HR: 1340h
AN: T13C-1469    [Abstracts]
TI: Provenance And Tectonomagmatic Setting Of The Santa Marta Schists, Northern Colombia Caribbean Region: Insights On The Styles Of Growth And Approach Of Caribbean Intra- Oceanic Domains To The Continental Margin
AU: * Cardona, A
EM: cardonaa@si.edu
AF: Smithsonian Tropical Research Institute, Balboa, Ancon, Panama, 0843-0392, Panama
AU: * Cardona, A
EM: cardonaa@si.edu
AF: Ecopetrol, Km 7, via Piedecuesta, Piedecuesta, Na, Colombia
AU: Jaramillo, C
EM: jaramillo@si.edu
AF: Smithsonian Tropical Research Institute, Balboa, Ancon, Panama, 0843-0392, Panama
AU: Ojeda, G
EM: german.ojeda@ecopetrol.com.co
AF: Ecopetrol, Km 7, via Piedecuesta, Piedecuesta, Na, Colombia
AU: Ruiz, J
EM: jruiz@email.arizona.edu
AF: University of Arizona, Gould-Simpson Building 1040 East Fourth St, Tucson, Arz 85721-0077, United States
AU: Valencia, V
EM: victorv@email.arizona.edu
AF: University of Arizona, Gould-Simpson Building 1040 East Fourth St, Tucson, Arz 85721-0077, United States
AU: Weber, M
EM: mweber@unalmed.edu.co
AF: Universidad Nacional, Calle 59A No 63 - 20, Medellin, Na, Colombia
AB: The life cycle of an intra-oceanic terranemincludes different phases and styles of magmatic growth, accretion with other terranes and translation before reaching a continental margin. In order to unveil the nature of these phases in crystalline rocks from northern Colombia, U/Pb LA-MC-ICP-MS detrital geochronology and whole rock geochemical data were obtained from stacks of intercalated metavolcanic-sedimentary rocks of the Santa Marta Schists in the Sierra Nevada de Santa Marta. Immobile elements whole rock geochemistry from greenschist to amphibolite facies units are characterized by low to moderate LREE/HREE, variable Th enrichment and weakly negative Nb and Ti anomalies, which are similar to island arc and MORB signatures. The intercalated metasedimentary rocks show a REE pattern similar to the PAAS and high Zr/Sc vs Th/Sc ratios, which suggest a felsic and highly diferentiated upper crust sources for the protoliths. Detrital zircons from three different units were obtained, The maximum depositional age for the northwestern unit is limited to the late Cretaceous, with a major peak of 83 Ma. Variable input of older crustal sources with Jurassic (153 Ma), Permo-Triassic (250-290 Ma), Cambrian to Late Neoproterozoic (520-560 Ma) and Middle Mesoproterozic (1000-1500 Ma) ages which are clearly recognized in older units of the Sierra Nevada de Santa Marta massif and the northern South American basement are also recorded. This type of volcano-sedimentary record within an intra-oceanic arc bears strong similarities with the modern Lesser-Antilles and the Tonga-Kermadec arcs, where continentally derived sediments can be transported houndred of kilometers to the fore-arc, back-arc or the accretionary prism of the active intra-oceanic arc. This record also suggests that this arc has an intra-Americas position, near to its final accretionary stop. Although the metamorphic overprint has obliterated the stratigraphic relations, apparent variations of the LREE/HREE in the metavolcanics and the preservation of continentally derived sediments, can be ascribed to variation in the sediment subduction vs accretion sediment budget in an evolving back-arc basin. Similar lithostratigraphic associations within the Caribbean metamorphosed and unmetamorphosed magmatic and sedimentary units can be related to a similar detrital continental input, whereas, the existence of coherent metamorphosed pre-Mesozoic crustal elements within subduction-accretion complexes, may reflect the existence of continental islands that were detached during the initial proto-Caribbean rifting phases and mixed within intra-oceanic accretionary prisms.
DE: 1000 GEOCHEMISTRY
DE: 8100 TECTONOPHYSICS
DE: 8139 Obduction tectonics
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting