Back to search
Immenhauser et al., 2003

An alternative model for positive shifts in shallow-marine carbonate δ<sup>13</sup>C and δ<sup>18</sup>O

Immenhauser, A., Della Porta, G., Kenter, J. A. M., Bahamonde, J. R.
Typearticle in journal


Positive shifts in global seawater δ13CDIC are related to changes in the ratio of organic relative to inorganic carbon burial in oceanic basins, whereas factors such as climatic cooling and the accumulation of polar ice are known to cause positive shifts in δ18O. Here, an alternative model is proposed for the formation of local positive isotope shifts in shallow-marine settings. The model involves geochemically altered platform-top water masses and the effects of early meteoric diagenesis on carbonate isotopic composition. Both mechanisms are active on modern (sub)tropical carbonate platforms and result in low carbonate δ13C and δ18O relative to typical oceanic values. During high-amplitude transgressive events, the impact of isotopically light meteoric fluids on the carbonate geochemistry is much reduced, and 13C-depleted platform-top water mixes with open oceanic water masses having higher isotope values. Both factors are recorded as a transient increase in carbonate 13C and 18O relative to low background values. These processes must be taken into consideration when interpreting the geochemical record of ancient epeiric seas.

Last change: 15.4.2023
KIKNATARCSARVTÜ Loodusmuuseumi geokogudEesti Loodusmuuseumi geoloogia osakond
All materials in the portal are for free usage according to CC BY-SA , unless indiated otherwise.
Portal is part of natianal research infrastructure and geoscience data platform SARV, hosted by TalTech.
Open Book icon by Icons8.