Panama Arc Research Articles

Spatial and temporal patterns of exhumation across the Venezuelan Andes: Implications for Cenozoic Caribbean geodynamics

[1] The Venezuelan Andes formed by complex geodynamic interaction between the Caribbean Plate, the Panama Arc, the South American Plate and the continental Maracaibo block. We study the spatial and temporal patterns of exhumation across the Venezuelan Andes using 47 new apatite fission track (AFT) ages as well as topographic analyses. This approach permits the identification of at least seven tectonic blocks (Escalante, Cerro Azul, Trujillo, Caparo, Sierra Nevada, Sierra La Culata and El Carmen blocks) with contrasting exhumation and cooling histories. The Sierra Nevada, Sierra La Culata and El Carmen blocks, located in the central part of the Venezuelan Andes and separated by the Bocono fault system, cooled rapidly but diachronously during the late Miocene–Pliocene. Major surface uplift and exhumation occurred in the Sierra Nevada block since before 8 Ma. A second phase of uplift and exhumation affected the El Carmen and Sierra La Culata blocks to the north of the Bocono fault during the late Miocene-Pliocene. The highest topography and steepest relief of the belt coincides with these blocks. The Caparo and Trujillo blocks, located at the northeastern and southwestern ends of the orogen, cooled more slowly from the Oligocene to the late Miocene. These blocks are characterized by significantly lower mean elevations and slightly lower mean slopes than the central blocks. Unraveling the cooling history of the individual blocks is important to better understand the control of preexisting faults and regional Caribbean geodynamics on the evolution of the Venezuelan Andes. Our data indicate a strong control of major preexisting fault zones on exhumation patterns and temporal correlation between phases of rapid exhumation in different blocks with major tectonic events (e.g., collision of the Panama arc; rotation of the Maracaibo block).

Dextral shear, terrane accretion and basin formation in the Northern Andes: best explained by interaction with a Pacific-derived Caribbean Plate?

Abstract The structure, stratigraphy and magmatic history of northern Peru, Ecuador and Colombia are only adequately explained by Pacific-origin models for the Caribbean Plate. Inter-American models for the origin of the Caribbean Plate cannot explain the contrasts between the Northern Andes and the Central Andes. Persistent large magnitude subduction, arc magmatism and compressional deformation typify the Central Andes, while the Northern Andes shows back-arc basin and passive margin formation followed by dextral oblique accretion of oceanic plateau basalt and island arc terranes with Caribbean affinity. Cretaceous separation between the Americas resulted in the development of a NNE-trending dextral–transpressive boundary between the Caribbean and northwestern South America, becoming more compressional when spreading in the Proto-Caribbean Seaway slowed towards the end of the Cretaceous. Dextral transpression started at 120–100 Ma, when the Caribbean Arc formed at the leading edge of the Caribbean Plate as a result of subduction zone polarity reversal at the site of the pre-existing Trans-American Arc, which had linked to Central America to South America in the vicinity of the present-day Peru–Ecuador border. Subsequent closure of the Andean Back-Arc Basin resulted in accretion of Caribbean terranes to western Colombia. Initiation of flat-slab subduction of the Caribbean Plate beneath Colombia at about 100 Ma is associated with limited magmatism, with no subsequent development of a magmatic arc. This was followed by northward-younging Maastrichtian to Eocene collision of the trailing edge Panama Arc. The triple junction where the Panama Arc joined the Peru–Chile trench was located west of present-day Ecuador as late as Eocene time, and the Talara, Tumbes and Manabi pull-apart basins directly relate to its northward migration. Features associated with the subduction of the Nazca Plate, such as active calc-alkaline volcanic arcs built on South American crust, only became established in Ecuador, and then Colombia, as the triple junction migrated to the north. Our model provides a comprehensive, regional and testable framework for analysing the as yet poorly understood collage of arc remnants, basement blocks and basins in the Northern Andes.

