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Supplementary modification and introduction of code numbers to the low-latitude coccolith biostratigraphic zonation (BUKRY, 1973; 1975)
... The abundance of nannofossil was calculated using the cascading counting method with 15 fields of view [7] . Data processing was carried out by sequencing samples in stratigraphic position, Relative age was determined based on the first occurrence and last occurrence of biostratigraphic marker species with reference to [8,9,5,10,11] . ...
... Previous researchers mentioned the first occurrence of Reticulofenestra umbilica coincide with the first occurrence of several species that were also recorded on samples in this interval, namely Sphenolithus furcatolithoides and Sphenolithus obtusus [5] . This zone corresponds to Zone NP16 [8], CP13ab [9], Reticulofenestra umbilica Zone [5] and CNE13-CNE15 [10] or Middle Eocene. Based on age dating, first occurance of Reticulofenestra umbilica was at 43.06 million years ago [11]. ...
... Previous researchers mentioned the first occurrence of Helicosphaera compacta coincide with the first occurrence of several species that were also recorded on samples, namely Discoaster tanii, D. tani nodifer, Reticulofenestra bisecta, R. stavensis ; and almost simultaneously with the last occurrence (LO) of Reticulofenestra dictyoda and Chiasmolithus solitus [5]. This zone corresponds to Zone NP17 [8], CP14b [9], Helicosphaera compacta Zone [5] , CNE15-CNE16 [10] or Middle Eocene. Based on age dating, Helicosphaera compacta Zone ranges from 38.7 to 37.9 million years ago [11]. ...
The first detailed mapping and recording of nannofossils was carried out on Kei Besar Island, Southeast Maluku. This area is mostly composed of the Elat Formation, which is mainly composed by intercalated calcarenite and calcareous claystone. Total 48 samples were taken on three measured sections (Hollat, Ngurdu and Mata Hollat). Samples were prepared using smear slide method, then observed under a polarized microscope at 1000 x magnification. Total 48 species of nannofossils were identified. Several index species were selected to define biostratigraphic zones based on their first and last occurrence. Three zones of nannofossils are identified, starting with the oldest those are: Reticulofenestra umbilica zone (NP16; 43.06 to 38.7 million years ago), Helicosphaera compacta zone (NP17; 38.7 to 37.9 Mya) and Helicosphaera eupratis zone (NP18-NP19; 37.9-36.8 Mya). It can be concluded that Elat Formation is deposited in Middle to Late Eocene (43.06 to 35.4 Mya). The Middle-Late Eocene boundary can be clearly defined based on nannofossils assemblages in the section of the Kei Besar Island.
... The Ypresian/Lutetian boundary (Y/L boundary; early/middle Eocene boundary; 47.8 Ma; Jenkins and Luterbacher, 1992) is marked by the Lowest Occurrence (LO) of the planktic foraminifera Guembelitrioides nuttalli (base of Zone E8 (Kapellos and Schaub, 1973), Pearson, 2005, 2006) and between Larger Benthic Foraminiferal zones 12-13 (Serra-Kiel et al., 1998) and the LO of the calcareous nannofossil Blackites inflatus (= base of Subzone CP12b, Okada and Bukry, 1980) and correlated with the calcareous nannofossil NP13/NP14 zonal boundary (e.g., Martini, 1971;Martini and Muller, 1986). At the Paris and Belgian basins, the Y/L boundary is placed in the lower part of the calcareous nannofossil Zone NP14 (Aubry, 1983;Bolli et al., 1985;Berggren et al., 1985;Cavelier and Pomerol, 1986;Steurbaut, 1988). ...
... The Paleogene calcareous nannofossil biostratigraphic schemes of Martini (1971), Okada and Bukry (1980) and Agnini et al. (2014) are used. The calcareous nannofossil assemblages from the three sections are diverse (53 taxa) with moderate to good preservation enabling species-level identification ( Fig. 3-5). ...
... The Discoaster kuepperi Subzone (CP12a/NP14a) is marked by the absence of B. inflatus and the presence of D. sublodoensis and spans from samples F171-F185 in the Wadi Ferian section (west-central Sinai, Egypt), from samples M51-M59 in the El Mishatii section (northeastern Sinai; Egypt) and from samples O1-O14 in the Gebel Outherite section (Jordan) . The Subzone CP12a of Okada and Bukry (1980) corresponds to zones CNE6 (D.sublodoensis/D.lodoensis) and CNE7 (D.barbadiensis) of Agnini et al. (2014). ...
The Ypresian/Lutetian boundary duration calcareous nannofossil biostratigraphy and bioevents from three sections, two from Sinai, Egypt (Wadi Ferian and El Mishatii; west-central and north-east Sinai, respectively) and one from Jordan (Outherite), are presented for the first time. Fifty-three calcareous nannofossil species are identified from 86 samples, spanning the calcareous nannofossil Zone NP14 (= Zone CP12; early‒middle Eocene). In the present study, the early/middle Eocene (Ypresian/Lutetian) boundary is defined by the Lowest Occurrence (LO) of Blackites inflatus, positioned at the base of NP14b/CP12b zones. The LO of B. inflatus is slightly above the LO of Turborotalia frontosa. In general, the present data is largely consistent with what is known from the GSSP (Gorrondatxe section, Spain, Basque Provinces) of the base of Lutetian, where the LO of B. inflatus also marks the base of NP14b/CP12b subzones. Here, the LO of B. inflatus is reaffirmed as a reliable marker for correlating the base of the Lutetian. Discoaster sublodoensis, D. saiipenensis, D. bifax, D. martini and Tribrachiatus orthostylus show diachronous occurrences.
... When using the Okada and Bukry (1980) zonation, the interval at the base of the section can be attributed to the CP17 zone (lower part of NP23). This unit spans from the LO of R. hillae or the LO of R. umbilicus to the FO of S. distentus, which occurs in the Cap Serrat section at 23 m (sample Cs6). ...
... The CP18 of Okada and Bukry (1980) ranges from the FO of S. distentus to the FO of S. ciperoensis (sample Cs12 at 150 m) (Plate 1: photo 7). The NP24 zone ranges from the FO of S. ciperoensis to the LO of S. distentus. ...
... The NP24 zone ranges from the FO of S. ciperoensis to the LO of S. distentus. This interval correlates with the CP19a of Okada and Bukry (1980), according to Perch-Nielsen (1985). These two events are recorded in the same sample (Cs12 at 150 m) in our work. ...
A detailed biostratigraphic study, based on calcareous nannofossils, was performed to re-evaluate the stratigraphic interpretation of the Numidian Formation and its structural relationship with the underlying El Haria, Boudabbous and Souar formations Tellian units (i.e., stratigraphic vs. tectonic). The new biostratigraphic results indicate that the Numidian Formation is not restricted to a Miocene age as considered in some recent works but spans from Oligocene (Rupelian and Chattian, NP23 to NP25) to early Miocene (Aquitanian and Burdigalian, NN1 to NN3). The Cap Serrat succession can be retained as the type section for the Tunisian Numidian Formation, where both the Chattian-Aquitanian (Oligocene/Miocene boundary) and the Aquitanian-Burdigalian transitions have been characterized.
Based on the new calcareous nannofossil findings, several duplications of the sedimentary succession were identified. They include the thick shales and marls of El Haria (Maastrichtian-Paleocene) and Souar (Eocene) formations, thrusted by the Numidian Formation. The updated regional structural cross-sections, confirm that the Numidian Formation is currently juxtaposed by southward major thrust contact to the underlying Kasseb structural unit in the studied area. The latter is intensively affected by poly-phased tectonics, resulting in the thrust events associated with the Alpine phase inversion. This has to be taken into consideration in oil and gas exploration in the area of the fold-thrust belt system, in both onshore and offshore Northern Tunisia.
... In the recent study, the biostratigraphic interpretations are based on the Lowest Occurrences (LOs) and Highest Occurrences (HOs) of stratigraphically important calcareous nannofossil taxa. The standard Neogene calcareous nannofossil zonal schemes of NN (Martini, 1971) and CN (Okada and Bukry, 1980) are used. Additionally, the Neogene calcareous nannofossil zonation schemes of CNM and CNPL of Backman et al. (2012) are also incorporated (Figs. 8 and 9). ...
... Remarks: The Zone NN13 (CN10c-CN11a) spans the interval from the Top of Ceratolithus acutus (5.04 Ma) to the Base common of Discoaster asymmetricus (4.04 Ma) (Backman et al., 2012) (Fig. 9). The LO of C. rugosus delineates the lower boundary of Zone NN13 (Martini, 1971), whereas, the HO of C. acutus has been used as a secondary marker (Bukry, 1973(Bukry, , 1975Okada and Bukry, 1980). However, in the Mediterranean areas, both these species are rare (Siesser and de Kaenel, 1999). ...
... Remarks: Rio et al. (1990) subdivided the Zone NN16 (of Martini, 1971) into two subzones, MNN16a and MNN16b. Okada and Bukry (1980), based on the HO of D. tamalis, subdivided Zone CN12 (= NN16) into two subzones, lower D. tamalis (CN12a) and the upper D. surculus (CN12b). The HOs of D. surculus (2.511 Ma) and D. tamalis (2.752 Ma), have been used to define the tops of subzones NN12b and NN12a, respectively (Fig. 9, Table 2). ...
In Egypt, biostratigraphic studies of calcareous nannofossils from the Miocene-Pliocene successions are scarce, irregular, and limited to certain areas. The present study is based on a review of calcareous nannofossils from 28 wells in the Gulf of Suez, North Nile Delta, and 7 exposed surface sections from west central Sinai (Egypt). Fifteen calcareous nannofossil zones from NN2 through NN16 are evaluated and discussed in this study. The NN2‒NN3 of early Miocene; NN4 of early/middle Miocene boundary; NN5‒NN6 of middle Miocene; NN7 of middle/late Miocene boundary; NN8‒NN11 of late Miocene; NN12 of Miocene/Pliocene; NN13‒NN15 of early Pliocene and NN16 of middle Pliocene are enumerated. The calcareous nannofossil events are also correlated regionally and globally and the Miocene and Pliocene Stage boundaries were briefly discussed.
