Naslov
Middle Permian calcispongal cement reef on the Velebit Mt

Autori
Marjanac, Tihomir ; Sremac, Jasenka

Izvornik
Vijesti Hrvatskoga geološkog društva (1330-1357) 37 (2000), 2; 135-138

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Permian; cement reef; ecology; Velebit Mt.

Sažetak
Middle Permian “middle zone of black limestones” exposed near Baške Oštarije on the Velebit Mt. is reinterpreted as ecological and morphological calcispongite reef. The reef framework is made of fenestellid bryozoans and calcisponges. It is possible to recognize two overgrowth generations. The reef framework is largely cemented by cyanobacterial coatings, so this reef complex belongs to cement reef family. The geometry of exposed sediments indicates a complex reef composition, which grew in three distinct phases. Reef growth was aborted by sea-level fall, which was followed by early cementation and creation of vadose silt which geopetally infilled the solutional cavities. The emersion lead to flattening of reef crest, whereas the weathering products deposited in internal cavities and on reef flanks. Three phases in reef growth were finally aborted by reef burial by thick black shales, what indicates rapid sea-level rise.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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