The Structure of the Cretaceous Volcanic Arc of Cuba Exemplified in Subsurface Studies of the Pina Area

R. Segura-Soto

In the Pina area of Central Cuba there have been drilled more than 30 deep wells that have reached 2200 meters in depth. The Cretaceous volcanic arc was drilled not completely through, and it could be determined that the two following complexes were encountered. They are sequenced from the bottom to the top.

The Lower, more than 1000 meters in thickness, found only in the deepest wells, represented by an effusive cycle of andesitic basaltic composition, with textures and mineralogical differentiation typical of calcalkaline complexes of island arcs. Fine intercalcations of lithic and crystalline tuffs of the proper composition were observed. The top of the cycle is limited by pelagic limestone lenses of Upper Albian-Cenemanian age. The complex is strongly fractured, with calcite, quartz and zeolites.

The Upper, around 300 meters in thickness, is represented by a vulcanoclastic or explosive cycle composed of sequences of lithic, crystalline and vitric tuffs with impurities of claystones, limestone and sandstones which accumulate conspicuously to the top of the complex. The fossils, poorly preserved, indicate Turonian-Campanian age. All data indicate an intense explosive subaqueous activity. Effusive rocks are not detached. The tuffs are strongly fractured and altered to clay minerals. From Maastrichtian to Recent are found the normal coverture rocks of the volcanic arcs.

The detailed study of the Pina area can be compared to the rest of Cretaceous volcanic arc deposits of Cuba and other sites in the Caribbean Region.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995