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The planktonic foraminifera assemblage across the Global Boundary Stratotype Section and Point (GSSP) for the base of the Cenomanian Stage defined at Mont Risou (Haute-Alpes in France) is here restudied to clarify the identification and stratigraphic distribution ofThalmanninella globotruncanoides( =Rotalipora globotruncanoidesSigal, 1948) andPseudothalmanninella tehamaensis( =Rotalipora tehamaensisMarianos & Zingula, 1966) whose appearance levels are primary and secondary criteria for placing the Albian/Cenomanian boundary. Since the ratification of the GSSP in 2002, the identification of the foraminifera index species across the Albian/Cenomanian boundary has been reported to be sometimes difficult either because of their rarity or uncertainty in the taxonomic identifications. We discuss the taxonomic status ofThalmanninella brotzeniSigal 1948, a species regarded for a long time to be a junior synonym ofTh. globotruncanoides, through images of Sigal's type materials deposited at the Musée National d’Histoire Naturelle (Paris), and elucidate the taxonomically important characters that enable unequivocal identification ofTh. brotzeni, Th. globotruncanoidesandPs. tehamaensis. Planktonic foraminifera marker species from Mont Risou are compared with well-preserved specimens from Blake Nose Plateau (ODP 171B, North Western Atlantic Ocean) to verify the reliability and stratigraphic distribution of these marker taxa outside the Mediterranean Tethyan area.

The outcrop of the Marnes Bleues at the Col de Pre-Guittard, 11 km north of the village of Remuzat in the Department of Drome in southeastern France is probably the most intensively studied succession spanning the Aptian/Albian boundary interval. Following the rejection of the proposed GSSP for the base of the Albian Stage (based on the first occurrence of the ammonite Leymeriellla tardefurcata in the section at Le Pillart, Tartonne, Alpes-de-Haute Provence), we re-visit the Pre-Guittard section. A new candidate GSSP defined by the first occurrence of the planktonic foraminifera Microhedbergella renilaevis Huber and Leckie, 2011 is here proposed. This first occurrence is placed in a 100 m section with 28 secondary markers, including calcareous nannofossils, planktonic foraminifera, palynomorphs, an inoceramid bivalve, ammonites, stable carbon isotopes, and local marker beds. The outcrop fulfils most of the physical criteria required of a Global Stratotype Section and Point.

The evolution and taxonomy of the planktic foraminifer genus Helvetoglobotruncana Reiss, 1957, are investigated to improve stability in the concepts of the biomarker species Hv. praehelvetica and Hv. helvetica , which have been used to correlate uppermost Cenomanian–middle Turonian (Upper Cretaceous) marine sediments worldwide. The study focuses on exquisitely preserved specimens obtained from Turonian marine claystones drilled on the coastal margin of Tanzania, and these are compared with specimens reported from a number of Cenomanian/Turonian boundary sequences worldwide. Absence of discernable shell recrystallization in the Tanzanian specimens provides an unprecedented opportunity for detailed observations of the external wall texture and wall microstructures, allowing for a more concise characterization of similarities and differences between the two species. Abundance counts of Turonian planktic foraminifer assemblages from one Tanzania borehole reveals that Hv. helvetica occurs in trace abundance early in its range and reaches maximum abundance of 35–45% of the total assemblage shortly before the simultaneous and abrupt extinction of both helvetoglobotruncanid species. The ratio between Hv. helvetica and Hv. praehelvetica increases gradually up-section, with a 1:1 ratio reached nearly halfway above the lowest occurrence level of Hv. helvetica and 9:1 dominance by Hv. helvetica near the top of its range. The helvetoglobotruncanid and mixed whiteinellid species yield δ 13 C and δ 18 O values that are nearly identical and slightly more enriched in δ 18 O than co-occurring Globoheterohelix paraglobulosa, and they are slightly more enriched in d 13 C and more depleted in δ 18 O than co-occurring species of Dicarinella and Praeglobotruncana. These isotopic results indicate that helvetoglobotruncanids lived at relatively shallow depths in the mixed layer. Using an age model developed for the Rock Canyon Anticline Cenomanian/Turonian Global Stratotype Section and Point (GSSP) sequence near Pueblo, Colorado, the age of the first occurrence of Hv. helvetica is calculated as 93.52 Ma. The extinction of Hv. helvetica has not been properly calibrated, but it must be younger than 92.77 Ma, which is the age of its occurrence at the top of the Rock Canyon Anticline GSSP section.

Wall texture and ornamentation in Cretaceous planktonic foraminifera, as with modern and Cenozoic taxa, are generally considered to be genetically controlled and thus taxonomically significant. For instance, the iterative development of meridional ornamentation is a diagnostic criterion used to discriminate between the Santonian–early Campanian genus Costellagerina , and the Campanian–Maastrichtian genus Rugoglobigerina . An alternative ecophenotypic explanation for differences based on observed poleward decreases in meridional ornamentation has not been widely accepted largely due to absence of evidence. Our study of Rugoglobigerina specimens recovered at three mid-low latitude localities (Exmouth Plateau, eastern Indian Ocean; Shatsky Rise, northwestern Pacific Ocean; Eratosthenes Seamount, eastern Mediterranean) confirms that meridional ornamentation is a primary character of their tests, but development of this feature is highly variable throughout the geographic and stratigraphic distribution of the genus. Within assemblages of Rugoglobigerina , there is a continuous morphological range from specimens with well-developed costellae arranged in a meridional pattern to specimens with relatively short ridges that are randomly oriented to meridionally aligned. Stable isotope (δ 13 C and δ 18 O) analyses indicate that specimens showing a more strongly developed meridional ornamentation consistently yield higher δ 13 C values than co-occurring less ornamented morphotypes at each examined locality, whereas patterns in the δ 18 O values are site-dependent. Interpretation of these patterns is not simple and might be related to different controlling factors acting together or separately. Potential explanations for the differential development of the ornamentation include: (1) adaptation to different ecological niches within a population, (2) species-level genetic differences, (3) variation in metabolic rate or activity within individuals, and (4) changes in the seawater carbonate ion saturation through space and time, including seasonality. In addition, we highlight the difficulty of discriminating between Rugoglobigerina and Costellagerina when they co-occur in lower Campanian deposits and among Rugoglobigerina , Costellagerina and Archaeoglobigerina at high latitude localities where species placed in all three genera show very similar shell morphology and ornamentation. Finally, our study challenges the general assumption that some external features of the wall are sufficiently reliable for taxonomic discrimination of Cretaceous planktonic foraminifera. This latter conclusion suggests that environmental conditions such as water temperature, water column stratification, nutrient concentration and carbonate ion saturation may have played a key role in triggering the external expression of genetically controlled wall ornamentation in the planktonic foraminifera.

