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Paul Mann - One of the best experts on this subject based on the ideXlab platform.
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western Caribbean intraPlate deformation defining a continuous and active microPlate boundary along the san andres rift and hess escarpment fault zone colombian Caribbean sea
AAPG Bulletin, 2018Co-Authors: Luis Carlos Carvajalarenas, Paul MannAbstract:The San Andres rift (SAR), located on the lower Nicaraguan Rise, is a previously poorly studied, active, 015°-trending, bathymetric, and structural rift basin that is 11–27 km (7–17 mi) wide and extends for 346 km (215 mi) across the western flank of the Caribbean Plate. In this study, we integrate bathymetric maps, potential field data, and high-resolution, two-dimensional (2-D) seismic lines to understand the crustal structure, tectonic history, and tectonic origin of the SAR, which is one of the active areas within the otherwise stable Caribbean Plate. We compiled regional gravity and magnetic data that revealed a negative gravity anomaly and positive magnetic anomaly that we interpret as a result of crustal thinning and an elevated Moho along the main rift axis of the SAR. Forward models of gravity data show four possible interpretations for the origin of the crust underlying and surrounding the SAR. Interpretations of 2-D seismic reflection data show structural features within the upper crust and sedimentary sections typical of other active rift systems including a SAR-parallel, north–south alignment of earthquakes with the larger events showing normal and strike-slip focal mechanisms. Sequential kinematic restorations based on 2-D seismic profiles reveal three major phases of SAR opening: (1) the initial early Eocene rifting stage; (2) middle Eocene extension; and (3) a rapid middle Miocene to early Pliocene extension accompanied by emergence of the San Andres Island as a rift shoulder. We propose slab rollback and intraPlate extension as main tectonic mechanisms to explain all rift phases and Neogene volcanism found in the western Caribbean region.
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regional provenance study of eocene clastic sedimentary rocks within the south america Caribbean Plate boundary zone using detrital zircon geochronology
Earth and Planetary Science Letters, 2010Co-Authors: Paul Mann, Xiangyang Xie, Alejandro EscalonaAbstract:Abstract Previous on- and offshore studies have postulated that the Caribbean Plate has translated hundreds of kilometers eastward during the Cenozoic along strike-slip and oblique thrust faults bounding the northern margin of the continental South America Plate. Two previously proposed tectonic-sedimentary models to explain the complex linkages between Plate motions and sedimentation within the broad Plate boundary zone include: 1) eastward bulldozing by the Caribbean Plate of a single, large point source, thick Eocene proto-Maracaibo deltaic system of northwestern South America, over 1000 km to the east and incorporation of these continentally derived sediments into the ∼ 12-km-thick Barbados accretionary prism along the leading edge of the Caribbean Plate; and 2) eastward bulldozing by less than 300 km of smaller point and line sources of Eocene and younger clastic sediments derived from erosion of the Guyana shield located in north-central and northeastern South America. We test both models by sampling eight Eocene localities that span a 1200-km-length of the Plate boundary zone from the proto-Maracaibo delta in western Venezuela to Barbados Island in the subaerial part of the large accretionary prism bounding the eastern margin of the Caribbean Plate. Ages of 972 single grains from samples at these eight localities support the multiple-source model, in which the Barbados prism was partly constructed from the bulldozing and incorporation of smaller point and line sources derived from older-than 1500 Ma crustal provinces of the Precambrian Guyana shield in central and northeastern South America. Eocene clastic sediments of the proto-Maracaibo delta derived from Paleozoic and Precambrian crustal provinces in northwestern South America are distinct in their ranges of detrital zircon ages from the ranges of the Guyana shield sources to the east.
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evolution of the southern Caribbean Plate boundary
Eos Transactions American Geophysical Union, 2006Co-Authors: A Levander, Hans Ave G Lallemant, Paul Mann, M B Magnani, C A Zelt, Michael Schmitz, Dale S Sawyer, G L Christeson, James E Wright, Gary L PavlisAbstract:It is generally accepted that the cores of the continents, called cratons, formed by the accretion of island arcs into proto-continents and then by proto-continental agglomeration to form the large continental masses. Mantle-wedge processes, combined with higher melting temperatures during the Archean (2.5–3.8 billion years ago) and possibly thrust stacking of highly depleted Archean oceanic lithosphere, produced a strong, buoyant, upper mantle chemical boundary layer. This stabilizing mantle layer, known as the tectosphere, has shielded the Archean cratons from most subsequent tectonic disruption and is highly depleted in iron, providing the positive buoyancy that is required to ‘float’ the continents more than four kilometers above the surrounding ocean basins.