... The lowermost part above the Marshall Paraconformity was about m thick and was assigned to Unit III, and this part consisted of nannofossil mudst nannofossil chalk and clay-bearing nannofossil chalk; an interval of about 8 m of thick was characterized by plastically deformed clayey nannofossil ooze and reported "debris flow", and it was present within this unit ( Figure 2). List of nannofossil bioevents detected at ODP Site 1123 (X) and bioevents adopted as zonal boundaries in standard [15,18,19,32,33] and most recent zonal schemes for oceanic successions [29]; ps stands for present study, nd stands for not detected. Most of the nannofossils index markers are illustrated in Figures A1-A3 in Appendix A. Figure 3. List of nannofossil bioevents detected at ODP Site 1123 (X) and bioevents adopted as zonal boundaries in standard [32,33] and most recent zonal schemes for oceanic successions [29]; ps stands for present study, nd stands for not detected. ...
... List of nannofossil bioevents detected at ODP Site 1123 (X) and bioevents adopted as zonal boundaries in standard [15,18,19,32,33] and most recent zonal schemes for oceanic successions [29]; ps stands for present study, nd stands for not detected. Most of the nannofossils index markers are illustrated in Figures A1-A3 in Appendix A. Figure 3. List of nannofossil bioevents detected at ODP Site 1123 (X) and bioevents adopted as zonal boundaries in standard [32,33] and most recent zonal schemes for oceanic successions [29]; ps stands for present study, nd stands for not detected. Most of the nannofossils index markers are illustrated in Figures A1-A3 in Appendix A. ...
... Pioneering studies are those of Bramlette and Riedel (1954) [34] and subsequently of Bramlette and Wilcoxon, 1967 [35], that represent the basis that gave rise to the standard zonal scheme by Martini, 1971 [32]. Later, the advent of the deep-sea drilling and the recovery of deep-sea sediments led to an everincreasing improvement in nannofossil biostratigraphic schemes, from Okada and Bukry, 7 of 20 1980 [33] and to Backman et al., 2012 [29] (Figure 3), and this topic field also benefited from advances in other fields of Earth Sciences (e.g., magnetostratigraphy, radiometric dating, cyclostratigraphy, etc.), highlighting the high degree of bio-and chronostratigraphic resolution that this group of organisms can provide in dating sediments of marine origin. ...
The quantitative analysis of the calcareous nannofossil content yield in the 600 m thick succession drilled at ODP Site 1123 (offshore New Zealand), considered as a reference section for the Southern Ocean region, allowed the recognition of 43 bioevents distributed along the last 20 Myr. The correlation with the excellent magnetostratigraphic record resulted in the attribution of numerical ages for the position of the detected horizons. Many of the marker species used in previous zonation were detected also at ODP Site 1123, but others revealed to be absent or of scarce applicability. On the other hand, the good applicability of additional events was verified and proved to be useful for the biostratigraphic subdivision and correlation. The obtained average bio- and chronostratigraphic resolution is about 0.6 Myr along the whole section, which increases to about 0.3 in the Pliocene–Holocene time interval. The final result is a detailed southern mid-to-high latitude nannofossil biochronology for the last 20 Myr, which confirms that the ODP Site 1123 succession represents a reference section for the Southern Ocean.
... The deep sea drilling project has shown the importance of this group for the detailed stratigraphic subdivision of the sediments and the establishment of large scale correlations based on the rapid evolution and wide geographic distribution of calcareous nanofossils and the identity of coeval associations over vast expanses (Martini, 1971;Okada and Bukry, 1980). ...
... Two scales based on nannoplankton-the Martini scale (Martini, 1971) and Bukry scale (Bukry, 1978) (which was later slightly modified) (Okada and Bukry, 1980)-are most widely used in the stratigraphy of Miocene deposits. The Martini scale was developed based on studying calcareous nannofossils mainly from sections of European marine sediments, which are characterized by incompleteness, relative shallowness, and uncoupled boundaries of many Miocene stratons. ...
... In the Martini scale (Martini, 1971), which was developed based on marine sediments exposed by sections on the continent, the boundary was established at the base of Zone NN1. According to H. Okada and D. Bukry (1980), whose scale is based on data from the Deep Sea Drilling Project, the Paleogene/Neogene boundary passes within subzone CN1b (i.e., in the middle subzone of Zone CN1, divided into three parts). The lower subzone CN1a and lower part of subzone CN1b are correlated with the Oligocene and the upper part of subzone CN1b (=Zone NN1) belongs to the Miocene. ...
The stratigraphic scale of the Eastern Paratethys is revised based on a study of the Neogene stratotype and reference sections, their biotic characteristics, and paleomagnetic and sedimentological data. New data on the correlation of its regional subdivisions with the Central Paratethys and Mediterranean stratotypes are presented. The section “Regional Stage Scale of the Eastern Paratethys” considers the history of identification and a brief description of the horizons of the regional scale, which later became regional stages, as well as their historical stratotypes and lectostratotypes, and division into Beds and Substages. The section “History of Separate Biota Groups” provides reviews on the most important groups of fauna, phytoplankton, and terrestrial vegetation, as well as on magnetostratigraphy, the possibility of correlation and dating of sections based on these data, and comparison with the Central Paratethys and stratotypes of the Mediterranean.
In conclusion, the main results of the revision of the stratigraphic scheme of the Neogene of the Eastern Paratethys are given.
... Calcareous nannofossils are strongly affected rather than other marine planktonic organisms (Melinte, 2004). In this study, standard zonation was used for calcareous nannofossil proposed by Martini, 1971 (the cosmopolitan to high latitude) and scheme proposed by Okada and Bukry, 1980 (the low latitude). ...
... The Discoaster which is likely to have an overgrowth made it difficult to distinguish one species from another. The age determination was made according to the presence of marker species of nannofossils, whether the First Occurrence (FO) or the Last Occurrence of marker species, with reference to Martini's zonal marker (1971) as well as Okada and Bukry's (1980). Therefore, biostratigraphy and relative age analysis of the rock in the studied area could be arranged in stratigraphic sequences of Tonasa Formation. ...
... The Discoaster have begun to appear from the first layer, but they were not found in the whole layers. Several marker species were also identified in this section, one of which is quite abundance, Cribrocentrum reticulatum, but in this paper the marker species proposed by Martini (1971) and Okada and Bukry (1980) are used. ...
... Age-diagnostic nannofossil specimens were imaged using a ZEISS Axiocam 305 color camera (Penn State University) or an Olympus DP22 camera and associated software (MARUM, University of Bremen) to help identify specimens to species level and to allow for internal taxonomic consistency. The nannofossil biostratigraphy utilized largely follows the Paleogene coccolith (CP) zonation of Okada and Bukry (1980) and the additional Paleocene calcareous nannofossils (CNP) biozones proposed by Agnini et al. (2014). ...
... Holes B and C, which do not preserve the K/Pg boundary and represent a later part of the Danian post-extinction interval, did not contain any of the usual age-diagnostic nannofossil taxa such as Chiasmolithus danicus (Base CP2; Okada and Bukry, 1980), Prinisus martinii (Base CNP4; Agnini et al., 2014), and Toweius pertusus (Base CNP5; Agnini et al., 2014), or contain the last occurrence (LO) of the Praeprinsius dimorphosus group (Agnini et al., 2014). Extremely rare primitive specimens of Cruciplacolithus tenuis (Base NP2; Martini, 1971) that lack the fullydeveloped "feet" diagnostic of this species are observed in only two samples (El Kef C 7R-1W, 61 cm and El Kef C 3R-1W, 1 cm; Fig. 5: 1 and 2); however, a true FO or stratigraphic range cannot be determined. ...
... Although planktic foraminiferal biozonation schemes continue to be refined and further developed (e.g., Arenillas et al., 2021), the standardized Wade et al. (2011) biozonation scheme is currently widely used within the planktic foraminifera community, which allows for consistency among different studies. In contrast, several alternate nannofossil biozonation schemes continue to be used during the early Danian (e.g., Martini, 1971;Okada and Bukry, 1980;Agnini et al., 2014), none of which has been as precisely calibrated to the GTS (Wade et al., 2011). In addition, each of the nannofossil biozonation schemes suffers from its own specific taxonomic challenge. ...
The Cretaceous/Paleogene (K/Pg) boundary is marked by one of the largest mass extinctions in Earth’s history, with geological evidence for this event being expressed in hundreds of locations worldwide. An extensively studied section located near El Kef, northwestern Tunisia, is characterized by the classic iridium-rich K/Pg boundary layer, abundant and well-preserved microfossils, and apparently continuous sedimentation throughout the early Danian with no previously described structural complication. These features led to its designation in 1991 as the Global Stratigraphic Section and Point (GSSP) for the base of the Danian (i.e., the K/Pg boundary). However, the outcrop section has become weathered, and the “golden spike” marking the GSSP is difficult to locate. Therefore, the El Kef Coring Project aimed to provide a continuous record of unweathered sediments across the K/Pg transition in cores recovered from five rotary-drilled holes located close to the El Kef GSSP. Here, we present new, high-resolution lithologic, biostratigraphic, and geochemical data from these cores. The recovered stratigraphic successions of each hole (all drilled within ∼75 m of one another) are unexpectedly different, and we identified a formerly unknown unconformity within planktic foraminiferal biozone P1b. Our results provide evidence that sedimentation at El Kef was not as continuous or free from structural complication as previously thought. Despite these challenges, we present a new composite section from the five El Kef holes and an age model correlated to the orbitally tuned record at Walvis Ridge, South Atlantic Ocean, which is critical in placing the paleoenvironmental and paleoecological records from El Kef in a global context.
... The paleobathymetry of the upper Ikego Formation and the Urago Formation has been estimated at between 500 and 2000 m based on benthic foraminiferal assemblages (Eto et al., 1987) and between 400 and 600 m based on molluscan asemblages (Utsunomiya and Majima, 2012). The upper part of the Ikego Formation has been assigned to the CN12a subzone of Okada and Bukry (1980) by Okada (1993) and to the RN12 Zone of Kamikuri et al. (2004) by Suzuki and Kanie (2012). ...
... These slides were then examined using a polarizing light microscope (BX-53, Olympus Co., Tokyo, Japan) with a magni cation of 1500× under cross-polarized and plane-polarized light. We used the zonal schemes of Okada and Bukry (1980 ...
