Naslov
Planktonic foraminifera assemblages near the Eocene/Oligocene boundary in the North Adriatic Sea (Croatia)

Autori
Premec Fuček, Vlasta ; Hernitz Kučenjak, Morana

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Meeting of the Paleogene Planktonic Foraminifera Working Group / - Fribourg, 2009, 14-14

Skup
Meeting of the Paleogene Planktonic Foraminifera Working Group

Mjesto i datum
Fribourg, Švicarska, 23.06.2009. - 25.06.2009

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Nije recenziran

Ključne riječi
biostratigraphy; Eocene/Oligocene boundary; planktonic foraminifera; Adriatic Sea; exploration well

Sažetak
Late Eocene and lower Oligocene sediments are deposited within the eastern part of the Venetian Basin (North Adriatic Sea). They consist of hemipelagic deposits of marls and silty marls and contain very well preserved planktonic foraminiferal assemblages. Biostratigraphical analyses were made on drill cuttings from the Istria more-3 Well. Planktonic foraminiferal associations of the late Eocene Zone E16 (Berggren & Pearson, 2005) are rich, highly diversified and contain 28 species. The most common species are Turborotalia cocoaensis and Subbotina linaperta. Three genera record the highest percentages: Subbotina (30%), Turborotalia (20%) and Globoturborotalita (14%), whereas Dentoglobigerina (9%) and Catasydrax (8%) are less abundant. Turborotalia ampliapertura is very rare in late Eocene and become more frequent after the Eocene/Oligocene boundary. The Eocene/Oligocene boundary in the Adriatic Sea is clearly defined by the extinction of all hantheninids, Turborotalia cerroazulensis group and the last globigerinathekids species Globigerinatheka tropicalic. The first appearance of Cassigerinella chipolensis has also been observed at the boundary, while Chiloguembelina cubensis become more abundant at the same level. In the small size fraction (<125&#956; m) a turnover in planktonic foraminiferal association is also very well visible. After E/O boundary Chilogeumbelina cubensis is more common than in the late Eocene. Two "morphotypes" of Chilogeumbelina cubensis have been observed. First possess more inflated chambers and deeper depressed sutures, whereas second "morphotype" has more flattened chambers and less distinct sutures. Cassigerinella chipolensis is present and represented by very few specimens. Other microperforate taxa are Chiloguembelina ototara, Streptochilus martini, Tenuitella praegema and T. gemma. Dipsidripella danvillensis has been found below the boundary. The begining of Zone O1 is marked by frequent occurances of Turborotalia ampliapertura, T. increbescens, Dentoglobigerina galavisi, Catapsydrax unicavus, Globorotaloides sp., Subbotina spp. and Globoturborotalita spp.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

POVEZANOST RADA