; soil K and available K; and soil pH and cation exchange capacity (CEC). These data were used for empirical prediction of SIC and SOC changes with changes in other soil properties via regression analysis. The second dataset comprised 111 data points from concurrent measurements of SOC and SIC from long-term fixed sites and paired sampling sites (long-term fertilization, tillage treatment, paired land-uses, degraded farmland afforestation etc), which were used to confirm the empirical predication. The third dataset comprised separated measurements of rates of changes in SIC (36 data points) and SOC (74 data points), and frequent distribution and averages were analyzed for finding changing rate differences. These datasets were used to determine the relative magnitude of rates of changes in SIC and SOC to identify the importance of co-inclusion of the two components for soil carbon budget estimation. Results. Empirical relationships between soil fertility parameters (total N and available N; total P and available P; total K and available K; and pH and CEC) and SOC were generally opposite to relationships between soil fertility parameters and SIC (p < 0.001), indicating that soil physicochemical changes as a result of management strategies may affect SOC and SIC in a divergent direction. A total of 111 concurrent measurements of SIC and SOC revealed that soil fertilization and tillage practices could increase SOC andlower SIC by 18% and 11%, respectively, compared to control practices. Similarly, the dataset comprising separated measurements showed that SOC changing rate averaged at 37.3 g m-2 yr-1(SOC accrual), and SIC changing rate averaged at -17.1 g m-2 yr-1(SIC loss), counteracting the SOC accumulation. Discussion. Changes in SIC are more complicated than those of SOC. In a semiarid region with abundant CO 2 and Ca 2+ , pedogenic formation of SIC was observed, while in a moist region (such as a karst land region) with sufficient water supply, dissolution-induced SIC loss in surface soils was frequently observed. Our findings highlight that SOC and SIC should be simultaneously included in the computation of soil carbon budgets to avoid false estimation of carbon changes as a result of using either SOC or SIC alone.

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Pedogenic carbonates: Forms and formation processes

Cited by 440 publications

References 168 publications

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

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

Accuracy vs. Precision: Understanding Potential Errors from Radiocarbon Dating on African Landscapes

Empirical model predictions and field measurements manifested divergent changes of SOC and SIC in calcareous soils in China

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