... The mudstone immediately below Nt was assigned to the CN10c subzone of Okada and Bukry (1980), which is de ned as the interval between the LAD (last appearance of datum) of Ceratolithus acutus (5. 2017) showed that IkT19 is located in the normal subchronozone immediately above the Mammoth subchronozone (Fig. A2). ...
The basement of the Tokyo metropolitan area consists of the Miocene–Pleistocene forearc basin fills that are well exposed around Tokyo Bay, especially on the Miura and Boso peninsulas. The forearc basin fills on these two peninsulas are called the Miura and Kazusa groups, and they were deposited during the late Miocene–Pliocene and Pliocene–middle Pleistocene, respectively. Because many biostratigraphic datum planes, paleomagnetic reversal events, and other chronostratigraphic tools are available for these deposits, they provide the “type stratigraphy” of other equivalent sedimentary sequences on the Japanese islands and in the northwest Pacific. However, the use of such stratigraphic markers has not been fully applied to understand the architecture of a basin-wide unconformity between the Miura and Kazusa groups called the Kurotaki unconformity. For our study, we made correlations among the Pliocene vitric tephra beds based on their stratigraphic levels, lithologic characteristics, the chemical compositions of glass shards, and calcareous nannofossil biostratigraphy. As a result, we were able to correlate tephra beds Ng-Ky25 just above the C3n.3n normal subchronozone (4.7 Ma), IkT16-An157.5 and IkT19-An158.5 near the top of the Mammoth reverse polarity subchronozone (3.21 Ma), and Ahn-Onr (2.6–2.7 Ma) across Tokyo Bay on the Miura and Boso peninsulas. We were able to recognize erosional surfaces and coeval mass-transport deposits immediately below the top of the Mammoth reverse polarity subchronozone, which suggests that submarine landslide(s) may have produced the lack of stratigraphic horizons (4.5–3.2 Ma) in the Miura and eastern Boso regions. Basal pebbly sandstone beds pervasively cover the erosional surfaces, and they show lateral variations into the thick (up to 60 m) mass-transport deposits and overlying turbidite sandstones. The lateral variations in sediment thickness of the post-failure deposits suggest that the basin-wide erosion was associated with the initial growth of a basin-bounding structural high that separates two distinct sub-basins in the forearc basin, which resulted in the subsequent onlapping deposition in the earliest stage of the Kazusa forearc basin. The basin-wide erosion marks the initiation of tectonic reconfigurations that led to segmentation of the forearc basin around the Tokyo Bay region.
... Various international calcareous nannofossil biozonation schemes built from data collected on land sections (northern Neo-Tethys margins) and marine sedimentary sequences (from deep-sea drilling sequences) are the standard references for the middle Eocene to the early Oligocene calcareous nannofossils biostratigraphy (Agnini et al., 2014;Fornaciari et al., 2010;Martini, 1971;Okada and Bukry, 1980). However, no work compares calcareous nannofossils bio-horizons from SW Neo-Tethys margins with other reference sections and the influence of different paleogeographical and paleoecological settings on the use of certain bioevents. ...
... Previous studies from different sites prove that the application of the standard "NP" zonation of Martini (1971) and the "CP" zonation of Okada and Bukry (1980), created for sections of the Atlantic Ocean, Messaoud et al., 2021) and El Rahma sections (CNE20 to CNO3, Messaoud et al., 2020). cannot provide zonation and correlation of sections from the Tethyan platform with a sufficient degree of details and confidence (e.g., Agnini et al., 2014;Fornaciari et al., 2010;Monechi and Thierstein, 1985). ...
... The assemblage's complete diversity was not evaluated. The species richness is much higher than what we reported in the El Rahma and Souar sections (Figs. 3 and 4) since this work aims to check the occurrence of the most abundant and the index species used for the different biostratigraphic schemes (Agnini et al., 2014;Fornaciari et al., 2010;Martini, 1971;Okada and Bukry, 1980). The species abundances were evaluated based on the number of specimens observed per field of view (FOV). ...
We integrate previous Bayesian and astronomically tuned age calibrations of the calcareous nannofossils events with our large-scale correlations to discuss using the standard calcareous nannofossil zonal schemes in the SW Neo-Tethys platform during a period of significant paleoceanographic, tectonic, and paleoclimatic perturbations (middle Eocene to early Oligocene). Two marine on-land sections extend from NP15 (Nanno-Plankton zone) to lower NP23, equivalent to upper CNE9 (Calcareous Nannofossil of the Eocene) to lower CNO3 (Calcareous Nannofossil of the Oligocene), are studied.
Calcareous nannofossils have been investigated at less than 96 kyr resolution between 45.55 Ma and 31.9 Ma. The Souar section covers the Top (T) of the Nannotetrina alata group zone (CNE9, Lutetian) to the Isthmolithus recurvus zone (CNE18, Priabonian) in the Pelagic facies of the Tunisian dorsal. The El Rahma section extends from the Helicosphaera compacta zone (CNE21) to the Reticulofenestra umbilicus (CNO2) zone in the Cap Bon peninsula. The distribution patterns were studied through semi-quantitative counts to test the reliability of the biohorizons used in the standard biozonations schemes (Martini, 1971; Agnini et al., 2014). We discuss 14 biohorizons that span 13.65 Myr to highlight the limitations (absence/scarcity) of the Chiasmolithus group, particularly Ch. grandis, Ch. oamaruensis, and Ch. solitus, as biohorizons in the SW Neo-Tethys. Our study shows that Sphenolithus furcatolithoides, Dictyococcites bisectus, Sphenolithus obtusus, and Reticulofenestra erbae are reliable horizons for large-scale correlations with the northern margins of the Neo-Tethys. Calcareous nannofossils from the SW Neo-Tethys margin were highly affected by the paleo-circulation changes due to the episodic restriction of the westward subtropical Eocene Neo-Tethys (STENT) current (Jovane et al., 2009Jovane et al., 2009), followed by the closure of the eastern Neo-Tethys.
... The inspiring peculiarity of Kheu section is the high nannofossil total abundance and species diversity that encourages the restudy of nannofossil assemblages from this classical section in more details to revise its Paleocene to Eocene stratigraphy. The midlatitude location of Kheu section allowed the cooccurrence of both low-and high-latitude nannofossil taxa in the most part of the succession that makes both oceanic low-to high-latitude (Okada and Bukry, 1980) and low-latitude (Martini, 1971) zonations use- ful for biostratigraphic division of the lower Paleogene sediments. Besides, the most markers of the recent nannofossil zonation of Agnini et al. (2014) and the Paleocene zonation of Varol (1989) are also identified in the succession studied. ...
... The lowest occurrence (LO) of Biantolithus sparsus is found ca. 1 m above the base of Elburgan Fm. The LO of this first Paleogene species defines the base of the Danian stage in the most Paleogene nannofossil zonations (Martini, 1971;Okada and Bukry, 1980;Varol, 1989). At the same time, the highest occurrence (HO) of Cretaceous taxa is considered as the marker for the base of Paleogene in the zonation of Agnini et al. (2014). ...
... The lower Paleocene (Danian) succession roughly corresponds to the Elburgan Fm. The very rapid diversification of nannofossil assemblage after the K/T extinction includes a series of nannofossil bioevents, which enabled the recognition of thin zones and subzones of Varol (1989) zonation (labeled NTp, Fig. 4) and coarser zones of Martini (1971), Okada and Bukry (1980) and Agnini et al. (2014). The total nannofossil abundance significantly increases toward the top of the Danian concurrently with the decrease of micarb, which constituted the most of CaCO 3 amount in the lower Danian. ...
A continuous outcrop of the neritic sediments ranging from the Cretaceous/Paleogene to
Eocene/Oligocene boundary is exposed along the Kheu R., Kabardino-Balkaria Republic, southern Russia.
High calcareous nannofossil abundance and species diversity in Kheu section make possible the application
of various standard calcareous nannofossil zonations for the investigated interval. This provides a direct correlation of the biohorizons used as zonal markers in these zonations and recognition of the stage boundaries
in this complete succession, which represents the reference Paleogene section of the NE Peri-Tethys. The
carbon and oxygen isotope records revealed a series of excursions correlated to peculiar Paleogene paleoecological events on the basis of nannofossil biostratigraphy. The continuous Maastrichtian/Danian transition displays ca. 1 m thick interval containing only scarce Cretaceous survivors between the highest occurrence (HO)
of the most Cretaceous nannofossil taxa and the lowest occurrence (LO) of the Paleogene taxa; this interval
is characterized by prominent positive δ13C and δ18O excursions. The Late Danian Event (LDE) is identified
as minor δ13C and δ18O excursions in the upper Danian. The base of Selandian stage is defined by the
2nd radiation of fasciculiths, followed by negative δ13C and δ18O shifts corresponding to the Danian/Selandian Transition Event. Mid-Paleocene Biotic Event (MPBE), A, B1/B2, C1/C2 and D1/D2 events are pronounced in the upper Paleocene C and O isotope record. Wide expansion of Discoasterales (Fasciculithus,
Heliotrochus, Heliolithus, Discoaster), served as a basis for nannofossil zonations, is featured for this time span.
The base of Ypresian (lower Eocene) corresponds to the onset of the carbon isotope excursion (CIE) documented at the base of the TOC-rich bed. This 0.6 m thick sapropelitic bed corresponds to the Paleocene–
Eocene Thermal Maximum (PETM) and contains specific nannofossil assemblage known as “excursion
taxa”. The high sedimentation rate and completeness of the early Eocene sedimentary succession allowed to
record the evolution of Tribrachiatus bramlettei–T. digitalis–T. contortus–T. orthostylus lineage spanning the
interval of NP10–NP12 zones. Multiple δ13C and δ18O excursions, occurred in the lower Ypresian sediments,
correspond to the early Eocene hyperthermals E1/E2, F1, F2, G, ETM2, I1/I2 and J. The intercalations of
a series of TOC-rich layers in the interval ranging the upper NP12 to lower NP13 zones correspond to ETM3
and individual episodes (L-T) of the Early Eocene Climatic optimum (EECO). Long-term cooling trend in
the Caucasian basin begins in the uppermost Ypresian (upper NP13 zone). The middle Eocene δ18O record
demonstrates a succession of negative excursions occurred against the background of relatively high values.