Geological evolution of the NW corner of the Caribbean Plate

Abstract The Caribbean Plate consists of a plateau basalt, formed probably in the Middle Cretaceous, complicated by a continental block, Chortís, several magmatic arcs, strike–slip motions along major fault systems such as the Motagua–Polochic fault zone in Guatemala, the pull-apart basin of the Cayman Trough and subduction zones below Central America and the Lesser Antilles. Five major collisional events have been identified: (i) Late Paleocene–Middle Eocene collision of the Greater Antilles with the Bahamas platform; (ii) Late Cretaceous collision of Chortís with the Maya Block; (iii) emplacement of nappes upon the Venezuelan foreland in the Cenozoic; (iv) collision of the Western Cordillera oceanic complex with the Central Cordillera of Colombia; and (v) Miocene collision of the eastern Costa Rica–Panama arc with the Western Cordillera. All these ‘orogenic events’ show an eastward movement of the Caribbean Plate relative to the Americas. Migration of the Jamaica Block from the Pacific caused obduction of the oldest ophiolites of Huehuetenango at the western end of the Polochic–Río Negro faults in Guatemala. South-southwest migration of the Chortís Block from west of Mexico and northward towards the Maya Block destroyed a trench associated with the Motagua–Jalomáx fault system and caused the Chuacús Orogeny, emplacing Guatemalan ophiolite complexes and metamorphosing the rocks from the Chuacús Series.

Tropical forests are both evolutionary cradles and museums of leaf beetle diversity.

The high extant species diversity of tropical lineages of organisms is usually portrayed as a relatively recent and rapid development or as a consequence of the gradual accumulation or preservation of species over time. These explanations have led to alternative views of tropical forests as evolutionary "cradles" or "museums" of diversity, depending on the organisms under study. However, biogeographic and fossil evidence implies that the evolutionary histories of diversification among tropical organisms may be expected to exhibit characteristics of both cradle and museum models. This possibility has not been explored in detail for any group of terrestrial tropical organisms. From an extensively sampled molecular phylogeny of herbivorous Neotropical leaf beetles in the genus Cephaloleia, we present evidence for (i) comparatively ancient Paleocene-Eocene adaptive radiation associated with global warming and Cenozoic maximum global temperatures, (ii) moderately ancient lineage-specific diversification coincident with the Oligocene adaptive radiation of Cephaloleia host plants in the genus Heliconia, and (iii) relatively recent Miocene-Pliocene diversification coincident with the collision of the Panama arc with South America and subsequent bridging of the Isthmus of Panama. These results demonstrate that, for Cephaloleia and perhaps other lineages of organisms, tropical forests are at the same time both evolutionary cradles and museums of diversity.

The Geology of the Darien, Panama, and the late Miocene-Pliocene collision of the Panama arc with northwestern South America

