Print this pageAAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Stratigraphy, Sedimentology and Heterogeneity of Carbonates Facies and Its Relation with Global and Local Sea Level Fluctuations in a Miocene to Pleistocene Carbonate Platform in the Caribbean, Isla de Mona, Puerto Rico
(1) Geology, The University of Kansas, Lawrence, KS.
(2) Geology, The University of Puerto Rico, Mayaguez.
Isla de Mona carbonate platform located at the south central part of the Mona Passage is one of the best-exposed Miocene-Pleistocene reef complexes in the Caribbean. Eustatic and Caribbean tectonic changes during the Miocene-Pleistocene make this platform one of the best places to study the effect of relative sea level fluctuations in the development of reef systems. The objective is to study facies, facies transition and depositional sequences to obtain a better understand of the origin of Isla de Mona rocks and the processes under which they was formed. Twelve stratigraphic sections (35-10m length) and 10 transects on the plateau surface were measured and sampled.
Platform was subdivided in 4 depositional stages: early Miocene heterozoan; middle-late Miocene barrier reef complex with episodes of subaerial exposure and dolomitization; Pliocene patch reefs, controlled by accommodation space after platform faulting; and Pleistocene fringing reef after relative sea level fall of >35m.
Facies described in the platform: off reef, rich planktonic wackestone; fore reef, mudstone-wackestones with rhodolites, Scolymia sp. and Isophyllia sp.; reef core, branching to finger corals i.e. Caulastrea portoricensis and Stylophora granulata suspended in a skeletal packstone to grainstone with red algae, bivalves and gastropods; reef groves, rudstone with imbricate Caulastra portoricensis fragments; back reef, packstone-wackestone with red algae, gastropods, bivalves, benthic foraminifera and equinoid spines; lagoonal facies, red algae foraminifera packstone-grainstone with rhodolites; patch reef, diverse corals i.e. Porites sp., Montrastrea sp. and Diploria sp. suspended in a skeletal grainstone; fringing reef, consists of diverse corals i.e. Montrastrea sp., Stiliphora sp. and Colpophyllia sp.
Distribution and transitions of carbonate facies makes a control in the depositional porosity and post-depositional diagenetic porosity. Heterogeneity in the platform was controlled by reef production and physical controls in the accommodation space. Relative sea level plays an important roll on the stabilization, diversification and extinction of corals reef and in dissolution, precipitation and dolomitization of carbonate units. This data provide valuable clues to our understanding of facies and porosity evolution of other surface and subsurface Miocene-Pleistocene carbonate platforms.