Discoaster Research Articles

Implications of calcareous nannoplankton biostratigraphy and biochronology of the Middle–Late Miocene of the Nile Delta, Egypt

The Middle–Late Miocene subsurface successions from the Southeastern Mediterranean coast were studied based on the calcareous nannoplankton. The study was established on three boreholes selected from the offshore Nile Delta region, which are Port Fouad M-5, Baltim-1, and NDOB-1. The boreholes were chosen from different petroleum concessions within the North Delta basin. The standard nannoplankton biozonation of Mediterranean areas was used in this study. The studied rock successions cover the Sidi Salim and Qawasim formations, which are widely recognized targets for gas exploration. The study of the calcareous nannoplankton in the studied successions revealed eight biozones, and they are from base to top: Sphenolithus heteromorphus (NN5), Discoaster exilis (NN6), Discoaster kugleri (NN7), Catinaster coalitus (NN8), Discoaster hamatus (NN9), Discoaster calcaris (NN10), Discoaster quinqueramus (NN11), and Amaurolitus tricorniculatus (NN12). The Langhian/Serravalian, the Serravalian/Tortonian, and the Tortonian/Messinian boundaries were defined and discussed. The biochronological dates of the identified nannoplankton biozones were used to calculate the sedimentation rates of the studied rock successions. The calculations revealed two cycles of successive changes of sedimentation rates, which are attributed to regressions phases in Sidi Salim and Qawasim formations.

Quantitative studies of the calcareous nannoplankton of Sarmatian deposits: case studies in the Sieniawa–Rudka area (Outer Carpathian Foredeep, Poland)

The aim of this study was the qualitative and quantitative analysis of the calcareous nannofossil assemblages of the Machow Formation, belonging to the supra-evaporitic complex of the Polish Carpathian Foredeep Basin (PCFB). The work was concentrated in the eastern part of the PCFB, in the Sieniawa–Rudka area (Ryszkowa Wola Horst). Samples were collected from the Rudka-13 and Wylewa-1 boreholes. On the basis of calcareous nannoplankton, these deposits were assigned to the upper part of the NN6 Zone combined with the NN7 Zone, which corresponds to the Sarmatian s.s. of the Central Paratethys (upper Serravallian of the Mediterranean scale). Conclusive determination of the biozone NN7 was problematic, owing to the absence of the rare zonal marker species Discoaster kugleri . The typical association of the undivided NN6–NN7 Zone was of low species diversity and usually dominated by Coccolithus pelagicus , C yclicargolithus floridanus and Reticulofenestra pseudoumbilica (> 7 µm). On the basis of the relative abundance of species, a significant amount of redeposition was deduced. The reworked nannofossils were mostly Eocene in age. The Oligocene, Early Miocene and Late Cretaceous species occurred much less frequently. The dominance of Eocene forms indicates the Carpathians as the main supply area. The Late Cretaceous taxa may have originated from the Senonian marly deposits of the Miechow Trough in the north. Statistical treatment of the quantitative data was performed using multivariate cluster analysis and Nonmetrical Multidimensional Scaling (nMDS). The composition of the calcareous nannofossil assemblages, together with the high percentage of allochthonous taxa, indicate a shallow, coastal environment with a high supply of nutrients.

(2265–2267) Proposals to conserve the name Discoaster against Eu-discoaster, Helio-discoaster and Hemi-discoaster, and the names Heliodiscoaster and Hemidiscoaster with those spellings (fossil Prymnesiophyta (Algae) vel Haptomonada (Protista))

