Dicarinella Asymetrica Research Articles

Planktonic foraminiferal biostratigraphy in the Surgah Formation (Turonian-Santonian), Zagros sedimentary Basin, SW Iran (Lorestan Zone)

The Surgah Formation was studied in four sections (Kuh-e-Surgah anticline, Zifel, Sarkan, and Mal-e-kuh) from the NW-SE of the Zagros sedimentary basin. Forty-one planktonic foraminiferal species belonging to 20 genera were observed. The recorded species were used to subdivide the Surgah Formation into three biozones: Marginotruncana sigali-Dicarinella primitiva Zone, Dicarinella concavata Zone, and Dicarinella asymetrica Zone. Based on these data, the Surgah Formation was estimated to be of late Turonian to late Santonian age. The Coniacian/Santonian boundary is placed at the Dicarinella asymetrica Zone. The base of the Santonian stage is identified on the FO of Globotruncana linneiana (pill box shaped), the FOs of Dicarinella asymetrica, Globotruncanita elevata and Globotruncana bulloides, and the LOs of Dicarinella primitiva, Dicarinella concavata and Muricohedbergella flandrini.

Biostratigraphy and determination of the base of the Santonian stage in the east of the Kopeh-Dagh Basin based on planktonic foraminifera, NE Iran

The Abderaz Formation has been studied in five stratigraphical sections (Qarehso, Abderaz village, Muzduran pass (type section of the formation), Padeha village, and Shorab) in the east of the Kopeh-Dagh Basin. Twenty-four species of planktonic foraminifera belonging to eleven genera were identified. The vertical distribution of these species helped to recognize five biozones within the Abderaz Formation as follows: 1) Whiteinella archaeocretacea Partial Range Zone, 2) Helvetoglobotruncana helvetica Total Range Zone, 3) Marginotruncana schneegansi Partial Range Zone, 4) Dicarinella concavata Interval Zone, 5) Dicarinella asymetrica Total Range Zone. Based on these data, the Abderaz Formation ranges from the latest Cenomanian to late Santonian. The base of the Santonian stage was placed close to the onset of the Dicarinella asymetrica Total Range Zone at the studied sections. It was precisely traced at the FO of Globotruncana linneiana (pillbox-like).

Biostratigraphy of the Early Turonian- Late Campanian pelagic limestone (Kometan and Gulneri formations) near Sayid Sadyq Town, Kurdistan Region, NE-Iraq.

This study aims at the presentation of a planktonic foraminiferal biozonation of the Late Cretaceous pelagic carbonate section in the east of Sulaymaniyah governorate Kurdistan region, Northeast of Iraq. The zonation proved the occurrence of the Kometan and Gulneri formations which belong to the Early Turonian – Late Campanian age. This is achieved by taking fifty-two (52) samples from the lower part of the section to the upper one with an interval of two meters between successive samples. From these samples, sixty-two (62) thin sections are prepared and (43) species from (11) genera of planktonic foraminifera are indicated and identified in the two formations of the studied section. According to the First and Last occurrence of identified planktonic foraminiferal assemblage, the studied section is divided into seven biozones, from older to young. These biozones are Whitenella archaeocretacea-Heterohelix moremani Total Range Zone, Marginotruncana sigali Partial Range Zone, Dicarinella concavata Interval Range Zone, Dicarinella asymetrica Total Range Zone, Globotruncanita elevata Partial Range Zone, Globotruncana ventricosa Interval Range Zone, Radotruncana calcarata Total Range Zone. The age of the two Formations is assigned as Early Turonian- Late Campanian based on the planktonic foraminiferal ranges from the lower part of the section to the upper part. The boundary of the Gulneri and Balambo formations is gradation while there is a gap between the former formation and Kometan Formation.