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slip rate and earthquake recurrence along the central septentrional fault north american Caribbean Plate boundary dominican republic
Journal of Geophysical Research, 2003Co-Authors: Carol S Prentice, Paul Mann, Luis R Pena, G S BurrAbstract:[1] The Septentrional fault zone (SFZ) is the major North American-Caribbean, strike-slip, Plate boundary fault at the longitude of eastern Hispaniola. The SFZ traverses the densely populated Cibao Valley of the Dominican Republic, forming a prominent scarp in alluvium. Our studies at four sites along the central SFZ are aimed at quantifying the late Quaternary behavior of this structure to better understand the seismic hazard it represents for the northeastern Caribbean. Our investigations of excavations at sites near Rio Cenovi show that the most recent ground-rupturing earthquake along this fault in the north central Dominican Republic occurred between A.D. 1040 and A.D. 1230, and involved a minimum of ∼4 m of left-lateral slip and 2.3 m of normal dip slip at that site. Our studies of offset stream terraces at two locations, Rio Juan Lopez and Rio Licey, provide late Holocene slip rate estimates of 6–9 mm/yr and a maximum of 11–12 mm/yr, respectively, across the Septentrional fault. Combining these results gives a best estimate of 6–12 mm/yr for the slip rate across the SFZ. Three excavations, two near Tenares and one at the Rio Licey site, yielded evidence for the occurrence of earlier prehistoric earthquakes. Dates of strata associated with the penultimate event suggest that it occurred post-A.D. 30, giving a recurrence interval of 800–1200 years. These studies indicate that the SFZ has likely accumulated elastic strain sufficient to generate a major earthquake during the more than 800 years since it last slipped and should be considered likely to produce a destructive future earthquake.
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neotectonics of puerto rico and the virgin islands northeastern Caribbean from gps geodesy
Tectonics, 2000Co-Authors: P E Jansma, Timothy H Dixon, G S Mattioli, Paul Mann, C Demets, Alberto Lopez, Eric CalaisAbstract:The boundary between the North American and Caribbean Plates is characterized primarily by left-lateral motion along predominantly east-west striking faults. Seismicity and marine geophysical survey data are consistent with at least two, and possibly three, microPlates in the diffuse boundary zone in the northeastern Caribbean: (1) the Gonave, (2) the Hispaniola, and (3) the Puerto Rico-northern Virgin Islands (PRVI). We discuss results from GPS geodetic measurements acquired since 1994 to test the microPlate hypothesis, define PRVI translation and rotation within the boundary zone, and constrain PRVI neotectonics. GPS-derived velocities are analyzed with respect to both North American and Caribbean Plate reference frames. Integrated displacements across PRVI are limited to a few millimeters per year, consistent with a rigid PRVI and permitting calculation of an average velocity for PRVI. The motions of PRVI relative to North America and the Caribbean are 16.9±1.1 mm/yr toward N68°E±3° (1σ) and 2.4±1.4 mm/yr toward S79°W±26° (1σ), respectively. In contrast with some recent models, ongoing rotation of PRVI about a nearby (< 25° distant) vertical axis is not supported by the geodetic data. In addition, we argue against eastward tectonic escape of PRVI and favor a simple, progressive increase in velocity across the Plate boundary zone, requiring that the summed magnitude of strike-slip fault slip rates will equal the total Plate motion rate between the Caribbean and North America. GPS data are consistent with components of left-lateral strike-slip faulting along the Muertos trough south of Puerto Rico and shortening across the Puerto Rico trench. Comparison of GPS velocities for PRVI with respect to North America with total North America-Caribbean relative motion suggests up to 85% of North American-Caribbean Plate motion is accommodated by the Puerto Rico trench and offshore faults north of Puerto Rico. Differences in GPS-derived velocities from Hispaniola and PRVI yield east-west extension across the N-S trending Mona rift of a few millimeters per year when estimated elastic strain accumulation effects along the north Hispaniola deformed belt and the Septentrional fault zone are considered. The opening rate implies an age of the Mona rift of 2–3 million years, agreeing with marine geophysical data that support a young age for the structure.