The geology of the Darien province of eastern Panama is presented through a new geologic map and detailed biostratigraphic and paleobathymetric analysis of its Upper Cretaceous to upper Miocene sediments. The sequence of events inferred from the stratigraphic record includes the collision of the Panama arc (the southwestern margin of the Caribbean plate) and South American continent. Three tectonostratigraphic units underlie the Darien region: (1) Precollisional Upper Cretaceous–Eocene crystalline basement rocks of the San Blas Complex form a series of structurally complex topographic massifs along the northeastern and southwestern margins of the Darien province. These rocks formed part of a >20 m.y. submarine volcanic arc developed in a Pacific setting distant from the continental margin of northwestern South America. The northerly basement rocks are quartz diorites, granodiorites, and basaltic andesites, through dacites to rhyolites, indicating the presence of a magmatic arc. The southerly basement rocks are an accreted suite of diabase, pillow basalt, and radiolarian chert deposited at abyssal depths. Precollisional arc-related rocks, of Eocene to lower Miocene age, consist of 4000 m of pillow basalts and volcaniclastics, and biogenic calcareous and siliceous deep-water sediments. They consist of the Eocene-Oligocene Darien Formation, the Oligocene Porcona Formation and the lower-middle Miocene Clarita Formation. Postcollisional deposits are mostly coarse- to fine-grained siliciclastic sedimentary rocks and turbiditic sandstone of upper middle to latest Miocene age. This 3000 m thick sedimentary sequence is deformed as part of a complexly folded and faulted synclinorium that forms the central Chucunaque-Tuira Basin of the Darien. The sedimentary package reveals general shallowing of the basin from bathyal to inner neritic depths during the 12.8−7.1 Ma collision of the Panama arc with South America. The sediments are divided into the upper middle Miocene Tapaliza Formation, the lower upper Miocene Tuira and Membrillo Formations, the middle upper Miocene Yaviza Formation, and the middle to upper Miocene Chucunaque Formation. The precollisional open marine units of Late Cretaceous–middle Miocene age are separated from the overlying postcollisional sequence of middle to late Miocene age by a regional unconformity at 14.8−12.8 Ma. This unconformity marks the disappearance of radiolarians, the changeover of predominantly silica deposition from the Atlantic to the Pacific, the initiation of the uplift of the isthmus of Panama, and the onset of shallowing upward, coarser clastic deposition. This pattern is also recorded from the southern Limon Basin of Caribbean Costa Rica to the Atrato Basin of northwestern Colombia. By the middle late Miocene, neritic depths were widespread throughout the Darien region, and a regional unconformity suggests completion of the Central American arc collision with South America by 7.1 Ma. No Pliocene deposits are recorded from either the Darien or the Panama Canal Basin, and no sediments younger than 4.8 Ma have been identified in the Atrato Basin of Colombia, suggesting rapid uplift and extensive emergence of the Central American isthmus in the latest Miocene. Northward movement of the eastern segment of the Panama arc along a now quiescent Panama Canal Zone fault during Eocene-Oligocene time may have dislocated the pre-collision arc. Since collision, the portion west of this fault (Chorotega Block) has remained stable, without rotation; to the east, in the Darien region, compression has been accommodated through formation of a Panama microplate with convergent boundaries to the north (North Panama deformed belt) and south (South Panama deformed belt), and suturing with South America along the Atrato Valley. Deformation within the microplate has been accommodated in the Darien province by several major left-lateral strike-slip faults that were active until the early Pliocene, since when the plate has behaved rigidly.

Wide plate margin deformation, southern Central America and northwestern South America, CASA GPS observations

Global positioning system data from southern Central America and northwestern South America were collected during 1991, 1994, 1996, and 1998 in Costa Rica, Panama, Ecuador, Colombia, and Venezuela. These data reveal wide plate boundary deformation and escape tectonics occurring along an approximately 1400km length of the North Andes, locking of the subducting Nazca plate and strain accumulation in the Ecuador–Colombia forearc, ongoing collision of the Panama arc and Colombia, and convergence of the Caribbean plate with Panama and South America. Elastic modeling of observed horizontal displacements in the Ecuador forearc is consistent with partial locking (50%) in the subduction zone and partial transfer of motion to the overriding South American plate. The deformation is hypothesized to reflect elastic recoverable strain accumulation associated with the historic seismicity of the area and active faulting associated with permanent shortening of 6mm/a. Deformation associated with the Panama–Colombia collision is consistent with elastic strain accumulation on a fully locked Atrato–Uraba Fault Zone suture.

Abstract: Fold and Thrust Belt Along the Western Flank of the Eastern Cordillera of Colombia: Style, Kinematics and Timing Constraints Derived >From Seismic Data and Detailed Surface Mapping 

