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The planktonic foraminiferal assemblages are tracked in the middle Eocene–early Miocene succession within N. El Faras‐1X Well, Qattara Depression, Egypt. This succession is composed mainly of three lithostratigraphic units the upper part of the Apollonia Formation (middle to late Eocene), Dabaa Formation (late Eocene and Oligocene) and the lower part of the Moghra Formation (early Miocene). Biostratigraphically, the recorded 77 planktonic foraminiferal species enabled the recognition of 12 planktonic foraminiferal biozones; 4 biozones belong to middle to late Eocene, 7 biozones belong to the Oligocene and 1 belongs to the early Miocene. The proposed biozones were compared with their equivalents in other Egyptian regions and other schemes. Eleven Lowest Occurrence and two Highest Occurrence planktonic foraminiferal bioevents were also recognized and correlated all over the world. The chronostratigraphy and the stage boundaries were mainly delineated according to the diagnostic planktonic foraminifera. The middle–late Eocene boundary (Bartonian–Priabonian boundary), The Eocene–Oligocene boundary (Priabonian–Rupelian boundary), the early Oligocene–late Oligocene boundary (Rupelian–Chattian boundary) and the Oligocene–Miocene boundary (Chattian–Aquitanian boundary) were accurately determined. Based on the % P, the palaeobathymetry was estimated and hence the sea‐level fluctuation. The reconstructed sea‐level curve revealed two major transgressive–regressive cycles with minor oscillation within them. These events were globally correlated and match in most parts with that of the worldwide sea‐level curves. The sequence stratigraphy framework consists mainly of two transgressive–regressive (T–R) depositional sequences (DS1 and DS2). The DS1 includes the TST1 below which is capped by mfs1 and the HST1 above. The DS2 involves the TST2 below that was capped by mfs2 and the HST2 above. [ABSTRACT FROM AUTHOR]

Facies analysis and paleogeographical reconstruction of the Asmari Formation in the Lorestan and Dezful Embayment Zones are documented by studying eight outcrop sections and two wells. The new observations provide a basis for correlation and description of the carbonate ramp evolution during the Early Oligocene–Middle Miocene time. Petrographic examinations on 877 thin sections revealed 16 facies which are deposited in tidal flat (4 facies), lagoon (4 facies), shoal (2 facies), shallow open marine (4 facies), and deep marine (2 facies). Tidal flat and lagoon facies associations are extended in the north and east, whiles shoal and shallow open marine facies are more frequent in the south and west of the study area. Detailed analysis of sedimentary facies indicates that in the Oligocene interval, the depositional system of the Asmari Formation was a distally steepened ramp. From northeast Lorestan towards central and south-west Lorestan, the Asmari Formation is replaced by pelagic deposits of the Pabdeh Formation. In the early Miocene, the depositional system changed to a NE–SW trending homoclinal ramp. [ABSTRACT FROM AUTHOR]

Studies of the Paleogene sequence in the Zagros Basin of Iran are crucial due to the existence of large oil fields such as the Pazanan oil field. This study examines calcareous nannofossils from the Eocene–Oligocene interval in the upper part of the Pabdeh Formation in the Zagros Basin. Samples were taken from a well drilled in the Pazanan oil field, located in the Dezful Embayment (Zagros Basin, southwestern Iran). The studied section is ~ 54 m thick and comprises mainly a succession of marls and limestones. Calcareous nannofossil biostratigraphy allows the studied interval to be assigned to Martini (Standard tertiary and quaternary calcareous nannoplankton zonation. In: Proceedings of the 2nd planktonic conference. Roma, Italy, p 739–785, 1971) Zones NP19 (Isthmolithus recurvus Zone) through NP22 (Helicosphaera reticulata Zone), which spans the Priabonian and Rupelian stages and includes the Eocene/Oligocene boundary. The nannoflora paleoecology allows us to characterize major changes in paleoproductivity during this interval. Late Eocene (Priabonian) assemblages are dominated by oligotrophic nannofossils. Above the Eocene/Oligocene boundary, there is a diverse assemblage of eutrophic calcareous nannofossils, with a significant decrease in the abundance of oligotrophic species. As well as nutrient supply, water temperature also appears to be another main controlling factor of the paleoenvironment in this region, where there is an increase in cold-water species recorded at the base of the Oligocene (Zone NP21), accompanied by a decrease in warm-water species. These variation in the calcareous nannofossil assemblages may indicate increased nutrient supply, climatic imbalances—associated with weather changes—and eventually sea-surface temperature (SST) cooling in this part of the Zagros Basin (Neo-Tethys domain) throughout the Eocene/Oligocene transition (EOT). [ABSTRACT FROM AUTHOR]

Introduction Asmari Formation is a thick succession of Oligocene-Miocene sedimentary rocks, the leading crude oil reservoir in the Zagros structural-sedimentary zone, and one of the largest oil reserves in the world (Alavi, 2004). Due to its economic significance, this formation has long been considered in recent decades. The presence of large benthic foraminifera as the most important fossil group in the Asmari Formation is essential for the biostratigraphic studies of this formation. This study aims to study the Asmari Formation in Gachsaran oil field in southwestern Iran, 200 km southeast of Ahvaz. In order to identify lithological changes and the biostratigraphic studies, three wells were selected from the Gachsaran oil field, including wells A, B, and C. Materials and Methods In the mentioned three wells of the Gachsaran oil field, the Asmari Formation has 590 m thickness in well A, 336 m in well B, and 382 m in well C. In this study, 3235 microscopic thin sections were prepared from the Asmari Formation, 1572 thin sections from well A, 809 from well B, and 854 from well C. Identification of microfossils have been done based on the Adams & Bourgeois (1967), Loeblish & Tappan (1988), and Hottinger (1997), and Biostratigraphic studies according to the Laursen et al. (2009) and Van Bochem et al. (2010). Discussion and Conclusion The Asmari Formation in the Gachsaran oil field consists of limestone, dolomitic limestone, and dolomite. Based on the distribution of benthic foraminifera in the studied wells, four faunal assemblages equivalent to those introduced by Laursen et al. (2009) and Van Bochem et al. (2010) have been recognized in the Asmari Formation. They are as follows : 1- Nummulites vascus - Nummulites fichteli Assemblage zone 2- Archaias asmaricus-Archaias hensoni - Miogypsinoides complanatus Assemblage zone 3- Miogypsina - Elphidium sp. 14- Peneroplis farsensis Assemblage Zone 4- Borelis melo curdica- Borelis melo melo Assemblage Zone Assemblage zone 1 is equal to zone No. 2 of Laursen et al. (2009) and Van Bochem et al. (2010) (Nummulites vascus - Nummulites fichteli Assemblage zone) and contains index nummulitids such as Nummulites vascus, Nummulites fichteli, Nummulites intermedius with Rupelian in age. This biozone has been recorded in all three wells. Assemblage zone 2 is equivalent to zone No. 4 in Laursen et al. (2009) and Van Bochem et al. (2010) (Archaias asmaricus-Archaias hensoni - Miogypsinoides complanatus Assemblage zone). This assemblage contains index fossils such as Miogypsinoides complanatus, Archaias kirkukensis, Archaias hensoni. The appearance, abundance, and extinction of Archaias are occurred in this zone and represent the Chattian. This zone has also been recognized in all three wells. Assemblage zone 3 which is again present in all three wells, corresponds to zone No. 5 of Laursen et al. (2009) and Van Bochem et al. (2010) (Miogypsina - Elphidium sp. 14- Peneroplis farsensis Assemblage Zone). It has significant fossils such as Miogypsina, Elphidium sp. 14, and Peneroplis farsensis. Due to the presence of these index fossils as well as the disappearance of the genus Archaias at the end of the Chattian, even the absence of Borelis melo curdica (Burdigalian index), this zone belongs to Aquitanian. Assemblage zone 4 is comparable to biozone No. 7 in Laursen et al. (2009) and Van Bochem et al. (2010) (Borelis melo curdica- Borelis melo melo Assemblage Zone). Due to the index species Borelis melo curdica, this part of the sequence belongs to the Early Miocene (Burdigalian). This biozone has been identified only in wells A and C. Therefore, biostratigraphically, the most complete sequence of Oligocene - Early Miocene Asmari Formation in this study is recorded in wells A and C. [ABSTRACT FROM AUTHOR]

