Magnesium and strontium stable isotopes in hypersaline microbial mats
Abstract
The mineral dolomite ((Ca,Mg)CO3) occurs abundantly in the geological record, yet its formation in modern environments is restricted to extreme, hypersaline environments. One possible explanation for this apparent contradiction is that the predominant mode of dolomite formation is the replacement of Ca-carbonate minerals during burial diagenesis (Ryb & Eiler, 2018). However, another, possibly important factor contributing to high dolomite abundances in the geological past is the existence of sedimentary environments favorable for microbially-mediated dolomite formation. We explore the possibility of distinguishing these modes of dolomite formation using magnesium and strontium stable isotopes in modern sabkah sediment from Qatar and experimentally precipitated dolomite. The distinction of secondary and primary dolomite formation in the sedimentary archive will allow constraining conditions in sedimentary environments in the geological past.
Ryb, U., & Eiler, J. M. (2018). Oxygen isotope composition of the Phanerozoic ocean and a possible solution to the dolomite problem. Proceedings of the National Academy of Sciences, 115(26), 6602-6607- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMPP41C1556T
- Keywords:
-
- 1039 Alteration and weathering processes;
- GEOCHEMISTRY;
- 1051 Sedimentary geochemistry;
- GEOCHEMISTRY;
- 4217 Coastal processes;
- OCEANOGRAPHY: GENERAL;
- 4912 Biogeochemical cycles;
- processes;
- and modeling;
- PALEOCEANOGRAPHY