Fossilized microorganisms preserved as fluid inclusions in epithermal veins, Vani Mn-Ba deposit, Milos Island, Greece
Ivarsson, M.; Kilias, S.P.; Broman, C.; Naden, J.; Detsi, K.. 2010 Fossilized microorganisms preserved as fluid inclusions in epithermal veins, Vani Mn-Ba deposit, Milos Island, Greece. In: Chrisotfides, G.; Kantiranis, N.; Kostopoulos, D.S.; Chatzipetros, A.A., (eds.) Scientific annals of the School of Geology : Proceedings XIX Congress of the Carpathian-Balkan Geological Association. Thessaloniki, Greece, Aristotle University of Thessaloniki, 297-307, 549pp. (Scientific Annals of the School of Geology, Special Volume, 100).Before downloading, please read NORA policies.
Fossilized microorganisms preserved as fluid inclusions are found in barite silica-Mn oxide veins in the marine rift basin-related Quaternary Mn-Ba deposit of Vani, Milos . Basin fill consists of 35-50 m thick sequence of glauconitic sediments sandwiched between volcaniclastic sandy tuffs, and, bedding-parallel barite Mn oxide( silica) horizons, pebble horizons, and massive gravel. Exhalative barite-rich deposits characteristic of sea-floor venting, such as white smoker(sulphate) structures in glauconitic sediments, feeder veins, bedding-conformable horizons, and extensive microbial mat- related structures in sandy tuffs, were recognized. The feeder veins host the microfossils and consist chiefly of banded barite and minor colloform quartz, Fe-oxyhydroxides, and hollandite-group minerals and MnO2 phases, and display epithermal textures characteristic of open-space precipitation. Curvilinear, branched filamentous microfossils with distinct segmentation of septa and a turgid appearance of knob-like outgrowths occur associated with spheroidal spore-like microfossils and small twisted microstructures. Both filamentous and spheroidal microstructures are filled with aqueous (liquid + vapour) and/or hydrocarbon phases. Oil and solid hydrocarbons in the fluid inclusions may represent decomposed biological material. Chitin was detected by the pigment Wheat Germ Agglutinin conjugated with Fluorescein Isothiocyanate (WGA-FITC) in some of the microfossils, indicating that they are fossilized fungi; a fungal interpretation is further supported by microfossil morphology. Smaller, often twisted filamentous microfossils with a simpler morphology in which chitin was not detected probably represent fossilized prokaryotes and, if so, prokaryotes and eukaryotes co-existed in the geothermal system of Vani. Fluid inclusion microthermometry shows that microfossils were trapped at temperatures of ~100°C in boiling water, probably evolved seawater. Preservation of microfossils occurred at shallow sub-marine conditions of <10 m depth. Our results show that fluid inclusions may contain valuable palaeobiological information and can be used both for establishing biogenicity but also for the reconstruction of the palaeoenvironment of fossilized microorganisms.
|Item Type:||Book Section|
|Programmes:||BGS Programmes 2010 > Minerals and waste|
|Additional Keywords:||fossilized fungi, chitin, WGA-FITC, epithermal vein, Milos, Vani|
|NORA Subject Terms:||Earth Sciences|
|Date made live:||24 Aug 2012 13:37|
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