The age and evolution of paleoenvironmental conditions in the Oligocene (Baba Formation) from the Bai-Hassan Well-4 section were studied from the distribution of Large Benthic Foraminifera (LBF), microfacies, and paleoecology. We identified 30 species from 21 genera of Large Benthic Foraminifera (LBF) in addition to corals and algae with remains of mollusca and echinoid spines, belonging to two assemblage zones which are Nummulites vascus, Nummulites fichteli Assemblage Zone and Lepidocyclina (Eulephidina) dilatata—Nummulites vascus, Nummulites fichteli Assemblage Zone. The Baba Formation spans Late Rupelian-to-Early Chattian age in the studied section. Bai-Hassan Well-4 section was subdivided into three carbonate microfacies from the lower to the upper part: fine-to-very coarse bioclastic larger foraminiferal wackestone–packstone (MF1), fine-to-very coarse bioclastic larger foraminiferal packstone (MF2), and fine-to-coarse bioclastic larger foraminiferal packstone–grainstone (MF3). The main depositional environment of the Baba Formation from the lower to the upper art of the studied section is represented by outer ramp starting from open shelf lagoon, and it was deposited from subtropical to a tropical environment from, the lower part to the middle and the upper part of the studied section, with mesotrophic-to- oligotrophic conditions, open marine to shallow and restricted environments with normal to higher water salinity (34–50 ‰), and mesophotic-to-oligophotic conditions of soft-to-hard sediments. [ABSTRACT FROM AUTHOR]

This study deals with planktic foraminiferal biostratigraphy of the Oligocene-Pliocene successions in the offshore Well A1-89 of the Sirt Basin. One hundred and forty-one ditch cutting samples covering the interval from 1050ft to 9000ft have been analyzed for this study. Fifty-five planktic foraminifera taxa belonging to seventeen genera have been identified. Ten planktic foraminiferal biozones have been recognized herein based on the integration of Bolli and Saunders's (1985), Berggren et al.(1995), Steininger et al. (GSSP 1997), and Wade et al. (2011), zonal schemes. In descending order, they are Sphaeroidinellopsis seminulina (Zanclean-Piacenzian); Praeorbulina sicana (Burdigalian-Langhian); Globigerinoides bisphericus (Burdigalian); Globigerinatella sp./Catapsydrax dissimilis (Burdigalian); Globigerinoides primordius (Aquitanian); Paragloborotaliakugleri (Aquitanian); Globigerinaciperoensis ciperoensis (Chattian);Globorotalia opima opima (Chattian); Globigerina ampliapertura (Rupelian);Cassigerinella chipolensis/Pseudohastigerina micra (Rupelian). The Oligocene/Miocene boundary is found to be conformable and placed at the top of the Globigerina ciperoensis ciperoensis Biozone. However, the Miocene/Pliocene boundary is unconformable and placed at the top of the Praeorbulina sicana Biozone. Additionally, the established biozones have been regionally correlated with their equivalents in Tunisia and Egypt. [ABSTRACT FROM AUTHOR]

The results of the palynological study of the Paleogene and the underlying Cretaceous sediments of the Cis-Donets Monocline, drilled by borehole 1238, are presented. Analysis of dinoflagellate cysts enabled the recognition of the Apectodinium hyperacanthum, Axiodinium augustum, and Ochetodinium romanum/Samlandia chlamydophora zone intervals and the Rhombodinium draco–Deflandrea spinulosa layers in the Paleogene part of the section. The age of regional formations and beds was updated: the Buzinovka Formation is dated by the early Thanetian; the Veshenskaya Formation is late Thanetian–earliest Ypresian age; the Surovikino and Osinovaya Beds are early–middle Ypresian; and the Ventsy and "Poltava" Beds are of the late Rupelian–Chattian age. Two major stratigraphic hiatuses, corresponding to the Maastrichtian–Selandian and the upper Ypresian–lower Rupelian, were recognized in the borehole 1238 section. The analysis of the quantitative fluctuations of different palynomorph groups through the section permitted to reconstruct changes in depositional environments of the Peri-Tethys Basin margin during the early and late Paleogene: the Buzinovka and Veshenskaya formations and the Surovikino and Osinovaya Beds were accumulated in an open-marine environments during the long late Paleocene–early Ypresian transgressive stage, whereas the Ventsy and "Poltava" beds were deposited in the half-landlocked basin during the Chattian. [ABSTRACT FROM AUTHOR]

The marine Oligocene deposits of Pakistan are exposed in the Baluchistan and Lower Indus Basins. The Baluchistan Basin deposits are referred to the Khojak Formation of Makran Group. They represent three planktic foraminiferal zones, the Globigerina ampliapertura Zone, G. ciperoensis Zone and Globorotalia kugleri Zone, corresponding to Early, Middle and Late Oligocene. The Lower Indus Basin deposits of Sind include the Kirthar and Nari Formations. On the basis of the larger Foraminifera these deposits are divided into Nummulites fichteli Zone (Early Oligocene), N. fichteli/Lepidocyclina (E.) dilatata Zone (Mid. Oligocene), and L. dilatata Zone (Late Oligocene). The Oligocene deposits are absent in the Upper Indus Basin due to the orogenic movement which took place at the end of the Eocene and continued in the Oligocene.