O Perez - One of the best experts on this subject based on the ideXlab platform.
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velocity field across the southern Caribbean Plate boundary and estimates of Caribbean south american Plate motion using gps geodesy 1994 2000
Geophysical Research Letters, 2001Co-Authors: O Perez, Roger Bilham, Rebecca Bendick, Jose R Velandia, Napoleon Hernandez, Carlos Moncayo, Melvin Hoyer, Mike KozuchAbstract:Global Positioning System (GPS) observations between 1994 and 2000 at twenty-two sites in the Lesser Antilles and northern South-America indicate that the Caribbean Plate, along its southern boundary, slips at a rate of 20.5±2 mm/a with an azimuth of N 84°±2°E at 65°W, relative to the South-American Plate. East of 68° W, 80% of the dextral slip is contained within a 80-km wide shear zone centered on the El Pilar-San Sebastian fault system. West of 68° W the Plate boundary broadens to more than 300 km with dextral shear shared between the northeast trending Bocono fault (9–11 mm/a) in western Venezuelan, and an offshore system near the northern coast.
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velocity field across the southern Caribbean Plate boundary and estimates of Caribbean south american Plate motion using gps geodesy 1994 2000
Geophysical Research Letters, 2001Co-Authors: O Perez, Roger Bilham, Rebecca Bendick, Jose R Velandia, Napoleon Hernandez, Carlos Moncayo, Melvin Hoyer, Mike KozuchAbstract:Global Positioning System (GPS) observations between 1994 and 2000 at twenty-two sites in the Lesser Antilles and northern South-America indicate that the Caribbean Plate, along its southern boundary, slips at a rate of 20.5±2 mm/a with an azimuth of N 84°±2°E at 65°W, relative to the South-American Plate. East of 68° W, 80% of the dextral slip is contained within a 80-km wide shear zone centered on the El Pilar-San Sebastian fault system. West of 68° W the Plate boundary broadens to more than 300 km with dextral shear shared between the northeast trending Bocono fault (9–11 mm/a) in western Venezuelan, and an offshore system near the northern coast.
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gps estimate of relative motion between the Caribbean and south american Plates and geologic implications for trinidad and venezuela
Geology, 2001Co-Authors: John Weber, Timothy H Dixon, C Demets, William B Ambeh, Pamela E Jansma, G S Mattioli, J Saleh, Giovanni Sella, Roger Bilham, O PerezAbstract:Global Positioning System (GPS) data from eight sites on the Caribbean Plate and five sites on the South American Plate were inverted to derive an angular velocity vector describing present-day relative Plate motion. Both the Caribbean and South American velocity data fit rigid-Plate models to within ±1–2 mm/yr, the GPS velocity uncertainty. The Caribbean Plate moves approximately due east relative to South America at a rate of ∼20 mm/yr along most of the Plate boundary, significantly faster than the NUVEL-1A model prediction, but with similar azimuth. Pure wrenching is concentrated along the approximately east-striking, seismic, El Pilar fault in Venezuela. In contrast, transpression occurs along the 068°-trending Central Range (Warm Springs) fault in Trinidad, which is aseismic, possibly locked, and oblique to local Plate motion.
Timothy H Dixon - One of the best experts on this subject based on the ideXlab platform.
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gps estimate of relative motion between the Caribbean and south american Plates and geologic implications for trinidad and venezuela
Geology, 2001Co-Authors: John Weber, Timothy H Dixon, C Demets, William B Ambeh, Pamela E Jansma, G S Mattioli, J Saleh, Giovanni Sella, Roger Bilham, O PerezAbstract:Global Positioning System (GPS) data from eight sites on the Caribbean Plate and five sites on the South American Plate were inverted to derive an angular velocity vector describing present-day relative Plate motion. Both the Caribbean and South American velocity data fit rigid-Plate models to within ±1–2 mm/yr, the GPS velocity uncertainty. The Caribbean Plate moves approximately due east relative to South America at a rate of ∼20 mm/yr along most of the Plate boundary, significantly faster than the NUVEL-1A model prediction, but with similar azimuth. Pure wrenching is concentrated along the approximately east-striking, seismic, El Pilar fault in Venezuela. In contrast, transpression occurs along the 068°-trending Central Range (Warm Springs) fault in Trinidad, which is aseismic, possibly locked, and oblique to local Plate motion.
