Cretaceous Planktonic Foraminifera and Bioevents

The Bornova Flysch Zone (BFZ), located between the Menderes Massif and the İzmir-Ankara Suture in westernmost Anatolia
(Turkey), forms the westernmost part of the Anatolide-Taurides. The BFZ comprises intensely sheared Upper Cretaceous-Palaeocene matrix and blocks of various origins. The matrix of the BFZ is mainly made up of unfossiliferous flysch-type sediments (alternations of sandstones and shales). In Bornova (İzmir, western Turkey) and its surroundings, these clastics locally include planktic foraminiferabearing pelagic micritic limestone and calcareous shale lenses and interbeds (Beytitepe Limestone). As a result of studies focusing on the
planktic foraminifera-bearing pelagic interlayers in three areas (Gökdere, Işıklar and Kocaçay areas) around Bornova, a detailed planktic foraminiferal biostratigraphy of the rocks is documented for the first time. The thickness of the laminated micritic limestones attains 360 m in the Gökdere area. Occurrences of late Maastrichtian species such as Abathomphalus mayaroensis (Bolli), Contusotruncana
contusa (Cushman), Globotruncanita conica (White) and Racemiguembelina fructicosa (Egger) within planktic foraminifera assemblages obtained from the laminated micritic limestones and red calcareous shales in the three areas suggest a late Maastrichtian age for these rocks. The occurrence of various species of Globanomalina, Morozovella, Igorina and Parasubbotina within the calcareous shales in
the Işıklar area suggests a late Palaeocene age. The Kocaçay area has well-preserved outcrops showing the stratigraphy of the matrix, despite the more complex geology. The upper Maastrichtian laminated micritic limestones are gradationally overlain by upper Maastrichtian calcareous shales. The calcareous shales are represented by rich planktic foraminiferal assemblages and include blocks derived from laminated micritic limestones. The upper Mastrichtian calcareous shales are overlain by Palaeocene red calcareous shales.
Poor assemblages including Parasubbotina varianta (Subbotina), Subbotina triangularis (White), Subbotina cf. velascoensis (Cushman), Globanomalina compressa (Plummer) and Globanomalina planoconica (Subbotina) indicate a late Palaeocene age for the lower part and a latest Palaeocene age for the upper part of the calcareous shale sequence. Therefore, the age of conglomerates and flysch overlying the calcareous shales should be latest Palaeocene or younger in the Kocaçay area.

Planktonic foraminifer distributions in seventeen stratigraphic sections of Upper Cretaceous hemipelagic and pelagic sequences of northern Bey Dagları Autochthon (western Taurides) yield six biozones such as, Dicarinella concavata Interval Zone, Dicarinella asymetrica Range Zone, Radotruncana calcarata Range Zone, Globotruncana falsostuarti Partial Range Zone, Gansserina gansseri Interval Zone, and Abathomphalus mayaroensis Concurrent Range Zone. Two of the zones, Dicarinella concavata Zone and Dicarinella asymetrica Zone, are identified in the massive hemipelagic limestones of the Bey Dagları Formation, of
Coniacian-Santonian age. They are characterized by scarce planktonic foraminifera and abundant calcisphaerulids.
The other four biozones are determined from the cherty pelagic limestones of the Akdag Formation and indicate a late Campanian-late Maastrichtian time interval. The planktonic foraminifera observed in these four biozones are diverse, complex morphotypes (K-selection), suggesting open
oceans. The assemblage of the Abathomphalus mayaroensis Zone shows that the latest Maastrichtian record is absent throughout the northern part of the autochthon. Two main sedimentary hiatuses are recognized within the Upper Cretaceous pelagic sequence. Early to middle Campanian and latest Maastrichtian-middle Paleocene planktonic foraminifera are absent in all measured stratigraphic sections. Hiatus durations differ between sections as a result of diachronism of onset of the hemipelagic and pelagic deposition and the post-Santonian and post-Maastrichtian erosional phases. Drowning event and the early-middle Campanian and latest Maastrichtian-middle Paleocene hiatuses in the pelagic
sequence are attributed to regional tectonics during the Late Cretaceous.

Romaniceras (Yubariceras) ornatissimum (Stoliczka, 1864), a Tethyan ammonite from the upper Middle-Turonian, is recorded for the first time from the chalks of the Paris basin. Curiously, the specimen has been collected at the level of the Round Down Marl, that is to say low in the Turonian succession, which suggests a reduced rate of sedimentation during the lower and the greatest part of middle Turonian.