The Santonian–Campanian interval is of particular interest as it encompasses a cooling trend after the Late Cretaceous greenhouse maximum warmth of the Turonian as well as a possibly related major faunal turnover among planktonic foraminifera. The recovery of pristinely preserved planktonic foraminifera from Santonian–Campanian sequences in southeastern Tanzania allows examination of faunal changes and documentation of species-specific stable isotope (δ 13 C and δ 18 O) signatures. These isotopic data are ideal for inferring species paleoecological preferences and for tracing major paleoceanographic changes. This study reports the first δ 18 O and δ 13 C data generated on “glassy” specimens of Marginotruncana coronata , M. undulata , M. marginata , and M. pseudolinneiana and Sigalia carpatica . Additional results from Shatsky Rise (Ocean Drilling Program Leg 198, Hole 1210B) and Exmouth Plateau (ODP Leg 122, Hole 762C) provide geographic control on species habitat preferences and paleoceanographic context. Isotopic analyses suggest that double-keeled species, including Globotruncana bulloides , Contusotruncana fornicata , C. plummerae and probably marginotruncanids, inhabited the surface mixed layer, whereas the biserial Gublerina rajagopalani was a permanent thermocline dweller. Thus, our study confirms recent suggestions that the depth-distribution models based on shell morphology and analogies with modern taxa are not applicable. At all the examined localities, changes in planktonic foraminiferal assemblages are used to define several ecological intervals, each one characterized by a distinctive taxonomic composition and/or increasing/decreasing species diversity. Combined geochemical and paleontological observations suggest that, by the middle–late Campanian, a stratified upper water column developed in Tanzania while less stratified and/or mesotrophic conditions prevailed at Shatsky Rise and Exmouth Plateau.

The study of past greenhouse climate intervals in Earth history, such as the Mesozoic, is an important, relevant and dynamic area of research for many sedimentary geologists, geochemists, palaeontologists and climate modellers. The Mesozoic sedimentary record provides key insights into the mechanics of how the Earth system works under warmer conditions, providing examples of natural climate change and perturbations to ocean chemistry, including anoxia, that are of societal relevance for understanding and contextualizing ongoing and future environmental problems. Furthermore, the deposition of widespread organic-carbon-rich sediments (‘black shales’) during the Mesozoic means that this is an era of considerable economic interest. In July 2015, an international group of geoscientists attended a workshop in Ascona, Switzerland, to discuss all aspects of the Mesozoic world and to celebrate the four-decade-long contributions to our understanding of this fascinating era in Earth history made by Hugh Jenkyns (University of Oxford) and Helmut Weissert (ETH Zurich). This volume of Sedimentology arose from that meeting and contains papers inspired by (and co-authored by!) Hugh and Helmi. Here a brief introduction to the volume is provided that reviews aspects of Hugh and Helmi's major achievements; contextualizes the papers of the Thematic Issue; and discusses some of the outstanding questions and areas for future research. This article is protected by copyright. All rights reserved.

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.

A detailed and quantitative study of foraminiferal assemblages across the Niveau Kilian in the Col de Pré-Guittard section (Vocontian Basin, southeast France) ably documents the planktic foraminiferal turnover across the Aptian-Albian boundary interval. The latest Aptian assemblage is dominated by few long-ranging Hedbergella and large-sized Paraticinella that completely disappear near the base of the Niveau Kilian organic-rich level. Planktic foraminiferal assemblages from across the Niveau Kilian to the top of the studied section are composed of minute, but very distinctive smooth-surfaced species of Microhedbergella miniglobularis and Mi. renilaevis. The appearance of Mi. renilaevis in the middle part of the Niveau Kilian represents a major step in the evolution and diversification of the Albian planktic fauna. The lowest occurrence of this taxon is recorded immediately above the extinction level of the Aptian hedbergellids and corresponds with a dramatic decrease in the number of planktic and benthic foraminifera specimens, with a 1‰ negative δ13C excursion in bulk carbonate, and evidence for regional rise in sea-surface temperature. Our careful study of the species composition permits refinement of the previous biozonation by using the appearance datum of Mi. renilaevis as a zonal boundary event. Changes include redefinition of the top of the Microhedbergella miniglobularis Zone and designation of a new Microhedbergella renilaevis Zone. The same sequence of events was reported from several deep-sea sites in the Atlantic and Indian Oceans. Therefore, documentation of the planktic foraminiferal turnover, combined with the carbon-isotope stratigraphy in the Col de Pré-Guittard section, provide new criteria for defining the Global Boundary Stratotype Section and Point for the base of the Albian Stage in a stratigraphically complete succession. © 2012 Gebrüder Borntraeger, Stuttgart, Germany.

We investigated shell characteristics and differential dissolution susceptibility of planktic foraminiferal species derived from upper Paleocene and lower Eocene deep-sea sequences, Ocean Drilling Program (ODP) Site 865 (Allison Guyot) and Sites 1209B, 1210B and 1212A (Shatsky Rise) in the North Pacific Ocean. The purposes of this study are: 1) assessing the effects of differential dissolution on upper Paleocene–lower Eocene planktic foraminiferal assemblages, at species level and within different biozones, to quantify dissolution susceptibility of genera and species; 2) investigating the differences in shell characteristics; 3) revealing the relationship between shell parameters and dissolution robustness of taxa, and 4) identifying the key shell parameter(s) influencing the dissolution susceptibility of foraminiferal taxa. Two independent experiments were carried out, one focusing on gradual qualitative deterioration of taxa by dissolution and the other documenting the weight loss of taxa. Shell parameters such as wall thickness, porosity and pore size were determined through Scanning Electron Microscopy (SEM) and image analysis (JMicroVision). We found that the large muricate Acarinina and Morozovella are most resistant, followed by the cancellate Subbotina and the small muricate Igorina, confirming results of previous work. At species level, the thick-walled Acarinina soldadoensis, Acarinina subsphaerica and the large Morozovella subbotinae are the most resistant species. Most of the large Morozovella species such as Morozovella aequa, Morozovella formosa-gracilis, Morozovella velascoensis and Morozovella pasionensis, together with Acarinina nitida show intermediate dissolution resistance, whereas the small muricate Igorina species, the cancellate Subbotina velascoensis and the thin-walled Morozovella acuta and Morozovella occlusa are the most vulnerable species. We propose a formula for calculating the dissolution resistance of taxa based on their wall thickness and size — two key parameters in dissolution resistance of a species. Application of this formula reveals good agreement between the calculated and measured dissolution resistance, indicating its robustness. Furthermore, the agreement between our experimental results, in-situ experimental results on live foraminifera and natural quantitative/qualitative records suggests that our experiments accurately mimic natural dissolution processes. Consequently, these experimental results strongly bear on interpretations of foraminiferal dissolution in natural environments, especially in studies on early Paleogene climatic events that are often associated with dissolution phenomena. More generally, a proper assessment of taphonomic alteration by dissolution should be part of every paleoenvironmental reconstruction based on quantitative foraminiferal records. ispartof: Marine Micropaleontology vol:81 issue:1 pages:1-21 status: published

