Neste trabalho são caracterizados corpos sub-vulcânicos expostos no nordeste da Cordilheira Ocidental da Colômbia através de estudos petrográficos, análises geoquímicas em rocha-total e datação U-Pb por SHRIMP IIe em zircão. A área de estudo, em um contexto regional, representa um orógeno de acreção no sistema andino, constituído por rochas ígneas de afinidade oceânica amalgamadas contra a margem ocidental de América do Sul e associadas ao desenvolvimento da Grande Província Ígnea do Caribe (Caribbean Large igneous Province-CLIP). As análises em geoquímica elementar evidenciam para os corpos subvulcânicos um ambiente de subducção intra-oceânico de arco primitivo a mais evoluído, com significante contribuição de sedimentos subductados e assinaturas similares às registradas para as rochas vulcânicas e plutônicas presentes na área (Formação Barroso e Tonalito de Santa Fe e Buriticá). Dados isotópicos de Sr e Nd (razão inicial 87Sr/86Sr entre 0.70334 a 0.70543 e ?Nd entre +6.25 a +7.42) indicam uma área fonte de cunha mantélica, típica de rochas de arco, com níveis subordinados de material crustal. Idades U-Pb por SHRIMP IIe em zircão mostram cinco populações de idades correspondentes a: idades Neoarquenas ao redor de 2700 Ma, Paleoproterozoicas em torno de 2100, 2000 e 1800 Ma, Neoproterozoicas ao redor de 600 Ma, Ordovicianas/Devonianas de 460 e 360 Ma, e Cretáceas ao redor de 90 Ma. A população de idades mais novas é interpretada como a idade de cristalização dos corpos estudados, indicando uma relação espacial e temporal com as rochas ígneas da área associadas ao desenvolvimento da CLIP. As quatro populações de idades mais antigas são atribuídas a xenocristais, interpretados como provenientes de sedimentos terrígenos que foram arrastados ao canal de subducção, refletindo processos de reciclagem crustal através do manto em zonas de subducção intra-oceânicas. Foram identificadas duas possíveis áreas fontes para os xenocristais de zircão: o Complexo Marañon e o Maciço de Arequipa, que constituem inliers expostos na margem ocidental de América do Sul e apresentam uma boa correlação entre os eventos magmáticos/metamórficos que registram e às idades dos xenocristais encontrados. A partir destas interpretações, foi restringido o local de formação dos corpos estudados em relação à paleomargem continental, considerando além dados paleomagnéticos e modelos paleogeográficos publicados na zona de estudo. O trabalho fornece um aporte significativo para a compreensão da evolução tectono-magmática da região durante o Cretáceo superior, associada à história geológica da CLIP. / In this study sub-volcanic bodies exposed in the northeast of the Western Cordillera of Colombia are characterized through petrographic descriptions, geochemical analysis in bulk rocks and geochronology U-Pb SHRIMP in zircon. The area, in a regional context, represents an accretion orogen in the Andean system, it is composed of igneous rocks of oceanic affinity accreted to the western margin of South America, and they are associated to the development of the Caribbean Large igneous Province (CLIP). Based on geochemical characterization, the sub-volcanic bodies display patterns of an intra-oceanic subduction environment of primitive to evolved island arc, with significant contribution of subducted sediments, and similar signatures to those reported for the volcanic and plutonic rocks present in the area. (Barroso Formation and Santa Fe and Buriticá Tonalite). The Sr and Nd isotopic data (initial ratios 87Sr/86Sr between 0.70334 a 0.70543 and ?Nd between +6.25 a +7.42) suggest a wed mantle source, typical of arc rocks, with subordinates levels of crustal material. SHRIMP U-Pb data show five age populations that include: Neoarchean age around 2700 Ma, Paleoproterozoic age about of 2100, 2000 and 1800 Ma, Neoproterozoic age of 600 Ma, Ordovician-Devonian age of 460 and 360 Ma, and Cretaceous age around 90 Ma. The younger age population is interpreted as the crystallization age of the studied bodies; it indicated a special and temporal relation with the igneous rocks of the area which are associated with the development of the CLIP. The other four age populations are attributed to xenocrystals, they are interpreted as coming from terrigenous sediments dragged for the subduction area, reflecting process of crustal recycling through the mantle in intra-oceanic subduction zones. We restricted two possible source areas for the xenocrystals zircon: The Marañon Complex and The Arequipa Massif. They are constitute inliers exposed of the western margin of South America and present a good correlation between the magmatic/metamorphic events and the ages of the finding in our xenocristals. Based on these interpretations, we constraint the local of formation of the studied bodies closer to the continental paleomargin, considering also paleomagnetic data and paleogeographic models published in the area. The present study provides a significant contribution for the understanding tectono-magmatic evolution of the region during of Cretaceous, associated with the geological history of the CLIP.