Planktonic Foraminiferal Biostratigraphy of the Kometan Formation from Kurdistan Region, NE Iraq

The Kometan Formation is widely spread in northeastern Iraq and is mostly composed of deep marine carbonates, with a predominance of planktonic foraminiferal assemblages throughout its sequences. Two outcrop sections, Smaquli and Tabin, were chosen to study the biostratigraphy of the Kometan Formation. The study identified 32 planktonic foraminiferal species belonging to 12 genera. According to stratigraphic distribution and the relative distribution of planktonic foraminifera assemblages, the study demonstrated the possibility of subdividing the sequence of the Kometan Formation into five foraminiferal biozones, including: Marginotruncana schneegansi Partial Range Zone, Dicarinella primitiva Interval Zone, Dicarinella concavata Interval Zone, Dicarinella asymetrica Total Range Zone, Globotruncanita elevata Partial Range Zone. The Planktonic zones were correlated with other zonal schemes inside and outside Iraq. They are considered to be extending from Late Turonian to Early Campanian.

Planktonic foraminiferal biostratigraphy of the upper Turonian-lower Santonian succession in the Lorestan Zone of the Zagros sedimentary Basin, SW Iran

The Surgah Formation was studied in four sections (Tang-e-Shirin Ab, Kuh-e-Surgah Holostem Valley, and Sarkan) from the NW-SE of the Zagros sedimentary Basin. Forty-one planktonic foraminiferal species belonging to eighteen genera were recognized. These species were used to identify three zones across the Surgah Formation from the bottom to the top: Dicarinella primitiva – Marginotruncana sigali Zone, Dicarinella concavata Zone, and Dicarinella asymetrica Zone. Based on these data, the Surgah Formation was assigned to the Late Turonian-Santonian age. The base of the Coniacian Stage projects within the lower part of the Dicarinella concavata Zone and is traced at the first occurrence (FO) of Pseudotextularia nuttalli. Owing to the absence of Pseudotextularia nuttalli at the Sarkan well, we utilized the extinction of Whiteinella aprica to estimate the base of the Coniacian Stage. The Coniacian/Santonian (C/S) boundary is placed within the basal part of the Dicarinella asymetrica Zone based on the FO of Globotruncana linneiana. The base of the Santonian Stage denotes marked radiation in the globotruncanids among the planktonic foraminiferal assemblage. Great lithofacies and thickness variations have been observed within the D. concavata Zone. These variations likely indicate that the shoreline was located northwest of the Lorestan province during the Coniacian. In contrast, the southwest extreme of the Lorestan province was characterized by deep-water settings.

Carbon isotopes, palynology and stratigraphy of the Santonian–Campanian boundary: The GSSP auxiliary sections, Seaford Head (England) and Bocieniec (Poland), and correlation between the Boreal and Tethyan realms

The stratigraphy and palynology of the upper Santonian–lower Campanian (Uintacrinus socialis–Gonioteuthis quadrata zones) Newhaven Chalk are described for the Campanian auxiliary GSSP section at Seaford Head, England. A new high-resolution bulk-sediment carbonate carbon stable-isotope (δ13Ccarb) curve provides the basis to refine the carbon-isotope event (CIE) stratigraphy of the section. Results are compared to a complementary palynological study of a second Campanian auxiliary GSSP section (U. socialis–O. pilula zones) at Bocieniec, Poland. Palynological assemblages are dominated by organic-walled dinoflagellate cysts (dinocysts; 208 taxa) at both sites. A stratigraphic framework is established via review of published lithostratigraphic, macrofossil, foraminifera and calcareous nannofossil records from the study sites. Carbon isotope curves with 13 major named CIEs provide a basis for correlation of Seaford Head and Bocieniec to sections at: Trunch, England; Poigny, France; Lägerdorf, Germany; and the Campanian GSSP at Gubbio, Italy. Correlations are constrained by biostratigraphic records, including dinocyst events. The Late Santonian δ13C Event (LSE, previously termed the Santonian–Campanian Boundary Event, SCBE) provides a key correlation level between Boreal and Tethyan sections and enables the placement of base Campanian markers: extinction levels of the crinoid Marsupites and the planktonic foraminifera Dicarinella asymetrica; the first appearance of the calcareous nannofossil Aspidolithus parcus parcus; and the C34n/C33r magnetozone boundary (the primary Campanian marker), in both Boreal and Tethyan sections. A holostratigraphy for the Santonian–Campanian boundary interval that integrates CIEs, macrofossils, benthic and planktonic foraminifera, calcareous nannofossils, dinocysts and magnetostratigraphy is presented. Rhynchodiniopsis juneae sp. nov. is described.

