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Productivity response of calcareous nannoplankton in the South Atlantic to the Eocene Thermal Maximum 2 (ETM2)  [PDF]
M. Dedert,H. M. Stoll,D. Kroon,N. Shimizu
Climate of the Past Discussions , 2011, DOI: 10.5194/cpd-7-2089-2011
Abstract: The Early Eocene Thermal Maximum 2 (ETM2) at ~53.7 Ma is one of multiple hyperthermal events that followed the Paleocene-Eocene Thermal Maximum (PETM, ~55 Ma). In order to reconstruct the primary productivity response to the ETM2 in the South Atlantic, we have analyzed Sr/Ca ratios in various size fractions of bulk sediments and in picked monogeneric populations of calcareous nannofossils. The latter technique of measuring selected nannofossil populations using the ion probe circumvents possible contamination with secondary calcite. Avoiding such contamination is important for interpretation of the nannoplankton productivity record, since diagenetic processes can bias the productivity signal, as we demonstrate for Sr/Ca measurements in the fine (<20 um) and other size fractions obtained from bulk sediments. The paleoproductivity signal as reconstructed from the Sr/Ca ratios appears to be dominantly governed by cyclic orbital forcing. The ~13 to 21 % increase in Sr/Ca above the cyclic background conditions as measured by ion probe in dominating genera is likely the result of a slightly elevated productivity during ETM2. This high productivity phase is the result of enhanced nutrient supply either from land or from upwelling. Our results show that calcareous nannoplankton productivity was not reduced by environmental conditions accompanying ETM2, but even showed a small increase during the extreme climatic conditions of ETM2.
Productivity response of calcareous nannoplankton to Eocene Thermal Maximum 2 (ETM2)
M. Dedert, H. M. Stoll, D. Kroon, N. Shimizu, K. Kanamaru,P. Ziveri
Climate of the Past (CP) & Discussions (CPD) , 2012,
Abstract: The Early Eocene Thermal Maximum 2 (ETM2) at ~53.7 Ma is one of multiple hyperthermal events that followed the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma). The negative carbon excursion and deep ocean carbonate dissolution which occurred during the event imply that a substantial amount (103 Gt) of carbon (C) was added to the ocean-atmosphere system, consequently increasing atmospheric CO2(pCO2). This makes the event relevant to the current scenario of anthropogenic CO2 additions and global change. Resulting changes in ocean stratification and pH, as well as changes in exogenic cycles which supply nutrients to the ocean, may have affected the productivity of marine phytoplankton, especially calcifying phytoplankton. Changes in productivity, in turn, may affect the rate of sequestration of excess CO2 in the deep ocean and sediments. In order to reconstruct the productivity response by calcareous nannoplankton to ETM2 in the South Atlantic (Site 1265) and North Pacific (Site 1209), we employ the coccolith Sr/Ca productivity proxy with analysis of well-preserved picked monogeneric populations by ion probe supplemented by analysis of various size fractions of nannofossil sediments by ICP-AES. The former technique of measuring Sr/Ca in selected nannofossil populations using the ion probe circumvents possible contamination with secondary calcite. Avoiding such contamination is important for an accurate interpretation of the nannoplankton productivity record, since diagenetic processes can bias the productivity signal, as we demonstrate for Sr/Ca measurements in the fine (<20 μm) and other size fractions obtained from bulk sediments from Site 1265. At this site, the paleoproductivity signal as reconstructed from the Sr/Ca appears to be governed by cyclic changes, possibly orbital forcing, resulting in a 20–30% variability in Sr/Ca in dominant genera as obtained by ion probe. The ~13 to 21% increase in Sr/Ca above the cyclic background conditions as measured by ion probe in dominating genera may result from a slightly elevated productivity during ETM2. This high productivity phase is probably the result of enhanced nutrient supply either from land or from upwelling. The ion probe results show that calcareous nannoplankton productivity was not reduced by environmental conditions accompanying ETM2 at Site 1265, but imply an overall sustained productivity and potentially a small productivity increase during the extreme climatic conditions of ETM2 in this portion of the South Atlantic. However, in the open oceanic setting of Site 1209, a significant decrease in dominant genera Sr/Ca is observed, indicating reduced productivity.
A new cephalopod find in the Eocene beds near Grdoselo in Istria, Croatia  [PDF]
Vasja Miku?,Milo? Bartol
Geologija , 2012,
Abstract: The article presents a cast fossil of a cephalopod found in sandy limestones (packstones) of Eocene age nearGrdoselo in Central Istria. The phragmocone remains most probably belong to the nautilid species Eutrephoceras(Simplicioceras) centrale (Sowerby, 1812). We have determined the age of the fossil with calcareous nannoplankton.The nannofossil assemblage is typical of the Middle Eocene and allows the assignment to the biozone NP15(Nannotethrina fulgens) of the Middle Eocene.
Late Pleistocene paleoproductivity patterns during the last climatic cycle in the Guyana Basin as revealed by calcareous nannoplankton
G.-E. López-Otálvaro,J. A. Flores,F. J. Sierro,I. Cacho
eEarth Discussions , 2008,
Abstract: Variations in the assemblages and abundances of calcareous nannoplankton have allowed us to interpret changes in oceanic and atmospheric dynamics in the Guyana Basin, mainly linked to the southeast trades over the last climatic cycle. Records of the paleoproductivity index of coccolithophores (N ratio) allowed us to monitor the nutri-thermocline fluctuations. Additionally, nannofossil accumulation rates vary closely with the N ratio, indicating a strong correlation between these two paleoproductivity proxies. The dominance of upper (small Noelaerhabdaceae, Emiliania huxleyi and Gephyrocapsa oceanica), over lower photic zone dwellers (Florisphaera profunda) during Termination II and interglacial substages 5.1 and 5.3 is related to eutrophic conditions due to a shoaling of the nutri-thermocline as a consequence of enhanced southeast Trade Winds. This activated an upwelling at the continental margin of the Guyana Basin. Low N ratio values and the dominance of F. profunda over the glacial substages of MIS 5 and glacial MIS 2-4 are linked to a deep nutri-thermocline (deep stratification of the mixed layer), at times of low influence of the southeast Trade Winds, and a weak upwelling. However, the N ratio during MIS 2-4 was slightly higher than those seen for the MIS 4/5 boundary and glacial substages 5.2 and 5.4. These micropaleontological proxies follow the insolation at high northern latitude (65° N): the high N ratio and NAR data from the Guyana Basin during Termination II and interglacials 5.1. and 5.3 are correlated with high insolation values, and low values of the N ratio and NAR during the MIS 4/5 boundary, glacials 5.2, 5.4 and MIS 2-4 are correlated with low insolation at the same latitudes. This situation suggests a link between the ITCZ, the southeast Trade Wind dynamics and the Northern Hemisphere climate changes during the last climatic cycle.
Scaled biotic disruption during early Eocene global warming events
S. J. Gibbs, P. R. Bown, B. H. Murphy, A. Sluijs, K. M. Edgar, H. P like, C. T. Bolton,J. C. Zachos
Biogeosciences (BG) & Discussions (BGD) , 2012,
Abstract: Late Paleocene and early Eocene hyperthermals are transient warming events associated with massive perturbations of the global carbon cycle, and are considered partial analogues for current anthropogenic climate change. Because the magnitude of carbon release varied between the events, they are natural experiments ideal for exploring the relationship between carbon cycle perturbations, climate change and biotic response. Here we quantify marine biotic variability through three million years of the early Eocene that include five hyperthermals, utilizing a method that allows us to integrate the records of different plankton groups through scenarios ranging from background to major extinction events. Our long time-series calcareous nannoplankton record indicates a scaling of biotic disruption to climate change associated with the amount of carbon released during the various hyperthermals. Critically, only the three largest hyperthermals, the Paleocene–Eocene Thermal Maximum (PETM), Eocene Thermal Maximum 2 (ETM2) and the I1 event, show above-background variance, suggesting that the magnitude of carbon input and associated climate change needs to surpass a threshold value to cause significant biotic disruption.
Scaled biotic disruption during early Eocene global warming events  [PDF]
S. J. Gibbs,P. R. Bown,B. H. Murphy,A. Sluijs
Biogeosciences Discussions , 2012, DOI: 10.5194/bgd-9-1237-2012
Abstract: Late Paleocene and early Eocene hyperthermals are transient global warming events associated with massive carbon injection or carbon redistribution in the ocean-atmosphere system, and are considered partial analogues for current anthropogenic climate change. Because the magnitude of carbon release varied between the events, they are natural experiments ideal for exploring the relationship between carbon cycle perturbations, climate change and biotic response. Here we quantify marine biotic variability through three million years of the early Eocene, including five hyperthermals, utilizing a method that allows us to integrate the records of different plankton groups through scenarios ranging from background to major extinction events. Our long-time-series calcareous nannoplankton record indicates a scaling of biotic disruption to climate change associated with the amount of carbon released during the various hyperthermals. Critically, only the three largest hyperthermals, the Paleocene Eocene Thermal Maximum (PETM), Eocene Thermal Maximum 2 (ETM2) and the I1 event, show above-background variance, suggesting that the magnitude of carbon input and associated climate change needs to surpass a threshold value to cause significant biotic disruption.
Calcareous Nannofossil Biostratigraphy and Stage Boundaries of the Santonian-Eocene Successions in Wadi El Mizeira Northeastern Sinai, Egypt  [PDF]
Hamza Khalil, Esam Zahran
International Journal of Geosciences (IJG) , 2014, DOI: 10.4236/ijg.2014.54041
Abstract:

The stratigraphic successions exposed in Wadi El Mizeira have been dated through the analysis of the calcareous nannofossil assemblages. The results of this study indicate that the successions comprise the Santonian-Late Maastrichtian (Sudr Formation), the Paleocene (Esna Formation) and the Early Eocene (Thebes Formation). The following biozones were recognized: Late Santonian, CC16 Zone; Late Santonian/Early Campanian, CC17 Zone; Early Campanian, Aspidolithus parcus Zone (CC18) Zone; Late Maastrichtian, CC25c Zone; Early Paleocene (Late Danian), NP3 Zone and NP4 Zone; Late Paleocene (Thanethian-Selandian), NP5 Zone; Early Eocene, NP9b Zone, NP10a Zone, NP11 Zone, NP12 Zone and NP14 Zone. Several stratigraphic hiatus were recorded in the studied interval including the absence of Cretaceous nannofossil Zones CC19 to CC25b and CC26 as well as the early Paleocene Zones NP1 and NP2 and probably the basal part of Zone NP3, in addition to the absence of the Zones NP6 and NP7/8. These hiatus may be attributed to environmental conditions, structural activity and/or post depositional processes. This work represents the first attempt to evaluate the nannofossil taxa of the Wadi El Mizeira, Northeastern Sinai.

