Examinando por Materia "Subduction zone"

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    Ítem
    Protolith and metamorphic conditions of the metapelites from the Rio Claro Region (Antioquia Departament)
    (Universidad EAFIT, 2021) Madrid Restrepo, Diana Carolina; Bustamante Londoño, Camilo
    The Cajamarca Complex is distributed along the Central Cordillera of Colombia, its formation is attributed to a Permian subduction zone, volcanic arc magmatism, opening and closing of basins and accretion of terrenes. The 16 samples studied in this research crop out near Rio Claro in the department of Antioquia. The analyzes were made with 7 metasedimentary, 2 metabasic belonging to the Cajamarca Complex and 7 pegmatites related to the magmatism of the Antioquia Batholith. Detailed petrography of the samples was performed and did total rock geochemistry for metamorphic rocks for analysis of major and trace elements. This study focuses on discussing the tectonic environment of protolith formation based on tectonic discrimination diagrams and P-T conditions for metamorphism, based on mineralogical reactions. In the N-MORB analysis it shows an enrichment in the LILE and a depleting in the HFSE, in the same way an inverse relationship is observed of the rare earth elements (REE) normalized with the primitive mantle. The metasedimentary rocks are mainly formed by quartz, muscovite, biotite, graphite, Andalusite and as accessory minerals titanite and zircon; the metabasics are composed of epidote, actinolite, chlorite, hornblende, and plagioclase. The P-T conditions yields a pressure of 6 to 4 kbar and a temperature that did not exceed 550 ° C. This represents a metamorphic gradient of medium pressure and medium temperature indicating a passage through the green schist to epidote-amphibolite facies which is linked to a Barrovian type metamorphism. This type of regional metamorphism led toward a depth approximately of 20 km. In this work it is suggested that the formation of the sedimentary protolith is in the accretion wedge of a subduction zone, unlike the igneous protolith that would be part of the formation of the crust. oceanic; this differs from what Blanco-Quintero et al. (2014) proposes south of the Cajamarca Complex. This oceanic crust would later subduct to the paleo western margin of South America; where the metamorphic event would finally be generated.
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    Ítem
    Segmentación estructural del plano de subducción de la placa Caribe en las cuentas Guajira y Sinú Offshore
    (Universidad EAFIT, 2021) Porras Morales, Sergio Alejandro; Alzate Rubio, Valentina; Duque Trujillo, José Fernando; Beltrán Triviño, Alejandro Iván
    Evidence such as seismic activity, geomorphological features such as diapirism and mud volcanism, accretionary prisms and the analysis of geodetic data, etc. indicate that the Colombian Caribbean is structurally segmented and that a subduction zone continues operating in an oblique convergent margin. To verify the above, seismic interpretation, surface modeling and calculation of focal mechanism solutions were carried out in the area between the offshore Sinú and offshore Guajira basins. The products obtained reflect different stress regimes from transtensive to transpressive throughout the study area, within the same convergent tectonic configuration, whose segmentation is represented by the Sierra Nevada de Santa Marta area between the Cuiza fault system and the offshore lineament of the Santa Marta-Bucaramanga fault system. Therefore, it was determined that in the Colombian Caribbean the subduction plane of the Caribbean plate is segmented and subducting at different shallow angles under the South American plate.