Dicarinella Concavata Research Articles

Biostratigraphy and Sequence Stratigraphy of the Gurpi Formation at Deh Dasht Area, Zagros Basin, SW Iran

A rich assemblage of planktonic foraminifera has been studied from an outcrop of the Gurpi Formation, the hydrocarbon source rock in the southwest Iran, Deh Dasht area (Kuh-e Siah anticline). Based on the distribution of the planktonic foraminifera, eight biozones have been recognized that included: Dicarinella concavata Interval Zone (Earliest Santonian), Dicarinella asymetrica Total Range Zone (Santonian to Earliest Campanian), Globotruncanita elevata Partial Range Zone (Early Campanian), Globotruncana ventricosa Interval Zone (Middle to Late Campanian), Radotruncana calcarata Total Range Zone (Late Campanian), Globotruncanella havanensis Partial Range Zone (Late Campanian), Globotruncana aegyptiaca Interval Zone (Late to latest Campanian), Gansserina gansseri Interval Zone (Latest Campanian to Early Maastrichtian). These biozones indicates that the Gurpi Formation deposited during the Early Santonian- Early Maastrichtian. These biozones are compared to the most standard biozones defined in Tethysian domain. Based on distribution of morphotype groups of planktonic foraminifera, planktonic to benthic ratio (P/B) and content of carbonate, nine third-order sequences are recognized.

Marine palynology of the Oceanic Anoxic Event 3 (OAE3, Coniacian – Santonian) at Tarfaya, Morocco, NW Africa – transition from preservation to production controlled accumulation of marine organic carbon

The paper presented is the first comprehensive, fully quantitative, high resolution study of marine palynology from an OAE3 black-shale environment. It is based on 175 m core spanning the upper Turonian to lower Santonian at Tarfaya, Morocco, NW Africa, which has been sampled from centimetre to 3 m intervals. The results are integrated and discussed with lithology and geochemistry data to (1) distinguish between potential changes in production and preservation of total organic carbon (TOC) accumulation and (2) constrain the stratigraphic position of the Oceanic Anoxic Event 3 (OAE3).The succession is characterized by increased total organic carbon (TOC), varying between 1% and 19% (average about 6%). Distinct black-shale horizons of variable thickness appear episodically throughout the succession, with higher frequency in the late Turonian. Higher TOC contents do not strictly correlate to lithologic black-shales or peaks of a specific taxon of organic-walled algae. The palynomorph spectrum is strongly dominated by organic-walled algae, with the ratio of terrigenous sporomorphs to organic-walled algae (t/m index) varying between zero and 0.05 (average 0.01). The dominance of algal organic matter is corroborated by the prevalence of Type I kerogen identified using Rock-Eval pyrolysis. Dinocyst diversity is low, with the absolute taxa number varying from 7 to 27 between single samples. The peridinioid/gonyaulacoid ratio of dinocysts (p/g ratio) shows strong fluctuations, varying between 1 and 283 (average of about 100).The upper Turonian interval is dominated by Bosedinia spp., a dinocyst taxon formerly described as abundant only in lacustrine sediments from the Oligocene and Miocene of SE Asia. This dominance is episodically modified by the increase of the warm-temperate waters dinocysts fraction, here mainly represented by the genera Alterbidinium, Isabelidinium and Spinidinium. Within the Coniacian-Santonian, black-shale horizons are limited in number and are concentrated within the upper Coniacian to lower Santonian interval. The dinocysts show alternating, prominent peak abundances of Palaeohystrichophora spp. and the warm-temperate water dinocysts fraction, here mainly represented by the genera Trithyrodinium and Chatangiella. However, a final episode of increased proportions of Bosedinia spp. is confined to a 5 m thick black-shale horizon closely spanning the Coniacian-Santonian boundary.Changes in the ratio of total sulphur to total organic carbon (TS/TOC) reflect fluctuating oxygen contents of bottom waters throughout the late Turonian to Santonian. These are significantly parallelled by the alternation of dinocysts assemblages suggestive of enhanced upwelling and water column stratification respectively, probably reflecting changes in the mode of TOC accumulation. Accordingly, preservation largely prevails during the late Turonian interval and changes towards increased production within the Coniacian-Santonian. However, a final preservation-event is probably represented by the black-shale horizon closely spanning the Coniacian-Santonian boundary (top Dicarinella concavata foraminifera zone), which may reflect an episodic shutdown of a major upwelling cell. It is thus proposed, that the “culmination” of the OAE3 at Tarfaya may represent intermittent preservation of TOC within an otherwise high productivity environment related to a global cooling trend.