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neotectonics of puerto rico and the virgin islands northeastern Caribbean from gps geodesy
Tectonics, 2000Co-Authors: P E Jansma, Timothy H Dixon, G S Mattioli, Paul Mann, C Demets, Alberto Lopez, Eric CalaisAbstract:The boundary between the North American and Caribbean Plates is characterized primarily by left-lateral motion along predominantly east-west striking faults. Seismicity and marine geophysical survey data are consistent with at least two, and possibly three, microPlates in the diffuse boundary zone in the northeastern Caribbean: (1) the Gonave, (2) the Hispaniola, and (3) the Puerto Rico-northern Virgin Islands (PRVI). We discuss results from GPS geodetic measurements acquired since 1994 to test the microPlate hypothesis, define PRVI translation and rotation within the boundary zone, and constrain PRVI neotectonics. GPS-derived velocities are analyzed with respect to both North American and Caribbean Plate reference frames. Integrated displacements across PRVI are limited to a few millimeters per year, consistent with a rigid PRVI and permitting calculation of an average velocity for PRVI. The motions of PRVI relative to North America and the Caribbean are 16.9±1.1 mm/yr toward N68°E±3° (1σ) and 2.4±1.4 mm/yr toward S79°W±26° (1σ), respectively. In contrast with some recent models, ongoing rotation of PRVI about a nearby (< 25° distant) vertical axis is not supported by the geodetic data. In addition, we argue against eastward tectonic escape of PRVI and favor a simple, progressive increase in velocity across the Plate boundary zone, requiring that the summed magnitude of strike-slip fault slip rates will equal the total Plate motion rate between the Caribbean and North America. GPS data are consistent with components of left-lateral strike-slip faulting along the Muertos trough south of Puerto Rico and shortening across the Puerto Rico trench. Comparison of GPS velocities for PRVI with respect to North America with total North America-Caribbean relative motion suggests up to 85% of North American-Caribbean Plate motion is accommodated by the Puerto Rico trench and offshore faults north of Puerto Rico. Differences in GPS-derived velocities from Hispaniola and PRVI yield east-west extension across the N-S trending Mona rift of a few millimeters per year when estimated elastic strain accumulation effects along the north Hispaniola deformed belt and the Septentrional fault zone are considered. The opening rate implies an age of the Mona rift of 2–3 million years, agreeing with marine geophysical data that support a young age for the structure.
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GPS geodetic constraints on Caribbean-North America Plate motion
Geophysical Research Letters, 2000Co-Authors: C Demets, Timothy H Dixon, Pamela E Jansma, Roger Bilham, Glen S. Mattioli, Fred Farina, Eric Calais, Paul MannAbstract:We describe a model for Caribbean Plate motion based on GPS velocities of four sites in the Plate interior and two azimuths of the Swan Islands transform fault. The data are well fit by a single angular velocity, with average misfits approximately equal to the 1.5–3.0 mm yr−1 velocity uncertainties. The new model predicts Caribbean-North America motion ∼65% faster than predicted by NUVEL-1A, averaging 18–20±3 mm yr−1 (2σ) at various locations along the Plate boundary. The data are best fit by a rotation pole that predicts obliquely convergent motion along the Plate boundary east of Cuba, but are fit poorly by a suite of previously published models that predict strike-slip motion in this region. The data suggest an approximate upper bound of 4–6 mm yr−1 for internal deformation of the Caribbean Plate, although rigorous estimates await more precise and additional velocities from sites in the Plate interior.