The deposits of the As Pontes Basin in north-west Spain yield extraordinarily well-preserved microfloral assemblages that have unmatched diversity within the European Oligocene. The comprehensive examination of 300 miospore taxa has led to the discovery of two new fossil pollen genera, Eucommiopsispollenites gen. nov. and Pistaciapollenites gen. nov., as well as seven new species: Eucommiopsispollenites compactus sp. nov., Eucommiopsispollenites gracilis sp. nov., Nymphaeapollenites asponticus sp. nov., Nymphaeapollenites perforatus sp. nov., Pistaciapollenites heteroporatus sp. nov., Punctilongisulcites cryptornatus sp. nov. and Symplocoipollenites diktyotos sp. nov. Moreover, the botanical affinity and geographic distribution of 13 additional species of particular interest are discussed in detail, because these are either recorded for the first time anywhere within the Paleogene (Lythraceaepollenites bavaricus, Myrtaceidites myrtiformis, Punctilongisulcites punctiechinatus, Rhuspollenites ornatus and Vitispollenites tener), in the Iberian Peninsula (Aglaoreidia pristina, Diospyrospollenites ovalis, Pseudospinaepollis pseudospinosus, Reevesiapollis reticulatus and Tricolporopollenites vancampoae), or are studied for the first time using scanning electron microscopy (SEM) (Pentapollenites regulatius, Polycolpites helmstedtensis and Triporopollenites robustus). SEM analysis has enabled the conclusive botanical assignment of two species: Polycolpites helmstedtensis, with affinity to the extant tropical genus Eriandra, and Triporopollenites robustus, related to Myricaceae. In view of these affinities, new combinations are proposed accordingly: Polygalacidites helmstedtensis comb. nov. and Myricipites robustus comb. nov. The results of this study carry significant biostratigraphic and palaeobiogeographic implications at a regional and wider, continental scale. Firstly, the similarities of the As Pontes microflora with other Oligocene assemblages located various thousands of kilometres apart indicates the spread of a relatively homogenous broadleaved evergreen flora in Europe and allows for the recognition of Myricipites robustus and the genus Pentapollenites as key biostratigraphic index taxa across the continent. Secondly, the last occurrence datums of thermophilous taxa that became extinct in the Eocene in more northern latitudes indicates that the Iberian Peninsula functioned as a refuge area for thermic vegetation at least since the early Oligocene. [ABSTRACT FROM AUTHOR]

The biostratigraphy and paleoenvironments of the İhsaniye Formation exposed at Karaburun in northwest Turkey is described based upon the study of abundant and well-preserved foraminifera, calcareous nannofossils and palynomorphs. The studied succession is Early Oligocene in age, with calcareous nannofossil zones upper NP21 (Subzone CNO1) to lower NP23 (Subzone CNO3) and planktonic foraminifera zones O1 (~P18) and O2 (~P19) represented, and palynological assemblages suggestive of zones D13 to D14a. Based on these new data, a revised interpretation of the stratigraphic succession is presented. Deposition was controlled by a now inverted normal fault, with deposition of older stratigraphy (upper NP21 to NP22) restricted to the original hanging wall. During NP23, deposition commenced on the footwall, resulting in progressive onlap of an exposed Eocene reefal limestone (Soğucak Formation). Three primary sedimentary facies are present: marls with thin calcareous siltstones, marls with synsedimentary slumps and debris flows, and coarse pebbly sandstones. The coarse pebbly sandstones were deposited in a fan-delta/shoreface paleoenvironment and represent the initial phase of onlap during biozone NP23 onto a rocky shoreline on the footwall side of the fault. The marl-dominated facies represent deposition in outer shelf-upper bathyal environments. The succession demonstrates evidence for a near-end Eocene relative sea-level fall. Changes in the abundance of planktonic foraminifera and the onlap onto the footwall demonstrate maximum subsequent transgression within NP23. This reflects eustasy rather than Paratethyan relative sea-level. No interpretation of sea-water salinity reduction can be made for the sediments deposited during biozone NP23 in the studied sections, although this is noted in coeval sediments in parts of Paratethys (the "Solenovian Event"). Together with the open marine nature of the diverse and abundant fossil assemblages, it is suggested that deposition of the Karaburun section was strongly influenced by a connection to the global ocean, via the Çatalca Gap, as suggested in a recent study. [ABSTRACT FROM AUTHOR]

Copyright of Anuario do Instituto de Geociencias is the property of Universidade Federal do Rio de Janeiro, Instituto de Geociencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Outcrops of a thick turbiditic succession are exposed on the northern bank of the Liptovská Mara reservoir near Liptovská Ondrašová and Ráztoky. The section consists of rhythmic, predominantly thin- to medium-bedded turbidites of the Rupelian age. Their biostratigraphy is based on the calcareous nannofossils. Facies associations of these deposits represent different components of depositional lobe deposits in the turbidity fan system, including mainly the lobe fringe and lobe distal fringe/inter-lobe facies associations and locally the medium bedded deposits of the lobe off-axis facies association. This interpretation is supported by statistical analysis. The deep-sea turbiditic deposits contain trace fossil associations, which include deep-tier fodinichnia and domichnia up to shallow-tier graphoglyptids. Paleocurrent measurements indicate that the majority of sedimentary material was transported from SW and W. [ABSTRACT FROM AUTHOR]

This study is about the microbiostratigraphy of the Asmari Formation in the Lorestan Zone, south-west Iran. Six biostratigraphical zones were defined after summarizing the available stratigraphical data and occurrence of the Early Oligocene-Early Miocene benthic foraminifera. The zones are: Nummulites intermedius, N. vascus Assemblage Zone (Ruplian, for the Laneh and Chenareh sections); Lepidocyclina-Operculina-Ditrupa Assemblage Zone (Chattian, for the Laneh section); Archaias asmaricus, Archaias hensoni-Miogypsinoides complanatus Assemblage Zone (Chattian, for Laneh and Chenareh sections); Elphidium sp.14–Miogypsina sp. Assemblage Zone (Aquitanian, for the Laneh, Chenareh and Sar Tang sections); and biozone Borelis melo curdica–Borelis melo melo Assemblage Zone (Burdigalian, for Chenareh, Sarkan and Sar Tang sections). The lower part of Asmari formation in the Sarkan section (from base to 38 m) has no index fossils, so we called it the Indeterminate Zone. The zones were successfully correlated with the biostratigraphical sachems in the Zagros Basin. [ABSTRACT FROM AUTHOR]