The Lindi Formation (upper Albian–Coniacian) and Tanzania Drilling Project Sites 36–40 (Lower Cretaceous to Paleogene): Lithostratigraphy, biostratigraphy and chemostratigraphy

The 2009 Tanzania Drilling Project (TDP) expedition to southeastern Tanzania cored a total of 572.3m of sediments at six new mid-Cretaceous to mid-Paleocene boreholes (TDP Sites 36, 37, 38, 39, 40A, 40B). Added to the sites drilled in 2007 and 2008, the new boreholes confirm the common excellent preservation of planktonic and benthic foraminifera and calcareous nannofossils from core samples that will be used for biostratigraphy, evolutionary studies, paleoceanography and climatic reconstructions from the Tanzanian margin, with implications elsewhere. The new sites verify the presence of a relatively expanded Upper Cretaceous succession in the region that has allowed a new stratigraphic unit, named here as the Lindi Formation (Fm), to be formally defined. The Lindi Fm (upper Albian to Coniacian), extending ∼120km between Kilwa and Lindi, comprises a 335-m-thick, outer-shelf to upper-slope unit, consisting of dark gray claystone and siltstone interbeds, common finely-laminated intervals, minor cm-thick sandstones and up to 2.6% organic carbon in the Turonian. A subsurface, composite stratotype section is proposed for the Lindi Fm, with a gradational top boundary with the overlying Nangurukuru Fm (Santonian to Maastrichtian) and a sharp bottom contact with underlying upper Albian sandstones.The section cored at TDP Sites 36 and 38 belongs to the Lindi Fm and are of lower to middle Turonian age (planktonic foraminifera Whiteinella archaeocretacea to Helvetoglobotruncana helvetica Zones and nannofossils subzones UC6b±UC7). The lower portion of TDP Site 39 (uppermost part of the Lindi Fm) is assigned to the lower to upper Coniacian (planktonic foraminifera Dicarinella concavata Zone and nannofossils zone UC 10), while the remaining part of this site is attributed to the Coniacian–Santonian transition and younger Santonian (planktonic foraminifera D. asymetrica Zone and upper part of nannofossils zone UC10). TDP Site 37 recovered relatively expanded (150m thick), monotonous calcareous claystones from the lower to upper Maastrichtian (planktonic foraminifera Pseudoguembelina palpebra to Abathomphalus mayaroensis Zones and nannofossils zones UC19 to UC20aTP) that were separated by a hiatus and/or a faulted contact from overlying brecciated carbonates of the Selandian (middle Paleocene: PF Zone P3 and nannofossil zone NP5). The lower portion of TDP Sites 40A and 40B recovered sandstones and conglomerates barren of microfossils. Their overlying parts were assigned to incomplete sections of the nannofossil zones NC6A to NC8 (uppermost Barremian to lower Albian). Benthic foraminiferal assemblages allowed the Barremian to lower Aptian to be identified in TDP Sites 40A and 40B, while the upper Aptian to middle Albian (Hedbergella trocoidea to Ticinella primula Zones) were assigned using planktonic foraminifera. Cores recovered at TDP 39 (Coniacian–Santonian) and at TDP Sites 40A and 40B (Barremian–middle Albian) represent the first time that these two intervals have been continuously cored and publicly documented in Tanzania.Bulk sediment isotope records generated for the new sites show lower δ18Ocarb values in the Turonian and Santonian (∼−3.5‰ to −5‰) than in the Maastrichtian (∼−3‰), a situation consistent with extreme global warmth in the older intervals and cooling toward the end of the Cretaceous. Also, similar to Turonian sites from previous TDP expeditions, a negative δ13Corg excursion was detected across the W. archaeocretacea–H. helvetica boundary of TDP Site 36 (close to, but above, the Cenomanian-Turonian boundary). This excursion probably responded to local processes in the region, but it is unknown whether they were related to the recovery phase from Ocean Anoxic Event 2.

Late Cretaceous-Early Paleogene (Turonian? to early Danian) planktic foraminifera from DSDP site 356: a biostratigraphic reappraisal

Biostratigraphic results obtained with a systematic study of the planktic foraminiferal assemblages recovered from Upper Cretaceous-Lower Paleogene strata (Turonian? to early Danian in age) of Deep Sea Drilling Program (DSDP) Site 356, Sao Paulo Plateau, are presented and discussed herein. Fifty-nine planktic foraminiferal species were identifi ed within the studied interval, enabling the identifi cation of 11 planktic foraminiferal zones (Turonian? to early Danian in age): Marginotruncana schneegansi, Dicarinella concavata, Dicarinella asymetrica, Globotruncanita elevata, Contusotruncana plummerae, Radotruncana calcarata, Globotruncanella havanensis, Pseudoguembelina palpebra, Abathomphalus mayaroensis, Pseudoguembelina hariaensis and Pα. An unconformity spanning at least 0.96 Ma could also be suggested within core 31 (Maastrichtian in age), due to the absence of the Racemiguembelina fructicosa Interval Zone from the studied section. High sedimentation rates were estimated within the Santonian (Dicarinella asymentrica Total-range Zone) and the uppermost Maastrichtian (Pseudoguembelina hariaensis Interval Zone) of DSDP site 356, while lower and more constant values were suggested for the Campanian-lower Maastrichtian interval (Globotruncanita elevata Partial-range Zone to Pseudoguembelina palpebra Interval Zone). The reliability in identifying the Contusotruncana plummerae Interval Zone (Campanian in age) in Cretaceous sections of the South Atlantic Ocean is confi rmed herein.