Globotruncanita insignis (Gandolfi, 1955) is a planktonic species commonly recognized in Late Cretaceous foraminiferal assemblages, but uncertainty about its morphologic variability and phyletic relationships have led to different interpretations of it. The taxon was considered to be morphologically and evolutionary related to Globotruncana rosetta (Carsey, 1926), phyletically linked to Globotruncanita elevata (Brotzen, 1934), or a junior synonym of the latter species. In addition, the neotype that replaced the lost holotype caused a taxonomic debate and compromised the identification of G. insignis , which has been assigned to both Globotruncanita and Globotruncana. This study resolves the taxonomic problems and reconstructs the phyletic lineage of this species on the basis of a continuous sequence of exceptionally well preserved and highly diversified planktonic foraminiferal assemblages in the Contusotruncana plummerae and Radotruncana calcarata zones, recently recovered from southeastern Tanzania drillholes. In addition to common G. insignis that characteristically have a strongly convex umbilical side, we recognized succession of morphotypes intermediate between Globotruncanita stuartiformis and G. insignis that demonstrates an ancestor–descendant relationship between the two taxa and further validates the assignment of G. insignis to Globotruncanita . Moreover, our results confirm that the neotype falls in the same phyletic lineage, but it represents a primitive form of G. insignis .

The evolution of planktic foraminifera in the Paleocene–Eocene time interval is characterized by a high rate of diversification after the major extinction event observed at the Cretaceous/Paleogene boundary. An accelerated speciation rate resulted in the appearance of several new genera. Phylogenetic relationships among many of genera are still poorly understood. This study investigates the origin and phylogeny of the genus Igorina , which is characterized by a thick, nonspinose and incrusted wall. Igorina appears in Subzone P3a (early late Paleocene) and disappears in Zone P11 (middle Eocene). To date, nine species have been assigned to the genus Igorina ( I. pusilla , I. trichotrocha , I. tadjikistanensis , I. convexa , I. albeari , I. laevigata, I. lodoensis , I. broedermanni , and I. anapetes ) based on both wall texture and morphologic similarities. However, the taxonomic identification at species level is affected by several problems, mainly those resulting from poor descriptions and illustrations of the primary type specimens of several species. This study reconstructs the phylogeny and evolution of the igorinids through cladistic analysis by applying the method of parsimony. Phylogenetic relationships of the species assigned to Igorina are determined through stratocladistic analysis by using a data matrix of 23 taxa (including key species of Acarinina ), 31 morphological characters (unordered), and a stratigraphic character (ordered) mapping the first occurrence of the taxa under investigation. The matrix (Appendix 1) was processed with PAUP* 4.0b10 software by using the heuristic search option to discover the most parsimonious trees. Results suggest that I. pusilla is the first representative of the Igorina lineage, and it is followed by I. laevigata , I. convexa , and I. albeari . Morphotypes of uncertain taxonomic identification have been coded and analyzed separately as morphotypes A–F to determine their ancestor-descendant relationships and to evaluate their validity as discrete species. As the result of our analysis, two new species are formally described as I. praecarinata (= morphotype A) and I. paraspiralis (= morphotypes C, E, and F). Finally, our analysis provides evidence that I. lodoensis , I. broedermanni , and I. anapetes are more closely related to Acarinina than to Igorina and clearly belong to a different lineage.

Dissolution experiments were carried out on a foraminiferal assemblage from the Paleocene–Eocene Thermal Maximum (PETM) at Dababiya, Egypt, in order to: 1) reveal the effects of differential dissolution on the composition of the foraminiferal assemblage and 2) develop objective criteria for the evaluation of dissolution in foraminiferal assemblages used in early Paleogene paleoenvironmental reconstructions, particularly with respect to neritic Midway-type assemblages from the Paleocene/Eocene transition. Our results confirm two general observations on modern foraminifera: 1) planktic foraminifera are much more vulnerable to dissolution than benthic foraminifera, leading to depressed P/B ratios and 2) dissolution susceptibility differs between size fractions, with the smaller specimens dissolving more rapidly than the bigger ones, leading to a larger average size of the remaining assemblage. Within a size fraction, wall structure and thickness are considered to be the main factors controlling differential dissolution susceptibility. We propose a ranking scheme for taxa with respect to dissolution resistance. Among the benthic taxa, Lenticulina is most resistant, followed by the agglutinated Gaudryina cf. ellisorae and Alabamina midwayensis. Biserial and triserial hyaline taxa and the porcelaneous Spiroloculina sp. are most susceptible to dissolution, whereas rotaliines, such as Cibicidoides and Anomalinoides have an intermediate susceptibility. This implies that mild dissolution of a Midway-type benthic assemblage leads to a relative enrichment in Lenticulina, Gaudryina and rotaliines. Amongst planktic foraminifera, the muricate taxa Acarinina and Morozovella are most resistant, followed by the cancellate Subbotina. The smooth and generally small Globanomalina and Zeauvigerina are least resistant to dissolution. Our data enable to objectively evaluate various degrees of dissolution in benthic and planktic foraminiferal assemblages retrieved from the lower Paleogene Tethyan outcrops. In this way taphonomic artifacts can be readily distinguished from paleoenvironmental signals affecting the primary composition of the assemblages. More generally, we propose that the combined use of foraminiferal numbers, P/B ratio and relative abundances of non-calcareous agglutinated taxa and Lenticulina may provide a powerful proxy for assessing dissolution in hemipelagic assemblages from Cenozoic and upper Cretaceous continental margins. In order to achieve more robust pre-Quaternary paleoenvironmental reconstructions based on quantitative foraminiferal data, application of dissolution proxies, like proposed here, or in slightly modified form, should become a more widely used micropaleontologic procedure. Particularly continental margin studies dealing with major biotic events (e.g. PETM) or employing P/B ratios for sea-level reconstructions should benefit from such an approach. ispartof: Marine Micropaleontology vol:73 issue:3 pages:241-258 status: published