The Eastern Cordillera of Colombia is considered to be the result of compression and uplift during the late Miocene–Pliocene Andean orogeny. Nevertheless, detailed mapping carried out on a portion of the fold belt exposed along the western flank of the Eastern Cordillera suggests that deformation began in late Paleocene–early Eocene time, in the form of a west-vergent, forward-propagating fold-and-thrust belt. Several structures related to this event remain concealed beneath the late Paleocene–late Eocene unconformity, and synkinematic sediments are preserved locally within some of these thrust sheets. The relief generated during this deformational episode constrained the depositional axis of late Eocene fluvial sediments to run along the present-day crestal zone of the Eastern Cordillera. Onlapping basal Miocene molassic sediments on tilted middle Miocene fluvial deposits suggest that a series of seismically delineated intercutaneous wedges located at the thrust front formed in late Miocene time. These structures mark the onset of the Andean deformational episode. Thrusting polarity reversed during the latter event, that is, toward the hinterland, and Paleogene structures were reactivated. Additionally, the late Paleocene–early Eocene unconformity surface was folded and incorporated into north-plunging folds, and Cretaceous extensional faults were inverted. As a result, the Eastern Cordillera developed its present pop-up, doubly vergent fold-belt geometry, flanked by thick molassic sequences that document the Miocene–Pliocene Andean orogeny. Regionally, the latest Campanian–Maastrichtian uplift of the Central Cordillera, Paleocene–early Eocene thrusting in the Middle Magdalena Valley and along the western flank of the Eastern Cordillera, and ultimately inversion and major uplift of the entire Eastern Cordillera in late Miocene–Pliocene time, attests to the eastward propagation of deformation from the Central toward the Eastern Cordillera. Kinematically, the driving element of deformation would have been the obliquely accreting western terranes of the Central and Western Cordilleras and the Panama arc. These transferred their easterly component of convergence to the Eastern Cordillera through a basal intracrustal detachment.

Depositional history of the western Colombian Basin, Caribbean Sea, revealed by seismic stratigraphy

Seismic-stratigraphic analysis of multichannel seismic-reflection profiles indicates that the sedimentary section in the western Colombian Basin comprises five principal units. The deposition of these units was strongly influenced by the basement relief of an oceanic plateau. The five units define three depositional episodes, the middle three units defining a single episode. The depositional history of the western Colombian Basin supports plate-tectonic models of this area based on the insertion of Pacific lithosphere. The first depositional episode is interpreted to be an extended period of biogenic pelagic sedimentation before and during the insertion of Pacific lithosphere. It is characterized by accumulation of a thick (0.5 km) layer of pelagic deposits on the crest of the plateau, above the carbonate compensation depth. These deposits probably correlate with similar rocks of Late Cretaceous to Eocene age bounded by reflection horizons A″ and B″ in the Venezuelan Basin. The second depositional episode represents a major change in sedimentation with the influx of a large volume of clastic sediment transported mainly by unconfined turbidity flows. This episode is inferred to span Eocene through Miocene time. Sediments were derived from sources north and west of the basin. Resuspension of some of these sediments in nepheloid layers probably led to hemipelagic deposition on topographically elevated areas. Pervasive internal deformation and physical properties suggest that this hemipelagic layer is undercompacted. The beginning of this episode apparently corresponds to initiation of predominantly eastward motion of the Caribbean Plate relative to the Americas. The final depositional episode began in the late Miocene epoch and extends to the present. It is characterized by deposition of turbiditefan complexes, including a large fan dominated by leveed-channel systems offshore of Costa Rica. Development of this fan was in response to uplift and increased volcanism in southern Central America caused by the collision between the Panama arc and South America.

Caribbean Basin Framework, 3: Southern Central America and Colombian Basin

The authors recognize three basin-forming periods in southern Central America (Panama, Costa Rica, southern Nicaragua) that they attempt to correlate with events in the Colombian basin (Bowland, 1984): (1) Early-Late Cretaceous island arc formation and growth of the Central American island arc and Late Cretaceous formation of the Colombian basin oceanic plateau. During latest Cretaceous time, pelagic carbonate sediments blanketed the Central American island arc in Panama and Costa Rica and elevated blocks on the Colombian basin oceanic plateau; (2) middle Eocene-middle Miocene island arc uplift and erosion. During this interval, influx of distal terrigenous turbidites in most areas of Panama, Costa Rica, and the Colombian basin marks the uplift and erosion of the Central American island arc. In the Colombian basin, turbidites fill in basement relief and accumulate to thicknesses up to 2 km in the deepest part of the basin. In Costa Rica, sedimentation was concentrated in fore-arc (Terraba) and back-arc (El Limon) basins; (3) late Miocene-Recent accelerated uplift and erosion of segments of the Central American arc. Influx of proximal terrigenous turbidites and alluvial fans in most areas of Panama, Costa Rica, and the Colombian basin marks collision of the Panama arc with the South American continentmore » (late Miocene early Pliocene) and collision of the Cocos Ridge with the Costa Rican arc (late Pleistocene). The Cocos Ridge collision inverted the Terraba and El Limon basins. The Panama arc collision produced northeast-striking left-lateral strike-slip faults and fault-related basins throughout Panama as Panama moved northwest over the Colombian basin.« less

