X-ray tomographic data of planktonic foraminifera species Globigerina bulloides from the Eastern Tropical Atlantic across Termination II

Zarkogiannis, Stergios D.; Fernández, Vincent; Greaves, Mervyn; Mortyn, P. Graham; Kontakiotis, George; Antonarakou, Assimina

doi:10.46471/gigabyte.5

Cited by 13 publications

(16 citation statements)

References 18 publications

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“…Sediment infilling is the specimen's internal volume percentage occupied by sediment impurities. The µCT analysis results for individual specimens are published in an accompanying paper [31]. [45], because after that, the sea level and atmospheric CO 2 rise continuously (Figure 4).…”

Section: Resultsmentioning

confidence: 99%

“…For X-ray microscopic analysis, in total, 27 specimens were scanned from 3 samples (9 specimens per sample) that correspond to the time interval of the increased mass event (132.2 ka), the penultimate glacial maximum (139.1 ka) prior to the event, and a time interval of increased shell weights that followed (122.5 ka). Each batch of shells was poured into a quartz cylindrical carrier 1 mm in diameter [31]. They were stabilized with diluted tragacanth glue and left to dry prior to scanning.…”

Section: X-ray Micro-computed Tomography (µCt)mentioning

confidence: 99%

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Evidence of Stable Foraminifera Biomineralization during the Last Two Climate Cycles in the Tropical Atlantic Ocean

Zarkogiannis

Antonarakou

Fernández

et al. 2020

JMSE

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Planktonic foraminiferal biomineralization intensity, reflected by the weight of their shell calcite mass, affects global carbonate deposition and is known to follow climatic cycles by being increased during glacial stages and decreased during interglacial stages. Here, we measure the dissolution state and the mass of the shells of the planktonic foraminifera species Globigerina bulloides from a Tropical Eastern North Atlantic site over the last two glacial–interglacial climatic transitions, and we report no major changes in plankton calcite production with the atmospheric pCO2 variations. We attribute this consistency in foraminifera calcification to the climatic and hydrological stability of the tropical regions. However, we recorded increased shell masses midway through the penultimate deglaciation (Termination II). In order to elucidate the cause of the increased shell weights, we performed δ18O, Mg/Ca, and μCT measurements on the same shells from a number of samples surrounding this event. Compared with the lighter ones, we find that the foraminifera of increased weight are internally contaminated by sediment infilling and that their shell masses respond to local surface seawater density changes.

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Section: Resultsmentioning

confidence: 99%

Section: X-ray Micro-computed Tomography (µCt)mentioning

confidence: 99%

Evidence of Stable Foraminifera Biomineralization during the Last Two Climate Cycles in the Tropical Atlantic Ocean

Zarkogiannis

Antonarakou

Fernández

et al. 2020

JMSE

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“…After weighing, the specimens were tomographically scanned using Synchrotron X-ray radiation at the Diamond Manchester Imaging Branchline (I13-2) at Diamond Light Source. The specimens were transferred into quartz capillaries of 1 mm inner diameter (similar to [29]) that were subsequently attached to magnetic cryo-cap holders and mounted on to a goniometer. The data was acquired with partially coherent, pink X-ray beam which has broader energy spectrum centered around 27 keV.…”

Section: Methodsmentioning

confidence: 99%

“…Residual clays or nano-ooze in poral spaces and shell surface obstruct the study of test ultrastructure that yield information about the degree of carbonate dissolution [25] or test porosity [26]. Furthermore, such coatings or infillings (in apertures) often precludes automated recognition software, which is based on morphological features of foraminifera shells [27], from classifying their images correctly [28] and greatly complicate specimen segmentation when using high resolution Xray tomographic techniques [29]. In the present study, by using SEM and X-ray tomography with reagents that are established not to alter the fossil geochemical signal, we propose a methodology that effectively diminishes surface and internal specimen contamination.…”

Section: Introductionmentioning

confidence: 99%

An Improved Cleaning Protocol for Foraminiferal Calcite: HyPerCal – A New Practice for Micropaleontological and Paleoclimatic Proxies

