Exhumation and uplift of the Southern Colombian Andes: implications for the migration of hydrocarbons into the Putumayo Basin

• Ano de defesa: 2024
• Autor(a) principal: Rodriguez, Eduer Giovanny Nova
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Exhumation; não disponível; Northern Andes; Orogenesis; Sedimentary provenance; Thermochronology
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/44/44141/tde-13112024-090851/

The Cenozoic Northern Andes building exhibits a complex history in subduction-related orogens with implications for paleogeography of the western Amazon Basin and the accumulation of mineral resources. This project examines the impact of the orogenic growth of the Colombian southern segment (0.5°-2°N Lat) of the Eastern Cordillera on the hydrocarbon generation in the Putumayo Basin. The initial phases of orogenic growth were evaluated through a multi-proxy provenance analysis of syn-orogenic sequences within the retroforeland of the Putumayo Basin. Our findings are based on new stratigraphic evidence, conglomerate clast counts, sandstone petrography, detrital zircon U-Pb geochronology data, and novel apatite detrital U-Pb age-light rare earth element analysis (AUPb-LREE) data, indicate that the change in sandstone composition and polarity of the U-Pb signatures are a consequence of the Eastern Cordillera exhumation, which began during the Late Cretaceous when the Caribbean plate collided obliquely with the South American plate. This phase of early exhumation is characterized by the uplift of the Central Cordillera, concurrent with the development of unroofed inverted intraplate highs of the Eastern Cordillera, thus forming the Putumayo Basin as a broken foreland. The subsequent growth stage was evaluated along two 2D geological cross-sections to quantify the exhumation rates and deformation mode. A total of 30 new and 14 previously published thermochronometric ages (ZHe, AFT, AHe) and new reflectance vitrinite data were obtained and thermokinematically modeled. The modeling was conducted initially along the southern section (1oN Lat), where the onset of cooling by exhumation occurred at 45 Ma in Jurassic granitoids and volcanoclastic sequences inverted in inherited east- vergence faults. The second northern section (1.7oN Lat) of the Garzon Massif, which is composed of Mesoproterozoic high-grade metamorphic rocks, was exhumed at 66 Ma in a transpressive regime related to the Algeciras Fault System along the inherited low-angle west-vergence Suaza Fault. The exhumation of the southern segment of EC was asynchronous with an acceleration in the last 10 Ma, with rates ranging from 0.13 to 0.35 km/Myr for the southern section and from 0.05 to 0.13 km/Myr for the northern section. The development of intraplate highs in the Paleogene and accelerated orogenic construction in the Late Miocene restricted hydrocarbon accumulation in the Putumayo Basin to an earlier age than previously documented. Furthermore, this accelerated uplift in the last 10 Ma allowed for the modification of drainage patterns in the Putumayo Basin, isolating it from the intermontane basin of the Upper Magdalena Valley located in the westernmost part of the Amazon Basin, which was intermittently connected throughout the Paleocene.