Cenomanio planktoninių foraminiferų įvairovė Lietuvoje
Cretaceous planktonic foraminifera haven't been given extensive studies in Lithuania. Best investigated are Jurassic and Cretaceous benthic foraminifers.On the basis of foraminifera A.Grigelis (1963) distinguished two zones in the Cenomanian of Lithuania, which are Gavelinella cenomanica zone i...
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| Format: | Article in Journal/Newspaper |
| Language: | Lithuanian English |
| Published: |
2005
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| Subjects: | |
| Online Access: | http://lsmu.lvb.lt/LSMU:ELABAPDB5494730&prefLang=en_US |
| Summary: | Cretaceous planktonic foraminifera haven't been given extensive studies in Lithuania. Best investigated are Jurassic and Cretaceous benthic foraminifers.On the basis of foraminifera A.Grigelis (1963) distinguished two zones in the Cenomanian of Lithuania, which are Gavelinella cenomanica zone in the Lower Cenomanian and Lingulogavelinella globosa zone in the Upper Cenomanian.In the current work 129 sampies from 17 boreholes of Lithuania were investigated.The results showed that planktonic foraminiferal fauna had been neither numerous nor various in Lithuania,Fifteen planktonic foraminifera species were determined.They belong to the Suborder Globigerinina Delage &Herouard,1896,the superfamily Planomali'nacea Bolli,Loeblich& Tappan,1957,the family HedbergeJIidae Loeblich&Tappan, 1961 and the subfamilies Hedbergellinae Loeblich Tappan, 1961, Rotundininae Bellier&Salaj, 1977,Whiteinellinae Salaj,1987, Concavatotruncaninae Korchagin, 2001.Most abundant species were Hedbergella portsdownensis (Williams-Mitchell,1948), Hedbergella delrioemis(Carsey, 1926),Hedbergella brittonensis Loeblich&Tappan,1961,Hedbergella planispira(Tappan,1940), Praeglobotruncana delrioensis (Plummet,1931),Praeglobotmncana stephani(Gandolfi,1942).Probably the reason for such a poor fauna is that the Lithuanian territory was located on the margin of the sea basin and the conditions(salinity, temperature,depth, currents) were not good for foraminifera.The genus Rotalipora was not found in samples from the Lithuanian territory.It is broadly distributed in the neighbouring regions.This genus is very important hi distinguishing planktonic foraminiferal zones.S. Abramavičiūtė-Garunkštienė in her publication (Abramavičiūte,1957) reported that she had found Rotalipora appenninica(Renz) species, but she provided neither description nor illustrations,and the collection is missing, either. Therefore the question of the existence of Rotalipora in the Lithuanian territory remains Lithuanian terr. |
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