Six associations of dinocysts, spores, and pollen of various ages are distinguished in the Cenozoic marine deposits of the Kvachina Bay section as a result of study of stratigraphic occurrence of palynomorphs. Their analysis allowed us to date the deposits of the Tigil and Belesovataya units to the Bartonian–Priabonian and Oligocene–Early Miocene, whereas the overlapping lower part of the Kavran Group is dated to the Early Miocene. The age of dislocated rocks beneath the Tigil Unit is estimated as late Ypresian–?early Lutetian. On the basis of the revealed changes in the ratios of the ecological groups of palynomorphs, conclusions were made about the paleoenvironments in which the formation of strata took place in various time intervals. [ABSTRACT FROM AUTHOR]

The uplift history of south-eastern Tibet is crucial to understanding processes driving the tectonic evolution of the Tibetan Plateau and surrounding areas. Underpinning existing palaeoaltimetric studies has been regional mapping based in large part on biostratigraphy that assumes a Neogene modernization of the highly diverse, but threatened, Asian biota. Here, with new radiometric dating and newly collected plant-fossil archives, we quantify the surface height of part of the south-eastern margin of Tibet in the latest Eocene (∼34 Ma) to be ∼3 km and rising, possibly attaining its present elevation (3.9 km) in the early Oligocene. We also find that the Eocene–Oligocene transition in south-eastern Tibet witnessed leaf-size diminution and a floral composition change from sub-tropical/warm temperate to cool temperate, likely reflective of both uplift and secular climate change, and that, by the latest Eocene, floral modernization on Tibet had already taken place, implying modernization was deeply rooted in the Palaeogene. [ABSTRACT FROM AUTHOR]

Copyright of Iraqi Bulletin of Geology & Mining is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bu çalışma ile, Doğu Toroslar’da Malatya ilinin batısındaki Akçadağ ilçesi civarında geniş alanlarda yüzeyleyen Oligo-Miyosen yaşlı Muratlı ve Petekkaya formasyonlarının bentik foraminifer biyostratigrafisi ortaya konulmuştur. Bölgede, stratigrafik ve paleontolojik incelemeler yapmak üzere seçilen dört lokasyondaki ölçülü stratigrafik kesitte sistematik örnek alımı gerçekleştirilmiştir. Toplam 182 adet sert kayaç örneğinden elde edilen bentik foraminiferler tanımlanarak bölgedeki sığ denizel çökellerde Oligosen’e ait SBZ 21-22 (RupeliyenErken Şattiyen), SBZ 23 (Geç Şattiyen) ile Alt Miyosen’e ait SBZ-25 olmak üzere toplam üç biyozon saptanmıştır. İstifte stratigrafik olarak Şattiyen ile Burdigaliyen yaşlı birimler arasındaki marnlarda tespit edilen planktik foraminifer ve nannoplankton topluluğunun olasılıkla Akitaniyen yaşını işaret ettiği belirlenmiştir. Ayrıca bu çalışma ile, bentik foraminifer taksonlarının biyostratigrafik konumlarına dayanarak bölgede Oligo-Miyosen geçişi belgelenmiştir.

Due to its intermediate geographical position between the Mediterranean and W Pacific, the Oligocene shallow-marine sequence of Kutch (India) is of key importance in paleobiogeographical interpretations. Larger benthic foraminifera (LBF) are a fundamental link for the correlation between the Mediterranean shallow benthic zones (SBZ) and the W Pacific 'letter stages'. LBF were re-evaluated by morphometric studies of the internal test from five stratigraphic sections of the Maniyara Fort Formation. Based on their significant affinity to coeval fauna in the Mediterranean, they were assigned to W Tethyan SBZ zones, supported by Sr-isotope stratigraphy. In the Basal Member, traditionally considered as early Rupelian, we identified Nummulites bormidiensis, N. kecskemetii and Heterostegina assilinoides assigning it to the early Chattian SBZ 22B Zone. The Coral Limestone Member, previously considered as late Rupelian, is also assigned to this zone, for the presence of N. bormidiensis, Eulepidina formosoides-dilatata and Nephrolepidina morgani-praemarginata. Its early Chattian age (26.5-29 Ma) is further supported by Sr-isotope data. Miogypsinoides complanatus and Spiroclypeus margaritatus in the Bermoti Member (the top of the formation) document the late Chattian SBZ 23 Zone and the Sr-isotope data (22.5-24 Ma) place it close to the Oligocene-Miocene boundary. [ABSTRACT FROM AUTHOR]

The Oligocene–Miocene carbonate record of the Zagros Mountains, known as the Asmari Formation, constitutes an important hydrocarbon reservoir in southern Iran. This marine carbonate succession, which developed under tropical conditions, is explored in terms of larger foraminiferal biostratigraphy, facies analysis and sequence stratigraphy in a new section at Papoon cropping out in the western Fars sub‐basin, in the south‐east of the Zagros belt. Facies analysis shows evidence of re‐working and transport of skeletal components throughout the depositional system, interpreted here as a carbonate ramp. The foraminifera‐based biozones identified include the Globigerina–Turborotalia cerroazulensis–Hantkenina Zone and Nummulites vascus–Nummulites fichteli Zone, both of Rupelian age, the Archaias asmaricus–Archaias hensoni–Miogypsinoides complanatus Zone of Chattian age and the 'Indeterminate' Zone of Aquitanian age. The vertical sedimentary evolution of the formation exhibits a progressive shallowing of the facies belts and thus the succession is interpreted as a high‐rank low‐order regressive systems tract. This long‐lasting Rupelian–Aquitanian regressive event is in accordance with accepted global long‐term eustatic curves. Accordingly, long‐term eustatic trends would have been a factor controlling accommodation during the deposition of the Asmari Formation studied in the western Fars sub‐basin. [ABSTRACT FROM AUTHOR]

One stratigraphic section was selected to study the biostratigraphy of the Oligocene and Lower Miocene deposits in Folded Zagros. The sediments include Asmari Formation (345 m) and the upper parts of Pabdeh Formation (180 m). Lithostratigraphy studies show that the Pabdeh Formation is composed of marls and medium-bedded argillaceous limestone alternation. The Asmari Formation is generally composed of medium- to thick-bedded limestone. Biostratigraphy studies for Pabdeh Formation indicate the four genera and six species of planktonic foraminifers. Based on assessment of foraminifera, one assemblage zone has been proposed for the Pabdeh Formation. The Asmari Formation biostratigraphy studies led to identify 27 genera and 35 species of benthic foraminifers. Based on the distribution of foraminifera, three assemblage zones and one indeterminate zone for Asmari Formation are suggested. Micropaleontology studies are offered Early Oligocene for Upper Pabdeh Formation and Late Oligocene to Early Miocene age for Asmari Formation. [ABSTRACT FROM AUTHOR]

