North Andean Plate
The North Andean plate contains parts of Ecuador, Colombia, and Venezuela, and naturally includes the northern Andes. (Bird, 2003). The North Andean plate is mostly composed of sedimentary rocks from the Jurassic, Cretaceous, and Paleogene (i.e. spanning from ~199 Ma to 23 Ma) that accumulated through accretion of sediments from the subducting Nazca plate (Ramos, 1999). A study by Cardona et al. (2011) found that there were five distinct tectonic episodes that resulted in the building of the northern Andes region: the collision of northern South America with the Caribbean (70 Ma), subduction related metamorphism and magmatism (65 Ma), the accumulation of a thick siliclastic accretionary wedge (60-58 Ma), arc magmatism (58-50 Ma), and regional uplift (<50 Ma). There is extensive volcanism in the North Andean plate, particularly in Ecuador and Colombia (Stern, 2004). The source of magmatism and volcanism is magma rising off of the partially melting Nazca plate, which then may rise to the surface (Stern, 2004). Venezuela does not host any volcanoes, although it does contain many mud volcanoes (Aslan, 2001). These are the result of dewatering sediments from the subducting Caribbean plate (Reed et al., 1989). This is discussed in more depth on the "Accretionary Wedges" page.
The oldest volcanics date to the pleistocene (2.58 Ma), and there are currently over 70 volcanoes in the North Andean plate (Stern, 2004). At the northern tip of the North Andean plate, the Caribbean plate is being subducted. While it is agreed that the Nazca plate is subducting underneath the North Andes plate at a rate of 7 cm/a, and the Caribbean plate is subducting underneath the North Andean plate, the eastern boundary of the plate is more poorly understood (Gutscher et al., 1999; Freymueller et al., 1993; NASA DTAM, 2002). The boundary of the North Andes plate with the South American plate has been mapped as a transform fault (M.A. Gutscher et al., 1999), a subduction zone (NASA DTAM, 2002), or a combination of both (Freymueller et al., 1993). The North Andean plate has four triple junctions (Bird, 2003).
Panama Plate
Much like the North Andean plate, the Panama plate is tectonically complex, and has four triple junctions (Bird, 2003). Even as recently as the late 1980s, the boundaries were not known (Adamek et al., 1988). Until 9.5 Ma, the Nazca plate was being subducted underneath of the Panama plate (Van Benthem et al., 2013), at which point it became what is now referred to as the Panama Fracture Zone, a right-lateral strike-slip area (Lowrie et al., 1979). The Panama plate is comprised of igneous rocks as a result of a magmatic arc (Coates et al., 2004). It is also composed of a variety of rocks which formed prior to the collision with the Americas, such as pillow basalts, biogenic carbonates, and cherts (Coates et al., 2004). Following the collision, more rocks were accreted on to the Panama plate, such as coarse grained sediments and turbidite sequences (Coates et al., 2004). Like Ecuador and Colombia, Panama is host to volcanoes, although all three of them are currently dormant (Harmon, 2005). As a result of its current collisions with South America and the Cocos plate, the Panama plate is currently moving northward (Harmon, 2005). Other consequences of this are regional uplift, bending of the plate, and strike-slip faulting within the plate (Harmon, 2005). Although the Panama plate is just a small isthmus, its position between the Americas has had major ramifications on the Earth’s climate. Approximately 3 Ma, the Panama plate closed the gap between North and South America, interrupting the circulation of water between the Pacific and Atlantic oceans (Schmittner et al., 2004). After the closure, the Atlantic ocean became increasingly warm and salty (Schmittner et al., 2004). It is thought that a warmer Atlantic ocean led to a higher moisture content in the Arctic, and thus larger amounts of snowfall (Schmittner et al., 2004). The effects of the closure are discussed in more detail on the "Special Features" page.
Links
References
Adamek, S., Frohlich, C. and Pennington, W. (1988). Seismicity of the Caribbean-Nazca boundary: Constraints on microplate tectonics of the Panama region. Journal of Geophysical Research, 93.
Aslan, A., Warne, A. G., White, W. A., Guevara, E. H., et al. (2001). Mud volcanoes of the Orinoco Delta, Eastern Venezuela. Geomorphology, 41. 323-336.
Bird, P. (2003). An updated digital model of plate boundaries. Geochemistry, Geophysics, Geosystems, 4(3).
Cardona, A., Valencia, V. A., Bayona, G., Duque, J., et al. (2011). Early-subduction-related orogeny in the northern Andes: Turonian to Eocene magmatic and provenance record in the Santa Marta Massif and Rancheria Basin, northern Columbia. Terra Nova, 23, 26-34.
