Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Przegląd Geologiczny

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: otwornice bentoniczne

Sortuj według:

Ogranicz wyniki do:

Stratygrafia wapieni tytonu dolnego-aptu dolnego skałki Niedźwiedź w allochtonie wierchowym polskich Tatr Zachodnich

Borowska U.

Przegląd Geologiczny

2015

Vol. 63, nr 3

164–-171

Benthic foraminifera, tintinnids and calcareous dinocysts provide new important biostratigraphic data on the age of the Raptawicka Turnia Limestone Formation and Wysoka Turnia Limestone Formation of the NiedŸwiedŸ crag geological section in the Polish Western Tatra Mts. Foraminiferal assemblages of shallow- water limestones from the NiedŸwiedŸ section contain some stratigraphically significant species, including Haghimashella arcuata (Haeusler), Protomarssonella kummi (Zedler), Uvigerinammina uvigeriniformis (Seibold & Seibold) and Textulariopsis jurassica (Guembel). Sporadic planktonic microfossils, such as the tintinnid Tintinnopsella carpathica (Murgeanu & Filipescu), calcareous dinocysts (Cadosina minuta Borza, Colomisphaera lucida Borza, C. tenuis (Nagy), C. varia Øechanek and Parastomiosphaera malmica (Borza), have also been identified. On the basis of these microfossil assemblages the lower and middle parts of the NiedŸwiedŸ section was dated as the Lower Tithonian–Barremian. Limestones of the Raptawicka Turnia Limestone Formation section represent peloidal, peloidal-oolitic and peloidal-oolitic-bioclastic facies. Limestones from the Wysoka Turnia Limestone Formation of the NiedŸwiedŸ section was dated as the Upper Barremian–Lower Aptian, based on a specific composition of foraminifera assemblages, that suggest an eroded carbonate platform as a source of Urgonian-type carbonate material. The boundary between the formations occurs within a poorly dated interval (Valanginian–Barremian).

Benthic foraminiferal response to the Cenomanian-Turonian and Cretaceous-Paleogene boundary events

Peryt D.

Przegląd Geologiczny

2004

Vol. 52, nr 8/2

827-8

The present paper summarizes previously published results of my studies on the Cenomanian-Turonian and Cretaceous-Paleogene changes in benthic foraminiferal assemblages. The recorded changes indicate that the rate and intensity of restructuring of benthic foraminiferal populations during the Cenomanian-Turonian Boundary Event (CTBE) and Cretaceous-Paleogene Boundary Event (KTBE) strongly depended on the duration and severity of environmental stress. A stepwise extinction within benthic foraminiferal assemblages, a bloom of infaunal and semi-infaunal morphotypes during the CTBE and a relatively long-lasting survival interval (the Whiteinella archaeocretacea chron) most likely reflect the decline in oxygenation level of the bottom waters at the end of the Rotalipora cushmani chron and persistence of these unfavourable conditions during the Whiteinella archaeocretacea chron. A catastrophic type of mass extinction within benthic foraminiferal assemblages, extinction or temporary emigration of most of infaunal morphogroups during the KPBE and a relatively short survival interval are interpreted to be the result of a sudden breakdown in food supply as the consequence of a sudden collapse in primary productivity, probably resulting from the impact of the K-P asteroid.