The time interval of the sedimentation in the southern Hellenic Thrace Basin (Lemnos Island, northeast Aegean Sea) was studied, based on the qualitative analysis of calcareous nannoplankton and quantitative analysis of planktonic foraminifera. The samples were collected from 4 different stratigraphic sections (Ifestia, Panagia, Kaspaka, and Kaminia). The biostratigraphic analyses on both calcareous nannoplankton and planktonic foraminifera reveal an age of Late Eocene-Early Oligocene (Priabonian-Rupelian). In particular, the Eocene-Oligocene boundary is recorded at the lower part of the turbiditic system, in the Ifestia section. The present study offers the first taxonomic analysis of planktonic foraminifera of this age in the Hellenic southern Thrace Basin (Lemnos Island). The species Catapsydrax unicavus, Chiloguembelina cubensis, Dentoglobigerina sp., Dipsidripella liqianyui, Globigerina officinalis, Paragloborotalia nana, Turborotalia cerroazulensis, and Turborotalia sp. were identified. Furthermore, D. liqianyui adds new data worldwide, as it is identified in the Mediterranean Sea (Lemnos Island) for the time interval of the O1-O4 zones (Early Oligocene). [ABSTRACT FROM AUTHOR]

Hegetotheriidae is one of the most advanced clades within the endemic South American placental Order Notoungulata. The speciesHegetotheriopsis sulcatusKramarz & Paz, 2013 differs from all other known hegetotheriids in having a peculiar combination of cranial and dental features, some of them shared with Archaeohyracidae (sister group of Hegetotheriidae). A previous cladistic analysis supportedH. sulcatusas the earliest diverging hegetotheriid. Nevertheless, a more recent analysis, based on a different data matrix, concluded that this species is an advanced form within the family, with the little-knownProhegetotherium sculptumAmeghino, 1897 (late Oligocene) being the most basal taxon. Here we present a revision of the concept and the content ofP. sculptumbased on a re-examination of the type specimens. We find that this material exhibits several dental and cranial characters not recognized in all previous studies; we conclude that no specimen other than the types can be assigned toP. sculptum, and that all the synonymies previously proposed (i.e.P. shumwayiandP. crassus) are unfounded. A new cladistic analysis, combining characters from the two aforementioned analyses, confirms the position ofH. sulcatusas the earliest diverging hegetotheriid. The taxon was originally described based on remains from early Miocene deposits in central and northern Patagonia (Sarmiento, Chichinales and Cerro Bandera formations). Here we report new material from the late Oligocene of Cabeza Blanca (central Patagonia), and reassign other material previously attributed toProhegetotheriumfrom presumably equivalent levels at Quebrada Fiera (central West Argentina). These remains extend the occurrence ofH. sulcatusback to the late Oligocene, and fill an important gap of the early record of Hegetotheriidae. [ABSTRACT FROM PUBLISHER]

Charophyte assemblages from the Qaidam Basin on the northern edge of the Tibetan Plateau were studied. The taxonomy of charophytes is based on a study of intraspecific gyrogonite polymorphism and biometric data. A total of 6 species belonging to 5 genera were identified, including Sphaerochara inconspicua Feist-Castel, 1977, Psilochara sp., Chara media Grambast, 1958, Lychnothamnus barbatus var. antiquus Soulié-Märsche, 1989, Lychnothamnus pinguis forma major (Grambast and Paul, 1965) Soulié-Märsche, 1989, Nitellopsi s (Tectochara) merianii (Braun ex Unger, 1852) Grambast and Soulié-Märsche, 1972. Lamprothamnium ganchaigouensis (Tang and Di, 1991) Li et al., 2020 and Lychnothamnus vectensis (Groves et al., 1926) Soulié-Märsche, 1989 have already been reported from the Xiaganchaigou Formation by Li et al. (2020). These Eurasian species allow direct correlation between Chinese and European basins. The distribution of these species in the Qaidam Basin is correlated to the high-resolution magnetostratigraphy of the Paleogene–Neogene sequence, ranging from > 52 Ma to ∼ 7 Ma at Dahonggou in the northern Qaidam Basin. N. (T.) merianii , with living representatives Nitellopsis obtusa , was reported to be expanded eastwards to Asia during the late Oligocene and Miocene. On the contrary, L. barbatus var. antiquus was found in the Oligocene (Chattian) of the Tibetan Plateau, representing the oldest record of this still living species. This may indicate that L. barbatus originated in Asia and expanded to other parts of Eurasia during the Miocene. • An Eocene to Miocene charophyte flora on the Tibetan Plateau was described. • A total of 6 species belonging to 5 genera were identified. • The age of flora is correlated to a high-resolution magnetostratigraphy. • Ancestor of living L. barbatus dispersed from Tibetan Plateau to Europe in Miocene. • A Eurasian distribution of Cenozoic flora in middle palaeolatitudes between ∼ 40° and ∼ 50° north latitude was found. [ABSTRACT FROM AUTHOR]

The Oligocene epoch represents a somewhat neglected chapter in paleoclimate and paleoceanographic history, which is at least partially due to the scarcity of complete Oligocene sedimentary archives and poor biostratigraphic age control. Many of the biotic events registered in Oligocene microfossils are strongly diachronous across latitudes as a response to increased global cooling and enhanced meridional temperature gradients. To improve biostratigraphic age control for the Oligocene of the North Atlantic Ocean, we carried out a high-resolution study of dinoflagellate cysts from Integrated Ocean Drilling Program (IODP) Sites U1405, U1406 and U1411 off Newfoundland. Together the sites comprise an apparently complete uppermost Eocene (34.9 Ma) to lowermost Miocene (21.7 Ma) sequence with good magnetostratigraphic age control. This allows us to firmly tie identified dinoflagellate cyst bioevents to the geomagnetic polarity timescale. In the dinoflagellate cyst assemblages studied we have identified and magnetostratigraphically-calibrated ten first and 19 last appearance datums. Our magnetostratigraphically-calibrated dinocyst-based biostratigraphy, which is based on an average sample resolution of a sample every ~ 150 kyrs, will contribute to an improved age framework for future paleoceanographical studies in the higher-latitude North Atlantic. [ABSTRACT FROM AUTHOR]

The Ulantatal area is well-known for its extraordinarily rich Oligocene mammalian fossils. The Ulantatal fauna was originally considered to be the representative fauna for the Chinese Land mammalian Age, Ulantatalian. However, the abundant fossils collected in the 1980s lack coordinates and/or detailed stratigraphic levels, and have been lumped together as either single, coeval fauna or grouped into three units. This lack of stratigraphic information hampers more precise biostratigraphic division and correlation of the faunas. Here we present a complete lithostratigraphic profile of the Ulantatal Formation with new fossil localities calibrated into the profile. Lithologically, the sequence shows a rather uniform pattern characterized by interbedded reddish to yellowish brown claystones and siltstones, with minor fine-grained sandstones. Preliminary biostratigraphic analysis shows that the Ulantatal Formation covers most of the Oligocene, and offers a long sequence and successive fossil records for understanding the evolution of mammal faunas after the critical Eocene/Oligocene transition. [ABSTRACT FROM AUTHOR]