L’histoire et les mécanismes de soulèvement des Andes centrales ont fait l'objet de débats animés depuis les années 1970. Notre étude se concentre sur l’analyse de la déformation Cénozoïque et de l'exhumation des Andes Centrales dans la région du Sud Pérou : à Cuzco, et dans la région de Nazca entre les cordillères Occidentale et Côtière. En effet, plusieurs auteurs soulignent le rôle du raccourcissement tectonique dans l'épaississement de la croûte, dans l’avant-arc Chilien ou à l’Est dans la région Subandine. Dans les modèles de déformation tectonique active issus du GPS, aucun raccourcissement ni transpression n’est pris en compte sur la bordure Occidentale des Andes au Cénozoïque ou dans les modèles de déformation crustale issus du GPS. La nouvelle cartographie des systèmes de failles actives dans la région sud du Pérou donnent un aperçu de la déformation active à l’échelle crustale pour la marge Pacifique des Andes Centrales. La géomorphologie et les paysages de l'avant-arc andin ont classiquement été présentés comme fossiles depuis le Miocène, sans évidence de structures actives accommodant la déformation cénozoïque. Cependant, les surfaces géomorphologiques bien préservées développées dans l'avant-arc du sud du Pérou fournissent d'excellents marqueurs et des évidences de déformation très nettes depuis le Cénozoïque jusqu’au Quaternaire récent. Ces marqueurs montrent tous un soulèvement des Andes le long de la marge ouest depuis les derniers Millions d’années. Bien que l’initiation et l’évolution de l'exhumation et du soulèvement cénozoïque aient été étudié dans les canyons de Colca et de Cotahuasi, il demeure peu contraint dans le segment nord de l'avant – arc, i.e., dans la région de Nazca. Dans cette étude, nous avons choisi d’apporter de nouvelles données (U-Th)/He et traces de fission sur apatite (AHe) et (AFT) respectivement dans cette région. L’échantillonnage a porté sur la Cordillère Occidentale entre Cañete et Nazca le long de deux nouvelles coupes transversales à la topographie. Le profil Age/Distance à la côte indique une mise en place de relief dans la région Andine au début du Miocène et une évolution découplée des deux systèmes de cordillères Cotière et Occidentale en terme d’exhumation dans le temps. A l’échelle Quaternaire, nous avons cartographié les failles actives pour déterminer leur géométrie, cinématique et les âges maximaux de l’activation de ces failles. Ceci afin de discuter du rôle de cette activité tectonique, précédemment supposée Miocène, dans le soulèvement et l’exhumation de l’avant-arc Andin. Nous avons utilisé la production et l’accumulation du 10Be cosmogénique dans les roches pour déterminer les âges d'exposition d’un escarpement tectonique marquant les derniers épisodes co-sismiques de la faille de Purgatorio. Nos nouveaux résultats, contrastent avec des conclusions précédentes qui concluaient à de l’extension et des vitesses lentes le long de l’avant arc Andin (<0.1mm/an). Les âges très récents indiquent une morphologie « historique » (free face) et deux tremblements de terre Mw6-7 sur ce système de failles transpressives qui se connectent au système principal d’Incapuquio. Les données suggèrent non seulement une déformation active significative de l’avant-arc, mais soulignent aussi l’existence d’un aléa sismique qui n’est toujours pas pris en compte pour les failles crustales dans les Andes. Tandis que l’hypothèse acceptée est que la déformation active est localisée dans le bassin d’avant pays subandin, ou à l’est de la cordillère orientale, nos données suggèrent qu’une partie de la déformation active se localise aussi sur la marge Occidentale ainsi que le long de la faille d'Incapuquio. De plus, les failles observées en néotectonique accommoderaient