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relative motion between the Caribbean and north american Plates and related boundary zone deformation from a decade of gps observations
Journal of Geophysical Research, 1998Co-Authors: Timothy H Dixon, Pamela E Jansma, Paul Mann, C Demets, Frederic Farina, E CalaisAbstract:Global Positioning System (GPS) measurements in 1986, 1994, and 1995 at sites in Dominican Republic, Puerto Rico, Cuba, and Grand Turk define the velocity of the Caribbean Plate relative to North America. The data show eastward motion of the Caribbean Plate at a rate of 21 ± 1 mm/yr (1 standard error ) in the vicinity of southern Dominican Republic, a factor of 2 higher than the NUVEL-1A Plate motion model prediction of 11 ± 3 mm/yr. Independent measurements on San Andres Island, and an Euler vector derived from these data, also suggest a rate that is much higher than the NUVEL-1A model. Available data, combined with simple elastic strain models, give the following slip rate estimates for major left-lateral faults in Hispaniola: (1) the North Hispaniola fault offshore the north coast of Hispaniola, 4 ± 3 mm/yr; (2) the Septentrional fault in northern Dominican Republic, 8 ± 3 mm/yr; and (3) the Enriquillo fault in southern Dominican Republic and Haiti, 8 ± 4 mm yr. The relatively high Plate motion rate and fault slip rates suggested by our study, combined with evidence for strain accumulation and historical seismicity, imply that seismic risk in the region may be higher than previous estimates based on low Plate rate/low fault slip rate models and the relatively low rate of seismicity over the last century.
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gps measurements across the northern Caribbean Plate boundary zone impact of postseismic relaxation following historic earthquakes
Geophysical Research Letters, 1998Co-Authors: Fred F Pollitz, Timothy H DixonAbstract:GPS measurements in the northern Caribbean suggest that the rate of Caribbean Plate motion relative to North America is about 10 mm/yr faster than predicted by global Plate motion model NUVEL-1A. Several of the key sites used in the GPS study are located in the Dominican Republic, near the rupture zones of large earthquakes in 1946 and in the previous two centuries. Postseismic relaxation of the crust and upper mantle is a possible explanation for the Plate velocity discrepancy. We explore a range of fault mechanisms and crustal and mantle theology to place an upper bound on postseismic relaxation effects. The upper bound velocity contribution in the southern Dominican Republic is 5-6 mm/yr, and the most plausible contribution is 1-2 mm/yr, suggesting that postseismic effects cannot account for the discrepan- cy. This implies that the NUVEL-1A model underesti- mates the rate of motion of the Caribbean Plate.
A Levander - One of the best experts on this subject based on the ideXlab platform.
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crustal structure of the south american Caribbean Plate boundary at 67 w from controlled source seismic data
Journal of Geophysical Research, 2009Co-Authors: M B Magnani, A Levander, C A Zelt, Michael SchmitzAbstract:[1] We present the results of new seismic reflection and wide-angle data across the SE Caribbean Plate boundary. The 550 km long N–S profile crosses the structures involved in the active 55 Ma long continent-arc oblique collision between the Caribbean (CAR) and the South American (SA) Plate. From the north to the south these structures include the accretionary prism, the extinct volcanic arc (Leeward Antilles arc), the Tertiary Bonaire basin, the continental-size dextral strike-slip fault system (San Sebastian–El Pilar fault), the allochthonous exhumed terranes, and the authocthonous fold and thrust belt (Caribbean Mountain system) and foreland basin. The wide-angle data show that these elements are characterized by different velocity structures and that they are separated by sharp lateral velocity variations. The Leeward Antilles arc exhibits a velocity structure similar to that of the Lesser Antilles active volcanic arc, indicating that the extinct arc has not been modified by the collision with the SA Plate. The data show a ∼20 km change in crustal thickness across the San Sebastian fault, suggesting that the dextral strike-slip fault is a crustal feature that likely continues in the mantle as a primary strand of the Plate boundary between the South American and the Caribbean Plates. South of the strike-slip fault and beneath the exhumed eclogitic terranes, the data image a north dipping, high-velocity (>6.5 km/s) anomaly in the upper crust (3–11 km), indicating that high-pressure/low-temperature rocks are the likely lithologies responsible for the high seismic velocities and suggesting that exhumation of these assemblages is enabled by the strike-slip fault.