Based on examination of the type material deposited by Jacques Sigal at the Musee National d’Histoire Naturelle in Paris, we have validated the hypothesis of Randrianasolo and Anglada (1998) that the holotype and paratype of Ticinella bejaouaensis Sigal 1966 belong to two different species, the distributions of which do not overlap. Indeed, the holotype is of late Albian age and from Madagascar whilst the paratype is of a latest Aptian age and from Tunisia. Sigal’s paratype is here confirmed to be the holotype of the species eubejaouaensis Randrianasolo and Anglada, 1998. It displays a distinctive wall texture bearing perforation cones that coalesce to form irregularly arranged rugosities and ridges, which tend to parallel the periphery. In addition, flaps may cover the umbilical area. However, it lacks true umbilical supplementary apertures and therefore cannot be included in the genus Ticinella Reichel, 1950. The new genus Paraticinella , with Paraticinella eubejaouaensis as the type species, is here formalized to accommodate uppermost Aptian trochospiral individuals with a wall texture bearing perforation cones, rugosities, and ridges in patterns paralleling the margin, and possessing an umbilical cover-plate. Paraticinella eubejaouaensis evolved from Hedbergella trocoidea in the upper Aptian. The evolutionary trend is exemplified by the increasing number of chambers, by flattening of the spire height, by widening of the umbilicus with the appearance of a cover-plate, by acquisition of well-developed ridges on wall surfaces, and by the appearance of weakly developed infralaminal accessory apertures in later specimens of P. eubejaouaensis . A close study of the holotype of Ticinella bejaouaensis Sigal, 1966 reveals a substantial similarity in morphology and wall structure with Ticinella roberti and a lack of distinguishing criteria between the two species. Consequently, the species Ticinella bejaouaensis is invalidated and is considered to be a junior synonym of T. roberti . A third species was observed associated with Ticinella roberti and Biticinella breggiensis in Madagascar and Spain, and it is attributable to the genus Ticinella based on the presence of true umbilical supplementary apertures and a typical Ticinella wall structure (muricate to coarsely pustulose), while in gross morphology, it resembles Paraticinella eubejaouaensis . We have named this new taxon Ticinella moulladei . It differs from T. roberti by its thinner test, more numerous chambers, and wider umbilicus. Finally, the last zone of the uppermost Aptian must be renamed the Paraticinella eubejaouaensis Zone to replace Ticinella bejaouaensis , which is now considered to be an invalid taxon.

One of the key objectives of Deep Sea Drilling Project (DSDP) Leg 75 was to shed light on the underlying causes of Cretaceous oceanic anoxia in the South Atlantic by addressing two major hypotheses: productivity productivity-driven anoxia vs. enhanced ocean stratification leading to preservation of organic matter and black shale deposition. Here we present a detailed geochemical dataset from sediments deposited during the Cenomanian/Turonian (C/T) transition and the global oceanic anoxic event 2 (OAE 2) at DSDP Site 530A, located off-shore Namibia (southeast Angola Basin, north of Walvis Ridge). To characterise the succession of alternating black and green shales at this site and to reconstruct the evolution of their paleoenvironmental setting, we have combined data derived from investigations on bulk organic matter, biomarkers and the inorganic fraction. The location of the C/T boundary itself is biostratigraphically not well constrained due to the carbonate-poor (but organic matter-rich) facies of these sediments. The bulk δ13Corg record and compound-specific δ13C data, in combination with published as well as new biostratigraphic data, enabled us to locate more precisely the C/T boundary at DSDP Site 530A. The compound-specific δ13C record is the first of this kind reported from C/T black shales in the South Atlantic. It is employed for paleoenvironmental reconstructions and chemostratigraphic correlation to other C/T sections in order to discuss the paleoceanographic aspects and implications of the observations at DSDP Site 530A in a broader context, e.g., with regard to the potential trigger mechanisms of OAE 2, global changes in black shale deposition and climate. On a stratigraphic level, an approximation and monitoring of the syndepositional degree of oxygen depletion within the sediments/bottom waters in comparison to the upper water column is achieved by comparing normalised concentrations of redox-sensitive trace elements with the abundance of highly source specific molecular compounds. These biomarkers are derived from photoautotrophic and simultaneously anoxygenic green sulphur bacteria (Chlorobiacea) and are interpreted as paleoindicators for events of photic zone euxinia. In contrast to a number of other OAE 2 sections that are characterised by continuous black shale sequences, DSDP Site 530A represents a highly dynamic setting where newly deposited black shales were repeatedly exposed to conditions of subtle bottom water re-oxidation, presumably leading to their progressive alteration into green shales. The frequent alternation between both facies and the related anoxic to slight oxygenated conditions can be best explained by variations in vertical extent of an oxygen minimum zone in response to changes in a highly productive western continental margin setting driven by upwelling.

A detailed, quantitative analysis of planktonic foraminiferal composition and shell fragmentation is presented for samples from Ocean Drilling Program Site 1209 (Leg 198, Shatsky Rise, Pacific Ocean) in a stratigraphic interval from the Paleocene/Eocene boundary, which is characterized by enhanced carbonate dissolution, to the base of the middle Eocene where no distinct dissolution layers are recorded. The aims are to evaluate whether the composition of the fossil Paleogene assemblage is representative of the original assemblage and to what extent it is influenced by carbonate dissolution. By comparing the absolute abundances of whole specimens and fragments of the three most common Paleogene genera (Morozovella, Acarinina and Subbotina), it is demonstrated that the percentage of foraminiferal fragments, identified to genus, is helpful in interpreting the paleoenvironment of fossil planktonic foraminiferal assemblages affected by marked carbonate dissolution. In addition, the absolute abundance of whole specimens and fragments of the three Paleogene genera collected at the Paleocene/Eocene boundary and in the Eocene reveal that, contrary to earlier suggestions, the spinose, asymbiotic, deep-dweller Subbotina is less resistant to dissolution than the muricate, symbiontbearing, surface-dwellers Morozovella and Acarinina. Distinguishing between primary and taphonomic signals in Paleogene planktonic foraminiferal assemblages will be an important challenge to overcome in order to better constrain paleoecologic and paleoclimatic signals of global significance. ispartof: Journal of foraminiferal research vol:38 issue:4 pages:357-371 status: published

The spillway of Lake Waxahachie, Ellis County (Texas), exposes a >17 m section of the Hutchins Member of the Austin Chalk Group, unconformably overlain by Taylor Clay. The Austin sequence was regarded as a potential Global Stratotype Section for the base of the Campanian Stage at the 1995 Brussels meeting on Cretaceous Stage boundaries, with the last occurrence of the crinoid Marsupites testudinarius (von Schlotheim, 1820) as the potential boundary marker. An integrated study of the geochemistry, stable carbon and oxgen isotopes, nannofossils, planktonic foraminifera, inoceramid bivalves, ammonites and crinoids of this section place the last occurrence of M. testudinarius in a matrix of eighteen ancillary biostratigraphic markers, while the boundary can also be recognised on the basis of a δ13C excursion that can, in principle, be detected globally in marine sediments. A new forma of the crinoid Marsupites testudinarius is introduced. The Waxahachie section fulfils sufficient geological criteria as to be an excellent candidate GSSP for the base of the Campanian Stage, if problems of ownership and access to the section can be resolved. © 2007 Elsevier Ltd. All rights reserved.