The hyperthermal C21r–H6 is recognized at the base of Lutetian stage defined by the LO of Blackites inflatus.
Two later excursions of this time interval corresponding to the Late Lutetian Event (LLE) and Middle
Eocene Climatic Optimum (MECO) occur in the enriched in TOC Kuma Fm. (late Lutetian to Bartonian)
and fall at the levels with highest TOC concentrations. Nannoplankton assemblages are widely dominated
by eurytopic reticulofenestrids during both events, while Chiasmolithus and Discoaster become oppressed
that can indicate lower salinity caused by enhanced humidity. The base of Priabonian is defined by the LO
of Chiasmolithus oamaruensis and the base of Cribrocentrum erbae acme. These bioevents are preceded by
the negative δ13C excursion and very positive δ18O values, possibly correlated to the Priabonian Oxygen
Maximum (PrOM). The relatively warm Priabonian time, characterized by recovery of Chiasmolithus, Discoaster and Sphenolithus, gives way to a new cooling phase known as Late Eocene Event (LEE). The base
of Clausicoccus subdistichus acme, approximated to the base of Oligocene, falls at the level ca. 0.5 m below
the facial change corresponding to the large-scale sea-level fall and, thus, slightly precedes the accumulation of low-calcareous oil-bearing Oligocene-lower Miocene Maikop Fm. The prominent positive δ13C
and δ18O excursions occur at the base of this formation.
... Nannofossil taxa were identified according to the taxonomic concepts summarized by Perch-Nielsen (1985). The standard calcareous nannofossil zonations of Martini (1971) and Okada & Bukry (1980) are widely used for low-and mid-latitude 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 biostratigraphic studies in the Palaeogene, and these were adopted in this paper. ...
... The following primary bioevents were identified in the Monte Cagnero section (from bottom to top; Fig. 7): (1) HO of Chiasmolithus solitus at 70.0 msl; (2) LO of Chiasmolithus oamaruensis at 84.0 msl; (3) HO of Chiasmolithus grandis at 85.50 msl; (4) HO of Chiasmolithus oamaruensis at 98.5 msl; (5) HO of Discoaster saipanensis at 108.5 msl; and (6) acme base (AB) of Clausicoccus obrutus .5.7 mm at 114.5 msl. The lower part of the section is assigned to zones NP16 and CP14a of Martini (1971) and Okada & Bukry (1980), respectively, based on the presence of Reticulofenestra umbilica and the absence of Blackites gladius (Fig. 7). The HO of C. solitus marks the NP16/NP17 and CP14a/CP14b zonal boundaries of Martini (1971) and Okada & Bukry (1980), respectively. ...
... The lower part of the section is assigned to zones NP16 and CP14a of Martini (1971) and Okada & Bukry (1980), respectively, based on the presence of Reticulofenestra umbilica and the absence of Blackites gladius (Fig. 7). The HO of C. solitus marks the NP16/NP17 and CP14a/CP14b zonal boundaries of Martini (1971) and Okada & Bukry (1980), respectively. Following the biostratigraphical scheme of Martini (1971), we used the LO of C. oamaruensis to define the base of NP17/ NP18-NP19 zonal boundary, and the HOs of C. oamaruensis and D. saipanensis to mark NP18-19/NP20 and NP20/NP21 zonal boundaries, respectively (Fig. 7). ...
The Monte Cagnero sedimentary section, which crops out in the northeastern Apennines near Urbania in the Umbria–Marche Basin (Italy), contains well-exposed strata spanning the middle Eocene to lower Oligocene interval. We use an integrated magnetobiostratigraphic approach to generate a high-resolution age model for the Monte Cagnero section, with the goal of obtaining a reliable chronostratigraphic framework for studying Eocene–Oligocene palaeoceanographic changes during the switch from greenhouse to icehouse conditions. The studied sediments consist of alternating reddish and greenish limestones and marlstones. A new integrated age model for the section is based on high-resolution palaeomagnetic analyses, combined with detailed planktonic.
... Therefore, preparations were examined looking for the biostratigraphically significant species. We use the nannoplankton biostratigraphic zonation schemes of Martini (1971) and Okada and Bukry (1980) , with some additional nannoplankton events as indicated by Young et al. (1994) , Raffi and Flores (1995) , Marino and Flores (2002) , Backman et al. (2012) and Agnini et al. (2017) . Taxonomic identification and age distribution of nannofossil species has been checked with the information in Nan-notax3 webpage ( https://www.mikrotax.org/Nannotax3/index.html ) ( Young et al., 2022 ). ...
... Here, the calcareous nannoplankton assemblage is dominated by discoasters, such as Discoaster brouweri, D. neorectus, D. challengeri, D. icarus, D. surculus , together with Triquetrorhabdulus rugosus and Helicosphaera carteri ( Figs 8 a-8 c). The first occurrence of D. surculus took place during the latest late Tortonian ( Young et al., 1994 ;Backman et al., 2012 ), in the upper part of the biozone NN11A of Martini (1971) or of the biozone CN9a of Okada and Bukry (1980) . Additionally, the last appearance of T. rugosus occurred at the top of the Messinian ( Young et al., 1994 ;Agnini et al., 2017 ). ...
... Here, Discoaster broweri, D. quinqueramus, D. berggrenii , and D. loeblichii ( Figs 8 h-8 k) are found. The presence of D. quinqueramus ( Fig. 8 i) allows assigning these samples to the biozones NN11 of Martini (1971) or CN9 of Okada and Bukry (1980) . This biozone ranges the late Tortonian-early Messinian interval. ...
Mixed siliciclastic-carbonate deposits accumulated in several satellite sub-basins at the southern margin of the Guadalquivir Basin, the foreland basin of the Betic Cordillera (S. Spain). The prevailing coarse-grained sediments and deposition in shallow-water settings make it difficult to establish the precise age of the complete successions. For this reason, in previous studies, these deposits were attributed to the late Tortonian, although a Messinian age was not totally ruled out. The age of the upper Miocene deposits in the central part of the Guadalquivir Basin is here re-evaluated based on the analysis of several sections distributed in different areas: Antequera, Iznájar-Cuevas de San Marcos, Teba, and Bobadilla Estación. According to planktonic foraminifer and nannoplankton assemblages, the marine sedimentary infill of this sector of the southern margin of the Guadalquivir Basin is late Tortonian-early Messinian (late Miocene) in age. The occurrence of marine deposits characterized by the dominance of Globorotalia miotumida group, dextrally-coiled G. scitula, and the presence of G. margaritae, Globigerina multiloba, Discoaster quinqueramus, Amaurolithus primus, A. amplificus, and Reticulofenestra rotaria at the northern end of the Guadalhorce Corridor, the last active gateway in the Betic Cordillera connecting the Atlantic and the Mediterranean, indicates that it remained open until the early Messinian.
... Se aprecia cómo esta cuenca se sitúa encima del contacto entre las zonas Internas y Externas de dicha cordillera Figura 2. Columna estra�gráfica de la sección de Gor. A la izquierda se indican las dataciones: el Langhiense inferior (parte superior de la zona CN3 de Okada & Bukry, 1980) . 2). ...
... y el Langhiense superiorSerrava lliense inferior (zona CN4,Okada & Bukry, 1980) (JiménezMoreno, 2005. Con las flechas se representa la situación de las muestras ana lizadas en este estudio ��������������������G������������������������������������� Gor serie pasan a conglomerados, cada vez más abundan tes y potentes(Fig. ...
COORDINACIÓN
José S. Carrión, Eduardo Barrón
EQUIPO EDITORIAL
José S. Carrión, Eduardo Barrón, Manuel Munuera, Manuel Casas-Gallego, José María Postigo-Mijarra, Juan Ochando, Gabriela Amorós
Secretaria Técnica y Maquetación
Maximiliano Gómez Rodríguez, Santiago Fernández, Manuel Munuera
Trabajo artístico y gráfico
Gabriela Amorós, Victoria Sánchez-Giner, Ariadna Amorós, Manuel Munuera, Manuel Fernández-Díaz, Pedro Pablo Reyes, Yolanda Carrión-Marco, Yul Altolaguirre
ISBN: 978-84-09-44691-9
CITACIÓN
Carrión JS, Barrón E, Postigo-Mijarra JM, Casas-Gallego M, Munuera M, Ochando J, Jiménez-Moreno G, Amorós G, Altolaguirre Y, Vieira M, Tosal A, Moreno-Domínguez R, Rivas-Carballo MR, Valle-Hernández M, Alonso-Gavilán G, Fernández S, Verdú M, Arroyo J, Di Rita F, Magri D, Gómez-Rodríguez M, Sánchez-Giner V, Amorós A, Fernández-Díaz M, Reyes PP. 2022. Paleoflora y Paleovegetación Ibérica I: Paleoceno-Plioceno. Ministerio de Ciencia e Innovación y Fundación Séneca, Murcia.
Dirección web: paleofloraiberica.org
© de las figuras: sus autores
© de los textos: JS Carrión, E Barrón
... Perulangan lapisan grainstone foraminifera dan napal mengindikasikan kontrol perubahan muka air laut. Formasi Ofu berumur Neogen terendapkan pada lingkungan slope [8,9]. Bagian atas Formasi Ofu secara tidak selaras dipotong oleh konglomerat yang terendapakan pada Pleistosen yang dikontrol oleh mass gravity flow (Gambar 4). ...
... Pengambilan data mencakup pengukuran stratigrafi, deskripsi megaskopis batuan, deskripsi mikroskopis (thin section), dan paleontologi nannofosil gampingan. Sampel yang diambil ini kemudian diolah dengan metode quick smear slide dengan pembagian zona dilakukan dengan mengaplikasikan biostratigrafi zonasi zonasi Standar Martini (1971) [7] dan standar Okada dan Bukry (1980)[8]. Sebanyak empat sampel nannofosil gampingan dipreparasi dengan metode smear slide dan diamati meggunakan mikroskop polarisasi dengan perbesaran 1000x. ...
Formasi Ofu berumur Neogen-Kuarter tersingkap baik di bagian tengah Pulau Timor. Kumpulan nannofosil gampingan Formasi Ofu berumur Neogen terdiri tujuh famili dan 25 spesies. Nannofosil gampingan berumur Neogen didominasi genus Discoaster, Dictyococcites, dan Reticulofenestra sedangkan umur Kuarter didominasi oleh genus Gephyrocapsa. Nannofosil gampingan Neogen terdiri dari dua zonasi, dan satu zona Kuarter. Permulaan Miosen, Burdigalian-Tortonian (zona NN 4-NN 10) ditandai pemunculan awal Reticulofenestra pseudoumbilica hingga pemunculan awal Discoaster quinqueramus. Zona NN11 yang berumur Tortonian-Messinian ditandai pemunculan awal hingga pemunculan akhir Discoaster quinqueramus. Kuarter (Zona NN20) ditandai pemunculan awal Ponthospaera indooceanica.
... autochthonous to parautochthonous accumulation of rhodoliths growing under low to moderate hydrodynamic conditions and low sediment supply for prolonged times (Aguirre et al., 2017 and references therein;. Rhodolith concentrations also occur in large-scale cross beds or clinoforms on the slope of platforms, such as in the early Miocene of Sardinia (Benisek et al., 2009(Benisek et al., , 2010 or on the steeply inclined distal part of ramps, such as in the Late Miocene ramp in Menorca (Obrador et al., 1992;Pomar, 2001;Pomar et al., 2002;Brandano et al., 2005) and in the foresets of a littoral wedge in the Miocene of Corsica (Brandano and Ronca, 2014). The clinoforms reflect a steep depositional profile on which in situ rhodolith growth was as important as downslope displacement of coralline nodules from shallower areas. ...
... The Acinipo rhodolith limestone unconformably overlies marls attributable to the early Messinian based on the dominance of the Globorotalia miotumida group (Sierro, 1985;Lirer et al., 2019) in the planktonic foraminifer assemblages and the presence of Amaurolithus amplificus, a calcareous nannoplankton species first occurring in the early Messinian (Martini, 1971;Okada and Bukry, 1980;Young et al., 1994;Raffi and Flores, 1995). ...
... For Sphenolithus species, the counting was performed on 50 sphenoliths, only where the taxon was sufficiently abundant to satisfy this method. The occurrence of biostratigraphically significant taxa allowed the recognition of some calcareous nannofossil Eocene biozones (CNE zones of Agnini et al., 2014, NP zones of Martini, 1971 and CP zones of Okada and Bukry, 1980) useful to date the Çayraz Formation, and detailed in the biostratigraphic scheme given in Figure 6. The numerical data are reported in Appendix A (Tables S1-S8). ...
... Taxonomic classification of planktonic foraminifera is mainly based on the "Atlas of Eocene Planktonic Foraminifera" by Pearson et al. (2006). The biozonal definition follows the standard biostratigraphic schemes of Berggren et al. (1995), Berggren and Pearson (2005) and Okada and Bukry (1980); NP: Nannoplankton Paleogene biozones according to Martini (1971); CNE: Calcareous Nannofossil Eocene biozones according to Agnini et al (2014). SBZ: Shallow Benthic Zones according to Serra-Kiel et al. (1998). ...
New field observations and discovery of calcareous nannofossils and planktonic foraminifera from the ‘shallow-marine’ Çayraz Formation (Haymana Basin, Central Anatolia), a contributing Eocene section to the shallow benthic zonation (SBZ) in the Tethys, allow us to revise its stratigraphy and establish an integrated biostratigraphic scheme for the first time. The hemipelagic marls in the uppermost part of the Eskipolatlı Formation that underlies the Çayraz Formation yielded nannofossil assemblages of Zone CNE3, pinning down the initiation of the Çayraz shelf system into the ‘middle’ Ypresian. The prominent marly part (Member B) between the carbonate-clastic packages of the Çayraz Formation with prolific occurrences of larger benthic foraminifers (LBFs) (Members A below and C above) yielded calcareous nannofossils suggesting Zone CNE6 (late Ypresian). We show that the mixed carbonate-siliciclastic sequence with abundant LBFs in the upper part of the formation (Member C) is overlain by newly discovered hemipelagic marls (here named as Member D). These marls yielded calcareous nannofossils indicating Zone CNE9 and CNE10 for the lower and Zone CNE12(?Lutetian) for the upper samples. The same beds yielded planktonic foraminifers indicating Zone E8 for the lower and Zone E9 for the upper samples. We conclude that shallow-marine sedimentation in the Çayraz section ended in the ‘middle’ Lutetian, challenging the previous Bartonian records by LBFs. A new lithostratigraphic scheme consisting of four members with distinctive lithological and biotic characteristics is proposed for the Çayraz Formation: two main shelf systems (Members A and C), each followed by deep-marine sedimentation (Members B and D).
... Using these global biozones as a foundation, industrial nannofossil zonation schemes have been developed by biostratigraphers in response to 15 increased deep-sea exploration and production activities in the Gulf of Mexico, North Sea, North and West Africa basins, southeast Asia etc., used in the grouping of strata into units based on their fossil content with the aim of zonation and correlation. Some examples of published industry nannofossil zonation schemes include those for the Paleocene of the North Sea (Varol, 1989), Upper Cretaceous of the Norwegian North Sea (Bergen and Sikora, 1999), Paleogene of the Gulf of Mexico and Miocene of the Gulf of Mexico (Bowman et al.2009) .Their biostratigraphy potential was first realized in the 1950s leading to the establishment of a standard zonation by Martini (1971), and subsequently by Okada and Bukry (1980). Ages of penetrated sequences are mostly monitored with the aid of calibrated bioevents whose ‗Tops' {Last Appearance Once sequences are dated and zoned, the relationship of the encountered strata can be deduced (Simmons and Lowe, 1996). ...
... Obiosio (2013) Martini (1971) and Okada and Bukry (1980) were identified. Blow (1969) and Bolli and Saunders (1985). ...
... The top boundary of Zone NP17 is marked by the last occurrence of Sphenolithus spiniger, the last occurrence of Sphenolithus furcatolithoides, and the last occurrence of Chiasmolithus gigas. Agnini et al. (2014) and Okada & Bukry (1980) marked the boundary between Zone NP17 and Zone NP18 using Chiasmolithus gigas as the biodatum, separating the Middle Eocene and the Late Eocene. However, in this study, the presence of this species is not reliable to take into account due to Zone NP18 being a partial range zone with an undefined top boundary. ...
... The biostratigraphy study shows that the Nanggulan Formation was deposited in the Middle Eocene to Early Oligocene, or according to the biozonation of Martini (1971), is equal to NP16 to NP23. It is also equal to CP14A-CP17 which was based on Okada & Bukry (1980), or to CNE15-CNO3, assumed by Agnini et al. (2014) (Figure 9). The result corresponds with the age of the Nanggulan Formation suggested by Purnamaningsih & Pringgoprawiro (1981), Lunt & Sugiatno (2003), and Marliyani (2005). ...
The Nanggulan Formation is the oldest sedimentary rock of Paleogene age that was deposited in the eastern part of the Southern Central Java Basin. A total of 103 nannofossil samples were taken from two traverses in the study area, i.e., the Watupuru and Jetis Routes. Based on the biodatum identified from the nannofossil samples, the biostratigraphy of the rock formation is divided into five zonations, namely the upper part of Zone NP16, Zone NP17, the lower part of Zone NP18, the upper part of Zone NP22, and the lower part of Zone NP23, expanding from 41.1 Ma to 32.2 Ma of age (Middle Eocene to Early Oligocene). Only Zone NP17 is identified as a complete zone, whereas the other four are observed as partial. The fluctuation of global sea level is believed to be an influence on the deposition of the Nanggulan Formation. The sedimentation rate and the change of nannofossil species shows a decrease of oligotrophic (Sphenolithus) and an increase of eutrophic (Reticulofenestra) taxa, especially in small reticulofenestrids (Reticulofenestra spp.). This occurrence suggests a shift in the environmental conditions from an oligotrophic condition around 41.1 Ma to a eutrophic one, particularly after 40.40 Ma. The enhanced eutrophication in the Watupuru and Jetis Routes was caused by an increasing terrigenous input in 40.40 Ma and after, consequently providing nutrient availability on the water surface. This interpretation is supported by the increase in the sedimentation rate when sea level slightly decreased in 40.40 Ma.
... This reflects autochthonous to parautochthonous accumulation of rhodoliths growing under low to moderate hydrodynamic conditions and low sediment supply for prolonged times (Aguirre et al., 2017 and references therein;Millar and Gagnon, 2018). Rhodolith concentrations also occur in large-scale cross beds or clinoforms on the slope of platforms, such as in the early Miocene of Sardinia (Benisek et al., 2009(Benisek et al., , 2010 or on the steeply inclined distal part of ramps, such as in the Late Miocene ramp in Menorca (Obrador et al., 1992;Pomar, 2001;Pomar et al., 2002;Brandano et al., 2005) and in the foresets of a littoral wedge in the Miocene of Corsica (Brandano and Ronca, 2014). The clinoforms reflect a steep depositional profile on which in situ rhodolith growth was as important as downslope displacement of coralline nodules from shallower areas. ...
... The Acinipo rhodolith limestone unconformably overlies marls attributable to the early Messinian based on the dominance of the Globorotalia miotumida group (Sierro, 1985;Lirer et al., 2019) in the planktonic foraminifer assemblages and the presence of Amaurolithus amplificus, a calcareous nannoplankton species first occurring in the early Messinian (Martini, 1971;Okada and Bukry, 1980;Young et al., 1994;Raffi and Flores, 1995). ...
