Papers by Giuliana Panieri
…, 2010
Earth scientists have searched for signs of microscopic life in ancient samples of permafrost, ic... more Earth scientists have searched for signs of microscopic life in ancient samples of permafrost, ice, deep-sea sediments, amber, salt and chert. Until now, evidence of cyanobacteria has not been reported in any studies of ancient DNA older than a few thousand years. Here, we investigate morphologically, biochemically and genetically primary evaporites deposited in situ during the late Miocene (Messinian) Salinity Crisis from the north-eastern Apennines of Italy. The evaporites contain fossilized bacterial structures having identical morphological forms as modern microbes. We successfully extracted and amplified genetic material belonging to ancient cyanobacteria from gypsum crystals dating back to 5.910-5.816 Ma, when the Mediterranean became a giant hypersaline brine pool. This finding represents the oldest ancient cyanobacterial DNA to date. Our clone library and its phylogenetic comparison with present cyanobacterial populations point to a marine origin for the depositional basin. This investigation opens the possibility of including fossil cyanobacterial DNA into the palaeo-reconstruction of various environments and could also be used to quantify the ecological importance of cyanobacteria through geological time. These genetic markers serve as biosignatures providing important clues about ancient life and begin a new discussion concerning the debate on the origin of late Miocene evaporites in the Mediterranean.
Palaeogeography, Palaeoclimatology, …, 2004
The Miocene Termina Formation of the northern Apennines (Italy) hosts small marl bodies containin... more The Miocene Termina Formation of the northern Apennines (Italy) hosts small marl bodies containing a fossil megafauna that is not seen elsewhere in the formation. This fauna consists of concentrations of large lucinid clams having living representatives that occur in cold-seep settings, where they house chemosymbiotic bacteria. Together with the megafauna, a 13C-depletion of their carbonate contents suggests a cold seep-derived origin for these bodies. They belong to the cluster of mostly carbonate, Oligo–Miocene bodies outcropping in the Apennine Range, from Piedmont to southern Italy, where they are included in deep-marine units at different geological settings. The relatively soft lithology of the bodies from the Termina Formation permitted the extraction of the microfossil component, so that a taxonomically detailed investigation of benthic foraminifera was performed. Moreover, a comparison with assemblages from nearby, non-seep deposits has allowed an evaluation of their use for recognizing fossil seeps. A total of more than 200 species and subspecies of benthic foraminifera has been identified in seep bodies and surrounding non-seep deposits and allowed paleodepth estimates within the middle bathyal zone (600–1000 m). Similarly to present-day isobathyal settings, the foraminiferal diversity is high, with a major contribution by the accessory taxa that account for up to nearly 50% of the total assemblage. Based upon the microhabitat categories, the epifaunal assemblages are largely outnumbered by the infaunal ones. Our results show that significant differences do not exist between the foraminiferal assemblages recovered from seep-influenced bodies and the ones from the enclosing deposits. These results agree with the findings from present-day seep environments, for which, however, a still limited and insufficient data set is at the moment available. A further complication that should be considered is the effect of time-averaging on fossil assemblages, which would be responsible for some homogenization between foraminiferal stocks of normal marine, non-seep settings and adjacent assemblages controlled by short-term events such as the ones produced by cold seepage.
In the Aeolian Arc area, benthic foraminiferal communities of surface sediments are associated wi... more In the Aeolian Arc area, benthic foraminiferal communities of surface sediments are associated with active or recently active shallow water (ca 100m depth) hydrothermal vents and exhibit rapid changes in taxonomic composition among next sites. The sea floor beyond fluid emissions (enriched with carbon dioxide, hydrogen sulphide, and methane) are characterized by hydrothermal deposit and consists of both high temperature massive sulphides and associated sulphates and low temperature Fe oxyhydroxides. There, presence/absence, taxonomic structure, foraminiferal diversity and abundance appear to be influenced by pH, fluid chemistry, nature of substrate and local oxygen content. Agglutinated foraminifera make up the greatest part of the population under the influence of fluids emission. The different composition of foraminiferal assemblages in samples appears therefore strongly controlled by the spatial variation of hydrothermal discharge.
