The microfacies and palaeoenvironment of Lower Oligocene carbonates of the Gornji Grad beds from Slovenia are investigated. These beds form part of a transgressive succession overlying both terrigenous sediments (sandstones and conglomerates) and marine carbonates of Eocene age as well as transgressing directly over Triassic limestones. They are followed by foraminiferal rich marls. The carbonates were investigated using multivariate statistical techniques on point counts of thin sections. They are dominated by poorly sorted biogenic rudstones with pack-/wackestone matrix; pack- and grainstones are subordinate. The biogenic components of the carbonates are dominated by coralline red algae (9 genera with 11 species), corals, small benthic, large benthic, and encrusting foraminifera as well as bivalves. Gastropods, bryozoans, brachiopods, echinoderms, serpulids, and green algae are subordinate. The well preserved components allow details pertaining to taxonomy, growth-forms and taphonomic features to be observed. The following carbonate facies are distinguished: 1) nummulitic, 2) bivalve, 3) foraminiferal - coralline algal, 4) grainstone, 5) coralline algal, 6) coralline algal - coral, and 7) coral facies. All the carbonate facies represent fully marine conditions within the photic zone. They are interpreted with respect to substrate composition and stability, water turbulence, terrigenous input and light.
Microfacies analysis and palaeoenvironmental interpretation of Lower Oligocene, shallow-water carbonates (Gornji Grad beds, Slovenia)
BASSI, Davide;
2000
Abstract
The microfacies and palaeoenvironment of Lower Oligocene carbonates of the Gornji Grad beds from Slovenia are investigated. These beds form part of a transgressive succession overlying both terrigenous sediments (sandstones and conglomerates) and marine carbonates of Eocene age as well as transgressing directly over Triassic limestones. They are followed by foraminiferal rich marls. The carbonates were investigated using multivariate statistical techniques on point counts of thin sections. They are dominated by poorly sorted biogenic rudstones with pack-/wackestone matrix; pack- and grainstones are subordinate. The biogenic components of the carbonates are dominated by coralline red algae (9 genera with 11 species), corals, small benthic, large benthic, and encrusting foraminifera as well as bivalves. Gastropods, bryozoans, brachiopods, echinoderms, serpulids, and green algae are subordinate. The well preserved components allow details pertaining to taxonomy, growth-forms and taphonomic features to be observed. The following carbonate facies are distinguished: 1) nummulitic, 2) bivalve, 3) foraminiferal - coralline algal, 4) grainstone, 5) coralline algal, 6) coralline algal - coral, and 7) coral facies. All the carbonate facies represent fully marine conditions within the photic zone. They are interpreted with respect to substrate composition and stability, water turbulence, terrigenous input and light.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