The upper Campanian (Cretaceous) of the Hacımehmet area (south of the city of Trabzon; Eastern Pontides) is mainly composed of calciclastic turbidites. The basinal unit of the 119 m thick succession includes thin red pelagic limestone interlayers and conglomerates dominated by volcanic clasts. The overlying upper slope and lower slope units of the sequence consist of an alternation of allochthonous calcarenite/calcirudite beds and pelagic marls and mudstones. Calcarenite/calcirudite beds dominate the upper slope unit of the succession and are composed of transported material, including benthic foraminifers, red algae, bryozoan, crinoid and rudist fragments, inoceramid bivalve prisms and neritic and pelagic carbonate lithoclasts. The occurrence of Helicorbitoides boluensis (Sirel) extracted from the calcarenite/calcirudite beds indicates a Campanian age. Identifiable rudists such as Joufia reticulata Boehm, Bournonia cf. anatolica Ozer, Biradiolites cf. bulgaricus Pamouktchiev and ?B...

In the Gaj section (Polish Carpathians, Skole Nappe, Ropianka Formation), the Upper Maastrichtian calcareous nannofossil biostratigraphy is compared with foraminiferal zonation based on the occurrence of the planktonic foraminiferid index species Abathomphalus mayaroensis. It appears that the LO of A. mayaroensis, which has been used previously in the studied section as the possible K/Pg boundary indicator is located below the boundary. The disappearance of A. mayaroensis along with other planktonic foraminiferids before the Cretaceous—Paleogene (K/Pg) boundary mass extinction event may be a consequence of the Late Maastrichtian rapid warming pulses. Moreover, the Paleogene age cannot be supported by the FO of the benthic foraminiferid Rzehakina fissistomata, because it first appears together with the nannofossil Ceratolithoides kamptneri (zonal marker for the latest Maastrichtian UC20c TP Zone). According to the present study, the whole studied section represents the lower Upper to...

In the Gaj section (Polish Carpathians, Skole Nappe, Ropianka Formation), the Late Maastrichtian calcareous nannofossil biostratigraphy is compared with foraminiferal zonation based on the occurrence of the planktonic foraminiferid index species

The upper Campanian (Cretaceous) of the Hacımehmet area (south of the city of Trabzon; Eastern Pontides) is mainly
composed of calciclastic turbidites. The basinal unit of the 119 m thick succession includes thin red pelagic limestone interlayers
and conglomerates dominated by volcanic clasts. The overlying upper slope and lower slope units of the sequence
consist of an alternation of allochthonous calcarenite/calcirudite beds and pelagic marls and mudstones. Calcarenite/calcirudite
beds dominate the upper slope unit of the succession and are composed of transported material, including benthic
foraminifers, red algae, bryozoan, crinoid and rudist fragments, inoceramid bivalve prisms and neritic and pelagic
carbonate lithoclasts. The occurrence of Helicorbitoides boluensis (Sirel) extracted from the calcarenite/calcirudite beds
indicates a Campanian age. Identifiable rudists such as Joufia reticulata Boehm, Bournonia cf. anatolica Özer, Biradiolites
cf. bulgaricus Pamouktchiev and ?Biradiolites sp. from the upper slope unit of the succession indicate a late Campanian–
Maastrichtian age. The planktonic foraminifers within the red pelagic limestone beds, marls and mudstones throughout
the succession consist mainly of Campanian–Maastrichtian forms and suggest mainly basinal depositional conditions.
The presence of Radotruncana cf. calcarata (Cushman) accompanied by Globotruncanita elevata (Brotzen) in the basinal
unit of the succession indicates an early late Campanian age for the lower part of the succession. Inoceramid bivalves
have been collected from the upper part of the succession. The fauna is dominated by ‘Inoceramus’ tenuilineatus Hall
and Meek, 1854 and Cataceramus haldemensis (Giers, 1964); other taxa recognised are: ‘Inoceramus’ algeriensis
Heinz, 1932, Platyceramus vanuxemi (Meek and Hayden, 1860), ‘Inoceramus’ cf. nebrascensis Owen, 1852, Cataceramus
aff. barabini (Morton, 1834), Cataceramus gandjaensis (Aliev, 1956), and ‘Inoceramus’ sp.; the assemblage indicates
the ‘Inoceramus’ tenuilineatus Zone; corresponding to the middle–late Campanian boundary interval. The uppermost
part of the succession is characterized by the presence of the trace fossils Scolicia strozzii and Scolicia isp., indicating
a mixed Skolithos-Cruziana ichnofacies. This ichnofacies suggests a well-oxygenated environment.