The Cenomanian-Turonian oceanic anoxic event (OAE-2) and continuous drowning up to the Santonian of the Western Valles-San Luis Potosi Platform, Central to Eastern Mexico: Biostratigraphy, chemostratigraphy and paleoenvironments

The Upper Cretaceous stratigraphic succession in the western part of the Valles-San Luis Potosi Platform (central to eastern Mexico) reflect the interaction between various paleo-oceanographic factors including sea-level change, tectonic factors, and the type and supply of sediments. The El Abra Formation is a shallow-water carbonate deposit that is overlain by the hemipelagic-pelagic Soyatal Formation, which represents the transition to a deeper, eutrophic, open marine environment in the latest Cenomanian-earliest Turonian (Whiteinella archaeocretacea Partial Range Zone). This unit is linked to a sea-level rise that occurred on a global scale and flooded the platform, coinciding with the Oceanic Anoxic Event 2 (OAE 2). This change is well–marked by faunal assemblages with a low diversity, and environmental stress–resistant species as well as values of delta 13C excursion, total organic carbon (TOC) and trace element signatures. These data suggest that in this time the ocean was oxygen deficient. During the early Turonian the platform was completely drowned, which led to re-establishment of the oligotrophic environment. These conditions favored for development of the planktonic foraminifera of the Helvetoglobotruncana helvetica Total Range Zone with the occurrence of keeled forms (k/strategists) even continuing as far as the late Santonian thus in the Soyatal interval two biostratigraphic zones are also recognized: the Dicarinella concavata Interval Zone (late Turonian-late Coniacian) and Dicarinella asymetrica Total Range Zone (early-late Santonian). This indicates that the studied part of the Valles-San Luis Potosi Platform remained flooded during this time, in contrast with Mediterranean Tethys regions where recovery of the shallow-water carbonate platforms occurred in the latest Turonian to mid-Coniacian. The planktonic foraminiferal assemblages of this interval are diverse, composed of large and complex keeled morphotypes, which indicate an open deep–sea environment.

Planktonic foraminiferal biostratigraphy and determination of the Santonian-Campanian boundary in the Zagros sedimentary basin, SW Iran

The carbonate-dominated Upper Cretaceous Ilam Formation is representative of an important reservoir in the Zagros Basin. In this study, planktonic foraminiferal biostratigraphy of the Ilam Formation was investigated in the Kuh-e-Surgah section in western Iran. In the studied section, the 170 m thick Ilam Formation is mainly composed of imestones with shale intercalations. The formation conformably overlies and underlies the Surgah and Gurpi formations, respectively. Twelve genera and 24 species of planktonic foraminifera were identified. The following planktonic foraminiferal biozones were identified: the Dicarinella asymetrica Total Range Zone (latest Coniacian- late Santonian), the Globotruncanita elevata Partial Range Zone (Santonian to early Campanian), the Globotruncana ventricosa Interval Zone (middle to late Campanian.), the Radotruncana calcarata Total Range Zone (late Campanian.), the Globotruncanella havanensis Partial Range Zone (late Campanian) and the Globotruncana aegyptiaca Interval Zone (late to latest Campanian). In general, the biozones show that the Ilam Formation in the studied section is latest Coniacian-late Campanian in age. The Santonian-Campanian boundary in the Kuh-e-Surgah section correlates with the Globotruncanita elevata Partial Range Zone. The recognized biozones in the Ilam Formation are comparable with those recorded in other parts of the Tethyan Realm. The crinoid species Marsupites testudinarius is absent in the studied section. Generally, the last occurrence of this cosmopolitan species indicates the base of the Campanian stage. The Santonian/Campanian boundary was placed in the lower part of the Globotruncanita elevata Partial Range Zone at the base of the Ilam Formation in the studied section.

