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Jurassic Forum » JURASSIC references & paper reviews » Jurassic around the world » Zatoń et al., 2009 (Redox conditions during sedimentation of the Mid Jurassic)
Zatoń et al., 2009
mhornДата: Wednesday, 10.11.2010, 16:32 | Сообщение # 1
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Zatoń M., Marynowski L., Szczepanik P., Bond D.P.G., Wignall P.B. (2009) Redox conditions during sedimentation of the Middle Jurassic (Upper Bajocian–Bathonian) clays of the Polish Jura
(south-central Poland) // Facies. Vol.55. P.103–114.
Pdf: http://rogov.zwz.ru/zaton_et_al__2009%20facies.pdf
Изучен характер окислительно-восстановительных условий в байосе-батских рудоносных глинах окрестностей Кракова. При этом применялись различные геохимические (соотношения Th/U и U/Th, степень пиритизации, стабильные изотопы серы, анализ биомаркеров) и петрографисеские (изучение фрамбоидов пирита, анализ микрофаций) методы. The Th/U and U/Th ratios indicate that oxic conditions prevailed on the sea-Xoor during this interval, and 34S isotopes suggest open-system conditions. DOP values, however, are rather scattered, and may reflect oxic, dysoxic, or anoxic conditions. We consider that the DOP values result from reducing conditions within the sediment and the chemistry of the pore-waters, rather than true sea-floor redox conditions. Pyrite framboid populations also indicate that dysoxic conditions prevailed within the sediment, beneath an oxygenated water column. Biomarker data did not provide any evidence of water column stratification or anoxia during sedimentation of the Middle Jurassic clays.

Depositional redox conditions of the uppermost Bajocian–Bathonian (Middle Jurassic) ore-bearing clays of the Gnaszyn/Kawodrza area in the Polish Jura have been determined using an integrated geochemical (Th/U and U/Th ratios, degree of pyritisation (DOP), sulphur stable isotopes, biomarker analysis) and petrographic approach (measurements of pyrite framboid diameters, and microfacies analysis). The Th/U and U/Th ratios indicate that oxic conditions prevailed on the sea-floor during this interval, and 34S isotopes suggest open-system conditions. DOP values, however, are rather scattered, and may reflect oxic, dysoxic, or anoxic conditions. We consider that the DOP values result from reducing conditions within the sediment and the chemistry of the pore-waters, rather than true sea-floor redox conditions. Pyrite framboid populations also indicate that dysoxic conditions prevailed within the sediment, beneath an oxygenated water column. Biomarker data did not provide any evidence of water column stratification or anoxia during sedimentation of the Middle Jurassic clays.


Middle Jurassic - Lower Cretaceous ammonites & aptychi
 
Jurassic Forum » JURASSIC references & paper reviews » Jurassic around the world » Zatoń et al., 2009 (Redox conditions during sedimentation of the Mid Jurassic)
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