Late Coniacian- Early Campanian planktonic foraminiferal bioevents and biostratigraphy of the northern Tunisia

Planktonic foraminifera were quantitatively analyzed across the Upper Coniacian - Lower Campanian succession at Jebel Ennahli and Ettout sections, northern Tunisia. This succession is characterized by hemipelagic facies domainated by a continuous sedimentary succession, allowing a good biostratigraphic correlation for this time interval. 55 planktonic foraminiferal species have been identified belonging to 13 genera. The distribution pattern of 17 heterohelicids and 38 trochospiral forms reveals to the identification of12 major bio-events and establishing three zones based on heterohelicids and five zones based on trochospiral forms. The trochospiral based zones are from base to top: Dicarinella primitiva Interval Zone, Dicarinella concavata Interval Zone, Dicarinella asymetrica Total Range Zone, and Globotruncanita elevata/Globotruncana arca Concurrent Range Zone, Globotruncana ventricosa Interval Zone; while the three heterohelicid based planktonic foraminiferal biozones are: Pseudotextularia nuttalli Interval Zone, Sigalia carpatica Interval Zone, Ventilabrella eggeri/Planoglobulina manuelensisConcurrent Range Zone. The bioevents and planktonic foraminiferal zones were correlated with the previously published works especially in Tunisia and other palaeolatitude provinces. There are no significant planktonic foraminiferal datums recorded across the Coniacian/Santonian boundary (CSB) except the lowest occurrence (LO) of Dicarinella asymetrica, which was recorded slightly below the LO of inoceramid Platyceramus cycloides cycloides representing a good proxy for the CSB. The Santonian/Campanian boundary of the studied sections are characterized by a major turnover represented by the highest occurrence of Sigalia, Dicarinella and Whiteinella genera; in addition to the lowest occurrence of Ventilabrella and Planoglobulina genera and above slightly the LO Globotruncana and Globotruncanita.

Planktonic foraminiferal biostratigraphy and paleoecology of Upper Cretaceous deposits from the Palmyride Region, Syria

Planktonic foraminifera were quantitatively analyzed across the Upper Coniacian - Lower Campanian succession at Jebel Ennahli and Ettout sections, northern Tunisia. This succession is characterized by hemipelagic facies domainated by a continuous sedimentary succession, allowing a good biostratigraphic correlation for this time interval. 55 planktonic foraminiferal species have been identified belonging to 13 genera. The distribution pattern of 17 heterohelicids and 38 trochospiral forms reveals to the identification of12 major bio-events and establishing three zones based on heterohelicids and five zones based on trochospiral forms. The trochospiral based zones are from base to top: Dicarinella primitiva Interval Zone, Dicarinella concavata Interval Zone, Dicarinella asymetrica Total Range Zone, and Globotruncanita elevata/Globotruncana arca Concurrent Range Zone, Globotruncana ventricosa Interval Zone; while the three heterohelicid based planktonic foraminiferal biozones are: Pseudotextularia nuttalli Interval Zone, Sigalia carpatica Interval Zone, Ventilabrella eggeri/Planoglobulina manuelensis Concurrent Range Zone. The bioevents and planktonic foraminiferal zones were correlated with the previously published works especially in Tunisia and other palaeolatitude provinces. There are no significant planktonic foraminiferal datums recorded across the Coniacian/Santonian boundary (CSB) except the lowest occurrence (LO) of Dicarinella asymetrica , which was recorded slightly below the LO of inoceramid Platyceramus cycloides cycloides representing a good proxy for the CSB. The Santonian/Campanian boundary of the studied sections are characterized by a major turnover represented by the highest occurrence of Sigalia , Dicarinella and Whiteinella genera; in addition to the lowest occurrence of Ventilabrella and Planoglobulina genera and above slightly the LO Globotruncana and Globotruncanita .

Chronostratigraphy of the Upper Cretaceous high productivity sequence of the southern Tethys, Israel

The Levantine high productivity sequence is a product of an extensive upwelling system that operated in the Late Cretaceous along the SE Tethyan margin. This system resulted in the deposition of a unique sequence of carbonate, chert, porcellanite, phosphorite and organic-rich (oil shale) sediments in a series of basins located proximally and marginally to the upwelling center. This study presents a detailed and updated chronostratigraphic framework for the high productivity sequence in Israel based on eight sections covering a N–S cross section of ∼90 km. The Shefela Basin (central Israel) represents the thickest and the most complete penetrated stratigraphic interval of the oil shale deposits in Israel. The newly drilled Aderet borehole in the Shefela Basin provided a continuous core record coupled with high quality geophysical well logs and was used in this study as a ‘type-section’ for the detailed chronostratigraphic scheme of the high productivity sequence. A total of 23 datum levels were recognized using planktic and benthic foraminiferal biostratigraphy, lithostratigraphy and gamma ray well log markers. The varying lithostratigraphic units (containing chert, phosphate, porcellanite and organic-rich carbonates) of the more proximal basins of southern Israel (Negev) were individually correlated to specific horizons within the monotonous organic-rich carbonates of the distal setting of the Shefela Basin.The first occurrence of the Late Cretaceous organic-rich carbonates in Israel is documented in the Negev during the late Coniacian, within the upper Dicarinella concavata Zone, and corresponds chronologically to the upper part of the lower Menuha Formation. The regional unconformity around the Santonian/Campanian boundary was found to be less substantial at the distal localities in comparison to the proximal ones. The distinct appearance of the ‘Mishash Tongue’ chert in the Shefela was correlated to the massive Chert Member (Mishash Formation) in the Negev, and assigned to the middle Campanian. Deposition of the overlying phosphate series spans from the lower Contusotruncana plummerae to the base of the Pseudoguembelina palpebra Zones (78.3–71.7 Ma) and co-occurs in both proximal and deeper distal areas, although in a much lesser magnitude in the latter. The top of the phosphatic unit is marked by a regional unconformity. The oil shale deposits in southern Israel coincide with the 100 m richest TOC interval (average of 15.2 wt.% TOC) in the Shefela. The diminishing phase of organic-rich deposition occurred in a diachronous step-wise manner across Israel, from the top of the P. palpebra Zone to the upper part of the Abathomphalus mayaroensis Zone in southern and central Israel, respectively. This indicates that the full duration of the high productivity sequence in Israel spans approximately 19 myr.Arabian Plate-wide maximum flooding surfaces (MFS) recorded during the Tectonic Mega-Sequence (TMS) AP9 timeframe (92–63 Ma) are identified here in the local sedimentary system of the Levant: K160 signifying the onset of organic-rich carbonates; K170 at the upper part of the massive and brecciated Chert Member; and K180 marking the diminishing phase of the high productivity sequence in Israel.

