Gonâve Microplate
Encyclopedia
The Gonâve Microplate forms part of the boundary between the North American Plate
and the Caribbean Plate
. It is bounded to the west by the Cayman
spreading center, to the north by the Septentrional-Oriente fault zone
and to the south by the Walton fault zone and the Enriquillo-Plantain Garden fault zone
. The existence of this microplate was first proposed in 1991. This has been confirmed by GPS measurements, which show that the overall displacement between the two main plates is split almost equally between the transform fault
zones that bound the Gonâve microplate. The microplate is expected to eventually become accreted
to the North American Plate.
of the Cayman Trough but including island arc
material at its eastern end on the western part of Hispaniola
. Further east a separate Hispaniola microplate has been identified. At its western end, the Gonâve Microplate is bounded by the mid-Cayman spreading centre. To the north it is bounded by the Septentrional-Oriente fault zone and to the south by a more complex strike-slip fault system that includes the Walton fault and the Enriquillo-Plantain Garden fault zone. As the northern and southern boundaries approach the eastern edge of the Caribbean Plate they become less distinct and the eastern boundary is not as well defined.
within the Cayman Trough suggests that displacement is increasingly being transferred from the northern fault system to the southern one. This observation is consistent with the eventual accretion of the Gonâve Microplate to the North American Plate.
) collided with the Bahamas platform
. This part of the plate was unable to move further to the east and a transform fault system developed to the south, effectively cutting off this northern area and accreting it to the North American Plate. A large left-stepping offset formed along this zone just east of the Yucatan peninsula creating a pull apart basin
, which continued to extend until the onset of seafloor spreading, creating the Cayman spreading centre. Further movement on this fault system created the Cayman Trough, although at that time the future microplate was still firmly attached to the Caribbean Plate. During the Late Miocene
, the part of the Caribbean Plate formed by Hispaniola
began to collide with the Bahamas platform and a new strike-slip fault system developed through Jamaica and southern Hispaniola, the Enriquillo-Plantain Garden fault zone, isolating part of the Cayman Trough and the central part of Hispaniola to form the Gonâve microplate. It has been suggested that the Gonave microplate will also become accreted to the North American Plate, as all the plate boundary displacement transfers onto the southern fault system.
North American Plate
The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, Bahamas, and parts of Siberia, Japan and Iceland. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust...
and the Caribbean Plate
Caribbean Plate
The Caribbean Plate is a mostly oceanic tectonic plate underlying Central America and the Caribbean Sea off the north coast of South America....
. It is bounded to the west by the Cayman
Cayman Trough
The Cayman Trough, is a complex transform fault zone pull apart basin which contains a small spreading ridge on the floor of the western Caribbean Sea between Jamaica and the Cayman Islands...
spreading center, to the north by the Septentrional-Oriente fault zone
Septentrional-Oriente fault zone
The Septentrional-Orient fault zone is a system of coaxial left lateral-moving strike slip faults which runs along the northern side of the island of Hispaniola where the Dominican Republic and Haiti are located...
and to the south by the Walton fault zone and the Enriquillo-Plantain Garden fault zone
Enriquillo-Plantain Garden fault zone
The Enriquillo–Plantain Garden fault zone is a system of coaxial left lateral-moving strike slip faults which runs along the southern side of the island of Hispaniola, where the Dominican Republic and Haiti are located...
. The existence of this microplate was first proposed in 1991. This has been confirmed by GPS measurements, which show that the overall displacement between the two main plates is split almost equally between the transform fault
Transform fault
A transform fault or transform boundary, also known as conservative plate boundary since these faults neither create nor destroy lithosphere, is a type of fault whose relative motion is predominantly horizontal in either sinistral or dextral direction. Furthermore, transform faults end abruptly...
zones that bound the Gonâve microplate. The microplate is expected to eventually become accreted
Accretion (geology)
Accretion is a process by which material is added to a tectonic plate or a landmass. This material may be sediment, volcanic arcs, seamounts or other igneous features.-Description:...
to the North American Plate.