Rhodolith limestones occur in the upper part of the Miocene infill of the Ronda Basin in southern Spain. This basin was an embayment at the southern margin of the Atlantic-linked Guadalquivir Basin, the foreland basin of the Betic Cordillera. Messinian rhodolith limestones crop out in the mesa of the Roman settlement Acinipo. They mostly consist of trough cross-bedded rhodolith rudstones, which change basinward to large-scale planar cross-bedded rhodolith rudstones, which in turn pass laterally to planar cross-bedded and flat-bedded bryozoan rudstones. Rhodoliths in rudstones are generally broken, exhibiting several phases of breakage and restarted growth of coralline algae. Many rhodoliths also show asymmetrical growth. The rudstone matrix is a packstone with fragments of coralline algae, bryozoans, calcitic bivalves, echinoids, and foraminifers. Large lithoclasts from the basement, heavily bored by bivalves, are common in the rhodolith rudstone, especially in the most massive type. Rhodolith characteristics and sedimentary structures suggest that trough cross-bedded rhodolith rudstones accumulated in submarine dunes moved by storm surges in a littoral wedge at the western side of a small bay (the Ruinas de Acinipo bay) in the Ronda Basin. Large-scale planar cross-bedded coralline algal and bryozoan rudstones formed in the foresets of the wedge progradation below the storm-wave base. The dominance of Lithophyllaceae and Hapalidiales, with scarce representatives of Corallinaceae in the coralline algal assemblages, reflects that Ronda and Guadalquivir basins opened to the Atlantic Ocean.
... The nannoplankton association was found five meters above the Corbula layers and includes the zonal species Sphenolithus cyperoensis. This means that the host deposits correspond to the uppermost zone CP19 Sphenolithus cyperoensis on the scale by Okada and Bukry (1980) or the lowest parts of zone NP25 on the scale by Martini (1971) and, therefore, to their Late Oligocene age. On the basis of Triquetrorhabdulus carinatus, an index species of zone NN1, and a decrease in the Late Oligocene species Spenolithus ciperoensis in the overlying sequence (45 m thick), Ts.D. Minashvili identified the Upper Oligocene-Lower Miocene transitional layers corresponding to the undivided zone NP25-NN1 on the Martini scale (Martini, 1979). ...
... 25-27). The C.D. Minashvili's data on nannoplankton 5 m above the Corbula layers made it possible to identify the zonal species Sphenolithus cyperoensis in terms of which the host layers were correlated with zones NP25 on the Martini scale (Martini, 1971) or CP19 on the Okada and Bukry scale (Okada and Bukry, 1980) and dated to the Chattian (Ananiashvili and Minashvili, 2000;Minashvili and Ananiashvili, 2017). The latter authors interpret these data as indicative of the Chattian age of the Corbula layers. ...
... This biozone is correlated with Tribrachiatus contortus Biozone CP9a by Okada and Bukry (1980), and agree to Tribrachiatus contortus Biozone NP10 by Martini (1971) based on Hay (1964) and Bukry (1973). All the authors above assigned the Early Ypresian age to this biozone, therefore the section age is Early Eocene (Early Ypresian) (Gradestein et al., 2012). ...
This study focuses on identifying the relative age in rock sequence of the Ratga Formation (Swab Member), Iraqi Western Desert. To achieve this goal, five samples are collected (mainly limestone) from the Keyhole KH7/7, at a depth between (119-130). Nineteen species belonging to eleven genera of calcareous nannofossils are described. The recorded assemblages identified from the stratigraphic succession of this formation confirm Early Eocene (Early Ypresian) age by the biozone Tribrachiatus contortus Interval Biozone CP9a.
... . بوکری (Bukry, 1973) . حالی در که بوکری (Bukry, 1973) و اوکادا و بوکری (Okada and bukry, 1980) حضور اولین از ...
... The interval studied in detail corresponds to Zones CNM6 and CNM7 (Backman et al. 2012), equivalent to Zones NN4 (Martini 1971) and Zones CN3 and CN4 (Okada & Bukry 1980). The zonal boundary is placed at 381.54 m and corresponds to the biohorizon B D. signus. ...
Reticulofenestra pseudoumbilicus is a Neogene calcareous nannofossil species whose highest stratigraphic occurrence (Top) is a reliable biohorizon in the Pliocene, calibrated at 3.82 Ma. The species is present in the stratigraphic record from at least the Middle Miocene, within an interval around the biohorizon Top Sphenolithus heteromorphus, calibrated at 13.53 Ma, but its lower distribution range is not precisely delineated. The study of nannofossil assemblages in sediment cores from Integrated Ocean Drilling Program IODP Site U1338 (eastern equatorial Pacific) indicates a lower stratigraphic position for the evolutionary emergence (Base) of R. pseudoumbilicus, detected in the Early Miocene with an estimated age of 16.46 Ma. This age results from a new astronomically tuned chronology, which dates the deepest sediments at Site U1338 to 16.67 Ma. Base R. pseudoumbilicus is followed above by a temporary disappearance of the taxon until a re-entrance after ~3 Myr. This lengthened stratigraphic range has been confirmed by data from other locations at low and mid-latitudes in the Atlantic. The distribution range of R. pseudoumbilicus, lasting ~13 Myr during the Neogene, is thus characterized by a variable pattern of repeated occurrences and disappearances. Comparison to benthic foraminifera δ18O and δ13C records suggests a control by global climatic/environmental conditions on these events, particularly by temperature variations. The recurrent presence of R. pseudoumbilicus at stratigraphically different intervals could represent an example of iterative evolution, expressed as repeated speciation events that are in part influenced by complex external factors related to the dynamic climate and environmental evolution during the Miocene.
... Diatoms from the Paleogene deposits (borehole Р-321). Scale bar, 20 μm for fig. 1 and 10 Martini (1971) Okada and Bukry (1980) Dracodinium eocaenicum (Strelnikova, 1992) Ulyanovsk-Syzran SFZ Sengilei-Karanino (Borehole no. С-29), after (Glezer, 1995) Sengilei (Oreshkina and Aleksandrova, 2017) Mitlehner (1996) identified the biotic event at the level of the -21 ash layer when studying a limited set of samples from the Fur Formation. ...
The diatom assemblage of the Veshenskaya Formation studied in the borehole P-321 of the Cis-Donets monocline (southern part of the Russian Plate) is assigned to the lower Ypresian Moisseevia uralensis Zone. According to the available data, this zone corresponds to the Deflandrea oebisfeldensis and Dracodinium (=Wetzeliella) astra dinocyst zones and, accordingly, to the nanoplankton NP10 Zone. The presence of the zonal silicoflagellate species Naviculopsis foliacea confirms the Early Eocene age of the Veshenskaya Formation. The taxonomic similarity of diatoms and silicoflagellates of the region under consideration with silicofossil assemblages of Northern Europe suggests a stable link between these paleobasins at the beginning of the Early Eocene.
... Thus, based on foraminiferal, mollusk, and radiolarian assemblages, the age of the Stolbovaya Group was arbitrarily constrained to the Late Maastrichthian-Late Eocene [1,2,6,7]. By now data on the calcareous nanno- [18]). This paper reports data on the first finds of nanoplankton in the lower part of the Stolbovaya Group. ...
Results of the study on calcareous nannofossils found for the first time in the lower part of the Stolbovaya Group of the Kamchatsky Mys Peninsula, eastern Kamchatka, are presented. Two assemblages of different age are identified, with one assigned to the Upper Cretaceous and the other to the Paleogene (not younger than the Lutetian Stage of the Middle Eocene). The obtained data help to refine the age of terrigenous-tuffaceous sequences in the lower part of the Stolbovaya Group, which are poor in organic remains.
... Vallejo et al. (2019) documented the existence in the region of early Eocene nannoplankton. These works applied the classic biozonal schemes of Martini (1971), Bukry (1973Bukry ( , 1975, Okada and Bukry (1980), and Backman et al. (2012). ...
... It is difficult to demarcate the biozonal boundaries but the calcareous nannofossil assemblage encountered in the studied samples is assignable to the NP10 biozone of Martini (1971). The studied interval is also correlative to Subzones CP9a by Okada and Bukry (1980), and to CNE2 (part)-CNE3 (part) by Agnini et al. (2014Agnini et al. ( , 2017. Therefore, the studied samples of KF fall in the NP10 biozone, representing an Early Eocene (Ypersian) age (Fig. 4). ...
The Early Eocene Kuldana Formation (KF) consists of variegated color shales, mudstone, and sandstone with limestone interbeds/
lenses in the Yadgar area, Muzaffarabad, of Sub-Himalayan foreland basin. We report, for the first time, 20 nannofossil species of 9 genera, discovered from carbonate units of KF. Based on this calcareous nannofossil assemblage, an Early Eocene Ypresian age (NP10) is determined. The presence of Coccolithus, Fasciculithus, Rhomboaster, Tribrachiatus and Sphenolithus indicates dominantly warm water and oligotrophic conditions during deposition of the carbonate units, while the presence of Zeugrhabdotus and Neococcolithes suggests minor cool-water, eutrophic to mesotrophic conditions. Five microfacies were identified based on the field and petrographic investigations of the study section, namely, Nummulitic wacke-packstone microfacies (KMF-1), Assilina wacke-packstone microfacies (KMF-2), Molluscan microfacies (KMF-3), Lime mudstone microfacies (KMF-4), and Ostracode wackestone microfacies (KMF-5), suggesting that the deposition occurred in inner to middle shelf, shallow marine environment.
... The lower boundary is determined by the first appearance of the species D. nobilis [10], and the upper boundary is determined by the first appearance of the species D. multiradiatus [10]. This biozone correlated with D. nobilis biozone (CP7) by [12], which aged L. Paleocene (Thanetian), and correlated with D. nobilis biozone (NP8) by [13], which aged Late Paleocene (Thanetian) too. Therefore, depending on the stratigraphic correlation above, this biozone aged Late Paleocene (Thanetian) [14]. ...
The Paleocene-Eocene Thermal Maximum (PETM) event, which represented a sudden and abnormal rise in temperature during the early Cenozoic Era, is regarded as one of the most important global geologic phenomena. Two important index microfossils (nannoplankton and Ostracoda) were utilised to understand and predict the paleoenvironment and describe the changes during this period. The basis of the study was 12 cutting samples taken from Aaliji and the lower part of Jaddala formations of a subsurface section of (Ba-8) borehole in central Iraq. Some geophysical data were used to determine the upper and lower contacts of the Aaliji Formation and define the shale rate in the studied formations. The micropaleontologic investigation reveals twenty-four nannoplankton species and twenty species belonging to seven genera of Ostracoda. The use of Nannoplankton fossils led to the identification of two types of biozones based on two species belonging to the genus Discoaster, which are ordered from bottom to top as follows; 1- Discoaster nobilis Interval Biozone (CP7) and 2- Discoaster multiraditus Interval Biozone (CP8). The biozones were compared locally and regionally with their equivalent biozones, which deduced the age of the Aaliji Formation as (Late Paleocene-Lower Early Eocene) whereas (Early Eocene) for the studied part of the Jaddala Formation. The determination of the upper and lower boundaries was determined by interpreting the geophysical logs. Ostracoda fossils were used to predict paleoecology and its changes in the area during the PETM episode. The transmutation of nanoplankton fossils from the Paleocene to the Eocene indicates an abnormal rise in global temperatures, flourishing and high diversity of some nanoplankton, such as some species belonging to Discoster, especially those in the CP8 zone.