Biozonation and Paleobathymetry on Foraminifera Upper Cretaceous Deposites of Central Iran Basins (Isfahan, Baharestan Section)

In this study Late Cretaceous stratum in central Iran, Baharestan section in Isfahan area, was evaluated by biozonation and paleobathymetry. These sediments have 89 meters thick, and strata have been formed of marl and marl limestone. In order to indicate the ancient depth of Upper Cretaceous at this time, planktonic and benthic foraminifera were studied. The percentage of the total planktonic foraminifera to the whole sample of foraminifera after the removal of indwell benthic foraminifera (%P*) using the formula D = e(3.58718 + (0.03534 × %P*)) was identified and depth of 200 - 450 meters was achieved for them. In the present investigation, 30 planktonic species of 11 genus have been identified. The Upper Cretaceous deposit was divided to 6 biozones on the basis of planktonic foraminifera which are cosmopolitan and consist of: Biozone 1—Marginotruncana sigali-Dicarinella primitiva partial range zone; Biozone 2—Dicarinella concavata interval zone; Biozone 3—Dicarinella asymetrica total range zone; Biozone 4—Globotruncanita elevata partial range zone; Biozone 5—Globotruncana ventricosa interval zone; Biozone 6—Radotruncana calcarata interval zone. Based on planktonic foraminifera, the Upper Cretaceous sediments in the study area are of the Turonian-Late Campanian ages.

Integrated biostratigraphy and stage boundaries of the Abderaz Formation, east of the Kopeh-Dagh sedimentary basin, NE Iran

The foraminiferal content of the well-known, foraminifera-rich Abderaz Formation of the Kopeh-Dagh basin in northeastern Iran was analyzed to determine biostratigraphy, age dating, chronostratigraphy and evolutionary trends. The Abderaz Formation was sampled at the following four sections: the Qarehso section, the Abderaz village section, the Muzduran section and the Shorab section. The Qarehso section is approximately 540 m thick and consists of 77 planktonic foraminifera species belonging to 18 genera in 5 biozones, 10 echinoid species belonging to 4 genera and 8 inoceramid species belonging to 5 genera. Based on this fossil content, the Qarehso section was dated to the lowermost Turonian to the upper Santonian. Based on the first occurrence datums of Cremnoceramus walterdorfensis walterdorfensis and Cremnoceramus deformis deformis and on the FODs of Micraster cortestudinarium and Dicarinella concavata, the Turonian–Conician boundary was detected in this section. In addition, based on the FODs of Echinocorys gr. scutata forma vulgaris, Echinocorys gr. scutata forma vulgaris-planodama and Di. Asymetrica, the base of the Santonian stage was also detected in the Qarehso section. The Abderaz village section is 556.5 m thick and contains 17 genera and 68 species of planktonic foraminifera that have been identified in 9 biozones and 7 genera and 15 species of invertebrates. The lowermost Turonian to the lowermost Campanian ages have been established in the Abderaz Formation. In the Abderaz village section, 3 boundaries were identified. Based on the FODs of Cremnoceramus walterdorfensis walterdorfensis, C. deformis deformis and C. crassus crassus and on the FODs of Contusotruncana fornicata and C. pateliformis, the base of the Coniacian stage was identified. Based on the FODs of Di. asymetrica and Macroglobigerinelloides alvarezi, the Coniacian–Santonian boundary was identified. Additionally, based on the extinction of the Marginotruncanid group and on the LOD of Pseudotextularia nuttalii, the base of the Campanian stage was identified. The Muzduran section of the Abderaz Formation is 400 m thick and contains 59 planktonic foraminifera species belonging to 19 genera, 10 inoceramid species belonging to 5 genera, 5 echinoid species belonging to 3 genera and 2 ammonite species belonging to 2 genera. Also based on this fossil content, the age of the formation is estimated to be the middle Turonian–early Campanian. In the Muzduran section, the base of the Coniacian stage was detected just below the first occurrence of C. deformis deformis, whereas the bases of the Santonian and Campanian stages were found at the first occurrence of Echinocorys ex gr. scutata and the LOD of the Marginotruncanids groups and of Ventilabrella austiniana, respectively. The Shorab section is 360 m thick. In this section, 51 planktonic foraminifera species belonging to 16 genera were identified, and 5 biozones were differentiated. In addition, 1 ammonite species and 8 inoceramid species belonging to 4 genera were found in this section. Based on this fossil assemblage, the age of the Shorab section dates to the lowermost Turonian–early Campanian. In this section, the study of macro- and microfauna shows three boundaries: the Turonian–Coniacian, Coniacian–Santonian and Santonian–Campanian boundaries. The base of the Coniacian stage was identified based on the FODs of the planktonic foraminifera Archaeoglobigerina cretacea and Dicarinella concavata, along with the FOD of Cremnoceramus walterdorfensis walterdorfensis of the inoceramid group, whereas the base of the Santonian stage was determined using the LOD of Dicarinella primitiva of the Whiteinellids group and the FODs of Dicarinella asymetrica and Inoceramus aff. vistulensis (an inoceramid species). The FODs of Globotruncanita elevata and Ventilabrella austiniana, along with the extinction of the Marginotruncanid group, were used to identify the base of the Campanian stage in the Shorab section.

