Tubular microfossils from ∼2.8 to 2.7Ga-old lacustrine deposits of South Africa: A sign for early origin of eukaryotes?

Unequivocal evidence for Archean eukaryotic life has been long sought for and is a matter of lively debate. In the absence of unambiguous fossils this debate has focused on biogeochemical signatures and molecular phylogenies. Most researchers agree that fossil forms comparable with modern eukaryotic cells can be credibly identified only in Proterozoic (∼1.8–1.6 Ga) and younger rocks. Herein, we report for the first time, Neoarchean mineralized tubular microfossils from ∼2.8 to 2.7 Ga lacustrine deposits of South Africa. The exceptional preservation of these microfossils allows recognition of important morphological details in petrographic thin section and in HF-macerates that links them to modern siphonous (coenocytic) green or yellow-green microalgae (Chlorophyta and Xanthophyta). The microfossil identification is supported by Raman spectroscopic analyses, EPMA, SEM/BSE and SEM/EDS microprobe analytical results, NanoSIMS elemental mapping and micro-tomographic sectioning of the thalli. All results point to indigenous, bona fide eukaryotic microfossils of algal affinity. These Neoarchean microalgae-like remains and their assumingly combined in vivo and early post-mortem precipitated mineral envelopes greatly improve our knowledge of early life and its habitats and may have far-reaching consequences for the studies of the evolution of life

3.46 Ga Apex chert 'microfossils' reinterpreted as mineral artefacts produced during phyllosilicate exfoliation

We acknowledge the facilities, scientific and technical assistance of the Australian Microscopy & Microanalysis Research Facility at: Centre for Microscopy Characterisation and Analysis, The University of Western Australia; Electron Microscopy Unit, The University of New South Wales. These facilities are funded by the Universities, State and Commonwealth Governments. DW was funded by the European Commission and the Australian Research Council (FT140100321). This is ARC CCFS paper number XXX. We acknowledge Martin van Kranendonk, Owen Green, Cris Stoakes, Nicola McLoughlin, the late John Lindsay and the Geological Survey of Western Australia for fieldwork assistance, Thomas Becker for assistance with Raman microspectroscopy, Anthony Burgess from FEI for the preparation of one of the TEM wafers, and Russell Garwood, Tom Davies, Imran Rahman & Stephan Lautenschlager for training and advice on the SPIERS and AVIZO software suites. We thank Chris Fedo and an anonymous reviewer for comments that improved the manuscript.Peer reviewedPostprin

Development of freeze-thaw processing technique for disaggregation of indurated mudrocks and enhanced recovery of calcareous microfossils

Microfossil extraction from indurated mudrocks is widely acknowledged as challenging, especially for foraminifera. Here we report development of the freeze–thaw extraction method through the addition of rapid heating, detergent and ultrasound stages. We use indurated mudrock samples from the Toarcian (Early Jurassic) of Yorkshire, UK to assess the effectiveness and develop the freeze–thaw method. We compare our results from freeze–thaw with those from standard foraminifera processing techniques, including the use of hydrogen peroxide. Processing by freeze–thaw increased the degree of mudrock disaggregation and resulted in no damage or dissolution of foraminifera. Following the freeze–thaw method with treatment in white spirit and sodium hexametaphosphate aided the separation of foraminifera from the disaggregated clays and was twice as efficient as pressure washing. Samples processed with hydrogen peroxide contained damaged microfossils and an under representation of delicate calcareous foraminifera. Many other studies of indurated mudrocks have used hydrogen peroxide to extract foraminifera, and this might have resulted in apparently barren intervals. The freeze–thaw method outlined here provides a low-cost, low-risk and successful method of disaggregating and extracting calcareous microfossils from indurated mudrocks. We anticipate our method may be relevant for other fossil groups and merits further development

Token Finds At Pre-Pottery Neolighic ‘Ain Ghazal, Jordan A Formal And Technological Analysis

‘Ain Ghazal is a Neolithic site located near Amman, Jordan. It was excavated between 1982 and 1998 by an American-Jordanian team directed by Gary O. Rollefson, Whitman College, Walla Walla, Wa. and Zeidan Kafafi, the University of Yarmouk at Irbid, Jordan. ‘Ain Ghazal was first settled about 7250 B.C., during the so-called Pre-Pottery Neolithic B (PPNB) period. In a matter of a few centuries the village of stone houses had spread over 30 acres along the Zarqa River. During a prosperous period when the mixed economy increasingly relied on farming, ca. 7250-6000 B.C., ‘Ain Ghazal witnessed what can be termed an explosion of symbolism. The site was abandoned in the Yarmoukian period ca. 5000 BC. The volume deals with the uniquely rich and varied ‘Ain Ghazal assemblage of symbols including tokens of many shapes, animal and human figurines, modeled human skulls, plaster statues and, mural and floor paintings.A collection of 137 clay and stone tokens from the Neolithic site of ‘Ain Ghazal in Jordan was studied in terms of formal and technological characteristics. The assemblage includes spheres, cones, and other shapes that are well known from Near Eastern token collections. A visual technological classification based on surface and fabric characteristics was supplemented by petrographic and XRD studies of smaller samples of artifacts and local clay and stone raw materials. Results show some correlations between shapes and technological processes and close technological similarities among tokens recovered as groups, suggesting single episode production, use and discard.Art and Art Histor

