ESR studies on calcite encrustation on Fili neotectonic fault, Greece

Abstract

Electron spin resonance (ESR) study was done on calcite encrustation on Fili neotectonic fault surface, Greece. Normally such calcite encrustations on fault surfaces are not observed. Significantly, the ESR study has detected the presence of nitrate NO~-radical in this calcite encrustation, having g• = 2.0063+0.0001 and hyperfine coupling constant A t = 3.44 mT, the second such detection of nitrate NO~-radical following a sample from Scott Glacier, Antarctica. From isochronal thermal annealing measurement the NO]-radical was found to be quite stable, only fully annealed at 475 ~ This study also shows that the ESR, as a tool, can be suitably applied to date the age of formation of the calcite encrustation with SO{ as an ESR dating signal by additive y-ray irradiation. A preliminary estimation indicates the age of formation of calcite precipitation at Fili fault, Greece to be about 5600 years.

Radiation Defects in Lime Mortars and Plasters Studied by EPR Spectroscopy

“…The presence of UV-induced signals in lime mortars confirms previous reports (Bartoll et al 2000;Sato et al 2004;Kundu et al 2005;Kabacińska et al 2014aKabacińska et al , 2017Kabacińska et al , 2019, showing that radiation defects in carbonates can also be generated, instead of bleached by UV radiation. From the physical point of view, the most intriguing aspect of this phenomenon is the mechanism of their generation by UV light.…”

“…Radiation Defects in Lime Mortars and Plasters 717 radiation-sensitive signal at g = 2.0040 was revealed with an aid of simulations, resembling the signal often referred to as an "organic radical" in carbonates (Grün and De Cannière 1984;Ikeya 1993Ikeya , 2004Callens et al 1998;Kundu et al 2005). As discussed by Callens et al (1998), COspecies can at least partially contribute to this signal.…”

“…Both γand UV-irradiation induced two main overlapping signals in Hippos samples, shown as simulated lines in Figure 2g-a triplet resulting from hyperfine structure (I = 1), with parameters g x = g y = 2.0060, g z = 2.0019, A x = A y = 3.40 mT, A z = 6.80 mT, and an orthorhombic signal with g x = 2.0029, g y = 2.0014, g z = 1.9971. While the latter is a well-known signal connected with CO 2 paramagnetic center (Ikeya 1993(Ikeya , 2004Callens et al 1998;Bartoll et al 2000), the triplet is assigned by several authors to NO 3 2ion (Eachus and Symons 1968;De Cannière et al 1988;Sato et al 2004;Kundu et al 2005;Sadło et al 2015). Additionally, a wide, isotropic, Figure 2 EPR spectra of UV-and γ-irradiated samples Hip10 (a, b), Hip8 (c, d) and 61H (e, f), and simulated signals present in those spectra (g).…”

“…contamination with bird droppings (Middendorf and Knöfel 2015), agricultural waste (Oguz et al 2014), and acid waters (Thomson et al 2004). The existence of nitrate deposits has been reported in some caves and deserts in hot and dry regions (De Cannière et al 1988;Ikeya 1993;Kundu et al 2005). In the case of mortars and plasters from Hippos the most likely explanation for the presence of nitrates is the decomposition of organic matter, such as straw added during the manufacturing process and the occurrence of nitrites in the desert evaporates.…”

“…Since those samples were not suitable for EPR dating, because of their relatively young (for this technique) age, and the collection method (suitable for 14 C, but not for trapped-change dating), we focused only on their physicochemical properties, and not age determination ( 14 C dates can be found in Michalska 2019 andMichalska andPawlyta 2019). Research conducted during the last few years by the main author and coworkers (Kabacińska et al 2014a(Kabacińska et al , 2017(Kabacińska et al , 2019 as well as a few different groups (Bartoll et al 2000;Sato et al 2004;Kundu et al 2005) clearly show that radiation defects can also be generated in calcite, instead of bleached, by UV radiation. Recently (Kabacińska et al 2017(Kabacińska et al , 2019, we proposed a mechanism of UV-induced generation of radiation defects in calcite, based on trapping the "secondary electrons"-electrons freed from non-carbonate traps by the incident UV radiation.…”