Biostratigraphy of the Tethyan cretaceous successions from northwestern Zagros fold–thrust belt, Kurdistan region, NE Iraq

Nineteen benthonic and planktonic foraminiferal zones and their subzones have been recognized in the Tethyan cretaceous successions along the four sections analyzed in the northwestern Zagros fold–thrust belt within the preforeland–foreland basin. A detailed micropaleontological investigation revealed eight benthonic zones from the Qamchuqa Formation (Barremian to Lower Early Cenomanian) including: the Choffatella decipiens interval zone, C. decipiens/Palorbitolina lenticularis total range zone, C. decipiens/Salpingoporella dinarica interval zone, Mesorbitolina texana total range zone, Mesorbitolina subconcava total range zone, Orbitolina qatarica total range zone, Orbitolina sefini total range zone, and the Orbitolina concava partial range zone. The Rotalipora cushmani total range zone was recorded in the Dokan Formation that overlies the Qamchuqa Formation of the Late Cenomanian age. The Gulneri Formation is represented only by the Whitnella archaeocretacea partial range zone/Heterohelix moremani total range subzone and indicates the Late Cenomanian/Early Turonian age. Six planktonic foraminiferal zones were recorded from the Kometan Formation, indicating the Late Cenomanian to Early Campanian age, and are represented by the R. cushmani/H. moremani subzone, Helvetotruncana helvetica total range zone, Marginotruncana sigali partial range zone, Dicarinella primitiva interval range zone, Dicarinella concavata interval zone, Dicarinella assymetrica total range zone, and Globotruncanita elevata partial range zone. Two planktonic foraminferal zones were recorded also and these are related to the Globotruncana (fornicata, stuartiformis, elevata, and ventricosa) assemblage zone, Globotruncana calcarata total range subzone, from the Shiranish Formation, Lower Late Campanian, while the second zone is nominated as the Globotruncana (arca, tricarinata, esnehensis, and bahijae) assemblage zone, Globotruncana gansseri interval subzone, and Globotruncana contusa total range zone of the Late Campanian to basal middle Maastrichtian age. The last zone is related to the Abathomphalus mayaroensis partial range zone (of Late Maastrichtian age) and occasionally intercalated with the Orbitoides–Loftusia benthic zones. An important hiatus, between the Qamchuqa and Kometan formations was proved and manifests Pre-Aruma unconformity, and is occasionally associated with the global Cenomanian–Turonian Oceanic Anoxic Euxinic Event, while the Maastrichtian red bed of the Shiranish Formations mostly points to Tethyan upper Cretaceous Oceanic Red Bed.

Integrated biostratigraphy of the Upper Cretaceous Abderaz Formation of the East Kopet Dagh Basin (NE Iran)

Based on planktonic foraminifera, inoceramids and echinoids, we present a detailed biostratigraphic analysis of the Abderaz Formation at the 606 m thick Padeha section, NE Iran. This sequence consists mainly of gray shales and marls with four levels of chalky limestones intercalated. The lower boundary of the Abderaz Formation with the Aitamir Formation is a paraconformity, while the upper boundary with the Abtalkh Formation represents a gradual transition. Fifty four species of planktonic foraminifera from 15 genera were identified, and five zones were recognized, namely: Whiteinella archaeocretacea (Bolli) Partial-Range-Zone; Helvetoglobotruncana helvetica (Sigal) Total-Range-Zone; Marginotruncana schneegansi (Dalbiez) Interval-Range-Zone; Dicarinella concavata (Brotzen) Interval-Range-Zone; and Dicarinella asymetrica (Sigal) Total-Range-Zone. Based on these data, the age of the Abderaz Formation is determined as earliest Turonian to earliest Campanian. Inoceramid bivalves Cremnoceramus walterdorfensis walterdorfensis (Andert) and Cremnoceramus deformis deformis (Meek) were identified in the uppermost Turonian and in the middle part of the early Coniacian, respectively. Echinocorys ex. gr. scutata and Cordiceramus sp. were recorded near the Coniacian/Santonian boundary.

