Origin of Middle Jurassic siderite rocks from Central Poland

• Autorzy: Maliszewska A. , Kozłowska A. , Kuberska M.
• Konferencja: International Congress on the Jurassic System (7 ; 06-18.09.2006 ; Kraków, Poland)
• Języki publikacji: EN

Abstrakty

EN

Siderite rocks in the Middle Jurassic marine deposits in Central Poland occur from Aalenian to Upper Bathonian in form of intercalations and concretions. Most frequently, they are clayey siderites composed of siderite and sideroplesite, being accompanied by illite, kaolinite, pyrite, quartz, sometimes also chamosite. Some layers contain also the chamositic and chamosite-sideritic ooids and fine bioclasts. Selected samples of the clayey siderites were isotopically analyzed in the Institute of Physics of UMCS in Lublin. It appears that δ18O values fall into the interval from -2.66 to 0.58‰ PDB. It was calculated, adopting a water temperature in the Middle Jurassic basin Central Poland between 18 and 24°C (Coleman et al. 1997), that the siderites crystallized mainly from the marine mixed with meteoric water of δ18O in the limits between -7 and -1‰ SMOW. The δ13C values oscillate between +11.78 and +5.67‰ PDB. That points to the origin of the carbon present in the crystallization waters from the organic matter altered in the zone of microbiological metanogenesis (Mc Kay et al. 1995). The abundance of pyrite is an evidence for strong reduction conditions of sedimentation and diagenesis of the siderite formation. Sulphide minerals and micas accumulated in the Aalenian and Bajocian dark bottom muds, further altered in the marine waters, were the most probable iron source. Layers of siderite coquinas also occur in the deposits under description. They contain numerous bioclasts built of calcite or ankerite, sideritic, sideroplesitic and ankeritic spars, less frequently - euhedral pistomesite crystals and pyrite. The chamosite, kaolinite, phosphates and detrital quartz are subordinate. According to present knowledge, the formation of the coquinas resulted from the intraformational alteration of the deposits connected with the Middle Jurassic salt tectonics and mobilization of the Zechstein saline waters rich in ions of metals. The results of chemical analyses of zonal siderites and sideroplesites point to the progressive increase of magnesium content in the pore solutions in the Jurassic deposits.

Słowa kluczowe

EN

siderite rocks; petrological studies; Middle Jurassic sediments; Poland

• Wydawca: Państwowy Instytut Geologiczny - Państwowy Instytut Badawczy
• Czasopismo: Volumina Jurassica
• Rocznik: 2006
• Tom: Vol. 4, no. 1
• Strony: 95--96
• Opis fizyczny: Bibliogr. 2 poz.

Twórcy

autor

Maliszewska A.

autor

Kozłowska A.

autor

Kuberska M.

• Polish Geological Institute, ul. Rakowiecka 4, PL-00975 Warszawa, Poland,

Bibliografia

• Coleman M. L., Feldman-Olszewska A., Gaździcka E. and Gruszczyński M. 1997. Sekwencje depozycyjne a zapis izotopowo-geochemiczny wybranych odcinków czasowych jury Środkowej i górnej w centralnej części Niżu Polskiego. Materiały konferencyjne, VI Krajowe Spotkanie Sedymentologów, Lewin Kłodzki, 4-6.
• Mc Kay J. L., Longstaffe F. J. and Plint A. G. 1995. Early diagenesis and its relationship to depositional environment and relative sea - level fluctuations (Upper Cretaceous) Marshybank Formation, Alberta and British Columbia. Sedimentology, 42, 1: 161-190.