The geology of the

Dominican Republic The Dominican Republic ( ; es, República Dominicana, ) is a country located on the island of Hispaniola in the Greater Antilles archipelago of the Caribbean region. It occupies the eastern five-eighths of the island, which it shares with ...

is part of the broader geology of Hispaniola with rocks formed from multiple island arcs, colliding with North America.

Geologic History, Stratigraphy & Tectonics

The oldest rocks on the island formed beginning in the early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

through island arc plutonism. Before the Aptian, the island was uplifted, particularly in the east, likely due to the collision of a volcanic island arc. In total, Hispaniola is formed from 11 distinct small island arcs. From the

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/ Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0 ...

to the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campani ...

, plutonism, metamorphism and volcanism began simultaneously, taking place underwater on the largely submerged landmass. In the Campanian a second arc collision took place.

Picrite Picrite basalt or picrobasalt is a variety of high-magnesium olivine basalt that is very rich in the mineral olivine. It is dark with yellow-green olivine phenocrysts (20-50%) and black to dark brown pyroxene, mostly augite. The olivine-rich p ...

from the Duarte Complex in central Hispaniola has been inferred as Galapagos hotspot-type island plateau rocks. The Cordillera Central in the middle of the island has obducted peridotite from the mid-Cretaceous on top of a

mylonite Mylonite is a fine-grained, compact metamorphic rock produced by dynamic recrystallization of the constituent minerals resulting in a reduction of the grain size of the rock. Mylonites can have many different mineralogical compositions; it is a ...

and phyllonite

schist Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes ...

shear zone in the Maimon Formation. Deformation appears in rocks north, as far as the volcanic and sedimentary Los Ranchos Formation. They are unconformably overlain by

- Cenomanian limestones.

Cenozoic (66 million years ago-present)

Into the Paleogene at the start of the Cenozoic, volcanism, metamorphism and plutonism continued underwater until the

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

, still largely below water. However, by the middle Eocene, the amalgamated island arcs collided with the southern margin of the North American Plate at the Florida-Bahama Platform, leading to the formation of extensive carbonates and the end of volcanism and plutonism. The island arc rocks became exposed above the water line and began to erode as an east-west strike-slip fault emerged. From the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

to recent times, oblique strike-slip faults formed along the sutures between old island arcs as the island compressed against North America and oceanic plateau terranes. Nine large fault bounded mountain ranges formed. Within the Dominican Republic, the central Cordillera Septentrional spans the strike-slip fault boundary between the North American and Caribbean plates. Faults and folds from the

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pal ...

to the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

pelagic carbonates. Transpression in the Miocene-Pliocene created an

anticline In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the ...

in shallow marine carbonates.

Natural resource geology

The large Pueblo Viejo oxide gold deposit formed due to gold, quartz and pyrophyllite weathering in a small basin within the Los Ranchos Formation. At its basin, the formation has conglomerate, ascending to sandstone and carbonaceous sandstone with plant fossils indicating proximity to land. Veins filled with metal due to hydrothermal emplacement.

References

{{Dominican Republic topics

Geologic History, Stratigraphy & Tectonics

Cenozoic (66 million years ago-present)

Natural resource geology

See also

References