Paleoenvironment of the Late Cretaceous (Late Touronian–Early Campanian) Ostarcoda in the Kometan Formation, Dokan Area, Kurdistan region, NE-Iraq

In the present study, selected the Kometan Formation (Late Turonian - Early Campanian) from the Dokan area, NE-Iraq. In this formation studied Ostracoda and identified fifteen open Ostracoda species belonging to ten genera (Bairdia, Bairdiacypris, Bythocypris, Bairdoppilata, Cavellina, Cypridina, Cytherella, Haplocytheridea, Pterygocythereis, and Paracypris). The goal of the present study is to identify Ostracoda species under polarizing microscopes for the first time in the Kometan Formation in the Dokan area. The Ostracoda assemblage such as Bairdia, Bairdiacypris, Cytherella, Cypridina, and Paracypris with foraminifera species Globotruncana linneiana, Globotruncanita stuartiformis, Marginotruncana schneeansi, and Dicarinella asymetrica indicate the Kometan Formation deposited in the deep marine environment.

Planktonic foraminiferal distribution of the Late Cretaceous to late Paleocene deposits of the Bandar Abbas area (Zagros Belt, SW Iran): An update of the bio- and lithostratigraphic framework

In this paper, we present a biostratigraphic study of the planktonic foraminiferal associations of the Gurpi Formation outcropping in the Bandar Abbas area of the Zagros Belt (SW Iran). Two stratigraphic sections, Kuh-e Khush and Kuh-e Khamir, were logged and sampled, and the identification of the planktonic foraminiferal assemblages has allowed the recognition of eight Cretaceous biozones, namely Dicarinella asymetrica Zone, Globotruncanita elevata-Globotruncana ventricosa Zone, Radotruncana calcarata Zone, Globotruncanella havanensis Zone, Radotruncana calcarata–Globotruncana aegyptiaca Zone, Globotruncana aegyptiaca-Gansserina gansseri Zone, Gansserina gansseri Zone and Contusotruncana contusa-Abathomphalus mayaroensis Zone. This planktonic foraminiferal zonal framework reveals a latest Coniacian to late Maastrichtian age for the deposits of the Gurpi Formation in the two studied sections. The Cenozoic Interval of the studied sections, represented by the Pabdeh Formation, is attributed to the P3–P6a integrated Zone in the Khush section and the P4c Subzone (Acarinina soldadoensis) in the Khamir section. The data show that the Gurpi Formation at the Khamir locality rests disconformably upon the shallow neritic facies of the Ilam Formation, while in the Khush section this formation disconformably overlies the shallow carbonates of the Sarvak Formation. In addition to the in situ biota, reworked microfossils, such as calpionellids, calcareous algae and benthic foraminifera from older Jurassic (Surmeh Formation) and Cretaceous formations (Surgah equivalent, Sarvak, Kazhdumi and Dariyan formations) are recorded within several stratigraphic levels of the Gurpi Formation.

Upper Cretaceous (Coniacian -Campanian) siliciclastic/carbonate ramp depositional sequences and relative sea-level changes in Sinai, Egypt: Implications from facies analysis

Through the analysis of biostratigraphy, facies types and distribution, lithofacies associations, and bounding surfaces, we derived high-resolution sequence stratigraphy of the mixed siliciclastic–carbonate rocks for four sections in the Coniacian–Campanian succession in Sinai (Egypt). These stratigraphic sections provide a framework for studying the sedimentary-facies evolution, the paleogeography, and the role of eustatic and tectonic processes in Egypt and surrounding countries. Twenty-six foraminiferal species and four foraminiferal zones (the Dicarinella concavata Interval Zone in the upper Coniacian, Dicarinella asymetrica Total Zone in the Santonian, Globotruncanita elevata Partial Range Zone in the lower–middle Campanian, and Globotruncanita ventricosa Partial Range Zone in the middle Campanian) are noted. Twenty-three lithofacies and microfacies types into six facies associations ranging from progradational shoreface to outer ramp are detected and categorized. These facies associations exhibit lateral variation and deepening toward the north from siliciclastic–carbonate (Matulla Formation) to dominant carbonate (Themed Formation). Three sequences separated by four sequence boundaries have been determined in the field and/or from strong vertical facies changes associated with short time gaps representing the Turonian–Coniacian; the lower–middle and upper Coniacian; the upper Coniacian–Santonian; and the Santonian–Campanian stage boundaries. Comparisons of the examined sequence boundaries in Egypt and in some parts of Europe, within the Arabian Plate, and in global charts suggest that eustatic and tectonic effects were simultaneous.

