Geologic map and databases of the Greater Antilles and Virgin Islands

As part of a U.S. Geological Survey (USGS) mineral-environmental assessment, a new digital geologic map and database for the Greater Antilles has been compiled from previously published mapping. At 1:250,000-scale, Hispaniola and Jamaica were sourced from (a) the Dominican Republic Ministry of Industry and Commerce, Department of Mining, (b) the Haitian Ministry of Mines and Energy Resources, and (c) the Jamaican Ministry of Mining and Natural Resources, Mines and Geology Division. Cuba, at 1:100,000-scale, was provided by the Cuban Ministry of Energy and Mines. Puerto Rico was available in a series of 64 USGS 1:20,000-scale geologic maps. Maps for the U.S. and British Virgin Islands were at scales between 1:24,000 and approximately 1:60,000.

Data for each island were digitized and integrated into a common database schema to facilitate correlation of map units from island to island and provide a uniform view of the geology. Each source map unit was assigned to a unit for the compilation based on its lithology, setting, and age. This unit then links to additional related tables that define the unit’s maximum and minimum age, geologic setting, a set of hierarchically defined lithologies, and the original source maps unit descriptions. We also defined a series of tectonostratigraphic terranes for the region. These terranes display unique lithologic assemblages, geologic histories, and commonly, distinct mineral deposit types. We obtained new U/Pb dates and compiled a region-wide database of nearly 1,100 radiometric ages.

Multiple distinct geologic features are present in the region. Cuba has the only unquestioned Jurassic, and perhaps older, rocks whereas on Hispaniola and Puerto Rico, Cretaceous metamorphic assemblages may contain Jurassic rocks. Cretaceous granitic rocks are present in Cuba, Hispaniola, and Puerto Rico as are gabbro and trondhjemite of inferred Early Cretaceous age in the U.S. Virgin Islands. Cretaceous volcanic rocks are widespread in the region; they are of variable ages and significantly, do not reflect a single magmatic arc system. Early Cretaceous keratophyre and spilite in the Virgin Islands and northeast Puerto Rico are distinctive.  Eocene volcano-plutonic complexes are prominent in southernmost Cuba, Puerto Rico, and the Virgin Islands and sparsely present in Haiti and eastern Jamaica. Volcanic rocks possibly as young as Miocene are present in southern Hispaniola; the youngest volcanic rocks in the region are the late Miocene or Pliocene Low Layton Lavas of Jamaica and Quaternary alkali basalt on Hispaniola.

Carbonate rocks are widespread in the Greater Antilles and are as old as Jurassic in Cuba and as young as Holocene in many areas. In Cuba, Early Cretaceous sedimentary rocks tend to be dominantly carbonates; volcanic clasts and debris are uncommon until Late Cretaceous. In contrast, Lower Cretaceous volcaniclastic sedimentary rocks are common in the Virgin Islands and Puerto Rico. Olistostromes are frequently described in uppermost Cretaceous and Eocene rocks; the Eocene deposits are commonly associated with mélange units. Sedimentary rocks that postdate the Eocene are dominantly carbonates or mixed clastic and carbonate rocks in which the clastic component reflects erosion of earlier volcanic units, as well as older carbonate rocks.