le partitionnement de la déformation le long de la subduction oblique et ceci n’a jamais été discuté précédemment. Ce mouvement, rigide, en bloc serait du à la présence du craton accrété sur le flanc Ouest et à sa rigidité. / ABSTRACTTiming and mechanisms of uplift in the Central Andes have been a matter of debate since at least the 1970’s. Our study focuses on Cenozoic deformation and exhumation of the Central Andean forearc in Peru, in Cuzco region, and between the Western Cordillera and the Coastal Cordillera in Nazca region. Our new mapping of active faults provides new insights into the Cenozoic to present-day crustal deformation of the Central Andean Western margin. Until now, apart from some local studies, the geomorphology of the Andean forearc has classically been presented as a remnant Miocene landscape with no significant active structures accommodating the Cenozoic deformation. Thanks to new high-resolution optical imagery, the well-preserved geomorphic surfaces developed within the forearc of southern Peru provide excellent regional markers to map patterns of deformation. Pertaining to the Cenozoic history, while the timing of uplift-related exhumation and Cenozoic exhumation has been studied in Colca and Cotahuasi canyons, it remain poorly constrained in the northern segment of the Central Andean forearc. I report new apatite (U–Th)/He (AHe) and fission track (AFT) ages from the western Cordillera between Cañete and Nazca along two new cross sections. The ages in Nazca region reflect relatively recent (since ~10Ma) relief creation along the western margin of the Altiplano, similar to what is described south in Colca region.The Quaternary tectonic history is revealed by the newly mapped fault segments affecting the Miocene deposits within forearc. Through field and remote mapping, I determined fault geometries and maximum ages for the activity of the faults systems based on stratigraphic relationships in order to assess the role of this tectonic activity in the Western Cordillera uplift and exhumation.To understand the Holocene tectonic history, we use in situ produced 10Be to determine the exposure ages of the free face and tectonic scarp of the Purgatorio Fault in order to map the temporal evolution of its seismotectonic activity. Our new results display evidence of transpression and the formation of meter-high coseismic scarps as well as very recent exposure ages indicating a youthful fault morphology and Mw6-7 earthquakes occurring along the Purgatorio fault segments. These new data are in contrast with some previous conclusions for this region which suggest extension and/or slow rates of deformation for this region and time period. Further, these new data not only suggest significant active deformation within the forearc, but also highlight a potential seismic hazard for the region that not take into account crustal forearc faults.While the general assumption is that active deformation is localized in the Subandean fold and thrust belt, or east of the Western Cordillera in the Altiplano, our data support a model where active deformation is occurring in the western margin as well, along the Incapuquio Fault and other neotectonic faults that accommodates the partitioning of the subduction oblique convergence.These crustal active faults and more precisely the “not migrating to the trench” Incapuquio fault zone reveal the rigid motion of the forearc. Our new model is nevertheless compatible with the recently published GPS data that measure a southeastward movement at 4–5 mm/yr relative to a stable South America reference frame. This rigid motion is in part due to the presence of the rigid Greenvillian accreted craton, that behave as a sliver, and rather tilt than deform through time.