Biozonation and paleobathymetry of the Gurpi Formation in the Dasht-e Arjan section , Zagros area , based on foraminifera

In this research the Gurpi Formation in the Zagros Basin outcropping in the Dasht-e Arjan section, Shiraz province ,for the purpose of biozonational and Paleobathymetric studies were investigated. The thickness of these sediments is about 130 m and consists of Limestones and Shales.To determine the palaeobathymetry of the Gurpi Formation, Planktonic and benthic foraminifera were investigated . A depth of about 270m to 510m was determined for these sediments based on the ratio of planktonic foraminifera to the total assemblages of foraminifera after omitting infaunal benthic foraminifera (%P*) by using the equation D = e (3.58718+(0.03534 × %P* )).In this study sixty-two species of planktonic foraminifera belonging to eighteen genera were recognised .According to the studied planktonic foraminifera the Upper Cretaceous deposits in this area were divided into nine biozones as following :biozone1- Dicarinella concavata Interval Zone. Biozone2- Dicarinella asymetrica Total Range Zone. Biozone3- Globotruncanita elevata Partial range zone .Biozone4- Globotruncana ventricosa Interval Zone. Biozone5- Radotruncana calcarata Interval zone. Biozone 6- Globotruncanella havanensis Partial Range Zone. Biozone7- Globotruncana aegyptiaca Interval Zone. Biozone 8- Gansserina gansseri Interval Zone. Biozone 9- Contusotruncana contusa Interval Zone Based on the studied planktonic foraminifera the Early Santonian to Maastrichtian ages were determined for the sediments .

Biostratigraphy of planktonic foraminifera in the Abtalkh Formation and determination of the Santonian/Campanian Boundary in the Kopeh-Dagh Sedimentary Basin

ABSTRACT:We studied the Abtalkh Formation from five outcrops (Sheikh, Hajgelichkhan, Qarehso, Muzduran, and Deraz-Ab) in the Kopeh-Dagh sedimentary basin. A total of 30 species of planktonic foraminifera belonging to 21 genera were recorded. These species were used to subdivide the Abtalkh Formation into seven biozones (Dicarinella asymetrica Zone, Globotruncanita elevata Zone, Contusotruncana plummerae Zone, Radotruncana calcarata Zone, Globotruncanella havanensis Zone, Globotruncana aegyptiaca Zone, and Gansserina gansseri Zone). The Abtalkh Formation was deposited during the late Santonian-latest Campanian and the Santonian-Campanian boundary is identified based on the last occurrence of Dicarinella asymetrica. The base of the Campanian stage was delineated by the extinction of the marginotruncanid group, the first occurrences of Pseudotextularia nuttalli and Rugoglobigerina rugosa, and on the last occurrence of Dicarinella asymetrica.

Santonian-Campanian planktonic foraminifera biostratigraphy of the northern Moghan area (NW Iran): implications for the timing of Cretaceous marine transgression

An Upper Cretaceous deep marine unit containing planktonic foraminifera was studied based on the material recovered from a subsurface section at the northern part of the Moghan area. The unit contains a relatively diverse assemblage of planktonic foraminifera, which allowed identifying a number of three biozones spanning the late Santonian to early late Campanian. These are Dicarinella asymetrica Zone, Globotruncanita elevata Zone, and Globotruncana ventricosa Zone. Based on the stratigraphic values of the identified planktonic foraminifera, a late Santonian to middle-late Campanian age is ascribed to the examined strata. The biostratigraphic results also point to the earlier marine transgression in the northern Moghan area starting in the late Santonian. Our biostratigraphic results indicate a prominent stratigraphic hiatus at the contact of Upper Cretaceous unit with the overlying Sarmatian strata, comprising the late Campanian to middle Serravallian.

