Carbon and oxygen isotopic survey of diagenetic carbonate deposits in the Agardhfjellet Formation (Upper Jurassic), Spitsbergen: preliminary results
ABSTRACT: Diagenetic carbonate deposits (concretions, cementation bodies and cement− stone bands) commonly occur in organic carbon−rich sequence of the Agardhfjellet Forma− tion (Upper Jurassic) in Spitsbergen. They are dominated by dolomite/ankerite and siderite. These deposits originated as a resu...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.513.8109 http://www.polish.polar.pan.pl/ppr25/ppr25-027.pdf |
| Summary: | ABSTRACT: Diagenetic carbonate deposits (concretions, cementation bodies and cement− stone bands) commonly occur in organic carbon−rich sequence of the Agardhfjellet Forma− tion (Upper Jurassic) in Spitsbergen. They are dominated by dolomite/ankerite and siderite. These deposits originated as a result of displacive cementation of host sediment in a range of post−depositional environments, from shallow subsurface to deep−burial ones. Prelimi− nary results of the carbon and oxygen isotopic survey of these deposits in southern Spitsbergen (Lågkollane, Ingebrigtsenbukta, Reinodden, and Lidfjellet sections) show the 13C values ranging between –13.0 ‰ and –1.8 ‰ VPDB, and the 18O values between –16.0 ‰ and –7.7 ‰ VPDB. These results suggest that the major stage of formation of the carbonate deposits occurred during burial diagenesis under increased temperature, most probably in late diagenetic to early catagenic environments. Carbonate carbon for mineral precipitation was derived from dissolution of skeletal carbonate and from thermal decom− position of organic matter. Key words: Arctic, Spitsbergen, Agardhfjellet Formation (Jurassic), diagenetic carbon− ate deposits, carbon and oxygen isotopes. |
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