TAXONVolume 63, Issue 1 p. 195-197 Proposals to Conserve or Reject NamesFree Access (2265–2267) Proposals to conserve the name Discoaster against Eu-discoaster, Helio-discoaster and Hemi-discoaster, and the names Heliodiscoaster and Hemidiscoaster with those spellings (fossil Prymnesiophyta (Algae) vel Haptomonada (Protista)) Alexander B. Doweld, Alexander B. Doweld sekretariat@doweld.pro nicar-sekretariat@yandex.ru National Institute of Carpology (Gaertnerian Institution), 21 Konenkowa Street, Moscow, 127560 Russian FederationSearch for more papers by this author Alexander B. Doweld, Alexander B. Doweld sekretariat@doweld.pro nicar-sekretariat@yandex.ru National Institute of Carpology (Gaertnerian Institution), 21 Konenkowa Street, Moscow, 127560 Russian FederationSearch for more papers by this author First published: 27 January 2014 https://doi.org/10.12705/631.26AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume63, Issue1February 2014Pages 195-197 RelatedInformation

INTEGRATED STRATIGRAPHY OF MIDDLE-LATE MIOCENE SYNOROGENIC DEPOSITS OF THE EASTERN SOUTHERN APENNINE CHAIN: THE SAN BARTOLOMEO FLYSCH

The present paper deals with the stratigraphic and biostratigraphic study of the middle-late Miocene thrust-top basin deposits of the San Bartolomeo Flysch, exposed north of Matese mountains and analysed during the geological survey of the sheet N° 405 Campobasso of the new Geological Map of Italy, 1:50.000 scale. The integrated study of calcareous nannofossils and planktonic foraminifera, based on the semi-quantitative distribution range of index species, revealed the presence of age-diagnostic assemblages which are comparable with those of different middle-late Miocene deep-marine sedimentary settings of the Mediterranean Basin. The biostratigraphic dataset suggests an early Serravallian – early middle Tortonian age. In terms of calcareous nannofossil biostratigraphy, the studied succession falls between the Last Occurrences of Sphenolithus heteromorphus and the First Occurrence of Discoaster bellus gr., corresponding to the MNN6 – MNN8 zone interval. In terms of planktonic foraminiferal biostratigraphy the studied sediments fall between the Last Occurrence of Globorotalia peripheroronda and the First Regular Occurrence of Neogloboquadrina acostaensis , corresponding to the MM6 p.p. - MMi10 p.p. zone interval. This study documents the applicability of the recent Mediterranean middle –late Miocene biozonations for the biostratigraphic study of siliciclastic synorogenic sediments, and challenges the most recent studies that dated the San Bartolomeo Flysch to the late Tortonian- early Messinian.

Nannofósiles del Serravalliano (Mioceno) en Patagonia, Argentina [Serravallian (Miocene) nannofossils in Patagonia, Argentina

For the first time, nannofossils found in the marine stratigraphic unit named Patagoniano which crops out at Cerro Chenque and Cerro Hermitte in southeastern Chubut, Argentina, are documented. They were recovered from pelitic levels in the lower part of coarsening-upward siliciclastic sedimentary sequences. The nannofossils are assigned in part to the Discoaster kugleri Zone NN7 (MARTINI, 1971) and CN5b (BUKRY, 1971, 1973) thus allowing correlation of the productive levels with the Serravallian Stage (upper Middle Miocene).

EARLY TO LATE OLIGOCENE CALCAREOUS NANNOFOSSIL BIOEVENTS IN THE MEDITERRANEAN (UMBRIA-MARCHE BASIN, CENTRAL ITALY)

Calcareous nannofossil assemblages have been investigated by means of quantitative analyses in three Oligocene pelagic sections located in the Umbria-Marche Apennines (Central Italy). The studied sections mainly consist of marly limestones and marls belonging to the Scaglia Cinerea Formation, and include the interval between NP23 and NP25 representing a time interval of about 3.5 Ma. Biostratigraphic resolution is extremely low and only two standard bioevents are known, which are the FO of Sphenolithus ciperoensis and the LO of Sphenolithus distentus . The distribution patterns of poorly known or recently described calcareous nannofossils provided a valuable tool for improving the current biostratigraphic framework. The studied interval is characterized by significant changes in the calcareous nannofossil assemblages and by several extinction events. The last occurrence (LO) and/or the last common occurrence (LCO) here proposed are: the LO of Sphenolithus akropodus , the LO of Reticulofenestra circus , the LCO of Helicosphaera ethologa , the LCO of Helicosphaera compacta the LO of Discoaster tanii nodifer . The reversal in abundance between Sphenolithus predistentus and S. distentus provided an additional biostratigraphic constraint at the NP23-NP24 transition. In addition biometric criteria enabled the recognition of the first common occurrence (FCO) of Cyclicargolithus abisectus > 12 mm as potential bioevent within NP24. The quantitative distribution of Sphenolithus distentus suggests to rely on the LCO of the species rather than on the LO, for the identification of NP24-NP25 boundary. The identified bioevents is a first step towards the improvement of the present Mediterranean biostratigraphic framework of the Oligocene geological record. A preliminary correlation of the bioevents to the Geomagnetic Polarity Time Scale is presented.

