## 5 Discussion
The increase in these values is correlated with decreasing serpentinization degrees. Negative correlations of the n\({}_{\rm{t}}\) (%), w (%) and S (%) with U.R.C.I.-N are attributed to the rise in the serpentinization degrees or L.O.I. (Figure 8b-d). Figure 8: Correlation diagrams of (**a**) Is (50) (MPa) vs. U.R.C.I.N; increasing LA values correspond to increasing primary mineral/serpentine (Srp) ratios. Negative correlations with U.R.C.I.N are noted for the (**b**) n\({}_{\rm{t}}\) (%), (**c**) w (%) and (**d**) S (%). Primary minerals include orthopyroxene (Opx), clinopyroxene (Cpx) and olivine (Ol). Figure 7: Correlation diagrams of (**a**) UCS (MPa) vs. U.R.C.I.N and (**b**) La (%) vs. U.R.C.I.N. The increase in both UCS (MPa) and LA (%) is correlated to increasing primary mineral/serpentine (Srp) ratios. Primary minerals include orthopyroxene (Opx), clinopyroxene (Cpx) and olivine (Ol). Through the correlation study between the mechanical test results compared to the U.R.H.I.N, two main groups were identified, which tend to display distinct mechanical behaviour. In particular, one consists of ultramafic rocks that, despite having been subjected to variable degrees of serpentinization, have preserved primary mineral phases and textural characteristics. The U.R.H.I.N values for this group range between 0.14 and 0.69, whereas values in the other group of ultramafic rocks are lower and range between 0.01 and 0.04. The latter correspond to highly serpentinized ultramafic rocks (L.O.I. = 13.4-15.3%) whose mechanical behaviour in most cases highly depends on the olivine/serpentine ratios (<0.21). During serpentinization, primary minerals within ultramafic rocks, namely olivine and orthopyroxene, are altered in favour of serpentine, whereas clinopyroxene promotes matilization processes forming fibrous amphiboles. Serpentine and less amphibole group minerals withhold in their crystal structure water contents. This fact leads to an increase in the rocks' volume and hence allows the development of cataclastic textures due to hydrofracturing. This fact may be responsible for their lower durability. Research studies suggest that serpentinization is greatly affected by the geotectonic settings of development. Rocks affected by MOR settings (back-arc region) are less likely to interact with fluids related to ocean-floor circulation, which explains the fact that the most well-preserved ultramafic rocks of our study suite were less exposed to alteration. The fore-arc region, on the other hand, is most often more affected by subduction-related hydrous components, which apart from serpentinization contribute to elevated degrees of partial melting, leading to gradually lower U.R.H.I.N values correlated with removal of primary phases and even more importantly of pyroxenes. Lherzolite and harzburgite from the Veria-Naousa ophiolite complex as well as harzburgite and dunite from the Gerania ophiolite complex present characteristics of a supra subduction zone and display a higher degree of serpentinization in contrast to ol-orthopyroxenite (Veria-Naousa ophiolite complex) and Iberzolite derived from the Gerania ophiolite complex, which present characteristics of abyssal peridotites and are characterized as fresher in contrast to the first ones (Table S1, Figure 9a). According to [PERSON] et al. [32], peridotites derived from supra subduction zones tend to be more serpentinized. Lherzolites, mainly from the Gerania complex, have characteristics of abyssal peridotites, as they present a moderate to low degree of serpentinization. Harzburgite was plotted in the overlap field of forearc and abyssal peridotites, while dunite was plotted in the edges of the forearc peridotites field, possibly due to its influence by the adjacent SSZ ophiolite complexes [93]. According to [PERSON] et al. [55], the ol-orthopyroxenites were formed after interaction between harzburgites and boninitic melts during the maturing of the SSZ and the subsequent opening of a backarc basin in the region of the Veria and Naousa.