Sedimentary Geology, 2010
During the Miocene, hydrocarbon seep-carbonates located atop intrabasinal highs and associated wi... more During the Miocene, hydrocarbon seep-carbonates located atop intrabasinal highs and associated with sediment instability, formed commonly at the deformation front of the Northern Apennine collisional orogen. The parallelism between the structural trend and the distribution of seep-carbonates suggests a close relationship between tectonics and gas/fluid emission.The “Montepetra intrabasinal high” was formed during the closure stage of the foredeep, being related to the synsedimentary growth of an anticline. Field geometry suggests that detachment folding was the leading mechanism of anticline growth and synsedimentary instability along the anticline flanks. Ten different bodies of seep-carbonates occur in the Tortonian–early Messinian sediments: nine in the hinge zone and one in the southern backlimb of the anticline.Foraminiferal study, geochemistry, facies investigation and the three-dimensional geometry of carbonate bodies with respect to the encasing terrigenous sediments indicate a protracted (late Tortonian–early Messinian) activity of fluid migration with re-mobilization and ascent of sediments from the core of the anticline, stabilization of chemosynthesis-related communities, and in-situ brecciation.Seepage atop the intrabasinal high was fed by different circuits: one related to the compaction-dewatering of shallow (Tortonian–early Messinian) sediments, and a deeper one related to the deformation of the anticline core and to the activity of detachment surfaces and of faults propagating through the sedimentary cover.►Seep-carbonates display habitat heterogeneity and different energies of fluid flow. ►Seepage occurred atop an intrabasinal high related to synsedimentary fold growth. ►High depositional load and fold geometry generated a long-term seafloor seepage. ►Deformation of fold core and detachment surfaces supplied deeper fluids. ►Gas hydrate dissociation favoured more intense fluid flow and sand/mud diapirism.
Marine Micropaleontology, 2008
In a 240 m × 70 m area at the top of the Blake Ridge Diapir (water depth ∼2150 m), the benthic fo... more In a 240 m × 70 m area at the top of the Blake Ridge Diapir (water depth ∼2150 m), the benthic foraminiferal assemblage in surface sediment (0-1 cm) consists of about 130 species. Hydrocarbon seepage is indicated here by the presence of methanotrophic bivalves and white bacterial mats, and by present-day formation of gas hydrate. The foraminiferal assemblage density is generally high, indicating an abundance of food. Bolivina lowmani and Globocassidulina subglobosa dominate the assemblage in the siltclay substrate, whether at the edge of bathymodiolid mussel beds or under bacterial mats. The only notable difference between these two sample groups is in the higher variation of foraminiferal density in the mussel bed samples. A control sample at 32°29.654′ N and 76°11.324 W, taken from bioturbated sediment (light-grey silt and clay with no visible bacterial or molluscan colonization), is comparable to the seep samples in the distribution of calcareous species, but shows a much higher diversity and abundance of agglutinated species. No segregation of foraminiferal species by substrate geochemistry can be inferred for the seep samples, and the possible effect of variable sulfide or methane fluxes on the community cannot be demonstrated by our data.
Rivista Italiana di Paleontologia e …, 2003
Journal of Foraminiferal Research, 2006
... from the samples of the rhizomes, and as number of individuals per surface area for epiphytic... more ... from the samples of the rhizomes, and as number of individuals per surface area for epiphytic species collected from the leaves (Table 3⇓). Among epiphytic taxa, species were included that have been directly observed on leaves (eg, Cibicidella variabilis, Lobatula lobatula and ...
Marine geology, 2005
Benthic foraminiferal assemblages from sediments around active or recently active hydrothermal ve... more Benthic foraminiferal assemblages from sediments around active or recently active hydrothermal vents in the Aeolian Arc have been investigated in four areas with different hydrothermal mineralization and seafloor exhalative activity at depths between~60 and~300 m. Active hydrothermal spots were distinguished from the surrounding sediments by direct observations by a Remotely Operated Vehicle (ROV) and subsequent seafloor sampling. Samples were taken at different water depths and are characterized by a number of mineralogies reflecting the changing temperature of the hydrothermal fluids.