Lithostratigraphy, biostratigraphy and chemostratigraphy of Upper Cretaceous and Paleogene sediments from southern Tanzania: Tanzania Drilling Project Sites 27–35

The 2008 Tanzania Drilling Project (TDP) expedition recovered common planktonic foraminifera (PF), calcareous nannofossils (CN) and calcareous dinoflagellates with extraordinary shell preservation at multiple Cenomanian–Campanian sites that will be used for paleoclimatic, paleoceanographic, and biostratigraphic studies. New cores confirm the existence of a more expanded and continuous Upper Cretaceous sequence than had previously been documented in the Lindi and Kilwa regions of southeastern coastal Tanzania. This TDP expedition cored 684.02m at eight Upper Cretaceous sites (TDP Sites 28–35) and a thin Paleocene section (TDP Site 27).TDP Sites 29, 30, 31 and 34 together span the lowermost Turonian to Coniacian (PF Whiteinella archaeocretacea to Dicarinella concavata Zones and CN Zones UC6a–9b), with TDP Site 31 being the most biostratigraphically complete Turonian section found during TDP drilling. A discontinuous section from the Santonian–upper Campanian (PF D. asymetrica to Radotruncana calcarata Zones and CN Zones UC12–16) was collectively recovered at TDP Sites 28, 32 and 35, while thin sequences of the lower Cenomanian (PF Thalmanninella globotruncanoides Zone and CN subzones UC3a–b) and middle Paleocene (Selandian; PF Zone P3a and CN Zone NP5) were cored in TDP Sites 33 and 27, respectively. Records of δ13Corg and δ13Ccarb from bulk sediments generated for all the Cretaceous sites show largely stable values through the sections. Only a few parallel δ13Corg and δ13Ccarb shifts have been found and they are interpreted to reflect local processes. The δ18Ocarb record, however, is consistent with Late Cretaceous cooling trends from the Turonian into the Campanian. Lithologies of these sites include thick intervals of claystones and siltstones with locally abundant, finely-laminated fabrics, irregular occurrences of thin sandstone layers, and sporadic bioclastic debris (e.g., inoceramids, ammonites). Minor lithologies represent much thinner units of up to medium-grained, massive sandstones. The %CaCO3 (∼5–40%) and %Corg (∼0.1–2%) are variable, with the highest %CaCO3 in the lower Campanian and the highest %Corg in the Turonian. Lithofacies analysis suggests that deposition of these sediments occurred in outer shelf-upper slope, a setting that agrees well with inferences from benthic foraminifera and calcareous dinoflagellates.

Upper Cretaceous volcanoclastic-sedimentary formations in the Timok Eruptive Area (eastern Serbia): new biostratigraphic data from planktonic foraminifera

Upper Cretaceous volcanoclastic-sedimentary formations in the Timok Eruptive Area (eastern Serbia): new biostratigraphic data from planktonic foraminifera The biostratigraphy of the Upper Cretaceous volcanoclastic-sedimentary formations cropping out in the Timok Eruptive Area of the eastern Serbian Carpatho-Balkanides is presented. Four lithostratigraphic units of formation rank are recognized in the Timok area: Stublica Clastics (Upper Albian/Cenomanian), Oštrelj (Lower Turonian/Santonian), Bor Clastics (Campanian/Maastrichtian) and Bukovo (Campanian/?Maastrichtian). Forty two species of planktonic foraminifera have been determined in the studied area. Eight planktonic foraminiferal zones of Middle Cenomanian through Middle Campanian age have been recognized. These are: Thalmanninella reicheli Interval Zone (Middle Cenomanian), Rotalipora cushmani Taxon Range Zone (Upper Cenomanian), Helvetoglobotruncana helvetica Taxon Range Zone (Lower Turonian), Marginotruncana sigali-Dicarinella primitiva Interval Zone (Upper Turonian to lowermost Coniacian), Dicarinella concavata Interval Zone (Lower Coniacian to lowermost Santonian), Dicarinella asymetrica Taxon Range Zone (Santonian), Globotruncanita elevata Interval Zone (Lower Campanian) and the Globotruncana ventricosa Interval Zone (Middle Campanian). The scarcity or lack of zonal species in the Lower Cenomanian and Upper Campanian/Maastrichtian strata prevents recognition of the nominal zones. The Upper Cretaceous planktonic foraminiferal zones from the Timok Eruptive Area are correlated with coeval zones from adjacent regions of Bulgaria and Romania and from other Tethyan regions.

Larger foraminifera distribution and strontium isotope stratigraphy of the La Cova limestones (Coniacian–Santonian, “Serra del Montsec”, Pyrenees, NE Spain)

The Upper Cretaceous La Cova limestones (southern Pyrenees, Spain) host a rich and diverse larger foraminiferal fauna, which represents the first diversification of K-strategists after the mass extinction at the Cenomanian–Turonian boundary. The stratigraphic distribution of the main taxa of larger foraminifera defines two assemblages. The first assemblage is characterised by the first appearance of lacazinids ( Pseudolacazina loeblichi) and meandropsinids ( Eofallotia simplex), by the large agglutinated Montsechiana montsechiensis, and by several species of complex rotalids ( Rotorbinella campaniola, Iberorotalia reicheli, Orbitokhatina wondersmitti and Calcarinella schaubi). The second assemblage is defined by the appearance of Lacazina pyrenaica, Palandrosina taxyae and Martiguesia cyclamminiformis. A late Coniacian-early Santonian age was so far accepted for the La Cova limestones, based on indirect correlation with deep-water facies bearing planktic foraminifers of the Dicarinella concavata zone. Strontium isotope stratigraphy, based on many samples of pristine biotic calcite of rudists and ostreids, indicates that the La Cova limestones span from the early Coniacian to the early-middle Santonian boundary. The first assemblage of larger foraminifera appears very close to the early-middle Coniacian boundary and reaches its full diversity by the middle Coniacian. The originations defining the second assemblage are dated as earliest Santonian: they represent important bioevents to define the Coniacian-Santonian boundary in the shallow-water facies of the South Pyrenean province. By means of the calibration of strontium isotope stratigraphy to the Geological Time Scale, the larger foraminiferal assemblages of the La Cova limestones can be correlated to the standard biozonal scheme of ammonites, planktonic foraminifers and calcareous nannoplankton. This correlation is a first step toward a larger foraminifera standard biozonation for Upper Cretaceous carbonate platform facies.

