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Campanian–Maastrichtian foraminiferal stratigraphy and palaeoenvironment of the Lower Tar Member in the Wadi Tar section, Western Sirte Basin (Libya)

Tshakreen S. O., Gasiński M. A., Machaniec E., Mącznik A.

Annales Societatis Geologorum Poloniae

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2017

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Vol. 87, No. 4

349--362

EN

Upper Campanian–Maastrichtian sections on the western flank of the Hun Graben in the Western Sirte Basin (WSB) are displaying two major type facies based on the foraminiferal assemblages. The first one indicates open-marine to outer-shelf conditions, and is represented by numerous bathy-pelagic planktonic foraminiferal species referable to the Radotruncana calcarata, Globotruncana aegyptiaca and the lower part of the Gansserina gansseri Zone (all late Campanian).The second type facies indicates an inner-shelf environment and is represented in the middle-upper part of the Gansserina gansseri Zone (early Maastrichtian) and Racemiguembelina fructicosa (late Maastrichtian) dominated by epi-pelagic planktonic and large benthic foraminifers. Large benthic foraminiferal index species Siderolites calcitrapoides Lamarck and Omphalocyclus macroporus (Lamarck) occur in abundance by the middle–late Maastrichtian. Correlation between planktonic foraminiferal zonation and large benthic foraminiferal zonation is given. An open-marine to outer-shelf environment passed into shallower marine conditions during the late Campanian–early Maastrichtian to late Maastrichtian, then a slight deepening and again shallowing is noticed.

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Late Maastrichtian foraminiferids and diatoms from the Polish Carpathians (Ropianka Formation, Skole Nappe): a case study from the Chmielnik-Grabówka composite section

Gasiński M. A., Olshtynska A., Uchman A.

Acta Geologica Polonica

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2013

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Vol. 63, no. 4

515--525

EN

Well-preserved foraminiferids have been found in the Chmielnik-Grabówka section (Skole Nappe, Polish Carpathians). The Abathomphalus mayaroensis (late Maastrichtian) and Racemiguembelina fructicosa (earlylate Maastrichtian) standard planktonic foraminiferal biozones have been recognized, based on the occurrence of their respective index species. Sediments of the R. fructicosa Zone contain diatoms, which are a rare component of Cretaceous flysch microfossil assemblages in the Carpathians. The diatom frustules and some foraminiferid tests are pyritized, probably after burial in the sediment, below the redox boundary or in the oxygen-deficient microenvironment inside the frustules or tests of microfossils; the presence of trace fossils and bioturbational structures in the same bed indicate an oxygenated sea floor.

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Early Eocene age of a sandstone from the Buntmergel Formation (Gresten Klippen Zone, Lower Austria)

Gasiński M. A., Hoeck V., Ślączka A., Ionescu C.

Geological Quarterly

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2012

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Vol. 56, No. 4

845--852

EN

The Gresten Klippen Zone is an individual geological unit, mainly outcropping at the northern rim of the Northern Calcareous Alps. It is best exposed between the Enns Valley in the west and the Vienna Forest in the east. It contains a rock sequence ranging from Early Jurassic to Early Cretaceous, including sandstones, various limestones, breccias and radiolarites. The late Early Cretaceous–Paleogene is represented by the Buntmergel Formation. A sandstone block from the latter yields well-preserved planktonic foraminiferids which allow an assignment to the Early Eocene (E-7 Zone). The low density currents which deposited the parallel laminated sandstones originated in the lower shelf-middle slope.

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A Middle Cenomanian foraminiferal assemblage from the Nowe Rybie section (Żegocina Tectonic Window, Subsilesian Unit, Polish Outer Carpathians)

Machaniec E., Gasiński M. A., Ślączka A., Leśniak T.

Studia Geologica Polonica

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2005

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Vol. 124

249-258

EN

The Żegocina Tectonic Window is the most eastward located tectonic window of the Lanckorona-Żegocina Zone in the Polish Outer Carpathians and represents the slope parts of the Silesian basin and intrabasinal uplifted zones of the Subsilesian Unit. Upper Cretaceous and Palaeocene variegated marls, typical deposits of the studied part of the basin, are intercalated with the so-called Rybie beds (local sediments of siliciclastic submarine fans). A Middle Cenomanian foraminiferal assemblage (Rotalipora reicheli Zone) is here described from these sediments. The assemblage contains numerous planktonic (epipelagic and bathypelagic) foraminiferids, which is rather unique within the "Flysch" type assemblages. A middle slope palaeodepth is suggested as the depositional environment, based on benthic and planktonic foraminiferal associations.

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Cretaceous-Paleogene boundary problem in Libya: the occurrence of the foraminiferal species Abathomphalus mayaroensis (Bolli) in the Western Sirt Basin

Tshakreen S. O., Gasiński M. A.

Geological Quarterly

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2004

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Vol. 48, No 1

77-82

EN

The position of the K/P boundary in wells in the Western Sirt Basin of Libya is problematic. The biostratigraphic definition of the K/P boundary in the subsurface is based on the extinction of the eponymous taxon of the standard latest Maastrichtian foraminiferal Abathomphalus mayaroensis Zone. We have unambiguously recognised this taxon from the Sirt Basin subsurface sections for the first time. All the latest Maastrichtian foraminiferal assemblages are dominated by planktonic foraminiferids. Some of specimens are pyritised, indicating organic flux to the basin floor, causing oxygen deficiency in the depositional environment. The occurrence of characteristic bathypelagic and some epipelagic species indicates that the environment of deposition is outer shelf–middle continental slope.

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The Latest Maastrichtian of the Subsilesian Unit (Polish Outer Carpathians)

Gasiński M. A., Leśniak T., Piotrowski M.

Biuletyn Państwowego Instytutu Geologicznego

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2001

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nr 396

46-47