... Descriptions and stratigraphic distributions of the calcareous nannoplankton genera and species were made by based on Martini (1971), Okada andBukry (1980), Perch-Nielsen (1985), Young (1998), Bown (1999), Raffi et al. (2003Raffi et al. ( , 2006, Hilgen et al. (2009), Backman et al. (2012, Galovic and Young (2012), Gradstein et al. (2012) and URL 1-42 sources. Wei's (1988) method was taken as a basis while determining the abundance distributions of calcareous nannoplankton species. ...
We report a detailed investigation and the geodynamic implications of a basaltic lava flow that is intercalated with the early–middle Miocene turbiditic sedimentary rocks (Karataş Formation) that are exposed near the İskenderun Basin in southern Turkey. In order to reveal the age and origin of the basaltic rocks, we systematically sampled clastic samples from measured sedimentary sections, which include the basaltic lava flow, from around Ceyhan (east of Adana city). Forty different species belonging to 14 calcareous nannoplankton genera were identified in the samples, representing the Langhian–Tortonian (middle–late Miocene) time interval. Considering the stratigraphic distribution of the calcareous nannoplankton species in the section, the age of the basaltic lava flow is determined to be Serravallian (middle Miocene). The basaltic rocks experienced only minor magmatic evolution and have a restricted compositional range. Analysed in situ major element contents (from electron microprobe analysis, EMPA) for minerals (plagioclase, olivine and clinopyroxene) hosted by the late Miocene basaltic rocks show that they originated in an intraplate setting. Geochemical analysis indicates that olivine have Fo (forsterite) compositions between 57.81% and 83.83%. The EMPA contents (primarily based on pyroxenes) suggests that the late Miocene volcanism was related to the Pleistocene Delihalil–Turunçlu basaltic volcanism. The studied late Miocene volcanism could have originated in two possible tectono-magmatic environments: 1) one involving collisional tectonics (e.g., folding) combined with a change from regional compression to strike-slip; or 2) an intraplate setting. We propose that the tectonic setting of the late Miocene basaltic lava flow was similar to that of the extensive Pleistocene Delihalil volcanism in the same region. This would extend the onset of the regional basaltic volcanism back to the middle–late Miocene, rather than being restricted to the Pleistocene–Quaternary.
... The age model used here (Table 1; Figure 2) represents an update from that published by the Expedition 364 Science Party , including small refinements in the placement of biozones and the identification of an unconformity at ∼607.8 mbsf (above the interval we discuss here). Calcareous nannofossil biostratigraphy is based on the CP zonation scheme of Okada and Bukry (1980) and the CNP scheme of Agnini et al. (2014), following the taxonomic concepts of Perch-Nielsen (1985) and Bown (1998). Planktic foraminifer biostratigraphy is based on the P zones of Berggren and Pearson (2005) as modified by Wade et al. (2011), following the taxonomic concepts of Olsson et al. (1999) and Pearson et al. (2006). ...
The Chicxulub impact caused a crash in productivity in the world's oceans which contributed to the extinction of ∼75% of marine species. In the immediate aftermath of the extinction, export productivity was locally highly variable, with some sites, including the Chicxulub crater, recording elevated export production. The long-term transition back to more stable export productivity regimes has been poorly documented. Here, we present elemental abundances, foraminifer and calcareous nannoplankton assemblage counts, total organic carbon, and bulk carbonate carbon isotope data from the Chicxulub crater to reconstruct changes in export productivity during the first 3 Myr of the Paleocene. We show that export production was elevated for the first 320 kyr of the Paleocene, declined from 320 kyr to 1.2 Myr, and then remained low thereafter. A key interval in this long decline occurred 900 kyr to 1.2 Myr post impact, as calcareous nannoplankton assemblages began to diversify. This interval is associated with fluctuations in water column stratification and terrigenous flux, but these variables are uncorrelated to export productivity. Instead, we postulate that the turnover in the phytoplankton community from a post-extinction assemblage dominated by picoplankton (which promoted nutrient recycling in the euphotic zone) to a Paleocene pelagic community dominated by relatively larger primary producers like calcareous nannoplankton (which more efficiently removed nutrients from surface waters, leading to oligotrophy) is responsible for the decline in export production in the southern Gulf of Mexico. Plain Language Summary The end Cretaceous mass extinction was caused by the impact of an asteroid in what is now the Yucatán Peninsula, México. The impact ejected aerosols and dust into the air that reduced sunlight transmission, causing a severe decline in photosynthesis and the collapse of marine food webs. However, the change in the amount of organic matter created by photosynthesizing plankton that was delivered to the seafloor (export productivity) was variable across the oceans. At some places, including the Chicxulub crater, export productivity was actually high immediately after the impact. We produced a ∼3-million-year record of export productivity in the crater to determine how long it remained elevated and why it eventually declined. Export production was very high for the first 320,000 years after the impact, declined from 320,000 to 1,200,000 years after the impact, and then remained low. We found that this production was not related to the input of nutrients nor the degree of stratification of the ocean, but instead was probably driven by the increase in the cell size of phytoplankton. Larger phytoplankton removed nutrients from the surface waters as they sank, prompting an increase in species which are better adapted to low-nutrient waters. LOWERY ET AL.
... Results were correlated with the calcareous nannofossil biostratigraphic NN zones of Martini (1971), CN zones of Okada and Bukry (1980), and/or intervals by Young (1998). Furthermore, absolute ages for datums and additional biostratigraphic events were assigned based on Raffi et al. (2006) and/or Backman et al. (2012) whenever possible. ...
... The Miocene-Pliocene sedimentary sequence exposed at this locality is part of the Cenozoic Mondego Basin, the fossiliferous Pliocene sediments corresponding to the basal transgressive beds of the Carnide Sandstone Formation (Cachão, 1990;Diniz et al., 2016). The calcareous nannofossil assemblage from these beds indicates placement in biozone CN12a of Okada and Bukry (1980). Based on calcareous nannofossils and gastropod mollusks, these beds have been assigned to the uppermost Zanclean to lower Piacenzian (Cachão, 1990;Silva, 2001;Diniz et al., 2016). ...
The cancellarid genus Sveltia Jousseaume, 1887, is widespread in western European and North African Neogene marine fossil assemblages. In Pliocene deposits it is commonly represented by Sveltia varicosa (Brocchi, 1814), which until recently was considered a widely distributed taxon in the Mediterranean Sea and adjacent Atlantic faunas. A recent review of the species from the Pliocene of Italy and Spain (Guadalquivir Basin), leading to the erection of S . confusa , prompted the reassessment of the Sveltia material from the Atlantic Pliocene of the Portuguese Mondego Basin and the subsequent description of Sveltia sofiae n. sp. Consequently, a mosaic of species has emerged from what was previously viewed as the broad Atlanto-Mediterranean range of the widespread and quite variable S . varicosa . From a biogeographic standpoint, it is now clear that S . varicosa was a Mediterranean species, occurring east of the Alboran Sea. Sveltia confusa had a mainly Atlantic distribution, from the French Pliocene Ligerian Gulf to the Gulf of Cadiz, at least, and straddling the Strait of Gibraltar into the Alboran Sea. Sveltia sofiae n. sp. was endemic to western Iberia, represented today only in the western Portuguese Mondego Basin. Sveltia is a thermophilic genus. Since early Pliocene times, because of northeastern Atlantic sea surface temperature decline, it underwent a southward range contraction, occurring today—in the eastern Atlantic—from Cape Blanc, Mauritania, south. This range reduction was coupled with the post mid-Piacenzian southward contraction of the Pliocene Mediterranean-West African tropical molluscan province and the consequent rise of the present-day Mediterranean-Moroccan subtropical province.
UUID: http://zoobank.org/0cf3c73a-8d57-472e-87e4-f1ad065e5fb6 .
... The morphological characteristics and forms of calcareous nannofossil were compared with the descriptions, monographs, diagrams and available publications of Young, J.R (1990). The calcareous nannoplankton biozones were based on the zonation schemes of Martini (1971) and Okada and Bukry (1980). The stratigraphic sequence study employed the approach of Armentrout (1991Armentrout ( , 1996 and Armentrout et al. (1999), which involved applying biostratigraphic zone, palaeobathymetric and lithofacies data in constraining the bounding surfaces through the calibration with Chronostratigraphic Chart of Haq et al., (1988) and Reijers (2011). ...
An integrated Micropalaeontological analysis approach was employed based on ditch cuttings samples northwest of the Niger Delta. Lithofacies description showed the entire sediment successions consisted of alternating shale and sand lithology. A moderate to the rich recovery of about seventy-one foraminifera and forty calcareous nannofossil species were recovered, having the presence of Miocene foraminifera ( Orbulina universa, Globigerinoides bulloideus, Globorotalia obesa, Globorotalia mayeri and Globorotalia continuosa ) and nannofossil ( Sphenolithus moriformis, Catinaster coalithus, Discoaster berggrenii and Discoaster kugleri ). Three foraminifera planktonic zones were proposed for this study and were correlated to other worldwide zones; Globerigenoides bulloideus , Globeriginoides obliquus obliquus and Globerigenoides primordius spanning the Neogene (N) 6 to N17 zone. Two calcareous nannoplankton zones were proposed, which are; Helicosphaera intermedia and Sphenolithus moriformis spanning the Neogene Nannofossil (NN) 3 to NN11 zone. Three third-order sea-level rises and falls occurred during the Early to Late Miocene within the Niger Delta, with a corresponding paleo-waterdepth from transitional to outer neritic. The Chiloguembelina -3 Shale (16.0 Ma), Dodo Shale (11.6 Ma) and the Uvigerina -8 Shale (9.2 Ma), were associated with transgression. The 15.5 Ma SB of Depositional Sequence 1(Early Miocene), 10.5 Ma SB of Depositional Sequence 2(Middle Miocene) and 8.5 Ma SB of Depositional Sequence 3(Late Miocene) due to progradation. The paleosalintiy based on shell type morphology assemblages suggests a transition from the brackish marginal marine environment to open neritic conditions. The study interval is said to have penetrated sediments of the parallic Early to Late Miocene Agbada formation.
