Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)

Isotopic geochemistry and geochronology of the skarn from Slatina, Moldanubian zone of the Bohemian Massif


Vojtěch Janoušek, Jaroslava Pertoldová, Zdeněk Pertold

Geoscience Research Reports 33, 2000 (GRR for 1999), pages 53–54

Full text (PDF, 0.08 MB)



Nd isotopic dating of garnet-pyroxene skarn from Slatina (20 km N of Znojmo, Gföhl nappe of the Moldanubian unit) indicates a major metamorphic event at 415 ˝ 24 Ma (2ň; WR-grt-cpx isochron with MSWD = 0.07). This is, within an error, identical with an age calculated on the basis of the grt-WR pair only (420 ˝ 42 Ma) and resemles Sm-Nd metamorphic ages of eclogite and granulite from Winklarn, Bavaria (von QUADT - GEBAUER 1993). As the closure temperature of the Nd diffusion in garnet is high (MEZGER 1990, HENSEN - ZHOU 1995), the obtained ages are interpreted as being close to the garnet growth during the high-grade metamorphism. Significantly lower e415Nd for zircon (-8.4) compared to WR, cpx and grt (-7.3) probably indicates presence of older, inherited cores, which are indeed observable in the BSE. High Sr initial ratio (87Sr/86SR415 ~ 0.713), and, above all, the low ţ415Nd (-7.3) and high two-stage Nd model age (T DMNd = 1.7 Ga; LIEW - HOFMANN 1988) support a long crustal residence of the protolith and rule out its direct derivation from depleted or CHUR-like mantle in Silurian-early Devonian times.