Absolute nannofossil abundance estimates: Quantifying the pros and cons of different techniques

Bordiga, Manuela; Bartol, Miloš; Henderiks, Jorijntje

doi:10.1016/j.revmic.2015.05.002

Cited by 49 publications

(45 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Quantitative counts of diatom concentrations (given as N*10 9 /g; cf. Bordiga et al, 2015) show a first appearance (more than one specimen per slide) of diatom frustules~12 Ma (Figure 5a), in accordance with the first occurrence of diatoms and radiolarians by Nigrini et al (1991), at the base of core 38X. Quantitative analysis shows that while initially diatom abundance is relatively low (>1 * 10 9 to max.…”

Section: Diatom Abundancessupporting

confidence: 85%

Monsoons, Upwelling, and the Deoxygenation of the Northwestern Indian Ocean in Response to Middle to Late Miocene Global Climatic Shifts

Bialik

Auer

Ogawa

et al. 2020

Paleoceanog and Paleoclimatol

View full text Add to dashboard Cite

Today, upwelling along the Oman margin in the Arabian Sea is governed by the South Asian Monsoon winds. The Oman upwelling results in the formation of an oxygen minimum zone (OMZ) spanning across the Arabian Sea and large parts of the Indian Ocean. While these conditions are recorded as early as the middle Miocene (~15 Ma), the long‐term dynamics of upwelling in the Arabian Sea are as of yet poorly constrained during the middle to late Miocene. Here, we use organic and inorganic proxies combined with sedimentary and paleontological records to constrain the evolution of upwelling at Ocean Drilling Program Site 722B between ~15 and ~8.7 Ma. Our record shows that Mn depletion occurred at ~14.5 Ma, likely due to regionally confined OMZ formation at that time. Biogenic silica accumulation intensified between ~12.5 and ~11 Ma. The δ15N values (>6‰) provide evidence for the onset of at least intermittent denitrification between ~11 and ~9.5 Ma during the apex of the global “carbonate crash.” Our data demonstrate that upwelling and OMZ intensity in the Arabian Sea were linked to the reorganization of the Indian Ocean circulation system and South Asian Monsoon during the Miocene. The initiation of these systems occurred once the regional tectonic configuration (i.e., the uplift of the Tibetan Plateau ~25 Ma and the closure of the Tethyan seaway ~20 Ma) was in place. The subsequent development of monsoonal upwelling after 14 Ma responded to latitudinal shifts in climatic belts following the progressive Miocene glaciation of Antarctica.

show abstract

Section: Diatom Abundancessupporting

confidence: 85%

Monsoons, Upwelling, and the Deoxygenation of the Northwestern Indian Ocean in Response to Middle to Late Miocene Global Climatic Shifts

Bialik

Auer

Ogawa

et al. 2020

Paleoceanog and Paleoclimatol

View full text Add to dashboard Cite

show abstract

“…Thibault et al (2012) and Koch and Young (2007) describe similar methods and have proved high reproducibility yielding a minimal error margin for counting absolute calcareous nannofossil abundances. The recent study of Bordiga et al (2015) further confirms that the simple technique used here provides high-reproducibility and allows for calibration to other techniques commonly used to calculate absolute nannofossil abundances. Semi-quantitative counts of calcareous nannofossil species were performed with a LEICA DM750P light microscope at a magnification of 1600X (x100 oil objective with a x1.6 additional lens and x10 oculars).…”

Section: Calcareous Nannofossilssupporting

confidence: 64%

Sinemurian–Pliensbachian calcareous nannofossil biostratigraphy and organic carbon isotope stratigraphy in the Paris Basin: Calibration to the ammonite biozonation of NW Europe

Peti¹,

Thibault²,

Clémence³

et al. 2017

Palaeogeography, Palaeoclimatology, Palaeoecology

View full text Add to dashboard Cite

Abstract:The biostratigraphy of Sinemurian to lower Toarcian calcareous nannofossils has been investigated in the Sancerre-Couy core (Paris Basin), which contains a mixed assemblage of species with affinities to the northern and southern areas of the peritethyan realm, thus allowing for the use and calibration of the Mediterranean Province (Italy/S France) and NW Europe (UK) biozonation schemes. This study is based on semi-quantitative analyses of the calcareous nannofossil assemblage performed on 145 samples and the recorded bioevents are calibrated to the NW European Ammonite Zonation and to a new organic carbon isotope curve based on 385 data points. The main bioevents, i.e. the first occurrences of Parhabdolithus liasicus, Crepidolithus pliensbachensis, Crepidolithus crassus, Mitrolithus lenticularis, Similiscutum cruciulus sensu lato, Lotharingius hauffii, Crepidolithus cavus and Lotharingius sigillatus as well as the last occurrence of Parhabdolithus robustus, have been identified. However, we show that a large number of standard biostratigraphic markers show inconsistent occurrences at the base and top of their range, possibly accounting for some of the significant discrepancies observed between the different domains. In addition to the nine main bioevents used for the biozonation of the core, we document an additional 50 distinct bioevents, evaluate their reliability and discuss their potential significance by comparison to previous studies. A total of five significant negative organic carbon isotope excursions are identified and defined in the Paris Basin including the well-documented Sinemurian-Pliensbachian boundary event. One positive excursion is further defined in the Pliensbachian interval. Our calibration of high-resolution calcareous nannofossil biostratigraphy to ammonite biostratigraphy and organic carbon isotopes represents a new stratigraphic reference for the Lower Jurassic series.