Zarkogiannis¹,

Kontakiotis²,

Gkaniatsa³

et al. 2020

Preprint

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Paleoclimatic and paleoceanographic studies routinely rely on the usage of foraminiferal calcite through faunal, morphometric and physico-chemical proxies. The application of such proxies presupposes the extraction and cleaning of these biomineralized components from ocean sediments in the most efficient way, a process which is often labor intensive and time consuming. In this respect, in this study we performed a systematic experiment for planktonic foraminiferal specimen cleaning using different chemical treatments and evaluated the resulting data of a Late Quaternary gravity core sample from the Aegean Sea. All cleaning procedures adopted here were made on the basis of their minimum potential bias upon foraminiferal proxies, such as the faunal assemblages, degree of fragmentation, stable isotope composition (δ18O and δ13C) and/or Mg/Ca ratios that are frequently used as proxies for surface-ocean climate parameters (e.g., sea surface temperature, sea surface salinity). Six different protocols were tested, involving washing, sieving, and chemical treatment of the samples with hydrogen peroxide and/or sodium hexametaphosphate (Calgon ®). Single species foraminifera shell weighing was combined with high-resolution Scanning Electron Microscopy (SEM) and synchrotron X-ray Microtomography (SμCT) of the material processed by each of the cleaning protocols, in order to assess the decontamination degree of specimen’s ultrastructure and interior. It appeared that a good compromise between time and cleaning efficiency is the simultaneous treatment of samples with a mixed hydrogen peroxide and Calgon solution, while the most effective way for an almost complete decontaminate of the calcareous components from undesirable sedimentary material is a two-step treatment - initially with hydrogen peroxide and subsequently with Calgon solutions.

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“…Residual clays or nano-ooze in poral spaces and shell surface obstruct the study of test ultrastructure that yield information about the degree of carbonate dissolution [25] or test porosity [26]. Furthermore, such coatings or infillings (in apertures) often precludes automated recognition software, which is based on morphological features of foraminifera shells [27], from classifying their images correctly [28] and greatly complicate specimen segmentation when using high resolution X-ray tomographic techniques [29]. In the present study, by using light microscope imaging, SEM and X-ray tomography to assess the cleanliness of tests treated with reagents that are established not to alter the fossil geochemical signal, we propose a methodology that effectively diminishes surface and internal specimen contamination.…”

Section: Introductionmentioning

confidence: 99%

An Improved Cleaning Protocol for Foraminiferal Calcite from Unconsolidated Core Sediments: HyPerCal—A New Practice for Micropaleontological and Paleoclimatic Proxies

Zarkogiannis

Kontakiotis

Gkaniatsa

et al. 2020

JMSE

Self Cite

View full text Add to dashboard Cite

Paleoclimatic and paleoceanographic studies routinely rely on the usage of foraminiferal calcite through faunal, morphometric and physico-chemical proxies. The application of such proxies presupposes the extraction and cleaning of these biomineralized components from ocean sediments in the most efficient way, a process which is often labor intensive and time consuming. In this respect, in this study we performed a systematic experiment for planktonic foraminiferal specimen cleaning using different chemical treatments and evaluated the resulting data of a Late Quaternary gravity core sample from the Aegean Sea. All cleaning procedures adopted here were made on the basis of their minimum potential bias upon foraminiferal proxies, such as the faunal assemblages, degree of fragmentation, stable isotope composition (δ18O and δ13C) and/or Mg/Ca ratios that are frequently used as proxies for surface-ocean climate parameters (e.g., sea surface temperature, sea surface salinity). Six different protocols were tested, involving washing, sieving, and chemical treatment of the samples with hydrogen peroxide and/or sodium hexametaphosphate (Calgon®). Single species foraminifera shell weighing was combined with high-resolution scanning electron microscopy (SEM) and synchrotron X-ray microtomography (SμCT) of the material processed by each of the cleaning protocols, in order to assess the decontamination degree of specimen’s ultrastructure and interior. It appeared that a good compromise between time and cleaning efficiency is the simultaneous treatment of samples with a mixed hydrogen peroxide and Calgon solution, while the most effective way to almost completely decontaminate the calcareous components from undesirable sedimentary material is a two-step treatment—initially with hydrogen peroxide and subsequently with Calgon solutions.

show abstract

X-ray tomographic data of planktonic foraminifera species Globigerina bulloides from the Eastern Tropical Atlantic across Termination II

Cited by 13 publications

References 18 publications

Evidence of Stable Foraminifera Biomineralization during the Last Two Climate Cycles in the Tropical Atlantic Ocean

Evidence of Stable Foraminifera Biomineralization during the Last Two Climate Cycles in the Tropical Atlantic Ocean

An Improved Cleaning Protocol for Foraminiferal Calcite: HyPerCal – A New Practice for Micropaleontological and Paleoclimatic Proxies

An Improved Cleaning Protocol for Foraminiferal Calcite from Unconsolidated Core Sediments: HyPerCal—A New Practice for Micropaleontological and Paleoclimatic Proxies

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