Cathodoluminescence and Laser-Induced Fluorescence of Calcium Carbonate: A Review of Screening Methods for Radiocarbon Dating of Ancient Lime Mortars

Radiocarbon ◽  
2020 ◽  
Vol 62 (3) ◽  
pp. 545-564 ◽  
Author(s):  
Michael B Toffolo ◽  
Giulia Ricci ◽  
Rémy Chapoulie ◽  
Luisa Caneve ◽  
Ifat Kaplan-Ashiri
Keyword(s):  
Calcium Carbonate ◽  
Radiocarbon Dating ◽  
Size Fraction ◽  
Laser Induced Fluorescence ◽  
Screening Methods ◽  
Particle Size Fraction ◽  
Mineralogical Characterization ◽  
Lime Mortars ◽  
Carbon Recovery

ABSTRACTAccurate radiocarbon (14C) dating of lime mortars requires a thorough mineralogical characterization of binders in order to verify the presence of carbon-bearing contaminants. In the last 20 years, cathodoluminescence (CL) has been widely used for the identification of geologic calcium carbonate (CaCO3) aggregates and unreacted lime lumps within the particle size fraction selected for carbon recovery. These components are major sources of older and younger carbon, respectively, and should be removed to obtain accurate age determinations. More recently, laser-induced fluorescence (LIF) has provided another means of investigating the preservation state and composition of CaCO3 binders. Considered the growing interest of the mortar dating community in the latest advancements of these analytical methods, here we review the principles of CL and LIF of CaCO3, their instrument setup, and their application to the characterization of ancient lime mortars used for 14C dating. In addition, we provide examples of SEM-CL and LIF analyses using high-resolution instrumentation, we discuss current issues and propose future lines of research.

scholarly journals Mortar Dating Using AMS 14C and Sequential Dissolution: Examples from Medieval, Non-Hydraulic Lime Mortars from the Åland Islands, SW Finland

Radiocarbon ◽  
2007 ◽  
Vol 49 (1) ◽  
pp. 47-67 ◽  
Author(s):  
Alf Lindroos ◽  
Jan Heinemeier ◽  
Åsa Ringbom ◽  
Mats Braskén ◽  
Ámy Sveinbjörnsdóttir
Keyword(s):  
Mass Spectrometry ◽  
Radiocarbon Dating ◽  
Pressure Curve ◽  
Direct Relation ◽  
Hydraulic Lime ◽  
Carbonate Formation ◽  
Lime Mortars ◽  
Dating Method ◽  
Total Dissolution

Non-hydraulic mortars contain datable binder carbonate with a direct relation to the time when it was used in a building, but they also contain contaminants that disturb radiocarbon dating attempts. The most relevant contaminants either have a geological provenance and age or they can be related to delayed carbonate formation or devitrification and recrystallization of the mortar. We studied the mortars using cathodoluminescence (CL), mass spectrometry (MS), and accelerator mass spectrometry (AMS) in order to identify, characterize, and date different generations of carbonates. The parameters—dissolution rate, 13C/12C and 18O/16O ratios, and 14C age—were measured or calculated from experiments where the mortars were dissolved in phosphoric acid and each successive CO2 increment was collected, analyzed, and dated. Consequently, mortar dating comprises a CL characterization of the sample and a CO2 evolution pressure curve, a 14C age, and stable isotope profiles from at least 5 successive dissolution increments representing nearly total dissolution. The data is used for modeling the interfering effects of the different carbonates on the binder carbonate age. The models help us to interpret the 14C age profiles and identify CO2 increments that are as uncontaminated as possible. The dating method was implemented on medieval and younger mortars from churches in the Åland Archipelago between Finland and Sweden. The results are used to develop the method for a more general and international use.

Smectite clay from the Sabga deposit (Cameroon): mineralogical and physicochemical properties

Clay Minerals ◽  
2013 ◽  
Vol 48 (3) ◽  
pp. 499-512 ◽  
Author(s):  
J. R. Mache ◽  
P. Signing ◽  
A. Njoya ◽  
F. Kunyukubundo ◽  
J. A. Mbey ◽  
...  
Keyword(s):  
Waste Water Treatment ◽  
Size Fraction ◽  
Chemical Properties ◽  
Chemical Characterization ◽  
Exchange Capacity ◽  
Mineralogical Characterization ◽  
North West ◽  
Potential Applications ◽  
Physical And Chemical

AbstractThe physicochemical and mineralogical characterization of the <250 μm particle-size fraction from six clay-rich samples from the Sabga deposit (north-west, Cameroon) were carried out to evaluate their potential applications. The major clay mineral is dioctahedral smectite and minor kaolinite is present in three of the clay samples. Cristobalite, feldspars, ilmenite and heulandite are accessory minerals. Application of the Greene-Kelly test revealed that the smectite present is montmorillonite. The chemical composition (wt.%) of the bulk clays consists of (66–70%) SiO2, (13–16%) Al2O3and (2–7%) Fe2O3. Physico-chemical characterization of the clays showed that the cation exchange capacity (CEC) and the specific surface area range from 38 to 46 meq/100 g and from 33 to 90 m2/g respectively. The physical and chemical properties are fully compatible with potential uses in environmental applications. After purification and chemical modification, these materials could also be used in refining edible oil as adsorbent, waste water treatment and wine technology.

