Although geochemical evidence suggests that dolomitization is most possibly through dissolution-reprecipitation at low temperatures and solid-diffusion is suggested to be too slow to be the way for dolomitization in many settings, I wonder if there is any petrological observation that can explicitly reflect dolomitization through dissolution-reprecipitation? Solid diffusion can be really excluded?
Favourable conditions for early diagenetic dolomitisation
- shallowwarm water(0 to 45 m)
- abundancein carbon dioxide causing partial solution of limestones and interchange
withMg saltsin sea-water
- porosity of limestones allowing the percolation of sea-water
- sufficiently low subsidenceand elevation to render complete the change from Ca
carbonate to dolomite
Favourable conditions for late diagenetic dolomitisation
- uplift and emergence of rocks in faulted and folded regions
- shearing stress favours late stage diagenetic
- porosity of limestones allowing the percolation of brines
It is mainly in the second type where the texture favors a replacement of calcite or aragonite. In the first type it is the pristine Ca/Mg ration of the marine or lacustrine brines that counts.
HGD
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