Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
Whole-rock geochemistry of the Sv. Jan diabase sills and dykes in the Loděnice-Bubovice area
AbstractWhole-rock geochemistry of the "Sv. Jan diabase" sills and dykes in the Lodenice-Bubovice area (Cernidla locality, Prague Basin) preserved within Motol Formation (Wenlock) was studied. "Sv. Jan diabase" is enriched in incompatible elements and resembles alkaline basalts. Spiderplots normalized by NMORB and incompatible element ratios such as Zr/Nb (5.6-9.9) and Nb/Yb (11.3-20.5) point to its affinity to an OIB magmatic reservoir. Highly enriched chondrite-normalized REE patterns (LaN/YbN = 6.2-9.4) and high GdN/YbN (2.6-2.7) suggest low degrees of partial melting of garnet peridotite mantle source. The overall geotectonic setting probably did not correspond to true oceanic islands but rather to an attenuated continental crust.