The purpose of this study is lithostratigraphic investigation of Oligocene-Miocene salt deposits in the SE Persian Gulf. This study is based on lithostratigraphy and biostratigraphy data, gamma ray and sonic logs of nine drilled wells along southeast Persian Gulf to Strait of Hormuz. As a result, the Oligocene-Miocene deposits of this region were subdivided into four formations (Fms) which include Pabdeh Fm (Rupelian-Chattian), Asmari Fm (Rupelian-Aquitanian), Gachsaran Fm (Aquitanian) and Mishan Fm (Burdigalian). The salt and evaporated deposits situated between the Pabdeh and Gachsaran Fms which are assigned to the Aquitanian age. Finally the stratigraphical setting and distribution of the salt deposits are cleared. [ABSTRACT FROM AUTHOR]

Three deep exploration wells in the Palmyride area (Syria) have beendrilled through Oligocene and Eocene deposits. A detailed micropalaeontological investigation has been performed on the planktonic foraminiferal assemblage from drill cuttings. Standard planktonic foraminiferal zones from P15 to P22 (E15 to O6) have been identified.The test morphology and diversity of the foraminiferal assemblageindicate a general cooling trend during the late Eocene andOligocene. The specialized Eocene forms (K-mode life strategy) suchas turborotaliids, globigerinathekids and hantkeninids become extinctin the uppermost late Eocene. The Oligocene is characterized by thedominance of cooler, opportunistic planktonic foraminifera (r-modelife strategy), such as pseudohastigerinids, chiloguembelinids, globigerinids and tenuitellids. A very low number of benthic foraminiferain late Eocene cuttings implies sedimentation in a deep, open seaenvironment. A gradual increase of the benthic foraminiferal proportionthrough the Oligocene indicates shallowing of the sedimentaryenvironment.

Three research wells were cored near Cape Roberts, McMurdo Sound, during the summers of 1997, 1998 and 1999. Rich marine palynomorph assemblages were obtained from the early Miocene and Oligocene sediments, and almost immediately described at a reconnaissance level by the original on-site science team. In these studies, a number of undescribed species were reported, most strikingly of the distinctive dinoflagellate cyst genus Lejeunecysta . This report continues that work with the description of six new species: ? Cymatiosphaera robertsii , Lejeunecysta acuminata , Lejeunecysta attenuata , Lejeunecysta katatonos , Lejeunecysta rotunda , and Lejeunecysta striata . A new zonation comprising five marine palynomorph biozones is proposed, largely based upon the new taxa. The taxon ranges are derived from earlier published ranges with some minor updates. [ABSTRACT FROM AUTHOR]

The paleoenvironmental evolution and biostratigraphy of the Oligocene Vima Formation from the north-western Transylvanian Basin (Maramureș county, Romania) is presented based on planktonic and benthic foraminiferal assemblages. The deposits were assigned to late Rupelian–early Chattian ages, more precisely the Globigerina angulisuturalis – Chiloguembelina cubensis CRZ (O4) and Paragloborotalia opima HOZ (O5) Biozones. The ecological preference of benthic foraminifera and statistical treatment of the raw data set were used to identify relationships between assemblages and reconstruct the ancient environments. Paleobathymetrical estimates indicate a deposition of the sediments in outer shelf to upper bathyal settings. The shelf is characterized by alternating well oxygenated bottom waters and poor oxygen content indicated by low-oxygen tolerant taxa. The upper bathyal assemblages dominated by tubular agglutinated foraminifera suggest oligotrophic environments periodically disturbed by turbidite currents, while the whole agglutinated communities suggest undersaturated bottom waters in respect to calcium-carbonate and possible depletion in oxygen content due to water column stratification. Paleoclimatic reconstructions based on planktonic foraminifera suggest cool to temperate surface water temperatures with boreal influences. The younger deposits of the Fântânele section indicate a warming trend at the surface waters. The aggradational to progradational stacking pattern of the identified high-frequency sequences suggest a high stand systems tract under the control of the regional tectonics. [ABSTRACT FROM AUTHOR]

For the first time the Carnivora and the Perissodactyla from Aubenas-les-Alpes are studied. Five taxa are identified: two Carnivora, Nimravus intermedius and a medium-sized species of amphicyonid and three Perissodactyla Ronzotherium romani , Molassitherium albigense and Cadurcotherium cayluxi . The microflora shows a subtropical to Mediterranean climate with a marked dry season and indicates an age near the Rupelian-Chattian boundary for the site. [ABSTRACT FROM AUTHOR]

Nannofossil data from ODP Site 711 (equatorial Indian Ocean) yield a set of consistent, reliable biohorizons that form the basis of a revised calcareous nannofossil biostratigraphy for the low-latitude Eocene-Oligocene. We discuss 31 biohorizons occurring over an 11 myr time interval which we correlate to previous magnetostratigraphic data. Calcareous nannofossils from the middle Eocene through the lower Oligocene of the studied section are characterized by moderately well preserved assemblages consisting largely of low latitude and cosmopolitan species. A significant nannofossil dissolution interval is evidenced at the middle Eocene Climatic Optimum (MECO). We document a significant increase in late Eocene nannoplankton exhibiting a eutrophic preference. Analysis of the assemblage suggests important changes in the equatorial oceanic regime just before the onset of the Eocene-Oligocene transition (EOT), that foreshadow the more dramatic climatic shift of the early Oligocene. [ABSTRACT FROM AUTHOR]

We report the discovery of a new early Oligocene vertebrate fauna from the vicinity of Zallah Oasis in the Sirt Basin of central Libya. The Zallah Incision local fauna has been recovered from the base of a fluvial channel within a rock unit that has been mapped as “Continental and Transitional Marine Deposits.” This rock unit has produced fossil vertebrates sporadically since the 1960s, but the Zallah Incision local fauna is the most diverse assemblage of fossil mammals currently known from this unit. In addition to lower vertebrates, the fauna includes an indeterminate sirenian, the anthracothere Bothriogenys , a new species of the hyracoid genus Thyrohyrax , new species of the hystricognathous rodent genera Metaphiomys and Neophiomys , Metaphiomys schaubi , and a new species of the parapithecid primate genus Apidium . The Zallah Incision local fauna from Libya appears to be close in age to Fayum quarries V and G in the Jebel Qatrani Formation of Egypt and the Taqah locality in the Ashawq Formation of Oman. Considered together, these early Oligocene faunas support a modest level of faunal provincialism across the northern part of Afro-Arabia during the early Oligocene. [ABSTRACT FROM AUTHOR]