Four-phase tectonostratigraphic development of the southern Caribbean

Although the stratigraphy of northern South America and the southern Caribbean has been studied in detail in many areas, a clear understanding of the sequence of tectonic events and their relation to regional stratigraphy has not been forthcoming. Since northern South America collided with southern North America in the Late Palaeozoic, we identify four discrete tectonic phases from the stratigraphy of the area that is now the southern Caribbean. These phases derived from a synthesis of regional stratigraphy were: (1) Panama arc collistion with Colombia in the Late Miocene/Early Pliocene which drove a complex triangular wedge bounded by strike-slip faults northward into the Caribbean; (2) right-lateral strike-slip faulting associated with post-Eocene eastern motion of the Caribbean ocean floor into the gap between the separating Americas; (3) island arc development and collision associated with the entry of the present Caribbean ocean floor, an area of buoyant ocean crust, into the gap between the separating Americas; and (4) continental rifting and passive margin development in the Late Jurassic/Early Cretaceous associated with the separation of North and South America approximately along the Palaeozoic suture zone. Overprinting of younger structures on inherited structures from previous phases is responsible for the overall complexity of the region.

A hierarchical tectonic model of the Gulf of Mexico and Caribbean region

A quantitative computer graphic methodology (hierarchical tectonic analysis) has been used to model the tectonic evolution of the Gulf of Mexico and Caribbean region. This method employs a highly structured, hierarchical description of the relative motions of pairs of tectonic elements in order to quantify the timing and style of plate interactions. The main features described in this model are: 1. (1) a revised fit of Pangea 2. (2) the opening of the Gulf of Mexico in the Middle-Late Jurassic 3. (3) the formation of a Proto-Caribbean Ocean due to the separation of North and South America during the Early Cretaceous 4. (4) the formation of the Greater Antilles Arc along the western margin of the Proto-Caribbean Ocean 5. (5) the insertion of the Farallon plate between North and South America during the Middle Cretaceous resulting in the northeastward advance of the Greater Antilles Arc and the subduction of Proto-Caribbean oceanic crust 6. (6) the complete subduction of the Proto-Caribbean Ocean and the collision of the Greater Antilles arc with the Bahamas Platform in the Late Cretaceous 7. (7) the truncation of the Caribbean section of the Farallon plate from its Pacific counterpart and the formation of the Panama Arc (latest Cretaceous), and 8. (8) the westward movement of North and South America with respect to the Caribbean plate resulting in the opening of the Yucatan Basin (Paleocene) and subsequently in the evolution of the Cayman Trough and E-W zone of strike-slip.

Seismicity of the Caribbean‐Nazca Boundary: Constraints on microplate tectonics of the Panama region

