Geometries and Origin of Young Dolomite in an Isolated Carbonate Platform, Bonaire, Southern Caribbean

Abstract

Previous work on Bonaire, Netherlands Antilles, has described dolomites within limited outcrops of the Mio-Pliocene Seroe Domi Fm. These are interpreted to have formed from reflux of hypersaline brines and parallels drawn with the reflux of hypersaline brines in lagoons in the south of Bonaire which formed of very young dolomites (<2.2ky). The Seroe Domi Fm is onlapped by a spectacular series of down-stepping Pleistocene terraces comprising reef and shallow-marine carbonates. Comparable terraces on nearby Curacao have been studied to elucidate Pleistocene sea-level history and compared to those in Barbados to unpick eustatic from local tectonic controls. However, this is the first study to recognised the presence of significant volumes of dolomite within the Pleistocene terraces of Bonaire. From photogrammetry acquired using a drone and traditional field mapping a three-dimensional digital outcrop model has been produced which reveals depositional geometries and facies distributions. The distribution of diagenesis under the seasonally arid climate has also been documented. At outcrop scale meteoric diagenesis is represented by highly karstified horizons and dissolution surfaces. In addition, we identify previously unrecognized bodies of sucrosic dolomite within terrace II (MIS 7 or 9) which have formed within the last 500 ky. The distribution of dolomites from Miocene to latest Pleistocene suggests multiple episodes of probable reflux dolomitization during the evolution of the platform and offers a unique opportunity to understand controls on the evolution of dolomite fabrics and porosity prior to burial.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016