High-resolution biostratigraphic and quantitative studies of subtropical Pacific planktonic foraminiferal assemblages (Ocean Drilling Program, Leg 198 Shatsky Rise, Sites 1209 and 1210) are performed to analyse the faunal changes associated with the Paleocene–Eocene Thermal Maximum (PETM) at about 55.5 Ma. At Shatsky Rise, the onset of the PETM is marked by the abrupt onset of a negative carbon isotope excursion close to the contact between carbonate-rich ooze and overlying clay-rich ooze and corresponds to a level of poor foraminiferal preservation as a result of carbonate dissolution. Lithology, planktonic foraminiferal distribution and abundances, calcareous plankton and benthic events, and the negative carbon isotope excursion allow precise correlation of the two Shatsky Rise records. Results from quantitative analyses show that Morozovella dominates the assemblages and that its maximum relative abundance is coincident with the lowest δ13C values, whereas subbotinids are absent in the interval of maximum abundance of Morozovella. The excursion taxa (Acarinina africana, Acarinina sibaiyaensis, and Morozovella allisonensis) first appear at the base of the event. Comparison between the absolute abundances of whole specimens and fragments of genera demonstrate that the increase in absolute abundance of Morozovella and the decrease of Subbotina are not an artifact of selective dissolution. Moreover, the shell fragmentation data reveal Subbotina to be the more dissolution-susceptible taxon. The upward decrease in abundance of Morozovella species and the concomitant increase in test size of Morozovella velascoensis are not controlled by dissolution. These changes could be attributed to the species' response to low nutrient supply in the surface waters and to concomitant changes in the physical and chemical properties of the seawater, including increased surface stratification and salinity. Comparison of the planktonic foraminiferal changes at Shatsky Rise to those from other PETM records (Sites 865 and 690) highlights significant similarities, such as the decline of Subbotina at the onset of the event, and discrepancies, including the difference in abundance of the excursion taxa. The observed planktonic foraminifera species response suggests a warm–oligotrophic scenario with a high degree of complexity in the ocean structure.

Paleocene–Eocene warming and changes in oceanic hydrography should have significantly impacted the ecology of marine microorganisms, both at the surface and on the seafloor. We analyzed several key characteristics of foraminifera from two Shatsky Rise (ODP Leg 198) cores spanning the P/E boundary including the maximum test diameters of the largest calcareous trochospiral benthic foraminifera and largest shallow-dwelling planktonic foraminifera, and the stable carbon and oxygen isotope ratios of benthic foraminifera and bulk samples. We also qualitatively constrained changes in bottom water dissolved oxygen concentrations by quantifying changes in benthic species abundances. We find warming synchronous with an unusual increase in the size of surface-water planktonic in contrast to deep-water benthic foraminifera which decrease in size. We suggest that a decline in bottom water dissolved oxygen is the primary mechanism responsible for the size reduction of Pacific deep-sea benthic foraminifera, whereas the contemporaneous size increase of surface-water planktonic foraminifera is attributed to an increase in thermal stratification and decrease in local nutrient supply.

The ancestor-descendant relationships of the late Albian Planomalina lineage have been reconstructed using morphologic observations obtained from the Scanning Electron Microscope and supported by morphometric analysis using X-ray images of the shell ontogeny. Both techniques are key to resolving questions on phylogeny and taxonomy, as they allowed us to propose that the trochospiral species Hedbergella wondersi is the ancestor of the genus Planomalina , and to document the Hedbergella wondersi - Globigerinelloides pulchellus - Planomalina praebuxtorfi - Planomalina buxtorfi evolutionary lineage.

A detailed taxonomic and biostratigraphic analysis of upper Albian planktonic foraminifera is presented for Ocean Drilling Program sites 1050 and 1052, which were deposited at ~23°N paleolatitude and ~1300 m and 300 m paleodepths, respectively, on the Blake Nose escarpment (subtropical western North Atlantic Ocean). The generally excellent preservation of the material, especially in the clay-rich layers, permits recognition of new bioevents within the uppermost Albian, in addition to most of the standard bioevents that have been previously defined in the Tethyan Realm. The taxonomic assignments and the stratigraphic range of some species that are often overlooked or misidentified in the stratigraphic record have also been clarified, and three species are formally described as new ( Hedbergella astrepta , H. praelibyca and H. blakensis ). Graphic correlation and age-depth curves constructed from integrated planktonic foraminifera and calcareous nannofossils datum events enable reliable estimation of the relative timing of species first and last occurrences and relative abundance variations, as well as determination of the timing and extent of an unconformity at Site 1050. While most of the species datum events are well correlated, several are found to be diachronous and/or unreliable probably as a result of different surface water conditions along the depth transect.

ODP Leg 198 drilling on Shatsky Rise recovered a lower Aptian porcellanite (∼120.5 Ma) deposited during oceanic anoxic event (OAE) 1a that contains C36–C39 alkadienones: C37:2 and C39:2 alkadien-2-ones and C36:2 and C38:2 alkadien-3-ones. This alkenone distribution differs from that typical of contemporary sediments and haptophyte algae, but resembles that of Cretaceous sediments from the Blake-Bahama basin. The discovery of alkenones in the early Aptian extends their sedimentary record by 15 M.y. to 120.5 M.y. and demonstrates the potential for long-term survival of these diagnostic functional lipids under favorable depositional conditions and subsequent shallow burial. It also contributes to the understanding and reconstruction of evolutionary developments in alkenone distributions and biosynthesis over geologic time.

The Late Cretaceous planktonic foraminiferal distribution recorded at several drill sites (Deep Sea Drilling Project and Ocean Drilling Program) in the South Atlantic and south Indian Ocean and from sediment outcrops in the Tethyan region (Gubbio and El Kef) have been analyzed in order to investigate the presence of a similar sequence of bioevents occurring at low, middle, and high latitude. Comparative analysis highlights the co-occurrence of several bioevents; some of them are isochronous bioevents occurring in the Tethys and in the Southern Ocean record, whereas others are diachronous across latitudes but can be used for correlation at regional scale, as they show the same stratigraphic distribution in the South Atlantic and Indian Ocean record. Isochronous bioevents are the first and the last occurrence of Helvetoglobotruncana helvetica , and the first appearance of Falsotruncana maslakovae in the lower-middle Turonian. The first occurrence of Heterohelix papula in the Southern Ocean sites, correlated with the first occurrence of large heterohelicids in the Tethyan area, allows the Coniacian/Santonian boundary to be identified. The most reliable bioevents useful for correlation at a regional scale in the Southern Ocean record are the last occurrence of the marginotruncanids in the upper Santonian, the first and the last occurrence of Globigerinelloides impensus from the uppermost Santonian to upper Campanian, the first occurrence of Heterohelix rajagopalani in the middle-upper Campanian, and the appearance of Abathomphalus mayaroensis in the lower Maastrichtian.

Available biomagnetostratigraphy suggests that the Palaeocene interval in the classic Tethyan setting of the Bottaccione section (Gubbio, central Italy) may be condensed relative to other outcrops in the area and/or that the Bottaccione succession may contain an unidentified stratigraphic gap in the lower Palaeocene. However, new integrated stratigraphic data, including from bio-, magneto-, chemo-, and cyclostratigraphy, provide robust evidence that the Bottaccione section is complete and comparable to other successions cropping out in the Umbria–Marche area, which solves potential conflicts in the interpretation of the regional biostratigraphic and lithostratigraphic records. The recognition of orbitally forced sedimentary cycles, together with the availability of a carbon isotope profile, makes the Bottaccione outcrop a potential reference section for comparison with the already-available record of carbon-cycle alterations in the early–middle Palaeocene.

The External Ligurian and Epiligurian Units in the Northern Apennines of Italy are tectonically juxtaposed with the Tertiary Piedmont Basin along the Villalvernia - Varzi Line, which represents a regional scale fault zone, E-striking. Our map, at the 1:20,000 scale, describes the tectono-stratigraphic evolution of this sector that resulted from multistage faulting along that fault zone. Four main tectonic stages are defined on the basis of the crosscutting relationships between mapped faults and stratigraphic unconformities: late Priabonian - Rupelian, Chattian - early Miocene, late Serravallian - Tortonian, and late Messinian - early Pliocene. Our results demonstrate that since the late Burdigalian, the Villalvernia - Varzi Line was sealed by the gravitational emplacement of a chaotic rock body. The deposition of the late Serravallian - early Messinian succession is controlled by NW-striking strike-slip faults that crosscut to the west the Villalvernia - Varzi Line. Extensional tectonics related to regional scale N-dipping tilting characterized the late Messinian - early Pliocene time interval.

The evolution of planktonic foraminifera during the Late Cretaceous is marked in the Santonian by the disappearance of complex morphotypes (the marginotruncanids), and the contemporary increasing importance and diversification of another group of complex taxa, the globotruncanids. Upper Turonian to lower Campanian planktonic foraminiferal assemblages from Holes 762C and 763B (Ocean Drilling Program, Leg 122, Exmouth Plateau, 47°S palaeolatitude) were studied in detail to evaluate the compositional variations at the genus and species level based on the assumption that, in the Cretaceous oceans as in the modern, any faunal change was associated with changes in the characteristics and the degree of stability of the oceanic surface waters. Three major groups were recognised based on gross morphology, and following the assumption that Cretaceous planktonic foraminifera, although extinct, had life-history strategies comparable to those of modern planktonics: 1 – r-selected opportunists; 2 – k-selected specialists; 3 – r/k intermediate morphotypes which include all genera that display a range of trophic strategies in-between opportunist and specialist taxa. Although planktonic foraminiferal assemblages are characterised by a progressive appearance of complex taxa, this trend is discontinuous. Variation in number of species and specimens within genera has allowed recognition of five discrete intervals each of them reflecting different oceanic conditions based on fluctuations in diversity and abundance of the major morphotypes. Planktonic forms show cyclical fluctuations in diversity and abundance of cold (r-strategists) and warm taxa (k-strategists), perhaps representing alternating phases of unstable conditions (suggesting a weakly stratified upper water column in a mesotrophic environment), and well-stratified surface and near-surface waters (indicating a more oligotrophic environment). Interval 1, middle Turonian to early Coniacian in age, is dominated by the r/k intermediate morphotypes which alternate with r-strategists. These cyclical alternations are used to identify three additional sub-intervals. Interval 2, aged middle to late Coniacian, is characterised by the increasing number of species and relative abundance of k-strategists. After this maximum diversification the k-strategists show a progressive decrease reaching a minimum value in Interval 3 (early to late Santonian), which corresponds to the extinction of the genus Marginotruncana. In the Interval 4, latest Santonian in age, the k-strategists, represented mainly by the genera Globotruncana, increase again in diversity and abundance. The last Interval 5 (early Campanian) is dominated by juvenile globotruncanids and r-strategists which fluctuate in opposite phase. The positive peak (Interval 2) related to the maximum diversification of warm taxa (k-strategists) in the Coniacian seems to correspond to a warmer episode. It is followed by a marked decrease in the relative abundance of warm taxa (k-strategists crisis) with a minimum in the late Santonian (Interval 3), reflecting a decrease in temperature. Detailed analysis of faunal variations allows the Santonian faunal turnover to be ascribed to a cooling event strong enough to cause the extinction of the marginotruncanids.

An almost complete Upper Cretaceous sedimentary sequence recently recovered on the Kerguelen Plateau (southern Indian Ocean) during ODP Leg 183 was analysed for planktonic foraminifera in order to refine and integrate the zonal schemes previously proposed for the Southern Ocean area. Detailed biostratigraphic analysis carried out on holes 1135A, 1136A and 1138A (poleward of 50°S palaeolatitude during Late Cretaceous time) has allowed recognition of low and mid–high latitude bioevents, useful for correlation across latitudes, in addition to known Austral bioevents. The low latitude biozonation can be applied to Turonian sediments, because of the occurrence of Helvetoglobotruncana helvetica, which marks the boundary between Whiteinella archaeocretacea and Helvetoglobotruncana helvetica zones. The base of the Whiteinella archeocretacea Zone falls within the uppermost Cenomanian–Turonian black shale level in Hole 1138A. The stratigraphic interval from upper Turonian to uppermost Santonian can be resolved using bioevents recognized in the mid–high latitude sections. They are, in stratigraphic order: the last occurrence of Falsotruncana maslakovae in the Coniacian, the first occurrence of Heterohelix papula at the Coniacian/Santonian boundary, the extinction of the marginotruncanids in the late Santonian, and the first occurrence of Globigerinelloides impensus in the latest (?) Santonian. The remainder of the Late Cretaceous fits rather well in the Austral zonal scheme, except that Globigerinelloides impensus exhibits a stratigraphic range in agreement with its record at the mid–high latitude sections and extends further downwards than previously recorded at southern sites. Therefore, despite the poor recovery in certain intervals and the presence of several hiatuses of local and regional importance as revealed by correlation among holes, a more detailed zonal scheme has been obtained (mainly for the less resolved Turonian–Santonian interval). Remarks on some species often overlooked in literature are also provided.