Santonian–Campanian Boundary Position in the Alan-Kyr Section (Central Crimea): New Micropaleontological Data

This work presents the results of determination of foraminifers and nannoplankton from the Upper Cretaceous deposits of the Alan-Kyr section (the central part of the Crimean Mountains). The interpretation of these data, together with previously obtained palynological and paleomagnetic data, allow us to justify the age of country deposits. In the lower part of the section, beds with planktonic foraminifera are correlated with the Santonian part of the Dicarinella asymetrica Zone. The benthic foraminiferal assemblages also belong to the Santonian interval and allow us to subdivide this interval in more detail. Based on the nannoplankton data the transitional Zone CC17 was identified, which corresponds to the Upper Santonian–Lower Campanian. The base of a probable analogue of Chron C33r is distinguished within these deposits and is proposed for use as a primary feature to define the lower boundary of the Campanian.

New microfossils data about the Santonian-Campanian boundary in the Alan-Kyr section (Central Crimea)

The article presents the results of the determinations of foraminifera and nannoplankton from the section of Upper Cretaceous deposits Alan-Kyr (Central part of Crimea Mountains). Interpretation of these data to gether with the palinological ans paleomagnethic materials obtained earlier in this section allows to justify the age of deposits. In the lower part of the section planktonic foraminifera assemblages are correlated with the Satonian part of the Dicarinella asymetrica Zone. The benthic foraminiferal assemblages also show on the Santonian interval and allow it to be divided in more detail. On the nannoplankton data it was possible to identify fossils of the transition Zone CC17, corresponding to Upper Santonian–Lower Campanian. Within these deposits is the base of a probable magnetic chron analogue C 33r, which is proposed to be used as a primary feature to define the lower boundary of the Campanian.

Timing of depositional regime changes during the Late Cretaceous evolution of the Southern Pontides (Ankara, Central Anatolia, Turkey)

During the Cretaceous, vast amounts of marine sediments were deposited along the south-facing active margin of the Eurasia. A stratigraphic section of 91 m was analyzed for planktonic foraminifera (75 samples), with the aim of establishing a refined biostratigraphy of Cenomanian–Campanian deposits in Central Anatolia. A biostratigraphic framework comprising nine biozones was established. In ascending order, the Rotalipora cushmani, Whiteinella archaeocretacea and Helvetoglobotruncana helvetica zones were defined in the uppermost Cenomanian–Turonian interval. The lack of Coniacian index markers suggests the existence of a hiatus for this interval. In the upper part of the section, the Dicarinella asymetrica, Globotruncanita elevata, Contusotruncana plummerae, Globotruncanella havanensis and Globotruncana aegyptiaca zones were identified for the Santonian and Campanian deposits. The presence of Gansserina gansseri, Globotruncanita angulata, G. conica and G. pettersi in the uppermost part of the section shows that the section ends at the base of the Gansserina gansseri Zone, indicating uppermost Campanian. The planktonic foraminifera biozonation framework provides strong evidence for the timing of the depositional history of the active continental margin that developed south of the Pontides. These phases are mainly the formation of olistostromes of pre-Santonian age, following condensed carbonate deposition during the Santonian and finally the switch from forearc deposition to the formation of a thick sequence of siliciclastic succession starting in the Campanian.

Biostratigraphy of Upper Cretaceous planktonic foraminifera of the Abtalkh Formation in an east-west transect, Kopet-Dagh Basin, northeastern Iran

The Upper Cretaceous Abtalkh Formation of the Kopet-Dagh Basin (northeastern Iran) was studied in four stratigraphic sections (Bahadorkhan, Hammam Galeh, Type section and Shorab). All sections display limestones, shales and calcareous shales. The Bahadorkhan section is approximately 480 m thick. We identified 32 planktonic foraminifera species belonging to 13 genera in 6 biozones: 1. Dicarinella asymetrica Total Range Zone, 2. Globotruncanita elevata Partial Range Zone, 3. Contusotruncana plummerae Interval Zone, 4. Radotruncana calcarata Total Range Zone, 5. Globotruncanella havanensis Partial Range Zone and Globotruncana aegyptiaca Interval Zone. Based on foraminiferal biostratigraphy, the Bahadorkhan section was dated to the latest Santonian to late Campanian. This study identifies 11 genera and 25 species of planktonic foraminifera in the 1500m thick Hammam Galeh section, spanning 7 biozones: 1. Dicarinella asymetrica Total Range Zone, 2. Globotruncanita elevata Partial Range Zone, 3. Contusotruncana plummerae Interval Zone, 4. Radotruncana calcarata Total Range Zone, 5. Globotruncanella havanensis Partial Range Zone, 6. Globotruncana aegyptiaca Interval Zone, 7. Gansserina gansseri Interval Zone. Latest Santonian to late Campanian ages have been established for the Abtalkh Formation. The type locality of the Abtalkh Formation is 750mthick and contains 31 planktonic foraminiferal species belonging to 12 genera. Based on this fossil content, we identified 6 biozones. The age of the formation is estimated to be the latest Santonian to late Campanian, as for the Bahadorkhan type section. The Shorab section of the Abtalkh Formation is 990m thick. In this section, 19 species belonging to 10 genera were identified, as were 5 biozones: 1. Globotruncanita elevata Partial Range Zone, 2. Contusotruncana plummerae Interval Zone, 3. Radotruncana calcarata Total Range Zone, 4. Globotruncanella havanensis Partial Range Zone, 5. Globotruncana aegyptiaca Interval Zone. Based on this fossil assemblage, the Shorab section dates to the early to late Campanian.