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upper mantle structure beneath the Caribbean south american Plate boundary from surface wave tomography
Journal of Geophysical Research, 2009Co-Authors: Meghan S Miller, A Levander, Fenglin NiuAbstract:[1] We have measured shear wave velocity structure of the crust and upper mantle of the Caribbean-South American boundary region by analysis of fundamental mode Rayleigh waves in the 20- to 100-s period band recorded at the BOLIVAR/GEODINOS stations from 2003 to 2005. The model shows lateral variations that primarily correspond to tectonic provinces and boundaries. A clear linear velocity change parallels the Plate bounding dextral strike-slip fault system along the northern coast of Venezuela, illustrating the differences between the South American continental lithosphere, the Venezuelan archipelago, and the Caribbean oceanic lithosphere. At depths up to 120 km beneath the Venezuelan Andes and the Maracaibo block, there is evidence of underthrusting of the Caribbean Plate, but there is no other evidence of subduction of the Caribbean Plate beneath the South American Plate. In eastern Venezuela, linear crustal low velocities are associated with the fold and thrust belts whereas as higher crustal velocities are imaged in the Guayana shield lithosphere. The subducting oceanic part of the South American Plate is imaged beneath the Antilles arc. The surface wave images combined with seismicity data suggest shear tearing of the oceanic lithosphere away from the buoyant continental South American Plate offshore of northeastern Venezuela. The continental lithosphere south of the slab tear is bent down toward the Plate boundary in response to the propagating tear in the lithosphere. We interpret a nearly vertical low-velocity ‘‘column’’ west of the tear centered beneath the Cariaco Basin, with three-dimensional asthenospheric flow around the southern edge of the subducting oceanic lithosphere, with the asthenosphere escaping from beneath continental South America and rising into the Plate boundary zone. The complex Plate boundary structure is best examined in three dimensions. We discuss the new surface wave tomographic inversion in the context of results from other researchers including local seismicity, teleseismic shear wave splits, and interpretations from active source profiling.
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receiver function study of the crustal structure of the southeastern Caribbean Plate boundary and venezuela
Journal of Geophysical Research, 2007Co-Authors: Fenglin Niu, Tammy Bravo, Gary L Pavlis, Frank L Vernon, Herbert Rendon, Maximiliano Bezada, A LevanderAbstract:[1] We have investigated crustal thickness and composition across the southeastern Caribbean Plate boundary with the receiver function technique. We used teleseismic data recorded by a temporary broadband array deployed under the BOLIVAR project and the permanent national seismic network of Venezuela. We used the primary P-to-S conversion and crustal reverberations to estimate crustal thickness and average crustal VP/VS ratio over the region. We observe large variations in crustal thickness and Poisson's ratio. Estimated Moho depth ranges from ∼16 km beneath the southeastern Caribbean Sea to ∼52 km beneath northeastern Venezuela and the Venezuelan Andes. There is a good correlation between crustal structure and tectonic terranes. Data from the Precambrian Guayana Shield suggest that the underlying crustal structure is relatively uniform with a moderate thickness (∼37 km) and an intermediate composition. A thick crust is found below the foreland basins. The two mountain systems in northern Venezuela, the Serrania del Interior and the Serrania del Falcon, have a thin crust with arc composition and are likely dynamically supported by elastic rebound or underthrusting of the oceanic Plateau that characterizes the southern Caribbean. On the other hand, the Venezuelan Andes and Perija Range on the western side of the country are probably isostatically balanced by thick crustal roots.
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evolution of the southern Caribbean Plate boundary
Eos Transactions American Geophysical Union, 2006Co-Authors: A Levander, Hans Ave G Lallemant, Paul Mann, M B Magnani, C A Zelt, Michael Schmitz, Dale S Sawyer, G L Christeson, James E Wright, Gary L PavlisAbstract:It is generally accepted that the cores of the continents, called cratons, formed by the accretion of island arcs into proto-continents and then by proto-continental agglomeration to form the large continental masses. Mantle-wedge processes, combined with higher melting temperatures during the Archean (2.5–3.8 billion years ago) and possibly thrust stacking of highly depleted Archean oceanic lithosphere, produced a strong, buoyant, upper mantle chemical boundary layer. This stabilizing mantle layer, known as the tectosphere, has shielded the Archean cratons from most subsequent tectonic disruption and is highly depleted in iron, providing the positive buoyancy that is required to ‘float’ the continents more than four kilometers above the surrounding ocean basins.
Roger Bilham - One of the best experts on this subject based on the ideXlab platform.