The two genera, Meridionalla El-Nakhal, 1982 and Costellagerina Petters, El-Nakhal and Cifelli, 1983, both erected to accommodate all the pre-Campanian meridionally costellate species, are discussed after comparison with the holotypes of the type species. Observations clearly indicate that Costellagerina is the appropriate genus, while the genus Meridionalla is inappropriate because its type species, Hedbergella murphyi Marianos and Zingula 1966 does not possess the textural ornamentation diagnostic for the genus.

The Late Cretaceous ‘greenhouse’ world witnessed a transition from one of the warmest climates of the past 140 million years to cooler conditions, yet still without significant continental ice. Low-latitude sea surface temperature (SST) records are a vital piece of evidence required to unravel the cause of Late Cretaceous cooling, but high-quality data remain illusive. Here, using an organic geochemical palaeothermometer (TEX86), we present a record of SSTs for the Campanian–Maastrichtian interval (~83–66 Ma) from hemipelagic sediments deposited on the western North Atlantic shelf. Our record reveals that the North Atlantic at 35 °N was relatively warm in the earliest Campanian, with maximum SSTs of ~35 °C, but experienced significant cooling (~7 °C) after this to, The Late Cretaceous experienced significant cooling, yet a lack of low-latitude records mean the regional extent of this cooling is poorly constrained. Linnert et al. present a TEX86 sea surface temperature record from a palaeolatitude of ~35 °N and show that Late Cretaceous cooling was global in nature.

Stagnant bottom-water conditions (e.g., low and stable redox potential, long-water residence time) is an assumption commonly used to explain the preservation and burial of high amounts of organic carbon (C-org) in marine sediments. Rather than stagnant conditions, the evidence presented here from north-central Tunisia supports dynamic conditions during formation of variably C-org-rich, outermost shelf carbonates of the early-middle Eocene. The dynamic conditions are inferred by the deposition of four distinct lithofacies in this outermost shelf setting. Shedding of carbonate (i.e., mud and fragmented bioclasts) from the shallower source areas controlled the distribution of all lithofacies, with higher amounts of transported benthic debris occurring in the most proximal lithofacies and vice versa. This carbonate shedding also controlled the deposition of three orders of lithological cycles, from limestone/marly limestone couplets grading to cycles made up of groups of couplets. Bottom-water redox potential varied in intensity throughout this depositional setting, with moderate oxygen depletion (suboxic conditions) in the southern sector of north-central Tunisia and much higher oxygenation in the northern area. Evidence for suboxic bottom waters in the southern sector (higher C-org contents) is provided by higher trace metal (Cu, Ni, Zn, Cr, Mo, U and V) enrichments than in the northern area. Regionally heterogeneous primary productivity of surface waters is suggested to have caused a higher C-org burial flux in the southern sector compared to the north, a situation interpreted to have been related to varying upwelling patterns due to the effects of regional palaeogeography and the dominant wind patterns.The deposition of the studied C-org-rich carbonates spanned part of the calcareous nannofossil Zones NP13 to NP14 (similar to 50-48 m.y. ago) and coincided with the initiation of the Cenozoic global cooling subsequent to the early Eocene climatic optimum (EECO) (similar to 52-50 m.y. ago). An implication is that an increased C-org burial in north-central Tunisia could have been part of a major event sequestering atmospheric CO2 in marine sediments that caused climatic cooling immediately after the EECO. This implication, however, is difficult to reconcile with the data available elsewhere. Other than our Tunisian carbonates, major C-org sequestration in marine sediments of the early-middle Eocene transition are poorly documented globally. If this scenario is confirmed, other negative feedbacks, such as enhanced continental weathering, increased terrestrial carbon stock, decreased CO2 outgassing and/or changes in ocean circulation, would have been more influential to the onset of the Cenozoic global cooling. (c) 2013 Elsevier B.V. All rights reserved.

An integrated study of the ammonites, inoceramid bivalves, planktonic foraminifera, calcareous nannofossils, geochemistry, stable carbon isotopes, and cyclostratigraphy is provided for the upper Middle to upper Upper Albian sucession exposed in the Col de Palluel section east of Rosans in Hautes-Alpes, France. The Albian-Cenomanian boundary interval described by Gale et al. at Mont Risou is re-examined, a total thickness of 370 m of the Marnes Bleues Formation. Zonal schemes based on ammonites, inoceramid bivalves, planktonic foraminifera, and calcareous nannofossils are integrated with the stable carbon isotope curve and key lithostratigraphic markers to provide a sequence of more than 70 events in the uppermost Middle Albian to basal Cenomanian interval. Time series analysis of the Al2O3 content of the 500 m Albian sequence present in the Col de Palluel and Risou sections reveals the presence of the 20 kyr precession, 40 kyr tilt, 100 kyr short eccentricity, and 406 kyr long eccentricity cycles. Correlation using planktonic foraminiferan and nannofossil data provide a link between the Col de Palluel and Risou sections and the Italian sequence at Gubbio, and in the Piobbico core. This provides a basis for the extension of the orbital time scale of Grippo et al. to the sequence. It reveals a major break in the Col de Palluel succession at the top of the distinctive marker bed known as the Petite Verde that may represent as much as 2 Ma. It also provides a basis for the estimation of the length of the Albian Stage at 4.12 Ma, 0.8 Ma for the early Albian, 2.84 Ma for the Middle Albian, and 3.68 Ma for the late Albian substages. (C) 2010 Elsevier Ltd. All rights reserved.

A late Albian–early Cenomanian record (~103.3 to 99.0 Ma), including organic-rich deposits and a ?13C increase associated with oceanic anoxic event 1d (OAE 1d), is described from Ocean Drilling Program sites 1050 and 1052 in the subtropical Atlantic. Foraminifera are well preserved at these sites. Paleotemperatures estimated from benthic ?18O values average ~14°C for middle bathyal Site 1050 and ~17°C for upper bathyal Site 1052, whereas surface temperatures are estimated to have ranged from 26°C to 31°C at both sites. Among planktonic foraminifera, there is a steady balance of speciation and extinction with no discrete time of major faunal turnover. OAE 1d is recognized on the basis of a 1.2‰ ?13C increase (~100.0–99.6 Ma), which is similar in age and magnitude to ?13C excursions documented in the North Atlantic and western Tethys. Organic-rich “black shales” are present throughout the studied interval at both sites. However, deposition of individual black shale beds was not synchronous between sites, and most of the black shale was deposited before the OAE 1d ?13C increase. A similar pattern is observed at the other sites where OAE 1d has been recognized indicating that the site(s) of excess organic carbon burial that could have caused the ?13C increase has (have) yet to be found. Our findings add weight to the view that OAEs should be chemostratigraphically (?13C) rather than lithostratigraphically defined.

