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SPEKTROSKOPIA MÖSSBAUERA 57 Fe W ANALIZIE PALEOŚRODOWISKOWYCH WARUNKÓW REDOX DEWOŃSKIEGO KRYZYSU HANGENBERG Jacek Gatlik 1 , Kamila Komędera 1 , Artur Błachowski 1 , Michał Rakociński 2 1 Laboratorium Spektroskopii Mössbauerowskiej, Instytut Fizyki, Uniwersytet Pedagogiczny, Kraków, Polska
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SPEKTROSKOPIA MÖSSBAUERA 57Fe W ANALIZIE PALEOŚRODOWISKOWYCH WARUNKÓW REDOX DEWOŃSKIEGO KRYZYSU HANGENBERG Jacek Gatlik1, Kamila Komędera1, Artur Błachowski1, Michał Rakociński2 1 Laboratorium Spektroskopii Mössbauerowskiej, Instytut Fizyki, Uniwersytet Pedagogiczny, Kraków, Polska 2 Katedra Paleontologii i Stratygrafii, Wydział Nauk o Ziemi, Uniwersytet Śląski, Sosnowiec, Polska ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Abundance of elements in Earth's upper continental crust ---------------------------------------------------------------------------------------------------------------------------------- Geochemical facies of marine environments based on the behavior of iron in various sedimentary conditions
Mössbauer Spectroscopy -ray energy is modulated by the Doppler effect due to the source motion vs. absorber (sample) Source (e.g. 57Co/Rh) Absorber (57Fe) Detector – v +v 1 mm/s 48neV
Hyperfine Interactions between Nuclei and Electrons Mössbauer Parameters Electric Monopole Interaction Isomer Shift S Electron density S S Electric Quadrupole Interaction Quadrupole Splitting Electric Field Gradient EFG S 1 mm/s3.4el./Bohr3 EFG EQ EFG 1 mm/s5.7 1021V/m2 S Magnetic Dipole InteractionMagnetic Splitting Magnetichyperfine fieldB B B -Fe33 Tesla -Fe2O3 52 Tesla -FeOOH 38 Tesla
The end-Devonian Hangenberg Event Marine extinction intensity (%) Ma
L. Marynowski et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 346-347 (2012) 66–86 Schematic geological map of the western and central part of the Holy Cross Mountains (a) with location of the Kowala Quarry (b) and investigated section (c).
L. Marynowski et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 346-347 (2012) 66–86 The outcropped section (August 2009) (a) and enlarged picture of the Hangenberg Black Shale (HBS) with numbers denoting the samples collected (b).
57Fe Mössbauer spectra Percentage distribution of iron on:hydrogen-sulphideFeS2, luminosilicateFe2+(AlSi) / Fe3+(AlSi)and hematite Fe2O3for samplesbeforeHangenberg Event.
57Fe Mössbauer spectra Percentage distribution of iron on:hydrogen-sulphideFeS2, luminosilicateFe2+(AlSi) / Fe3+(AlSi)and hematite Fe2O3for samplesduringHangenberg Event.
57Fe Mössbauer spectra Percentage distribution of iron on:hydrogen-sulphideFeS2, luminosilicateFe2+(AlSi) / Fe3+(AlSi)and hematite Fe2O3for samples post Hangenberg Event.
Percentage distribution of iron on:hydrogen-sulphide FeS2, aluminosilicate Fe2+(AlSi) / Fe3+(AlSi)and hematite Fe2O3 Geochemical facies vs. Eh-pH redox conditions
Eh redox conditions strongly reducing oxidizing reducing
CONCLUSION • Mössbauer spectroscopy allows to determine iron containing minerals and to define the relative distribution of iron in these minerals. • Behavior of iron in various sedimentary conditions allows to assign samples to specific geochemical facies and determine the redox conditions. • Based on the redox conditions model, strong anaerobic (anoxic and euxinic) conditions during the Hangenberg Event can be confirmed. ---------------------------------------------------------------------------------------------------------------------------------- Mössbauer Spectroscopy Laboratory, Pedagogical University, Kraków, Poland Thank you for your attention!