Riassunto analitico
Submarine mud volcanoes (MV) are particular geological structures of cold seeps (no extreme thermal gradients with its surroundings in contrast to the hot vents) characterized by the rise of fluids to the seafloor, consisting of solid material (mud and mud-breccia) and volatile elements, mainly methane (e.g., Dimitrov, 2002). The ascent of methane-rich fluids favors precipitation of 13C-depleted authigenic cold-seep carbonates near the seafloor through microbially mediated anaerobic oxidation of methane (AOM; e.g., Aloisi et al., 2002): CH4 + SO42- à HCO3- + HS- + H2O (AOM) 2HCO3- + Ca2+ à CaCO3 + CO2 + H2O (carbonate precipitation) In addition to the increase of carbonate alkalinity through the production of HCO3-, AOM-produced HS- supports chemosynthetic organisms that host sulphide oxidizing bacteria as symbionts in their tissues like vestimentiferan tube worms and large bivalves (e.g., vesicomydae and lucinidae). The aim of the thesis is to analyze one piece of authigenic cold-seep carbonate associated with large vestimentiferan tube worms, sampled at Athina mud volcano (Anaximander seamounts, northeastern Mediterranean Sea) during expedition M70/3 with the german research vessel R/V METEOR in 2006. The main objectives are: - to study the mineralogical composition of the sample in a qualitative and quantitative manner with particular attention to the content of MgCO3 by using the Rietveld method (University of Modena and Reggio Emilia); - to measure stable carbon and oxygen isotopes (δ13C and δ18O) of the sample in order to characterize the fluid from which the carbonate formed (the isotope measurements will be conducted at the MARUM, University of Bremen, Germany). - to analyze carbonate-associated lipid biomarkers in order to understand what kind of microbes were responsible for the precipitation of carbonate phases and what are the species that lives in symbiosis with vestimentiferan tube (the lipid biomarker study will be conducted at the MARUM, University of Bremen, Germany). - to analyze the sedimentological characteristics, mainly textures and microfacies of these recent authigenic carbonates with their fossil counterparts in the Miocene of the northern Apennines, for an assessment of the signatures attributable to methane seepage permanently imprinted in the rock record.
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Abstract
Submarine mud volcanoes (MV) are particular geological structures of cold seeps (no extreme thermal gradients with its surroundings in contrast to the hot vents) characterized by the rise of fluids to the seafloor, consisting of solid material (mud and mud-breccia) and volatile elements, mainly methane (e.g., Dimitrov, 2002). The ascent of methane-rich fluids favors precipitation of 13C-depleted authigenic cold-seep carbonates near the seafloor through microbially mediated anaerobic oxidation of methane (AOM; e.g., Aloisi et al., 2002):
CH4 + SO42- à HCO3- + HS- + H2O (AOM)
2HCO3- + Ca2+ à CaCO3 + CO2 + H2O (carbonate precipitation)
In addition to the increase of carbonate alkalinity through the production of HCO3-, AOM-produced HS- supports chemosynthetic organisms that host sulphide oxidizing bacteria as symbionts in their tissues like vestimentiferan tube worms and large bivalves (e.g., vesicomydae and lucinidae).
The aim of the thesis is to analyze one piece of authigenic cold-seep carbonate associated with large vestimentiferan tube worms, sampled at Athina mud volcano (Anaximander seamounts, northeastern Mediterranean Sea) during expedition M70/3 with the german research vessel R/V METEOR in 2006. The main objectives are:
- to study the mineralogical composition of the sample in a qualitative and quantitative manner with particular attention to the content of MgCO3 by using the Rietveld method (University of Modena and Reggio Emilia);
- to measure stable carbon and oxygen isotopes (δ13C and δ18O) of the sample in order to characterize the fluid from which the carbonate formed (the isotope measurements will be conducted at the MARUM, University of Bremen, Germany).
- to analyze carbonate-associated lipid biomarkers in order to understand what kind of microbes were responsible for the precipitation of carbonate phases and what are the species that lives in symbiosis with vestimentiferan tube (the lipid biomarker study will be conducted at the MARUM, University of Bremen, Germany).
- to analyze the sedimentological characteristics, mainly textures and microfacies of these recent authigenic carbonates with their fossil counterparts in the Miocene of the northern Apennines, for an assessment of the signatures attributable to methane seepage permanently imprinted in the rock record.
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