The systematic revision of the Rhinocerotoidea collected at Nuceto and Sassello (Northwestern Italy) enabled to recognize the presence of two species: Eggysodon cadibonense (Roger, 1898) and Molassitherium delemontense Becker and Antoine, 2013. E. cadibonense is only recorded at Sassello; a lectoype is selected for this species and its description is emended. E. cadibonense displays some morphological features close to those of E. pomeli and of E. gaudryi , but it is larger than these two species and is characterized by advanced features, such as the constriction of the metaloph and the presence of a well-developed crista. M. delemontense is recorded at Nuceto. The occurrence of this species suggests an Early-early Late Oligocene age for the Nuceto fossiliferous deposit. [ABSTRACT FROM AUTHOR]

Biostratigraphic studies of cuttings from wells located in the Lower Congo Basin, offshore northwestern Angola, document with unprecedented wealth of data the organic-walled dinoflagellate cyst (dinocyst) assemblages of the Malembo Formation. The identification of a series of dinocyst events (highest and lowest occurrences, influxes and acmes) recurring in the same stratigraphic position in different wells and cross-calibrated by calcareous nannofossil data, provides a tool for age control and correlation of the Oligocene and lower Miocene in the equatorial and South Atlantic region. Proceeding downwards in the stratigraphy of the examined succession, the lowest occurrence of Pyxidinopsis pastilliformis , detected within the CN3 nannofossil Zone, approximates the Langhian-Burdigalian boundary, whereas the lowest occurrences of Sumatradinuim druggii and Sumatradinium hispidum occur at the base of the CN2 nannofossil Zone in the Burdigalian. The lowest occurrences of Sumatradinium soucouyantiae and Barssidinium taxandrianum fall within the Zone of acme of Hystrichokolpoma rigaudiae at the Burdigalian-Aquitanian transition, and immediately above the acmes of Cribroperidinium tenuitabulatum and Systematophora - Cleistosphaeridium group that are supposed to reflect climate cooling pulse Mi-1a. The presence of Chiropteridium spp. and Membranophoridium aspinatum is limited to the upper part of the Chattian. An influx of Tuberculodinium vancampoae , possibly related to a warmer interlude during a period of overall climate cooling, occurs in proximity of the Chattian-Rupelian boundary. The nearly synchronous highest occurrences of Gerdiocysta conopeum , Eocladopyxis peniculata and Heterosphaeridium sp. provide a robust infra-Rupelian biohorizon. Further down in the Rupelian, the influxes of Pentadinium laticinctutm and Distatodinium paradoxum are interpreted as responses to cooling pulses. The lowest occurrence of G. conopeum , detected in the basal part of the NP23 nannofossil Zone, corresponds to the global first appearance of this excellent Rupelian marker. Genera Deflandrea and Wetzeliella are noticeably missing in the studied material just as they lack in some coeval dinocyst assemblages reported in the literature from low paleolatitude Atlantic sections. The recorded alternation of influxes and acmes of Gonyaulacoid dinocyst taxa indicative of cooler and warmer water conditions was probably climate-driven, i.e. paced by cooling pulses and relatively warmer interludes characterizing the climate evolution during the Oligocene and early Miocene. Indeed, the lack of acmes of Peridinioid cysts suggests that climate, rather than constantly elevated nutrient levels ensured by the Congo River discharge, was the discriminant factor triggering the observed blooms of Gonyaulacoid cyst-forming taxa. The delivery of large volumes of sands into deepwater settings via gravity-driven fluxes was favored by sea-level drops and is ultimately associated with pulses of climate cooling and Antarctic ice-sheet growth, finally reflected by the composition of the dinocyst assemblages. In addition to paleoecological factors, hydraulic fractionation resulting from sedimentary processes that transported palynomorphs down the slope as part of turbidite fluxes, contributed to shape the palynological assemblages observed in this study. • Ditch cuttings from 20 wells offshore Angola were investigated for biostratigraphy. • Palynoflora and calcareous nannoflora abound in the Oligocene-Miocene Malembo Fm. • A recurrent series of dinocyst events provides a tool for age control and correlation. • Dinocyst acmes were supposedly paced by climate cooling pulses and warmer interludes. • Hydraulic fractionation induced by turbidite fluxes shaped palynological assemblages. [ABSTRACT FROM AUTHOR]

We present a series of 13 paleogeographic maps representing development of the Waikato–King Country Basin through the Late Eocene to Early Miocene in central-western North Island when the New Zealand platform was undergoing widespread marine inundation. The maps are the end-point of a basin analysis of the Te Kuiti Group, which has included development of a revised lithostratigraphy, biostratigraphy, chronostratigraphy and the application of facies analysis. The new stratigraphic framework has identified six major unconformity-bound sequences within the Te Kuiti Group and the paleogeographic maps are drawn for time-slices through unconformities and systems tracts. A major unconformity between the Whaingaroa Formation and the Aotea Formation dated c. 29 Ma marks the start of reverse faulting on the Taranaki Fault. At c. 27 Ma, reverse displacement on the Manganui Fault started. Several phases of displacement on the Manganui Fault ensured that land persisted over part of the Herangi High throughout the Duntroonian (Ld) and Waitakian (Lw) Stages spanning the Late Oligocene and earliest Miocene. [ABSTRACT FROM PUBLISHER]

The onset of endorheic sedimentation in the Ebro Basin is a prominent feature of the basin’s evolution and has recently been characterized as a rapid event occurring in the Early Priabonian. In the north-eastern part of the basin this event coincides with the deposition of the Artés Formation (Fm.), mainly built up by red beds of alluvial origin. The marine-continental boundary has been poorly studied up to now in the so-called Lluçanès area, and what was previously thought to be the base of the Artés Fm. is actually a transitional unit, which we define as the Sant Boi Formation, which covers the underlying marine Milany Depositional Sequence and passes laterally to the Terminal Complex, extending over 15km along the eastern margin of the Ebro Basin. The Sant Boi Fm. is formed by up to 15-20m of alternating siltstones and lutite, grading upwards to brackish and lacustrine marls and lignite, and represents deposition in a brackish to freshwater floodplain. It is characterized biostratigraphically by the fossil charophyte assemblage Harrisichara lineata, Harrisichara vasiformis-tuberculata and Nodosochara jorbae, from the middle part of the Priabonian. In contrast, the overlying red beds of the Artés Fm. are characterized by assemblages containing Harrisichara tuberculata, Nodosochara jorbae and Lychnothamnus longus from the Late Priabonian. These results are largely consistent with recent magnetostratigraphic studies performed south of the studied area, and have enabled us to refine the stratigraphy of the marine-continental transition in the north-eastern Ebro Basin.