Lower Eocene on Majevica north of Tuzla (NE Bosnia)
Rajko Pavlovec,Jernej Pav?i?,Sejfudin Vrabac
Geologija , 2005,
Abstract: In Lower Eocene marlstones on Mt. Majevica in northeastern Bosnia species Nummulites atacicus and N. robustus were determined, the latter first found on the Balkan Peninsula.In the beds occur next to Paleogene many redeposited Cretaceous nannoplankton species, an indication of the exposure of Cretaceous beds in Lower Eocene in the investigated area.
Lithostratigraphy and biostratigraphy of the Upper Albian–Lower/Middle Eocene flysch deposits in the Bystrica and Ra a subunits of the Magura Nappe (Beskid Wyspowy and Gorce Ranges; Poland)
Nestor OSZCZYPKO,Ewa MALATA,Krzysztof B?K,Mariusz K?DZIERSKI
Annales Societatis Geologorum Poloniae , 2005,
Abstract: Lithostratigraphy and biostratigraphy of the Bystrica and Ra a subunits of the Magura Nappe have been studied in the southern part of the Beskid Wyspowy Range and on the northern slopes of the Gorce Range (Polish part of the Western Flysch Carpathians). Six new lithostratigraphic units (Jasień Formation, Bia e Formation, Jaworzynka Formation, Szczawina Sandstone Formation, Krzysztonów Member, and Ropianka Formation) of the Upper Albian–Palaeocene age have been established, and five other units (Malinowa Shale Formation, Ha uszowa Formation, abowa Shale Formation, Beloveza Formation, Bystrica Formation) have been additionally described. The newly created formations as well as the Malinowa Shale Formation and the Ha uszowa Formation have been included to a new Mogielica Group of units (Upper Albian–Palaeocene). This group of units passes upwards into the Beskid Group (Eocene–Oligocene).The Mogielica Group, spanning over 40 myrs, represents the turbidite depositional system, separated by highstand variegated clays which can be correlated with minor sequences in terms of sequence stratigraphy.The following biostratigraphic zones have been recognised in the Cretaceous–Lower/Middle Eocene deposits: Plectorecurvoides alternans, Bulbobaculites problematicus, Uvigerinammina jankoi, U. jankoi-C. gigantea, Caudammina gigantea, Remesella varians, Rzehakina fisistomata, Glomospira div. sp., and Saccamminoides carpathicus. A few lithostratigraphic units consisting of calcareous sediments have been correlated with the standard calcareous nannoplankton zonation and the chronostratigraphy.
Paleoenvironmental changes across the Eocene-Oligocene boundary: insights from the Central-Carpathian Paleogene Basin
Ján Soták
Geologica Carpathica , 2010, DOI: 10.2478/v10096-010-0024-1
Abstract: The sedimentary sequence of the Central-Carpathian Paleogene Basin provides proxy records of climatic changes related to cooling events at the Eocene/Oligocene boundary (TEE). In this basin, climatic deterioration is inferred from the demise of the carbonate platform and oligotrophic benthic biota in the SBZ19 and from the last species of warm-water planktonic foraminifers in the E14 Zone. Upper Eocene formations already indicate warm-temperate to cool-temperate productivity and nutrient-enriched conditions (Bryozoan Marls, Globigerina Marls). Rapid cooling during the earliest Oligocene (Oi-1 event) led to a temperature drop (~11 °C), humidity, fresh water influx and continental runoff, water mass stratification, bottom water anoxia, eutrofication, estuarine circulation and upwelling, carbonate depletion, sapropelitic and biosiliceous deposition, H2S intoxication and mass faunal mortality, and also other characteristics of Black Sea-type basins. Tectonoeustatic events with the interference of TA 4.4 sea-level fall and the Pyrenean phase caused basin isolation at the beginning of the Paratethys. The Early Oligocene stage of Paratethyan isolation is indicated by a stagnant regime, low tide influence, endemic fauna development, widespread anoxia and precipitation of manganese deposits. The episodic rise in the sea-level, less humid conditions and renewed circulation is marked by calcareous productivity, nannoplankton blooms and the appearance of planktic pteropods and re-oxygenation. Paleogeographic differentiation of the Carpatho-Pannonian Paleogene basins resulted from plate-tectonic reorganization during the Alpine orogenesis.
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