Dolomitization of a Miocene-Pliocene progradational carbonate platform by mesohaline brines: Re-examination of the reflux model on Bonaire Island

Neogene dolomites are common in island settings, and they have been used to understand the complex processes of dolomitization. The Bonaire was one first locations where concept reflux dolomitization applied. Given this historical significance, here we re-evaluate importance nature using a previously unstudied set outcrops Bonaire. Mio-Pliocene units Seru Grandi northwestern show well-defined bodies dolomite that extend along clinoform surfaces beneath subhorizontal erosional unconformity. distribution suggests early as result fluids moving downwards through succession subtidal facies, expected from model. However, non-stoichiometric compositions, weak 18O enrichment, low trace element concentrations sedimentological context suggest refluxing fluid more likely be mesohaline composition rather than hypersaline proposed. In addition, our findings did not dolomitize uniformly, but elongate were developed within selected clinoforms different events. This variability may due temporal changes flux, chemistry reactive textural original sediment, whereas downdip trends reflect evolution magnesium exchange efficiency with distance brine source reactivity rock.