There are at least three kinds of models that have been used to explain plate motions and boundaries in the Panama region. These models suggest that the major Caribbean‐Nazca boundary is (1) a thrust fault along which the Panama Deformed Belt has developed, (2) a left‐lateral strike‐slip fault along the southern margin of Panama, or (3) a diffuse array of mostly thrust faults which cause internal deformation to occur throughout Panama. In this paper, we use joint epicenter location methods to obtain improved locations for earthquakes that occurred in this region between 1964 and 1985 and we use waveform modeling to obtain more precise depths for five events. Hypocenters of 13 events beneath the Panama Deformed Belt suggest that overthrusting of Panama upon the Caribbean plate causes active deformation which supports model 1 but does not rule out models 2 and 3. The nature of seismic faulting along the Panama Deformed Belt is complex and supports the premise that slow north‐south convergence loads the cold thick Caribbean lithosphere and causes it to fail seismically. Epicenters of 64 events along the Panama Fracture Zone indicate that this north–south trending rightlateral transform fault is splayed north of 6°N. Overall, the seismicity throughout suggests that the Panama arc can be treated as a microplate, in accordance with models 1 or 2. Similarly, a possible second microplate may exist south of Panama, but if so it does not affect regional plate motions significantly. The strongest evidence for model 3 occurs in the easternmost and westernmost portions of Panama, where the diffuse seismicity prevents us from resolving specific microplate triple‐junction boundaries.

Dynamics of an End-On Collision, Interpreted from SeaMARC II Swath Mapping and Migrated Seismic Reflection Data on North Margin of Panama: ABSTRACT

The authors have imaged nearly the entire North Panama thrust belt (NPTB) to determine the dynamics of the Panama arc colliding end-on with South America. Observations support a simple flexural beam model in which eastward collision of the arc against the continent is transformed into northward relative motion of the NPTB. Fold axes and thrust faults within the NPTB show remarkable uniformity in strike (075/sup 0/), changing only on the east margin across a major fault and on the west margin across a sharp flexure. The belt increases in width (and presumably convergence) eastward, as predicted by the beam model. Displacement along the Uraba fault zone separated a thin sliver of the NPTB, and two earthquake focal mechanisms on the fault show right-oblique slip. Vergence of thrust sheets within the accretionary wedge is dominantly landward in much of the central part of the thrust belt, indicating low basal shear stresses and high fluid pressures along the decollement. Mud volcanoes within the accretionary wedge attest to elevated fluid pressures. Because of an exceptionally well-developed and widespread gas hydrate layer, they suggest that pore fluids are a mixture of water and methane. However, near the central part of the thrust belt, amore » concentrated zone of mud volcanoes has breached the crests of seaward-verging anticlines. They propose that the zone of anomalous seaward-verging thrust sheets results from widespread release of pore fluids from the decollement, leading to increased basal friction.« less

Experiments on the strength of materials

We present a velocity field for northwestern South America and the southwest Caribbean based on GPS Continuously Operating Reference Stations in Colombia, Panama, Ecuador and Venezuela. This paper presents the first comprehensive model of North Andean block (NAB) motion. We estimate that the NAB is moving to the northeast (060°) at a rate of 8.6 mm/yr relative to the South America plate. The NAB vector can be resolved into a margin-parallel (035°) component of 8.1 mm/yr rigid block motion and a margin-normal (125°) component of 4.3 mm/yr. This present-day margin-normal shortening rate across the Eastern Cordillera (EC) of Colombia is surprising in view of paleobotanical, fission-track, and seismic reflection data that suggest rapid uplift (7 km) and shortening (120 km) in the last 10 Ma. We propose a “broken indenter” model for the Panama-Choco arc, in which the Choco arc has been recently accreted to the NAB, resulting in a rapid decrease in shortening in the EC. The Panama arc is colliding eastward with the NAB at approximately 15–18 mm/yr, and the Panama-Choco collision may have been responsible for much of the uplift of the EC. The present on-going collision poses a major earthquake hazard in northwestern Colombia from the Panama border to Medellin area. Since the northeastward margin-parallel motion of the NAB is now greater than the rate of shortening in the EC, northeast trending right-lateral strike-slip faulting is the primary seismic hazard for the 8 million inhabitants of Bogota, the capital city of Colombia. There continues to be a high risk of a great megathrust earthquakes in southern Colombia along the Ecuador-Colombia trench. Trench earthquakes have only released a fraction of the energy accumulated in the Ecuador-Colombia trench since the 1906 Ecuador earthquake, and interseismic strain is accumulating rapidly at least as far north as Tumaco, the rupture area of the 1979 earthquake.