Lithostratigraphy, biostratigraphy and chemostratigraphy of Upper Cretaceous sediments from southern Tanzania: Tanzania drilling project sites 21–26

The 2007 drilling season by the Tanzania drilling project (TDP) reveals a much more expanded Upper Cretaceous sequence than was recognized previously in the Lindi region of southern Tanzania. This TDP expedition targeted recovery of excellently preserved microfossils (foraminifera and calcareous nannofossils) for Late Cretaceous paleoclimatic, paleoceanographic and biostratigraphic studies. A total of 501.17 m of core was drilled at six Upper Cretaceous sites (TDP Sites 21, 22, 23, 24, 24B and 26) and a thin Miocene–Pleistocene section (TDP Site 25). Microfossil preservation at all these sites is good to excellent, with foraminifera often showing glassy shells and consistently good preservation of small and delicate nannofossil taxa. In addition to adding to our knowledge of the subsurface geology, new surface exposures were mapped and the geological map of the region is revised herein. TDP Sites 24, 24B and 26 collectively span the upper Albian to lower-middle Turonian (planktonic foraminiferal Planomalina buxtorfi– Whiteinella archaeocretacea Zones and calcareous nannofossil zones UC0a–UC8a). The bottom of TDP Site 21 is barren, but the rest of the section represents the uppermost Cenomanian–Coniacian ( W. archaeocretacea– Dicarinella concavata Zones and nannofossil zones UC5c–UC10). Bulk organic δ 13C data suggest recovery of part of Ocean Anoxic Event 2 (OAE2) from these four sites. In the upper part of this interval, the lower Turonian nannofossil zones UC6a–7 are characterized by a low-diversity nannoflora that may be related to OAE2 surface-water conditions. TDP Site 22 presents a 122-m-thick, lower-middle Turonian ( W. archaeocretacea– Helvetoglobotruncana helvetica Zones) sequence that includes the nannofossil zones UC6a(-7?), but invariable isotopic curves. Further, a lower to upper Campanian ( Globotruncana ventricosa– Radotruncana calcarata Zones and nannofossil subzones UC15b TP–UC15d TP) succession was drilled at TDP Site 23. Lithologies of the new sites include thin units of gray, medium to coarse sandstones, separating much thicker intervals of dark claystones with organic-rich laminated parts, irregular silty to fine sandstone partings, and rare inoceramid and ammonite debris. These lithofacies are interpreted to have been deposited in outer shelf and upper slope settings and indicate relatively stable sedimentary conditions during most of the Late Cretaceous on the Tanzanian margin.

Planktonic foraminiferal biostratigraphy of the Coniacian-Maastrichtian sequences of the Bey Dağları Autochthon, western Taurides, Turkey: thin-section zonation

Planktonic foraminifer distributions in seventeen stratigraphic sections of Upper Cretaceous hemipelagic and pelagic sequences of northern Bey Dağları 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 Dağları 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 Akdağ 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.

Attempt for Upper Cretaceous planktic foraminiferal zonation of the Srednogorie and Eastern Balkan Zones (Bulgaria)

Thirteen biostratigraphical zones were defined as a result of summarizing of the available data on the taxonomy, stratigraphical range and occurrence of the Upper Cretaceous planktic foraminifera from the Srednogoriå and East Balkan. The zones are: Rotalipora cushmani Taxon Range Zone (Late Cenomanian), Dicarinella imbricata Interval Zone (Early Turonian), Marginotruncana renzi – Marginotruncana sigali Interval Zone (Middle Turonian), Marginotruncana schneegansi Interval Zone (Late Turonian), Dicarinella primitiva Interval Zone (Early Coniacian), Dicarinella concavata Interval Zone (Late Coniacian to Early Santonian), Globotruncanita elevata Interval Zone (Early Campanian), Globotruncanita stuartiformis Interval Zone (Early Late Campanian), Radotruncana calcarata Taxon Range Zone (Late Late Campanian), Globotruncana falsostuarti Interval Zone (Early Maastrichtian), Contusotruncana contusa Interval Zone (Early to Late Maastrichtian), Abathomphalus mayaroensis Taxon Range Zone (Late Late Maastrichtian). The zones were successfully correlated to the biostratigraphical schemes in the Carpathians, Mediterranean Basin, Caribbean Basin, and some generalized zonations.