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velocity field across the southern Caribbean Plate boundary and estimates of Caribbean south american Plate motion using gps geodesy 1994 2000
Geophysical Research Letters, 2001Co-Authors: O Perez, Roger Bilham, Rebecca Bendick, Jose R Velandia, Napoleon Hernandez, Carlos Moncayo, Melvin Hoyer, Mike KozuchAbstract:Global Positioning System (GPS) observations between 1994 and 2000 at twenty-two sites in the Lesser Antilles and northern South-America indicate that the Caribbean Plate, along its southern boundary, slips at a rate of 20.5±2 mm/a with an azimuth of N 84°±2°E at 65°W, relative to the South-American Plate. East of 68° W, 80% of the dextral slip is contained within a 80-km wide shear zone centered on the El Pilar-San Sebastian fault system. West of 68° W the Plate boundary broadens to more than 300 km with dextral shear shared between the northeast trending Bocono fault (9–11 mm/a) in western Venezuelan, and an offshore system near the northern coast.
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velocity field across the southern Caribbean Plate boundary and estimates of Caribbean south american Plate motion using gps geodesy 1994 2000
Geophysical Research Letters, 2001Co-Authors: O Perez, Roger Bilham, Rebecca Bendick, Jose R Velandia, Napoleon Hernandez, Carlos Moncayo, Melvin Hoyer, Mike KozuchAbstract:Global Positioning System (GPS) observations between 1994 and 2000 at twenty-two sites in the Lesser Antilles and northern South-America indicate that the Caribbean Plate, along its southern boundary, slips at a rate of 20.5±2 mm/a with an azimuth of N 84°±2°E at 65°W, relative to the South-American Plate. East of 68° W, 80% of the dextral slip is contained within a 80-km wide shear zone centered on the El Pilar-San Sebastian fault system. West of 68° W the Plate boundary broadens to more than 300 km with dextral shear shared between the northeast trending Bocono fault (9–11 mm/a) in western Venezuelan, and an offshore system near the northern coast.
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gps estimate of relative motion between the Caribbean and south american Plates and geologic implications for trinidad and venezuela
Geology, 2001Co-Authors: John Weber, Timothy H Dixon, C Demets, William B Ambeh, Pamela E Jansma, G S Mattioli, J Saleh, Giovanni Sella, Roger Bilham, O PerezAbstract:Global Positioning System (GPS) data from eight sites on the Caribbean Plate and five sites on the South American Plate were inverted to derive an angular velocity vector describing present-day relative Plate motion. Both the Caribbean and South American velocity data fit rigid-Plate models to within ±1–2 mm/yr, the GPS velocity uncertainty. The Caribbean Plate moves approximately due east relative to South America at a rate of ∼20 mm/yr along most of the Plate boundary, significantly faster than the NUVEL-1A model prediction, but with similar azimuth. Pure wrenching is concentrated along the approximately east-striking, seismic, El Pilar fault in Venezuela. In contrast, transpression occurs along the 068°-trending Central Range (Warm Springs) fault in Trinidad, which is aseismic, possibly locked, and oblique to local Plate motion.
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GPS geodetic constraints on Caribbean-North America Plate motion
Geophysical Research Letters, 2000Co-Authors: C Demets, Timothy H Dixon, Pamela E Jansma, Roger Bilham, Glen S. Mattioli, Fred Farina, Eric Calais, Paul MannAbstract:We describe a model for Caribbean Plate motion based on GPS velocities of four sites in the Plate interior and two azimuths of the Swan Islands transform fault. The data are well fit by a single angular velocity, with average misfits approximately equal to the 1.5–3.0 mm yr−1 velocity uncertainties. The new model predicts Caribbean-North America motion ∼65% faster than predicted by NUVEL-1A, averaging 18–20±3 mm yr−1 (2σ) at various locations along the Plate boundary. The data are best fit by a rotation pole that predicts obliquely convergent motion along the Plate boundary east of Cuba, but are fit poorly by a suite of previously published models that predict strike-slip motion in this region. The data suggest an approximate upper bound of 4–6 mm yr−1 for internal deformation of the Caribbean Plate, although rigorous estimates await more precise and additional velocities from sites in the Plate interior.