Isotopic composition of siderite as an indicator of depositional environment

Compilation of available oxygen and carbon isotopic data for siderites from different depositional environments indicates that marine and continental siderites are characterized by distinctive compositional fields. The most notable difference between the fields is the generally higher Delta (super 13) C values of continental vs. marine siderites. This difference appears to reflect the fact that marine sediments generally undergo a more extensive period of sulfate reduction than do the continental sediments in which siderite forms. Analysis of siderite geochemistry may assist in determination of depositional environment in cases where the available sedimentological evidence is ambiguous.