UPPER CRETACEOUS PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY OF THE BEY DAGLARI AUTOCHTHON IN THE KORKUTELI AREA, WESTERN TAURIDES, TURKEY

The Upper Cretaceous sequence of the Korkuteli area (Western Taurides) comprises two formations. The Bey Daglari Formation lies at the base and can be divided into two parts. A 600-m-thick neritic lower part is capped with thin, massive, hemipelagic limestones. The Akdag Formation disconformably overlies different stratigraphic levels of the Bey Daglari Formation along a prominent erosional surface and consists of thin-bedded, cherty, pelagic, clayey limestones. Paleogene marls form the base of the Tertiary sequence and disconformably overlie different stratigraphic levels of the Upper Cretaceous succession. This study identifies from thin sections and analyzes the Late Cretaceous planktonic foraminifera. Identification of forty-five species belonging to the genera Contusotruncana , Dicarinella, Gansserina , Globotruncana , Globotruncanella , Globotruncanita, Marginotruncana and Radotruncana has led to the recognition of five biostratigraphic zones, in ascending order: Dicarinella concavata Interval Zone (IZ), Dicarinella asymetrica Total Range Zone (TRZ), Radotruncana calcarata TRZ, Globotruncana falsostuarti Partial Range Zone (PRZ) and Gansserina gansseri IZ, from the Senonian succession of the Bey Daglari autochthon. The Dicarinella concavata IZ and Dicarinella asymetrica TRZ have been identified from the massive hemipelagic limestones of the Bey Daglari Formation and indicate a Coniacian-Santonian age. The Radotruncana calcarata TRZ, Globotruncana falsostuarti PRZ and Gansserina gansseri IZ have been recognized from the pelagic limestones of the Akdag Formation and suggest a late Campanian-early Maastrichtian age. The identified planktonic foraminiferal biozones indicate that the Bey Daglari carbonate platform drowned after the late Turonian; the Upper Cretaceous (Coniacian-early Maastrichtian) pelagic succession includes two stratigraphic gaps in the Korkuteli area corresponding to lower-middle Campanian and upper Maastrichtian. Slight drowning of the platform after the late Turonian may have been related to the regional extension which affected peri-Mediterranean alpine belts. The regional hiatuses in the pelagic succession are also ascribed to the tectonic events, as the Late Cretaceous is a time of great tectonic activity in this critical area of Tethys. Eustatic sea-level changes may have had a secondary effect on the Upper Cretaceous carbonate succession of the Bey Daglari autochthon.

Biostratigraphy of Late Cretaceous pelagic limestones from surroundigns of Bovec in the Julian Alps (Slovenia)

In the western part of Julian Alps in many places small erosion remains of Late Cretaceous pelagic, light grey and reddish limestones and marls (scaglia) are preserved. These limestones and marls that contain very numerous globotruncanas overlie southwest of Bovec after a hiatus the Lower Jurassic Pliensbachian oolitic and biospariotic limestone. Between the two limestones appears an angular disconformity. Total thickness of the Upper Cretaceous limestone and marl is 8.80 m. The lower 6.20 m of the column were sampled in detail. In the scarcely 6.20 m thick section three globotruncana zones were established: Helvetotruncana helvetica (3-5 cm), Dicarinella concavata (120 cm) and Dicarinella asymetrica (490 cm). The H. helvetica zone is not developed in its entire thickness owing to the hiatus below. Deposition of the Late Cretaceous pelagic limestones started in Turonian and lasted into Campanian. The considered beds in Bovec basin are overlain by Campanian-Maastrichtian flysch beds.

Planktonic foraminifera of the Nkalagu Formation type locality (southern Nigeria, Cenomanian–Coniacian): biostratigraphy and palaeoenvironmental interpretation

A study on the planktonic foraminifera of the southern Nigerian Nkalagu Formation (Cenomanian–Coniacian) was carried out. Four biostratigraphic zones are proposed for the (?)middle Turonian–Coniacian interval in southern Nigeria: (1) Praeglobotruncana cf. stephani Zone (middle? Turonian); (2) Marginotruncana sigali Zone (late Turonian); (3) Dicarinella primitiva Zone (latest Turonian); and (4) Dicarinella concavata Zone (Coniacian). Based on planktonic/benthonic foraminiferal ratios and environmental index forms, a general deepening of depositional environments is indicated from late Cenomanian–Turonian and Coniacian ages. Upper Cenomanian sediments were deposited on an inner shelf (0–70 m, 0–20% planktonic foraminifera; only one Heterohelix species occurs). During the (?)middle to early late Turonian, an upper bathyal environment of about 600 m water depth is indicated (46–94% planktonic foraminifera, with heterohelicids dominating and a relatively large number of keeled specimens). The middle late to latest Turonian interval is characterized by 20–71% planktonic foraminifera with heterohelicids dominating and very rare keeled specimens, pointing to an upper bathyal depositional environment (ca. 250 m water depth). A (deeper) upper bathyal environment (ca. 600 m water depth), dominated by heterohelicids but with up to 30% hedbergellids during the Coniacian, is indicated by 63–93% planktonic foraminifera with a relatively large number of keeled specimens. In general, an open marine deep-water environment (upper bathyal) is indicated by the (?)middle Turonian–Coniacian planktonic foraminiferal faunas, further influenced by periods of eutrophication or (weak) salinity fluctuations. The (?)middle Turonian and latest late Turonian were time intervals of highest surface productivity in southern Nigeria.