Cediel, F., R. P. Shaw, and C. Ca ́ceres. (2003), Tectonic assembly of the Northern Andean Block. The Circum-Gulf of Mexico and the Caribbean: Hydrocarbon habitats, basin formation, and plate tectonics: AAPG Memoir 79, 815–848.Freymueller, J. T., Kellogg, J. N., Vega, V. (1993). Plate Motions in the North Andean Region. Journal of Geophysical Research, 98(B12), 853-861.
Stern, C. R. (2004). Active Andean volcanism: its geologic and tectonic setting. Rev. Geol. Chile, 31(2), 161-206.
Gutscher, M. A., Malavielle, J., Lallemand, S., Collot, J. Y. (1999). Tectonic segmentation of the North Andean margin: impact of the Carnegie Ridge collision. Earth and Planetary Science Letters, 168, 255-270.
Haug, H. H., Keigwin, L. D. (2004). How the Isthmus of Panama Put Ice in the Arctic. Oceanus Magazine, 42(2).
Harmon, R. S. (2005). The Geological Development of Panama. Water Science and Technology Library, 52, 45-64.
Lowrie, A., Aitken, T., Grim, P., McRaney, L. (1979). Fossil spreading center and faults within the Panama Fracture Zone. Marine Geophysical Researches, 4(2), 153-166.
Ramos, V. A. (1999). Plate tectonic setting of the Andean Cordillera. Episodes, 22(3), 183-190.
Reed, D. L., Silver, E. A., Tagudin, J. E., Shipley, T. H., Vrolijk, P. (1989). Relations between mud volcanoes, thrust deformation, slope sedimentation, and gas hydrate, offshore north Panama. Marine and Petroleum Geology, 7. 44-54.
Schmittner, A., et al. (2004). Global Impact of the Panamanian Seaway Closure. Eos, 85(49), 526-527.
Van Bethem, S., Govers, R., Spakman, W., Wortel, R. (2013). Tectonic evolution and mantle structure of the Caribbean. Journal of Geophysical Research: Solid Earth, 118, 3019-3036.
Aslan, A., Warne, A. G., White, W. A., Guevara, E. H., et al. (2001). Mud volcanoes of the Orinoco Delta, Eastern Venezuela. Geomorphology, 41. 323-336.
Bird, P. (2003). An updated digital model of plate boundaries. Geochemistry, Geophysics, Geosystems, 4(3).
Cardona, A., Valencia, V. A., Bayona, G., Duque, J., et al. (2011). Early-subduction-related orogeny in the northern Andes: Turonian to Eocene magmatic and provenance record in the Santa Marta Massif and Rancheria Basin, northern Columbia. Terra Nova, 23, 26-34.
Cediel, F., R. P. Shaw, and C. Ca ́ceres. (2003), Tectonic assembly of the Northern Andean Block. The Circum-Gulf of Mexico and the Caribbean: Hydrocarbon habitats, basin formation, and plate tectonics: AAPG Memoir 79, 815–848.Freymueller, J. T., Kellogg, J. N., Vega, V. (1993). Plate Motions in the North Andean Region. Journal of Geophysical Research, 98(B12), 853-861.
Stern, C. R. (2004). Active Andean volcanism: its geologic and tectonic setting. Rev. Geol. Chile, 31(2), 161-206.
Gutscher, M. A., Malavielle, J., Lallemand, S., Collot, J. Y. (1999). Tectonic segmentation of the North Andean margin: impact of the Carnegie Ridge collision. Earth and Planetary Science Letters, 168, 255-270.
Haug, H. H., Keigwin, L. D. (2004). How the Isthmus of Panama Put Ice in the Arctic. Oceanus Magazine, 42(2).
Harmon, R. S. (2005). The Geological Development of Panama. Water Science and Technology Library, 52, 45-64.
Lowrie, A., Aitken, T., Grim, P., McRaney, L. (1979). Fossil spreading center and faults within the Panama Fracture Zone. Marine Geophysical Researches, 4(2), 153-166.
Ramos, V. A. (1999). Plate tectonic setting of the Andean Cordillera. Episodes, 22(3), 183-190.
Reed, D. L., Silver, E. A., Tagudin, J. E., Shipley, T. H., Vrolijk, P. (1989). Relations between mud volcanoes, thrust deformation, slope sedimentation, and gas hydrate, offshore north Panama. Marine and Petroleum Geology, 7. 44-54.
Schmittner, A., et al. (2004). Global Impact of the Panamanian Seaway Closure. Eos, 85(49), 526-527.
Van Bethem, S., Govers, R., Spakman, W., Wortel, R. (2013). Tectonic evolution and mantle structure of the Caribbean. Journal of Geophysical Research: Solid Earth, 118, 3019-3036.