Integrated stratigraphy and astronomical tuning of the Serravallian and lower Tortonian at Monte dei Corvi (Middle–Upper Miocene, northern Italy)

An integrated stratigraphy (calcareous plankton biostratigraphy, magnetostratigraphy and cyclostratigraphy) is presented for the Serravallian and lower Tortonian part (Middle–Upper Miocene) of the Monte dei Corvi section located in northern Italy. The detailed biostratigraphic analysis showed that both the Discoaster kugleri acme and the first influx of Neogloboquadrina acostaensis are recorded at Monte dei Corvi; these events, which passed unobserved in previous studies, play an important role in delineating the Serravallian–Tortonian boundary. Thermal and alternating field demagnetization revealed a characteristic low-temperature component marked by dual polarities. The resultant magnetostratigraphy for the upper part of the section can be unambiguously calibrated to the GPTS ranging from C5n.2n up to C4r.2r. Unfortunately, the lower part of the section, including the Serravallian–Tortonian boundary interval, did not produce a reliable magnetostratigraphy despite the fact that some short reversed intervals and a single normal interval are recorded. Using sedimentary cycle patterns in combination with the calcareous plankton biostratigraphy the section can be correlated cyclostratigraphically in detail to the partially overlapping and previously tuned section of Monte Gibliscemi on Sicily. The Monte dei Corvi section is dated astronomically by calibrating the basic small-scale sedimentary cycles to the precession and 65°N lat. summer insolation time series of the La93 solution following an initial tuning of larger-scale cycles to eccentricity. An almost perfect fit is found between the cycle patterns and intricate details, especially precession–obliquity interference, in the insolation target between 8.5 and 10 Ma. The tuning to precession remains robust for most intervals back to the base of the section dated at 13.4 Ma and shows that the section is continuous apart from a possible short hiatus in the Tortonian. It provides accurate astronomical ages for all sedimentary cycles, calcareous plankton events, polarity reversals and ash layers and marks a significant improvement of the recently proposed astronomical calibrations of the Monte dei Corvi section and of parallel sections in the Mediterranean. Astronomical ages for the Ancona and Respighi ashbeds are significantly older than previously reported 40Ar/ 39Ar biotite ages, even if the revised older age for the FCT-san dating standard of 28.02 Ma is applied. The astronomical dating of the magnetic reversals in the Monte dei Corvi section results in the completion of the astronomical polarity time scale for the last 13 Myr. The Monte dei Corvi section has recently been proposed as the stratotype section for the Serravallian–Tortonian boundary despite the moderate to poor preservation of the calcareous microfossils and the lack of a reliable magnetostratigraphy across the boundary interval. Finally, our study reveals that a single dominantly precession controlled oscillatory climate system is responsible for late Neogene sapropel formation in the Mediterranean during the last 13.5 million years.

K-Ar age of the Am-4 Tuff related to the CN5a/CN5b boundary on the Miocene marine sequence in the Boso Peninsula, central Japan.