Palaeogeography Palaeoclimatology Palaeoecology, 2009
Benthic foraminifera from seep carbonates and from enclosing non-seep marls present within Miocen... more Benthic foraminifera from seep carbonates and from enclosing non-seep marls present within Miocene formations in the Northern Apennines (Italy) were investigated as proxies of methane seepage in the marine environment. Negative δ13C values of benthic foraminifera from these seeps indicate unambiguously the local influence of CO2 produced by microbial anaerobic methane oxidation on the benthic ecosystem. Calcareous species living within methane seeps display δ13C values ranging from − 9.04 to − 25.74‰ PDB, whereas in the coeval surrounding marls the same species display δ13C values from − 1.54 to 0.62‰ PDB. Different species (Cibicidoides kullenbergi, C. pachyderma, Siphonina rethiculata, Planulina wuellestorfi, Bolivina miocenica, Brizalina dilatata, Vulvulina pennatula, and Cibicides praecinctus) in different seep carbonates indicate that benthic foraminifera, independently of the taxa and of microhabitat preferences, have more negative δ13C values than those found in the enclosing marls. Therefore each species represents a potential proxy for past seafloor methane emissions. In addition to the calcareous species, the agglutinated species Vulvulina pennatula displays − 27.5‰ PDB in seep carbonates against − 2.69‰ PDB in the enclosing marls. This suggests that the species utilized strongly 13C depleted carbonate particles from authigenic carbonate precipitation during the mineralization of their tests.
... Giuliana Panieri1,2, Stefano Lugli3, Vinicio Manzi4, Katarzyna A. Palinska5, Marco Roveri3 1D... more ... Giuliana Panieri1,2, Stefano Lugli3, Vinicio Manzi4, Katarzyna A. Palinska5, Marco Roveri3 1Dipartimento di Scienze della Terra e Geologico-Ambientali ... [email protected] 3Dipartimento di Scienze della Terra, Università degli Studi di Modena e Reggio Emilia, Largo ...
Marine Micropaleontology, 2006
It has been analysed the taxonomic structure and isotopic composition of the cytoplasm and tests ... more It has been analysed the taxonomic structure and isotopic composition of the cytoplasm and tests of living (Rose Bengal stained, protoplasm-full) and dead (empty tests) benthic foraminifera (>63 μm) in surface sediments from sites with and without methane seepage at water depths of about 25 m water in the northern Adriatic Sea, and compared these data to isotope analyses of carbonate rocks at the same locations. Foraminiferal density is higher in seep samples than in control ones, despite the low oxygen and high sulphide contents in sediments. The δ 13 C values in foraminiferal cytoplasm at the seep sites are lower than those in cytoplasm of the same species in control samples, suggesting that Beggiatoa may be a food source for the foraminifera, and explaining the higher foraminiferal density at the seep site. In contrast, the δ 13 C values of tests of living and dead benthic foraminifera at seep sites were not significantly different from those in tests of the same species collected at the control sites. Therefore, the carbon isotope values of foraminiferal tests in this area do not reflect the ones of the methane seepage, although the authigenic carbonate in calcareous sandstones of the methane seepage area is significantly negative and indicates the contribution of methane seepage. The similar carbon isotope values measured in the foraminiferal tests from shallow settings of the north-eastern Adriatic Sea seem therefore to be independent of methane seepages.
Geobios, 2005
Recent benthic foraminiferal assemblages in surface sediments of the Rockall Trough (NE Atlantic)... more Recent benthic foraminiferal assemblages in surface sediments of the Rockall Trough (NE Atlantic) have been qualitatively and quantitatively studied in order to investigate the effects of hydrocarbon seepage on benthic foraminiferal populations. Species diversity and abundance data have been examined in samples of similar lithology collected from hydrocarbon seep and non-seep (control) areas at a water depth of about 1000 m. Three species groups with different environmental preferences can be recognized. Group 1 dominates seep samples, and includes species tolerant to hydrocarbon emission, especially Angulogerina bradyana. In contrast, the less tolerant Group 2 species are weakly represented at seeps but dominate control samples. Group 3 species occur in low frequencies in both seep and non-seep samples. Furthermore, the measurement of species diversity (Shannon-Wiener and Simpson indices) demonstrates a difference in foraminiferal occurrence and frequencies between the seep and non-seep sites. Thus, the benthic foraminiferal distribution pattern is guided by different sensitivities of the species to hydrocarbons, reduced bottom-water oxygen usually associated with seepage and/or to a relatively elevated organic matter content in the sediment.
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Papers by Giuliana Panieri