Micropalaeontology reveals the source of building materials for a defensive earthwork (English Civil War?) at Wallingford Castle, Oxfordshire

Microfossils recovered from sediment used to construct a putative English Civil War defensive bastion at Wallingford Castle, south Oxfordshire, provide a biostratigraphical age of Cretaceous (earliest Cenomanian) basal M. mantelli Biozone. The rock used in the buttress – which may have housed a gun emplacement – can thus be tracked to the Glauconitic Marl Member, base of the West Melbury Marly Chalk Formation. A supply of this rock is available on the castle site or to the east of the River Thames near Crowmarsh Gifford. Microfossils provide a unique means to provenance construction materials used at the Wallingford site. While serendipity may have been the chief cause for use of the Glauconitic Marl, when compacted, it forms a strong, almost ‘road base’-like foundation that was clearly of use for constructing defensive works. Indeed, use of the Glauconitic Marl was widespread in the area for agricultural purposes and its properties may have been well-known locally

Palynomorphs of brackish and marine species in cores from the freshwater Lake Sapanca, NW Turkey

Lake Sapanca, which is located on the Sakarya–Sapanca–İzmit corridor in NW Turkey, is a freshwater lake with numerous fish farms in its catchment. Palynological analyses including non-pollen palynomorphs of a short (38.5 cm) and a longer sediment core (586 cm), taken in the centre of the lake and dated in previous investigations, revealed the presence of brackish and marine palynomorphs. The longer sediment sequence shows the occurrence of Brigantedinium sp., Impagidinium caspienense and Spiniferites cruciformis from the base of the core at c. AD 580 years up to 300 cm depth at shortly after c. AD 910. A similar assemblage, but this time with the additional presence of dinoflagellate thecae and the acritarch, Radiosperma corbiferum, was found in the recent core, especially from AD 1986 until the present. Past connections between the Gulf of İzmit and the Black Sea, via the River Sakarya and Lake Sapanca, could be the origin of these two microfossil assemblages. Accidental re-introduction via fish translocation since the Roman times may have been a additional mechanism. The consequences of the survival of brackish and marine forms in a freshwater lake are discussed in terms of wider euryhalinity than has been suggested for those still poorly known organisms

Fossil biomass preserved as graphitic carbon in a late paleoproterozoic banded iron formation metamorphosed at more than 550°C

Metamorphism is thought to destroy microfossils, partly through devolatilization and graphitization of biogenic organic matter. However, the extent to which there is a loss of molecular, elemental and isotope signatures from biomass during high-temperature metamorphism is not clearly established. We report on graphitic structures inside and coating apatite grains from the c. 1850 Ma Michigamme silicate banded iron formation from Michigan, metamorphosed above 550°C. Traces of N, S, O, H, Ca and Fe are preserved in this graphitic carbon and X-ray spectra show traces of aliphatic groups. Graphitic carbon has an expanded lattice around 3.6 Å, forms microscopic concentrically-layered and radiating polygonal flakes and has homogeneous δ13C values around −22‰, identical to bulk analyses. Graphitic carbon inside apatite is associated with nanometre-size ammoniated phyllosilicate. Precursors of these metamorphic minerals and graphitic carbon originated from ferruginous clayrich sediments with biomass. We conclude that graphite coatings and inclusions in apatite grains indicate fluid remobilization during amphibolite-facies metamorphism of precursor biomass. This new evidence fills in observational gaps of metamorphosed biomass into graphite and supports the existence of biosignatures in the highly metamorphosed iron formation from the Eoarchean Akilia Association, which dates from the beginning of the sedimentary rock record

Bolboforma from Leg 105, Labrador Sea and Baffin Bay, and the chronostratigraphy of Bolboforma in the North Atlantic

The genus Bolboforma, first described by Daniels and Spiegler (1974), is a problematic group of calcareous microfossils. Solbaforma is most probably a planktonic cyst (Rogl and Hochuli, 1976) having protozoan or algal affinities (Poag and Karowe, 1986). Its known distribution at present suggests that various species may have potential for becoming good stratigraphic indicators. Bolboforma also may be useful in areas where other calcareous planktonic microfossils are poorly preserved, i.e., the North Sea, the Norwegian-Greenland Sea, and Baffin Bay. This report summarizes the known occurrences of Bolboforma in the North Atlantic and correlates them with a standard geochronology (Berggren et al., 1985a, 1985b). In addition, further occurrences of Bolboforma are reported from Sites 645, 646, and 647 (Fig. 1)