scholarly journals 14C Mortar Dating: The Case of the Medieval Shayzar Citadel, Syria

Radiocarbon ◽  
2013 ◽  
Vol 55 (2) ◽  
pp. 514-525 ◽  
Author(s):  
Sara Nonni ◽  
Fabio Marzaioli ◽  
Michele Secco ◽  
Isabella Passariello ◽  
Manuela Capano ◽  
...  
Keyword(s):  
Radiocarbon Dating ◽  
Good Accuracy ◽  
Time Constraints ◽  
X Ray ◽  
Ams Radiocarbon Dating ◽  
Lime Mortars ◽  
Biasing Effects ◽  
Centrifugation Protocol

This paper reports the results from applying the Cryo2SoniC (Cryobreaking, Sonication, Centrifugation) protocol to some lime mortars sampled from the citadel of Shayzar (Syria). The overall aims of this project are 1) to use the properties offered by high-precision accelerator mass spectrometry (AMS) radiocarbon dating for the evaluation of absolute chronology with its typical robust time constraints (i.e. 25 14C yr), and 2) to apply the dating directly to the citadel structures in order to prevent possible biasing effects potentially affecting indirect 14C dating on organic materials found at the study site. The analyses presented in this paper have been mainly performed as a preliminary check of the Cryo2SoniC methodology in order to assess its applicability to this study site by comparing observed mortar results with archaeological expectations about the citadel development phasing and charcoals found encased in mortars. Petrographic and mineralogical thin-section analyses by optical microscopy (TSOM), X-ray powder diffraction (XRD), and scanning electron microscopy plus energy dispersive spectroscopy (SEM/EDS) investigations were carried out for characterization of the mortar samples to verify the occurrence of some features, related to their production technology, which may introduce dating offsets. The resulting 14C calibrated ages were in agreement with the archaeological expectations based on type and stratigraphic site reconstructions, in situ inscriptions, and written sources. Such results showed also a general (with 1 exception) statistical agreement among the charcoals and the analyzed mortars simultaneously, confirming the archaeological expectations for the Shayzar citadel. Results presented in this paper indicate good accuracy for the applied procedure for chronology reconstruction and highlight the capability of Cryo2SoniC to further characterize the Shayzar site.

Three-Dimensional Morphological and Mineralogical Characterization of Testate Amebae

2013 ◽  
Vol 19 (6) ◽  
pp. 1511-1522 ◽  
Author(s):  
Eric Armynot du Châtelet ◽  
Catherine Noiriel ◽  
Maxence Delaine
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Three Dimensional ◽  
Size Fraction ◽  
Environmental Scanning Electron Microscopy ◽  
Mineralogical Composition ◽  
Mineralogical Characterization ◽  
Sediment Size ◽  
Morphological Studies

AbstractTestate amebae are unicellular shelled protozoa commonly used as indicators in ecological and paleoecological studies. We explored the potential application of three-dimensional (3D) X-ray micro-tomography used in addition to 2D techniques (environmental scanning electron microscopy, electron probe micro-analysis, and cathodoluminescence) for detailed characterization of agglutinated shells of protozoa. We analyzed four specimens of the aquatic testate ameba Difflugia oblonga (Arcellinida), to test whether size distribution and mineral composition of shell grains diverged from sediment size distribution and mineralogical composition. From the 3D images, the geometry of the specimens (size and mass) and of the individual grains forming the specimen (grain size distribution and volume) were calculated. Based on combined chemical, mineralogical, and morphological analyses we show that D. oblonga is able to selectively pick up the small size fraction of the sediment with a preference for low-density silicates close to quartz density (~2.65). The maximum size of the grains matches the size of the pseudostome (shell aperture), suggesting the existence of a physical limit to grain size used for building the shell. This study illustrates the potential of this combined approach to characterize agglutinated shells of protozoa. This data can be useful for detailed morphological studies with applications in taxonomy and ecology.

Multi-analytical approach for chemical-mineralogical characterization of reaction rims in the lime mortars from Amaiur Castle (Navarre, Spain)

2020 ◽  
Vol 152 ◽  
pp. 104303 ◽  
Author(s):  
Graciela Ponce-Antón ◽  
Maria Cruz Zuluaga ◽  
Luis Angel Ortega ◽  
Juantxo Agirre Mauleon
Keyword(s):  
Analytical Approach ◽  
Mineralogical Characterization ◽  
Lime Mortars
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