K-Ar age of the Am-4 Tuff in the Miocene marine sequence of the Kanigawa section in the Boso Peninsula, central Japan, was determined. The obtained age is 11.73±0.24Ma (1σ error), which represents an age of the last occurrence (LO) horizon of Cyclicargolithus floridanus, because this biohorizon locates only two meters below the dated tuff (Mita and Takahashi, 1998). As the LO horizon of C. floridanus almost coincides with the first occurrence (FO) level of Discoaster kugleri, defining the CN5a/CN5b boundary of calcareous nannofossil zone of Okada and Bukry (1980), the age of the Am-4 can be regarded as an age of the CN5a/CN5b boundary. Precisely established age for the CN5a/CN5b boundary in central Japan is well concordant with previous estimation of Berggren et al. (1995).

High resolution biochronology in the Monte Narbone Formation of the Capo Rossello section and the Mediterranean first occurrence of Globorotalia truncatulinoides

Quantitative analysis on the planktonic foraminiferal assemblages in the Late Pliocene - Early Pleistocene segment of the Capo Rossello section evidences the same number of relative abundance fluctuations of the Globigerinoides ruber taxonomic unit recorded in the same stratigraphic interval of other Mediterranean sequences. Between the Globorotalia inflata FO and the Discoaster brouweri LO 4 relative abundance fluctuations are present. Since the D. brouweri LO is recorded in the Mediterranean basin below the base of the Olduvai magnetic event and in coincidence of relative abundance fluctuation 73, the Gt. inflata FO is coincident with fluctuation 80. The first appearance ol Globorotalia truncatulinoides is recorded on the second fluctuation above the Gt . inflata FO and on the second fluctuation below the D. brouwueri LO. Therefore the Gt. truncatulinoides FO is coincident with fluctuation 77. The absolute age proposed for these 3 bio-events is 1.99,2.07 and 2.13 MA respectively. The most important calcareous nannofossil events, recognized by quantitative analysis, have been correlated to the abundance fluctuations of the Globigerinoides ruber taxonomic unit.

Middle Miocene planktonic microfossils and lower bathyal foraminifera from offshore southern California

Lower bathyal sediments representing portions of the Luisian and Mohnian stages of Kleinpell (1938) occur on a submarine ridge near Tanner Bank, offshore southern California. The presence of abundant and well-preserved calcareous nannofossils, diatoms, silicoflagellates, radiolarians and foraminifera allows accurate correlations with the onshore type sections of these stages. In terms of the calcareous nannofossil zones, the age range is from the Sphenolithus heteromorphus Zone to the Discoaster kugleri Zone. Although abundant benthic foraminifera indicative of the Luisian and Mohnian are present, they are accompanied by species more characteristic of the Pliocene Repettian Stage of Natland (1952) and the Pliocene-Miocene “Delmontian” Stage of Kleinpell (1938). Many of these latter species live today at lower bathyal depths (below 2,000 m), others occur in lower bathyal sediments as old as Oligocene, but are absent in the onshore type sections of the Luisian and Mohnian stages in coastal California. We ascribe their absence in onshore sequences to deposition at middle bathyal depths. The known chronostratigraphic ranges of several species are extended and five new species and two new subspecies of benthic foraminifera are described.The following new taxa are described: Bolivina pelita n. sp., Cassidulinella inflata n. sp., Globocassidulina undulata n. sp., Cibicidoides mckannai miocenicus n. subsp., C. mckannai sigmosuturalis n. subsp., Pullenia fragilis n. sp., Parafissurina inornata n. sp.

Discoasters of the Blue Clay (Middle Miocene) of Malta and Gozo

SummaryTwenty-three species of the Family Discoasteraceae Vekshina, 1959 recovered from 18 samples of the Blue Clay at Fort Chambray, Gozo, and 31 samples from Fomm-Ir-Rih Bay, Malta, have been studied under light and scanning electron microscopes. Fourteen Middle Miocene species are reviewed, their stratigraphical ranges and importance as marker species discussed. Nine species are described as new. On the basis of the discoaster species present, a Middle Miocene age (NN.6 Discoaster exilis Zone – NN.7 Discoaster kugleri Zone) for the Blue Clay in Malta and Gozo is suggested.

