The predominance of organic-rich lamellar and paralamellar tissues in these conodont elements makes them suitable for this study (Muller & Nogami 1971).
The study of thin and polished sections of conodont elements in association with micro-CT and optic microscopy data allow elaborating the histological model of the P1 element of P.
The diagenetic degradation of the organic matter of conodont elements was estimated by their demineralization in 1N solution of HCl.
In any case similar preservation of the studied conodont elements provides uniform degradation of organic matter and suggests good preservation of relative variations in the isotope composition.
These values of Sr/Ca are close to those of the Frasnian polygnathid conodont elements of exceptional preservation (0.003-0.012) (Zhuravlev & Shevchuk 2017).
The redeposition, reworking, and mixing rate of conodont elements differs significantly along the klint area, being largest in the western part.
This conclusion is also supported by the lack of redeposited conodont elements in this part of the basin.
Despite the relatively low abundance of conodont elements in general, and zonal index platforms in particular, the lowermost interval sampled (Est09:OS1) can be assigned to a level within the M.
Among the three samples, Est09:OS1 proved to be the one with the lowest conodont element abundance; the 1205.3 g sample yielded 281 elements, i.e.
By contrast to the previous sample interval, the conodont element abundance in Est09:OS2 must be considered fairly high; the 2047.2 g sample yielded 2851 elements, i.e.
On the other hand, differences in the apatite lattice parameter values of various histological types of mineralized matter of conodont apparatus reported earlier (Zhuravlev & Sapega 2007) should be expressed as decrease in the crystallinity of the studied samples, causing the lowering of the lattice parameter a for a bulk sample of conodont elements
. While this phenomenon was not recorded, we explain it by prevalence of enamel-type tissue in conodont material.
The same situation is recognized in the Uuga section, NW Estonia, where conodont elements
of these two zones are mixed in the whole range of the P.