The results of a study of calcareous nannofossils found for the first time in the lower part of the Stolbovaya Group of the Kamchatsky Mys Peninsula in Eastern Kamchatka are presented. Two assemblages of different age are identified, with one assigned to the Upper Cretaceous and the other to the Paleogene (not older than the Lutetian Stage of the Middle Eocene). These data make it possible to refine the age of terrigenous–tuffaceous sequences in the lower part of the Stolbovaya Group, which are poor in organic remains.
An accurate and high-resolution age model in marine sediments is essential for reconstructing past oceanographic and climate changes. The southeastern Indian Ocean is an important component of oceanographic circulation and global climate. However, the integrated biostratigraphy for the Late Pleistocene interval is not well known in the region. To address this issue, we constructed a new chronology for International Ocean Discovery Program (IODP) Hole U1516B in the Mentelle Basin, offshore southwestern Australia. We employ planktonic foraminifera δ18O to construct an astronomically tuned age model for Hole U1516B. Biostratigraphic analysis was performed for Hole U1516B using planktonic foraminifera, nannofossils, radiolarian taxa and diatoms. Seven planktonic foraminifera events are recorded, including the PT1a and PT1b boundaries. Eight nannofossil events were recorded including the boundaries between CN14a, CN14b and CN15. The planktonic foraminifera datums marked in Hole U1516B are mostly synchronous with datums reported in the southern hemisphere but are diachronous with datums in the northern hemisphere. The nannofossil datums marked in Hole U1516B have a close affinity with globally reported datums but small inconsistencies are probably due to strong ecological control. The diatom events are inconsistent and only recorded in short intervals during interglacials and several key radiolarians taxa are absent.
Radiolarians are marine zooplankton possessing a tough, central capsular membrane that divides the cytoplasm into intracapsular (containing the nucleus, organelles, and food reserves) and extracapsular (with food-gathering rhizopodia and digestive vacuoles) portions (Figure 1). They bear two kinds of pseudopodia, the axopodia and filopodia. The axopodia extend radially through the ectoplasm and capsular membrane to the interior of the endoplasm. The axopodia are inserted into a special structure, the axoplast (Figure 1). The development of the axoplast and its complex is of fundamental importance in radiolarian taxonomy. For a detailed description of radiolarian cytology, biology, and reproduction, see Anderson (1983).
In this chapter we consider the previously published stratigraphic schemes and datum levelsDatum level of planktic foraminiferal and nannofossil index species from the Atlantic. The stratigraphic frameworksStratigraphic framework developed for the Ioffe Drift in this study covers the last 3.8 Ma recovered from sediment cores collected from the area. The Pliocene/Pleistocene boundaryPliocene/Pleistocene boundary is placed at about 2.59 Ma, according to the generally accepted International Chronostratigraphic ChartInternational Chronostratigraphic Chart (Cohen et al. (2013) The ICS international chronostratigraphic chart. Episodes 36; Cohen et al. (2020) The ICS international chronostratigraphic chart. Episodes 36). The ages of zonal boundaries are generally defined by the index species datum levelsDatum level, that is, firstFirst species occurrence (FO)or last occurrencesLast species occurrence (LO), mostly adopted from recent publications.
Short-lived (104–105 years) carbon isotope excursions (CIEs), many of which are associated with some degree of ocean warming, are a feature of the warm climates of the early Paleogene. Here we present new calcareous nannofossil and geochemical data through the first of these Paleogene carbon cycle perturbations, known as the DAN-C2 event (65.8–65.7 Ma), from ODP Site 1049C on Blake Nose, in the western sub-tropical North Atlantic. Increased Hg/TOC (ppb/%) and Hg/Al (ppb/cps) ratios recorded at 65.9 Ma strongly suggest that volcanic activity, likely related to Deccan Traps, preceded the DAN-C2 event. Approximately 20 kyr after the onset of DAN-C2, Shannon diversity (H) index shows increased nannofossil species richness, with greater abundances of eutrophic and high fertility species, most likely a response to more intense weathering during the event. During the DAN-C2 event, there is a shift towards smaller morphotypes of the dominant placolith species, Coccolithus pelagicus and Cruciplacolithus primus, together with a calcium carbonate dissolution interval. Finally, we suggest that surface ocean currents dynamics, influenced by an eccentricity maxima cycle, is likely a potential mechanism to explaining the strong δ13C (∼1.3 ‰) negative excursion observed in Blake Nose.
Calcareous nannofossil and planktic foraminiferal assemblages were examined to determine the depositional ages for some seafloor sediments and sedimentary rock samples obtained during GB21-1 cruise at around the Tokara Islands, northern Ryukyu arc. Seven samples from three localities, one in the forearc side and two in the back-arc, were prepared for biostratigraphic study．Unconsolidated and partially consolidated muddy samples from the back-arc sites represent the depositional age younger than Middle Pleistocene (0–0.29 Ma). On the other hand, the depositional age of latest Early to Middle Pleistocene is indicated for calcareous microfossil assemblages in the sedimentary rocks dredged at both forearc and back-arc sites, most likely constrained from 0.9 or 0.8 Ma to 0.43 Ma.
Fossils of Microporina species were collected and examined from the Soebetsu Sandstone Member of the Pleistocene Setana Formation in southwestern Hokkaido. A description is provided for M. japonica Canu and Bassler, and four species (M. sakakurai, M. minuta, M. quadristoma and M. soebetsuensis) are newly described. Some of them were previously reported as M. articulata (Fabricius). Among the five species, three (M. japonica, M. sakakurai, M. minuta) have a semielliptical or elliptical orifice, relatively large and deep frontal pseudopores, opesiules occluded with a thin plate showing vein-like surface sculpturing, and avicularia that are longer than wide. The other two (M. quadristoma, M. soebetsuensis) have a rounded-quadrate orifice (sometimes with a convex proximal margin), smaller frontal pseudopores, opesiules occluded but lacking vein-like surface sculpturing, and avicularia that are circular or wider than long. Marked orificial dimorphism is observed in two species, M. sakakurai and M. soebetsuensis.
Miocene sedimentary sequences are distributed widely in Oki Dogo Island, Shimane Prefecture, Southwest Japan. Among them, the lowermost part of the Kumi Formation recorded a transition from freshwater to marine environments associated with the opening of the Japan Sea. We analyzed radiolarian fossils collected from the Kumi Formation in its type locality. We identified Eucyrtidium inflatum, Subzone and Lychnocanoma magnacornuta Zone in the upper part of the Kumi Formation and the Melittosphaera magnaporulosa Zone in the lower part. In addition, the lowe part of theKumi Formation yielded the P-C assemblage composed of two species: Pentactinosphaera hokurikuensis and Cyrtocapsella tetrapera. This assemblage is unique to the earliest stage of the Japan Sea opening because it was identified immediately above non-marine sedimentary rocks. In contrast to Miocene in coastal area of Japan Sea, the specific assemblage is considered to be the most similar to that of Okushiri Island based on the composition of siliceous microfossils.
Microporina articulata notoensis Sakakura, 1936, from the Nanao Calcareous Sandstone (Middle Miocene) was restudied and raised to species rank, mainly based on the orifice morphology. Sakakura interpreted small depressions along lateral sides of the cryptocyst as additional opesiules, but it is not clear whether they function as opesiules or not, based on the SEM image. This and other Neogene to Recent Microporina species in Japan are compared, and one more species, Microporina iwayaensis sp. nov. is erected.
A new Miocene phidoloporid, Iodictyum akaishiensis sp. nov., was collected from the Moniwa Formation (Langhian) near the Akaishi Bridge, Sendai City, Japan. It is the first fossil record of Iodictyum in Japan, and the fifth discovery of Miocene fossils of the genus from the Indo-Pacific area. The species resembles some Recent species from the western Pacific, especially in the large marginal pores, an open peristomial sinus and shaft, and subtriangular ooecial labellum. The characteristics of Iodictyum from Eocene to Recent are compared, and the trend of evolution in the genus is inferred.
The upper Miocene to Pleistocene Shimajiri Group, composed mainly of siltstone and sandstone, occurs on some of the Ryukyu Islands in southwestern Japan. This group is thought to have been deposited in a shelf-slope to fore-arc basin setting before the accumulation of Pleistocene coral reef deposits (Ryukyu Group). We investigated the calcareous nannofossil biostratigraphy of the Shimajiri Group in the Offshore Okinawa 1-x well, drilled near the northeastern margin of the Okinawa-Miyako Submarine Plateau, Ryukyu Islands. A sample from 280 m, at the base of Ryukyu Group, contains Gephyrocapsa parralella, which first occurred at 0.987 Ma. Discoaster quinqueramus and D. berggrenii, which define both the top and bottom of the calcareous nannofossil zone NN11, are found throughout the Shimajiri Group, consistent with a late Miocene age between 8.10 Ma and 5.53 Ma. A large sedimentary gap between the Shimajiri and Ryukyu groups suggests that part of the Okinawa-Miyako Submarine Plateau may have been above sea level during the early Pliocene, implying deposition of the Shimajiri Group here was completed earlier than in other regions. This study provides key constraints on the Cenozoic geological history and phylogeography of the Ryukyu Islands.
THE stratigraphic value of a group of marine minute algae usually referred to as the calcareous nannoplankton, first shown by Bramlette and Riedel1, has already been discussed2. A standard zonation, based partly on the investigations of Hay et al.3 and Bramlette and Wilcoxon4, has been proposed, and the Neogene calcareous nannoplankton zones have been numbered NN 1 to NN 21.
Zonation of the Paleocene—Lower Eocene interval
- Mohler