We present new stable (C, O) isotopic, biostratigraphic and organic geochemical data for the Vigla Shale Member of the Ionian Zone in NW Greece, in order to characterize organic carbon-rich strata that potentially record the impact of Cretaceous Oceanic Anoxic Events (OAEs). In a section exposed near Gotzikas (NW Epirus), we sampled a number of decimetre-thick, organic carbon-rich units enclosed within marly, locally silicified, Vigla Limestone (Berriasian-Turonian). All these units are characterized by largely comparable bulk geochemical characteristics, indicating a common marine origin and low thermal maturity. However, the stratigraphically highest of these black shales is further distinguished by its much higher total organic-carbon (TOC) content (28.9 wt%) and Hydrogen Index (HI) (529), and much enriched δ13Corg value (-22.1‰). Planktonic foraminiferal and calcareous nannofossil biostratigraphy indicate a lower to middle Albian age for the strata immediately above, and a lower Aptian age for the strata below, the uppermost black shale. In terms of molecular organic geochemistry, the latter black shale is also relatively enriched in specific isoprenoidal compounds (especially monocyclic isoprenoids), whose isotopic values are as high as - 15‰, indicating a substantial archaeal contribution to the organic matter. The striking similarities between the molecular signatures of the uppermost Vigla black shale and coeval organic-rich strata from SE France and the North Atlantic (ODP Site 1049C) indicate that this level constitutes a record of the Paquier Event (OAE 1b). © 2004 Cambridge University Press.

The Paleocene-Eocene Thermal Maximum (PETM) has been attributed to a rapid rise in greenhouse gas levels. If so, warming should have occurred at all latitudes, although amplified toward the poles. Existing records reveal an increase in high-latitude sea surface temperatures (SSTs) (8° to 10°C) and in bottom water temperatures (4° to 5°C). To date, however, the character of the tropical SST response during this event remains unconstrained. Here we address this deficiency by using paired oxygen isotope and minor element (magnesium/calcium) ratios of planktonic foraminifera from a tropical Pacific core to estimate changes in SST. Using mixed-layer foraminifera, we found that the combined proxies imply a 4° to 5°C rise in Pacific SST during the PETM. These results would necessitate a rise in atmospheric pCO 2 to levels three to four times as high as those estimated for the late Paleocene.

The lozanoi group appeared in the early Eocene and includes two taxa, Globigerina prolata Bolli, 1957, characterized by a globigerinid test, and Globigerina lozanoi Colom, 1954, which is distinguished by having 5–6 globular chambers in the final whorl that tend to increase the height of the coiling axis to a medium-high trochospire and an intraumbilical aperture that tends to extend extraumbilically. The two species both possess a non-spinose, irregularly cancellate wall texture (dutertrei-type) very similar to the praemuricate-type typical of the Paleocene genus Praemurica Olsson et al., 1992. However, the stratigraphic gap and the lack of intermediate morphotypes between the two groups suggest that the lozanoi group evolved independently from a different ancestor. Therefore, Alicantina n. gen. is here proposed to accommodate the species lozanoi and prolata, the ancestor of which is presently unknown.

The global stratotype sections and points for the bases of the Selandian (Middle Paleocene) and Thanetian (Upper Paleocene) stages have been defined in the coastal cliff along the ltzurun Beach at the town of Zumaia in the Basque Country, northern Spain. In the hemipelagic section exposed at Zumaia the base of the Selandian Stage has been placed at the base of the ltzurun Formation, ca. 49 m above the Cretaceous/ Paleogene boundary. At the base of the Selandian, marls replace the succession of Danian red limestone and limestone-marl couplets. The best marine, global correlation criterion for the basal Selandian is the second radiation of the important calcareous nannofossil group, the fasciculiths. Species such as Fasciculithus ulii, F. billii, F. janii, F. involutus, F. pileatus and F. tympaniformis have their first appearance in the interval from a few decimetres below up to 1.1 m above the base of the Selandian. The marker species for nannofossil Zone NP5, F. tympaniformis, first occurs 1.1 m above the base. Excellent cyclostratigraphy and magnetostratigraphy in the section creates further correlation potential, with the base of the Selandian occuring 30 precession cycles (630 kyr) above the top of magnetochron C27n. Profound changes in sedimentology related to a major sea-level fall characterize the Danian-Selandian transition in sections along the margins of the North Atlantic. The base of the Thanetian Stage is placed in the same section ca. 78 m above the Cretaceous/Paleogene boundary. It is defined at a level 2.8 m or eight precession cycles above the base of the core of the distinct clay-rich interval associated with the Mid-Paleocene Biotic Event, and it corresponds to the base of magnetochron C26n in the section. The base of the Thanetian is not associated with any significant change in marine micro-fauna or flora. The calcareous nannofossil Zone NP6, marked by the first occurrence of Heliolithus kleinpelli starts ca. 6.5 m below the base of the Thanetian. The definitions of the global stratotype points for the bases of the Selandian and Thanetian stages are in good agreements with the definitions in the historical stratotype sections in Denmark and England, respectively. Open access journal ispartof: Episodes: International Geoscience Newsmagazine vol:34 issue:4 pages:220-243 status: published

The new genus Pearsonites with P. broedermanni as type species is herein formalized to accommodate the early to middle Eocene globorotaliform taxa of the broedermanni lineage with a wall texture bearing muricae. Our analysis of specimens from the Pacific Ocean reveals a substantial similarity in wall structure with the genus Acarinina . In particular, the development and organization of the muricae, the hourglass shape of the pores, and the morphological features suggest that Pearsonites nov. gen. evolved from Acarinina in the late Paleocene. Herein we group three species previously considered morphologically and evolutionarily related to the Paleocene genus Igorina Davidzon, 1976, within Pearsonites nov. gen.: P. broedermanni (Cushman & Bermudez, 1949), P. lodoensis (Mallory, 1959), and P. anapetes (Blow, 1979). Species assigned to Pearsonites nov. gen. are relatively common in the stratigraphic interval from the late Paleocene (Zone P5) to the middle Eocene (Zone E9).