Calcareous Nannoplankton Biostratigraphy and Paleoecology in Oligo-Miocene of California: ABSTRACT

Calcareous nannoplankton are abundant in some rocks assigned to the California microfaunal stages. Most species are stratigraphically long ranging, although some have restricted stratigraphic ranges in low-latitude tropical regions. These species permit partial correlation of the California stages with the widely recognized plankton biostratigraphic zones of the tropics. The upper Zemorrian is correlative with the Sphenolithus distentus through the lower Triquetrorhabdulus carinatus (NP 24-NN1) zones (upper Oligocene) the Saucesian with the upper T. carinatus through the lower Helicopontosphaera ampliaperta (NN1-4) zones (lower Miocene), the Relizian with the upper H. ampliaperta through the lower S. heteromorphus (NN4-5) zones (lower-middle Miocene), the Luisian with the upper S. heteromorphus through Discoaster kugleri (NN5-7) zones (middle Miocene), and the Mohnian with the Catinaster coalitus through D. calcaris (NN8-10) zones (middle-upper Miocene). The species diversity of nannofossils in the California Oligocene-Miocene rocks is low. Like the planktonic Foraminifera from the same rocks, the nannofossils are analogous to species now living in the modern transitional water mass off California. There are no elaborate species as in the tropics and the floras tend to be dominated by single species (i.e., Coccolithus). These observations indicate that California was under the influence of a current flowing southward, with velocities nearly that of the modern California Current. The dominance of the assemblages by a single species, as well as other evidence from the rocks, indicates that upwelling was likely as important during the Miocene as it is today. End_of_Article - Last_Page 436------------

Correlation of Marine Middle Tertiary Stages of California with Tropical Planktonic Zones: ABSTRACT

The Oligocene-Miocene boundary is equated with End_Page 467------------------------------ the Globigerinoides trilobus datum of the tropics; this is approximately equivalent to the base of the Saucesian Stage of California. In ascending order, the lower Miocene Catapsydrax dissimilis, C. stainforthi, and Globigerinatella insueta zones correlate with the Saucesian and basal Relizian Stages. Assemblages characterizing the Catapsydrax stainforthi zone have been identified in the upper part of the lower Saucesian Stage of Reliz Canyon, California. Further, Sphenolithus belemnos is a good index of the lower Miocene of tropical areas and of the Saucesian Stage of California. The orbuline datum of the tropics, which is in the uppermost part of the Globigerinatella insueta zone, is the base of the middle Miocene. This level appears to correspond to the base or the lower part of the Relizian Stage of California. In ascending order, the middle Miocene Turborotalia peripheroronda and Globorotalia peripheroacuta zones correlate with the Relizian Stage, and the Globorotalia praefohsi and Globorotalia fohsi zones correlate with the Luisian Stage. Sphenolithus heteromorphus occurs in the Relizian Stage and also in the Globigerinatella insueta and Turborotalia peripheroronda zones of the tropics. Discoaster kugleri is an index of the uppermost zone of the G. fohsi sequence and it is identified in the upper Luisian Stage of Newport Bay, California. Orbulines first a pear in the Luisian Stage in California. The Globorotalia menardii datum is the base of the upper Miocene in tropical areas, and it corresponds approximately to the Globigerina pachyderma datum of California or the base of the lower Mohnian. The dextral Globigerina pachyderma zone of the lower Mohnian contains Catinaster coalitus and Discoaster bollii, which are indices of the Turborotalia mayeri and Globorotalia menardii zones of the tropics. The sinistral Globigerina pachyderma zone of the upper Mohnian and basal Delmontian Stages represents the first major cool event in the middle Neogene; it correlates with the Turborotalia acostaensis (Globigerina bulloides) zone of tropical areas and with the sinistral G. pachyderma zone of the Messinian of Italy. The base of the Pliocene is marked by the appearance of Sphaeroidinella dehiscens and by the change from sinistral to dextral populations of Neogloboquadrina dutertrei. End_of_Article - Last_Page 468------------