PETROGENESIS OF VOLCANICLASTIC CARBONATE ROCKS FROM THE SEROE DOMI FORMATION, CURACAO

Several sections of the Mio-Pliocene Seroe Domi Formation on Curacao contain abundant volcanic fragments from weathering and erosion of the underlying Curacao Lava Formation. Many of the slopes of the Seroe Domi Formation are interpreted as reef front and fore-reef slopes deposited by sediment gravity flows. These rocks were deposited as grainstones containing fragments of corals, red algae, foraminifera, echinoids, mollusks, and volcanic rock fragments. The most abundant volcanic clasts are found at the base of these outcrops. These volcanic clasts have been altered to clay. SEM and TEM analyses found microbial communities in association with this clay material.

Portions of the Seroe Domi Formation have been partially to pervasively dolomitized by mixing zone dolomitization. In addition to this older generation of dolomite, TEM identified dolomite (likely protodolomite) crystals nucleating within and around the biofilms of microbial communities associated with clay material. EDS analyses reveal subequal Mg and Ca concentrations in these rhombohedral precipitates. TEM combined with EDS reveal the spatial relationships among the clay-sized material, microbial biofilms, and carbonate precipitates. TEM micrographs show microbial dumbbell structures which suggests a mechanism similar to other early dolomite precipitate studies.