Neste trabalho são caracterizados corpos sub-vulcânicos expostos no nordeste da Cordilheira Ocidental da Colômbia através de estudos petrográficos, análises geoquímicas em rocha-total e datação U-Pb por SHRIMP IIe em zircão. A área de estudo, em um contexto regional, representa um orógeno de acreção no sistema andino, constituído por rochas ígneas de afinidade oceânica amalgamadas contra a margem ocidental de América do Sul e associadas ao desenvolvimento da Grande Província Ígnea do Caribe (Caribbean Large igneous Province-CLIP). As análises em geoquímica elementar evidenciam para os corpos subvulcânicos um ambiente de subducção intra-oceânico de arco primitivo a mais evoluído, com significante contribuição de sedimentos subductados e assinaturas similares às registradas para as rochas vulcânicas e plutônicas presentes na área (Formação Barroso e Tonalito de Santa Fe e Buriticá). Dados isotópicos de Sr e Nd (razão inicial 87Sr/86Sr entre 0.70334 a 0.70543 e ?Nd entre +6.25 a +7.42) indicam uma área fonte de cunha mantélica, típica de rochas de arco, com níveis subordinados de material crustal. Idades U-Pb por SHRIMP IIe em zircão mostram cinco populações de idades correspondentes a: idades Neoarquenas ao redor de 2700 Ma, Paleoproterozoicas em torno de 2100, 2000 e 1800 Ma, Neoproterozoicas ao redor de 600 Ma, Ordovicianas/Devonianas de 460 e 360 Ma, e Cretáceas ao redor de 90 Ma. A população de idades mais novas é interpretada como a idade de cristalização dos corpos estudados, indicando uma relação espacial e temporal com as rochas ígneas da área associadas ao desenvolvimento da CLIP. As quatro populações de idades mais antigas são atribuídas a xenocristais, interpretados como provenientes de sedimentos terrígenos que foram arrastados ao canal de subducção, refletindo processos de reciclagem crustal através do manto em zonas de subducção intra-oceânicas. Foram identificadas duas possíveis áreas fontes para os xenocristais de zircão: o Complexo Marañon e o Maciço de Arequipa, que constituem inliers expostos na margem ocidental de América do Sul e apresentam uma boa correlação entre os eventos magmáticos/metamórficos que registram e às idades dos xenocristais encontrados. A partir destas interpretações, foi restringido o local de formação dos corpos estudados em relação à paleomargem continental, considerando além dados paleomagnéticos e modelos paleogeográficos publicados na zona de estudo. O trabalho fornece um aporte significativo para a compreensão da evolução tectono-magmática da região durante o Cretáceo superior, associada à história geológica da CLIP. / In this study sub-volcanic bodies exposed in the northeast of the Western Cordillera of Colombia are characterized through petrographic descriptions, geochemical analysis in bulk rocks and geochronology U-Pb SHRIMP in zircon. The area, in a regional context, represents an accretion orogen in the Andean system, it is composed of igneous rocks of oceanic affinity accreted to the western margin of South America, and they are associated to the development of the Caribbean Large igneous Province (CLIP). Based on geochemical characterization, the sub-volcanic bodies display patterns of an intra-oceanic subduction environment of primitive to evolved island arc, with significant contribution of subducted sediments, and similar signatures to those reported for the volcanic and plutonic rocks present in the area. (Barroso Formation and Santa Fe and Buriticá Tonalite). The Sr and Nd isotopic data (initial ratios 87Sr/86Sr between 0.70334 a 0.70543 and ?Nd between +6.25 a +7.42) suggest a wed mantle source, typical of arc rocks, with subordinates levels of crustal material. SHRIMP U-Pb data show five age populations that include: Neoarchean age around 2700 Ma, Paleoproterozoic age about of 2100, 2000 and 1800 Ma, Neoproterozoic age of 600 Ma, Ordovician-Devonian age of 460 and 360 Ma, and Cretaceous age around 90 Ma. The younger age population is interpreted as the crystallization age of the studied bodies; it indicated a special and temporal relation with the igneous rocks of the area which are associated with the development of the CLIP. The other four age populations are attributed to xenocrystals, they are interpreted as coming from terrigenous sediments dragged for the subduction area, reflecting process of crustal recycling through the mantle in intra-oceanic subduction zones. We restricted two possible source areas for the xenocrystals zircon: The Marañon Complex and The Arequipa Massif. They are constitute inliers exposed of the western margin of South America and present a good correlation between the magmatic/metamorphic events and the ages of the finding in our xenocristals. Based on these interpretations, we constraint the local of formation of the studied bodies closer to the continental paleomargin, considering also paleomagnetic data and paleogeographic models published in the area. The present study provides a significant contribution for the understanding tectono-magmatic evolution of the region during of Cretaceous, associated with the geological history of the CLIP.