Since the '60s geologists discussed if the Tuscan Nappe includes the Macigno, the Mt. Modino Sandstone and the olistostromes interposed between these two clastic wedges or instead the foredeep deposits of the Tuscan Nappe is the Macigno and, therefore, the Mt. Modino Sandstone sedimented in a distinct basin and belongs to a different tectonic unit. One of the main difficulties to unravel the Macigno-Mt. Modino Sandstone relationships is the absence of continuous biostratigraphic records, helpful to date these formations and the underlying units. To fill this gap, a quantitative biostratigraphical analysis of calcareous nannofossils was performed on a large number of smear slides. The results confirm the stratigraphic continuity between the Tuscan Shale and the Macigno, and prove the stratigraphic continuity between the Fiumalbo Shale, the Marmoreto Marl and the Mt. Modino Sandstone (Mt. Modino Unit auctt.), supporting the tectonic superposition of the Mt. Modino Unit onto the Tuscan Nappe. In fact, the upper portion of the Tuscan Nappe ranges from the Late Eocene (MNP19/20) to the lower Miocene (MNN1c) and the Tuscan Shale-Macigno boundary lies within the upper Rupelian-Chattian (MNP24-MNP25a), whilst the sampled part of the Mt. Modino Unit spans in age the middle Eocene-lower Miocene (MNP15-MNN1c), and the Fiumalbo Shale-Marmoreto Marl and Marmoreto Marl-Mt. Modino Sandstone boundaries lie within the Rupelian (MNP23) and the uppermost Chattian (MNP25b-MNN1a).

This study analyses the regressive phase of the marine Froidefontaine Subgroup and the subsequent fluvio-lacustrine Niederroedern formation in the southern Upper Rhine Graben during the Late Rupelian and the position of the Rupelian/Chattian boundary. The study is based on the sedimentary record and several microfossil groups from two boreholes, with a focus on new records of fish otoliths, Bolboforma and Charophyta. The biostratigraphic evaluation of these groups provides evidence for a position of the Rupelian/Chattian boundary within the upper Niederroedern Formation. This is contrary to the results from a previous sedimentological approach, which places the boundary at the base of the Niederroedern Formation. The fish fauna indicates a biogeographic relation to southern France, the Molasse Basin of Switzerland and southern Germany. [ABSTRACT FROM AUTHOR]

The small sandpit “Chrummorge” on the Lägern hill (N-Switzerland) was searched for small mammal fossils. Bone fragments and about 100 teeth were retrieved while screen-washing of about 300 kg of Late Oligocene river channel-sands. Sedimentology indicates a probably meandering stream type, which likely followed a more erosional environment with tropical karsts and the formation of bolus-clay and iron ore. Even though, most of the micromammal teeth were rolled due to river transport before sedimentation, it was still possible to identify teeth of biostratigraphical importance, dating this new mammal assemblage to MP28/29 (about 24.6 ± 0.2 Ma). These Late Oligocene river channel sands are the oldest molasse sediments in the Lägern area, and they are in direct contact with Late Jurassic limestone. Thus they add important information for the reconstruction of the regional geological history. [ABSTRACT FROM AUTHOR]

The detailed micropaleontological analysis carried out on four offshore Oligocene (Tineh Formation) Nile Delta successions revealed the identification of 44 foraminiferal species and subspecies. Nine benthic and two planktonic zones are identified. The established benthic zonation has been chronostratigraphically calibrated with those based on the planktonic foraminiferal ones. This sequence is assigned to the Oligocene (Chattian), and possibly extends to the upper part ofRupelian. Are markable feature of thisOligocene succession is the almost complete absence of planktonic foraminifera in its major lower part, a situation that caused a difficulty of subdividing it into smaller units. The environmental interpretation for theOligocene succession implies deposition under a background of persistent subsidence with remarkable paucity or complete absence of any calcareous fauna, probably related to deposition in carbon dioxide-rich marine conditions hostile to the precipitation of any calcareous material and caused by volcanic activity, lowered temperature or situation under the lysocline or carbonate-compensation depth. [ABSTRACT FROM AUTHOR]

Six late Rupelian populations ofNephrolepidina praemarginata(Douvillé, 1908) have been isolated from a succession of the Caltavuturo Formation (Madonie Mts, Sicily). A total of 25 embryonal parameters were obtained from oriented equatorial sections of megalospheric specimens; 8 indexes were derived from selected parameters and 9 indexes were considered for the neanic apparatus, out of which 2 are introduced here:N05(number of annuli in a radius of 0.5 mm) andr5(distance occupied by the first five annuli). The data show marked deviations from the expected trend of traditional biometric measures; this is interpreted as dependent on environmental factors. Previous studies on the succession evidenced an increase in basin depth; this can be inferred also from the biometric analysis of the inner characters of the allochthonousNephrolepidinatests. Here, we explore the paleobiological potential of parameters linked to embryo size and wall thickness, and discuss how depth-dependent parameters may affect the interpretation of evolutionary trends and biostratigraphy in radial foraminifers. [ABSTRACT FROM AUTHOR]

The aim of the present work is to describe the Oligocene (Rupelian-early Chattian) shallow water larger foraminifera from central Turkey (Sivas Basin). Among them is a new miliolid genus, Sivasina n. gen. SİREL & ÖZGEN-ERDEM (type species Sivasina egribucakensis n. gen. n. sp. SİREL & ÖZGEN-ERDEM), which occurs in the Eğribucak, Bakımlı, Tuzlagözü and Çaygören sections (E of Sivas). One new Rupelian-early Chattian lagoonal very shallow water peneroplid species Peneroplis flabelliformis n. sp. SİREL & ÖZGEN-ERDEM from the Eğribucak, Tuzlagözü and Çaygören sections and Rupelian lagoonal two new peneroplid species Coscinospira sivasensis n. sp. SİREL & ÖZGEN-ERDEM, Coscinospira elongata n. sp. SİREL & ÖZGEN-ERDEM from the Eğribucak section (E of Sivas), two new Rupelian very shallow water alveolinid species Praebullalveolina oligocenica n. sp. SİREL & ÖZGEN-ERDEM and Praebullalveolina minuta n. sp. SİREL & ÖZGEN-ERDEM from the Bakımlı section are described and figured. Furthermore, details on several already known Oligocene species are given (soritids: Praearchaias diyarbakirensis SİREL, Praearchaias minimus SİREL, Archaias kirkukensis HENSON, Archaias asmaricus SMOUT & EAMES; austrotrillinids: Austrotrillina brunni MARIE). In addition, the biostratigraphy of four studied sections is discussed. [ABSTRACT FROM AUTHOR]