Stratigraphy and microfossils (radiolarians and planktonic foraminifers) of the Upper Cretaceous (upper Santonian–lower Campanian) Struganik limestone (Western Serbia)

Radiolarians and planktonic foraminifers were studied from several sections of the Upper Cretaceous lithographic limestones near Struganik Village (Western Serbia). These deposits were formed in a local basin, in a low-energy sedimentary environment surrounded by a shallow-water carbonate platform. The Struganik limestone is represented by alternating micritic limestone with calcarenite, rudite and tuffaceous rocks. The sections of the Struganik limestone have a narrow stratigraphic interval that covers the upper Santonian and probably includes the lower Campanian, with a total thickness reaching 120–150 m. The radiolarian zones Crucella robusta and Afens perapediensis were traced within the unit. The foraminiferal zone Dicarinella asymetrica was tentatively identified.

Upper Cretaceous volcaniclastic complexes and calcareous plankton biostratigraphy in the Western Pontides, NW Turkey

This study describes and interprets Upper Cretaceous volcaniclastics interbedded with hemipelagic to pelagic limestones, marls, and turbidites from the Western Pontides, northwestern Turkey. The Derekoy Formation, the Unaz Formation (red pelagic limestone unit), and the Cambu Formation can be distinguished, overlain by the turbiditic Akveren Formation. Biostratigraphic ages from the predominantly volcaniclastic Derekoy Formation indicate Turonian (Dicarinella concavata planktonic foraminifera zone, CC13/UC8-9 nannofossil zones) to middle/late Santonian ages up to CC17/UC13. The Unaz Formation, deposited during the late Santonian (UC13, Dicarinella asymetrica Zone), is overlain by the volcaniclastic Cambu Formation of latest Santonian (CC17b/UC13) to early/middle Campanian (CC20/UC15a) age. However, turbidite intercalations are already present diachronously from CC19/UC14d onwards, and the turbiditic Akveren Formation ranges up into the late Maastrichtian (Abathomphalus mayaroensis Zone). Geochemistry of the volcaniclastic units reveals information about the volcanic series and tectonic setting, although element mobility has to be considered. An overall trend of calc-alkaline to high-K calc-alkaline series and basaltic to basalt-andesitic rock types was identified. A negative Nb anomaly with respect to Th and Ce in all samples confirms the existence of a volcanic arc, also indicated by a negative Ti anomaly. Biostratigraphic age constraints give evidence for volcanic arc activity mainly between Turonian and early Campanian, ca. 91 - 79 Ma. Various geochemical data, especially element variations normalized to N-MORB, show two types of volcanic arc basalts (VAB): (1) Calc-alkaline to high-K calc-alkaline VAB have increased Nb and Zr values, (2) more tholeiitic VABs are depleted in Nb, Zr, Ti, V. The volcaniclastics successions were deposited in an arc setting triggered by different stages of subduction of the Neotethys Ocean to the south and contemporaneous spreading in the Western Black Sea Basin to the north. An extensional regime caused formation of small but deeper-water sedimentary basins along the southern shore of the Black Sea where volcaniclastic complexes interfingered within short lateral distances with pelagic and mass-flow deposits.