Geographic extent
The Gonâve Microplate is an approximately 1,100 km long strip, consisting mainly of oceanic crustOceanic crust
Oceanic crust is the part of Earth's lithosphere that surfaces in the ocean basins. Oceanic crust is primarily composed of mafic rocks, or sima, which is rich in iron and magnesium...
of the Cayman Trough but including island arc
Island arc
An island arc is a type of archipelago composed of a chain of volcanoes which alignment is arc-shaped, and which are situated parallel and close to a boundary between two converging tectonic plates....
material at its eastern end on the western part of Hispaniola
Hispaniola
Hispaniola is a major island in the Caribbean, containing the two sovereign states of the Dominican Republic and Haiti. The island is located between the islands of Cuba to the west and Puerto Rico to the east, within the hurricane belt...
. Further east a separate Hispaniola microplate has been identified. At its western end, the Gonâve Microplate is bounded by the mid-Cayman spreading centre. To the north it is bounded by the Septentrional-Oriente fault zone and to the south by a more complex strike-slip fault system that includes the Walton fault and the Enriquillo-Plantain Garden fault zone. As the northern and southern boundaries approach the eastern edge of the Caribbean Plate they become less distinct and the eastern boundary is not as well defined.
Evidence for existence
The presence of a separate Gonâve Microplate was first suggested by the analysis of sidescan sonar results from the Cayman Trough. This study found evidence for continuous transform type faults along the southern flank of the trough, to both sides of the spreading centre. GPS data supports the existence of the microplate by showing that the relative motion between the North American and Caribbean plates is split almost equally between the two bounding transform fault systems. Comparison of these rates with observations of magnetic stripesMagnetic anomaly
In geophysics, a magnetic anomaly is a local variation in the Earth's magnetic field resulting from variations in the chemistry or magnetism of the rocks. Mapping of variation over an area is valuable in detecting structures obscured by overlying material...
within the Cayman Trough suggests that displacement is increasingly being transferred from the northern fault system to the southern one. This observation is consistent with the eventual accretion of the Gonâve Microplate to the North American Plate.
History
The Gonâve Microplate began to form in the Early Eocene after the northern part of the leading edge of the Caribbean Plate (present day CubaCuba
The Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...
) collided with the Bahamas platform
Bahama Banks
The Bahama Banks are the submerged carbonate platforms that make up much of the Bahama Archipelago. The term is usually applied in referring to either the Great Bahama Bank around Andros Island, or the Little Bahama Bank of Grand Bahama Island and Great Abaco, which are the largest of the...
. This part of the plate was unable to move further to the east and a transform fault system developed to the south, effectively cutting off this northern area and accreting it to the North American Plate. A large left-stepping offset formed along this zone just east of the Yucatan peninsula creating a pull apart basin
Pull Apart Basin
250px|thumb|[[Cami Lake]] in [[Tierra del Fuego]] develops on a [[Patagonian Ice Sheet|glacially]] excavated pull apart basin along the [[Magallanes-Fagnano Fault]], hence its elongated form...
, which continued to extend until the onset of seafloor spreading, creating the Cayman spreading centre. Further movement on this fault system created the Cayman Trough, although at that time the future microplate was still firmly attached to the Caribbean Plate. During the Late Miocene
Late Miocene
The Late Miocene is a sub-epoch of the Miocene Epoch made up of two stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch....
, the part of the Caribbean Plate formed by Hispaniola
Hispaniola
Hispaniola is a major island in the Caribbean, containing the two sovereign states of the Dominican Republic and Haiti. The island is located between the islands of Cuba to the west and Puerto Rico to the east, within the hurricane belt...
began to collide with the Bahamas platform and a new strike-slip fault system developed through Jamaica and southern Hispaniola, the Enriquillo-Plantain Garden fault zone, isolating part of the Cayman Trough and the central part of Hispaniola to form the Gonâve microplate. It has been suggested that the Gonave microplate will also become accreted to the North American Plate, as all the plate boundary displacement transfers onto the southern fault system.