show abstract

“…For the quantitative analysis of fossil coccolith assemblages, microscope slides were prepared directly from freeze-dried bulk sediments using the drop technique (Bordiga et al, 2015). The 74 samples were analysed at 1000x magnification under an Olympus BX53 polarized-light microscope.…”

Section: Coccolith Abundance Counts and Paleo-fluxesmentioning

confidence: 99%

A 15 million-year long record of phenotypic evolution in the heavily calcified coccolithophore <i>Helicosphaera</i> and its biogeochemical implications

Šupraha¹,

Henderiks²

2020

Preprint

Self Cite

View full text Add to dashboard Cite

Abstract. The biogeochemical performance of coccolithophores is defined by their overall abundance in the oceans, but also by a wide range in cell size, degree of calcification and carbon production rates between different species. Species’ sensitivity to environmental forcing has been suggested to relate to their cellular PIC : POC ratio and other physiological constraints. Understanding both the short and longer-term adaptive strategies of different coccolithophore lineages, and how these in turn shape the biogeochemical role of the group, is therefore crucial for modeling the ongoing changes in the global carbon cycle. Here we present data on the phenotypic evolution of a large and heavily-calcified genus Helicosphaera (order Zygodiscales) over the past 15 million years (Ma), at two deep-sea drill sites from the tropical Indian Ocean and temperate South Atlantic. The modern species Helicosphaera carteri, which displays eco-physiological adaptations in modern strains, was used to benchmark the use of its coccolith morphology as a physiological proxy in the fossil record. Our results show that, on the single-genotype level, coccolith morphology has no correlation with physiological traits in H. carteri. However, significant correlations of coccolith morphometric parameters with cell size and physiological rates do emerge once multiple genotypes or closely related lineages are pooled together. Using this insight, we interpret the phenotypic evolution in Helicosphaera as a global, resource limitation-driven selection for smaller cells, which appears to be a common adaptive trait among different coccolithophore lineages, from the warm and high-CO2 world of the middle Miocene to the cooler and low-CO2 conditions of the Pleistocene. However, despite a significant decrease in mean size, Helicosphaera kept relatively stable PIC : POC (as inferred from the coccolith aspect ratio) and thus highly conservative biogeochemical output on the cellular level. We argue that this supports its status as an obligate calcifier, like other large and heavily-calcified genera such as Calcidiscus and Coccolithus, and that other adaptive strategies, beyond size-adaptation, must support the persistent, albeit less abundant, occurrence of these taxa. This is in stark contrast with the ancestral lineage of Emiliania and Gephyrocapsa, which not only decreased in mean size but also displayed much higher phenotypic plasticity in degree of calcification while becoming globally more dominant in plankton communities.

show abstract

Absolute nannofossil abundance estimates: Quantifying the pros and cons of different techniques

Cited by 49 publications

References 13 publications

Monsoons, Upwelling, and the Deoxygenation of the Northwestern Indian Ocean in Response to Middle to Late Miocene Global Climatic Shifts

Monsoons, Upwelling, and the Deoxygenation of the Northwestern Indian Ocean in Response to Middle to Late Miocene Global Climatic Shifts

Sinemurian–Pliensbachian calcareous nannofossil biostratigraphy and organic carbon isotope stratigraphy in the Paris Basin: Calibration to the ammonite biozonation of NW Europe

A 15 million-year long record of phenotypic evolution in the heavily calcified coccolithophore <i>Helicosphaera</i> and its biogeochemical implications

Contact Info

Product

Resources

About

Absolute nannofossil abundance estimates: Quantifying the pros and cons of different techniques

Cited by 49 publications

References 13 publications

Monsoons, Upwelling, and the Deoxygenation of the Northwestern Indian Ocean in Response to Middle to Late Miocene Global Climatic Shifts

Monsoons, Upwelling, and the Deoxygenation of the Northwestern Indian Ocean in Response to Middle to Late Miocene Global Climatic Shifts

Sinemurian–Pliensbachian calcareous nannofossil biostratigraphy and organic carbon isotope stratigraphy in the Paris Basin: Calibration to the ammonite biozonation of NW Europe

A 15 million-year long record of phenotypic evolution in the heavily calcified coccolithophore &lt;i&gt;Helicosphaera&lt;/i&gt; and its biogeochemical implications

Contact Info

Product

Resources

About

A 15 million-year long record of phenotypic evolution in the heavily calcified coccolithophore <i>Helicosphaera</i> and its biogeochemical implications