Syn-deformation fluid-assisted growth of monazite during renewed high-grade metamorphism in metapelites of the Central Rhodope (Bulgaria, Greece)

Polycyclic alpine orogeny in the Rhodope metamorphic complex: the record in migmatites from the Nestos shear zone (N. Greece)

“…The same holds true for the age of "around 77 Ma" (in fact, three ages scattered between 77 and 97 Ma, in addition to ages of ∼150 Ma and more), which was obtained on a pegmatite vein from the CSZ for which Th-Pb monazite data document an emplacement at ∼36 Ma (Bosse et al, 2009). In two recent U-Th-Pb monazite dating studies of the garnetkyanite metapelites from the NSZ and CSZ (Didier et al, 2014) and at Thermes (Wawrzenitz et al, 2015), two peaks of ages have been obtained, at ∼130-150 Ma and ∼36-55 Ma, as well as a series of intermediate ages, some of which fall in the 70-115 Ma time range. As discussed by Didier et al (2014) and Wawrzenitz et al (2015) on the basis of textural and geochemical arguments, these intermediate ages should be understood as geologically meaningless.…”

“…In two recent U-Th-Pb monazite dating studies of the garnetkyanite metapelites from the NSZ and CSZ (Didier et al, 2014) and at Thermes (Wawrzenitz et al, 2015), two peaks of ages have been obtained, at ∼130-150 Ma and ∼36-55 Ma, as well as a series of intermediate ages, some of which fall in the 70-115 Ma time range. As discussed by Didier et al (2014) and Wawrzenitz et al (2015) on the basis of textural and geochemical arguments, these intermediate ages should be understood as geologically meaningless.…”

“…The second argument stems from the observation that the RMC contains rocks, or rock assemblages, that display two sets of "Alpine" ages related to high-temperature metamorphic conditions (U-Pb zircon and U-Th-Pb monazite ages), the two sets being separated by a time laps of at least 60 Myr, between ≥ 115 and 55 Ma (Liati, 2005;Bosse et al, 2009;Didier et al, 2014;Wawrzenitz et al, 2015). More generally, except in the Eastern Rhodope (Fig.…”

“…Like the studies of Didier et al (2014) and Petrik et al (2016), this work aimed at dating the garnetkyanite gneisses exposed along the CSZ. Collings et al (2016) have obtained five Sm-Nd garnet -whole rock ages ranging between ∼70 and ∼90 Ma and argued that these ages date the UHP metamorphic event testified by the presence of microdiamond inclusions in garnet.…”

“…The two shear zones were initially regarded as distinct, synthetic thrust zones (Ricou et al, 1998). Because they display roughly the same petro-geochronological record (e.g., Bosse et al, 2009;Didier et al, 2014), the NSZ and CSZ have been reinterpreted as two occurrences of the same shear zone (Turpaud and Reischmann, 2010;Nagel et al, 2011;Burg, 2011). With respect to the NSZ, Papanikolaou and Panagopoulos (1981) initially defined a lower unit and an upper unit, later named the Pangaeon Unit (PU) and Sidironero Unit (SU).…”