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Université de Fribourg

The initiation of the southern central Great Barrier Reef: New multiproxy data from Pleistocene distal sediments from the Marion Plateau (NE Australia)

Dubois, Nathalie ; Kindler, Pascal ; Spezzaferri, Silvia ; Coric, Stjepan

In: Marine Geology, 2008, vol. 250, p. 223–233

Significant synchronous shifts in the chemistry, mineralogy, grain sizes and color of the sediments at 6 m below sea floor (mbsf) at ODP Site 1195 on the Marion Plateau (NE Australia) are interpreted to reflect a major regional paleoceanographic change: the initiation of the southern province of the Great Barrier Reef (GBR). The onset of this massive carbonate production centre nearby resulted...

Université de Fribourg

In situ measurements of calcium isotopes by ion microprobe in carbonates and application to foraminifera

Rollion-Bard, Claire ; Vigier, Nathalie ; Spezzaferri, Silvia

In: Chemical Geology, 2007, vol. 244, no. 3-4, p. 679-690

An analytical procedure has been developed for the in situ measurement of calcium isotope composition of carbonates with a spatial resolution of 15–20 μm on a Caméca IMS 1270 ion microprobe. By using two Faraday cup detectors, the ⁴⁰Ca and ⁴⁴Ca can be measured simultaneously, improving the internal reproducibility. Instrumental mass fractionation (IMF) of calcium isotopes was observed...

Université de Fribourg

Scanning electron microscope images of uncoated microfossils: applications, perspectives and limitations

Spezzaferri, Silvia ; Neururer, Christoph ; Pirkenseer, Claudius ; Grobéty, Bernard

In: The Journal of Foraminiferal Research, 2007, vol. 37, no. 3, p. 270-276

We present a recently developed method using a field emission scanning electron microscope (FEG) to view and photograph microfossil specimens that are not coated by conductive material. The FEG microscope provides high electron flux and offers the option to capture images at low beam voltage. Balancing incident energy with absorbed energy from the detector leads to charge-free images of...

Université de Fribourg

Miocene shallow-water limestones from São Nicolau (Cabo Verde): Caribbean-type benthic fauna and time constraints for volcanism

Bernoulli, Daniel ; Hottinger, Lukas ; Spezzaferri, Silvia ; Stille, Peter

In: Swiss Journal of Geosciences, 2007, vol. 100, no. 2, p. 215-225

Shallow-water limestones of presumed Late Cretaceous and Eocene age, interbedded with basaltic lavas, were described by earlier authors from São Nicolau in the northwestern part of the Cabo Verde archipelago. If confirmed, these ages would imply late Mesozoic shallow-marine and subaerial volcanic activity in the Cabo Verde archipelago, and document a geological history very different from that...

Université de Fribourg

Hyalinea marmarica, a new species of benthic foraminifera from the Sea of Marmara (Turkey)

Spezzaferri, Silvia ; Yanko-Hombach, Valentina

In: The Journal of Foraminiferal Research, 2007, vol. 37, no. 4, p. 309-317

Traditionally, the benthic foraminifera Hyalinea balthica (Schröter) has been considered a species with high intraspecific variability, possibly related to climatic changes, and, therefore, a potential indicator of paleoclimate in the Mediterranean Sea. However, a stable and characteristic morphology very different from the syntype of the species can be observed in specimens from the Sea...

Université de Fribourg

Dicarinella imbricata (Mornod 1949): First SEM documentation of the lost holotype and foraminiferal assemblage from the type horizon (Upper Cretaceous, Switzerland)

Caron, Michele ; Spezzaferri, Silvia

In: Eclogae Geologicae Helvetiae, 2006, vol. 99, no. 3, p. 295-299

The foraminifer species Dicarinella imbricata, from the Upper Cretaceous of Switzerland, was established in 1949 by L. Mornod. The holotype was figured only by Mornod’s drawings and the specimen was never made available. As the holotype was missing since a long time, it was considered as lost and a neotype was established. However, the holotype was recently found.We present here the first...

Université de Fribourg

In situ measurements of Li isotopes in foraminifera

Vigier, Nathalie ; Rollion-Bard, Claire ; Spezzaferri, Silvia ; Brunet, Fabrice

In: Geochemistry Geophysics Geosystems, 2007, vol. 8, p. Q01003

In situ measurement of Li isotope ratios in foraminifera has been developed using a Cameca ims 1270 ion microprobe. In situ δ⁷Li analyses have been performed in biogenic calcite of planktonic foraminifera from various locations. Results show that for west Pacific mixed Globigerinoides and Globorotalia (22°S161°E), the isotopic variability between tests and within a...

Université de Fribourg

Scanning electron microscope documentation of the lost holotypes of Mornod, 1949: Thalmanninella reicheli and Rotalipora montsalvensis

Caron, Michele ; Spezzaferri, Silvia

In: The Journal of Foraminiferal Research, 2006, vol. 36, no. 4, p. 374-378

The species Globotruncana (Rotalipora) reicheli and Gobotruncana (Rotalipora) montsalvensis, were established in 1949 by Mornod. The two holotypes were figured only by drawings and the specimens were never made publicly available. Since their first description, these two species have acquired great importance as biostratigraphic markers. However, holotypes had been considered as...

Université de Fribourg

Bolboforma (Phytoplankton Incertae Sedis), Bachmayerella and other Calciodinelloidea (Phytoplankton) from the Middle Miocene of the Alpine–Carpathian Foredeep (Central Paratethys)

Spezzaferri, Silvia ; Rögl, Fred

In: Journal of Micropalaeontology, 2004, vol. 23(2), p. 139

Bolboforma is a microfossil of uncertain origin with affinities to protophytic algae. It generally occurs at high latitudes and/or in cool and temperate waters and has a high stratigraphic potential especially for the Miocene. Calcareous cysts of dinoflagellates represent the ‘benthic cyst stage’ of unicellular organisms belonging to the marine phytoplankton.The occurrence of...