Volume 1 Quaternary Chapter 10 Neogene https://doi.org/10.32685/pub.esp.35.2019.10 Fragments of a Permian Arc on the Western Published online 26 September 2019 Margin of the Neoproterozoic Basement of Colombia Paleogene Gabriel RODRÍGUEZ–GARCÍA1* , Ana María CORREA–MARTÍNEZ2 , 1 [email protected] Servicio Geológico Colombiano 3 4 Juan Pablo ZAPATA–VILLADA , and Gloria OBANDO–ERAZO Dirección de Geociencias Básicas Grupo de Estudios Geológicos Especiales Cretaceous Calle 75 n.° 79A–51 Abstract New petrographic, whole–rock geochemical, and U–Pb–zircon geochro- Medellín, Colombia nologic data combined with data from previous studies enabled identification of 2 [email protected] a fragmented Permian magmatic arc with ages ranging from 294 to 260 Ma in the Servicio Geológico Colombiano Dirección de Geociencias Básicas Colombian Andes. The arc is exposed along the southeastern slope of the Central Grupo de Estudios Geológicos Especiales Calle 75 n.° 79A–51 Jurassic Cordillera towards the Upper Magdalena Valley, serranía de San Lucas, and Sierra Medellín, Colombia Nevada de Santa Marta. 3 [email protected] Servicio Geológico Colombiano The arc fragments consist of plutons on the western margin of the Neoproterozo- Dirección de Geociencias Básicas ic basement and show wide lithological variation in both igneous (monzodiorites, Grupo de Estudios Geológicos Especiales Calle 75 n.° 79A–51 Triassic quartz monzonites, tonalites, granodiorites, monzogranites, and syenogranites) and Medellín, Colombia metamorphic (migmatites, gneisses, and mylonitic gneisses) rocks. The granites have 4 [email protected] Servicio Geológico Colombiano a metaluminous to peraluminous character and correspond to calc–alkaline to high– Dirección de Geociencias Básicas potassium calc–alkaline series formed in a continental arc environment. Some bodies Grupo de Estudios Geológicos Especiales Calle 75 n.° 79A–51 Medellín, Colombia are associated with metamorphic rocks (La Plata Granite and Icarco Complex), which Permian may correspond to the roots of the arc, and others show superimposed dynamic meta- * Corresponding author morphism (the Nechí Gneiss and El Encanto Orthogneiss). The Permian plutons, un- identified in previous studies because of their lithological similarities to the volume of Supplementary Information: magmatism that occurred during the Early to Middle Jurassic, are dispersed along with S: https://www.sgc.gov.co/LibroGeologiaColom- bia/tgc/sgcpubesp35201910s.pdf the Neoproterozoic basement. The Permian plutonism that intruded the basement of Carboniferous the northern Andes possibly originated in a subduction zone located on the western margin of Gondwana. Keywords: geochemistry, U–Pb geochronology, Colombian Andes, igneous and metamorphic rocks. Devonian Resumen Nuevos datos de petrografía, geoquímica de roca total y geocronología U–Pb en circón junto con la reinterpretación de datos reportados en trabajos previos per- mitieron identificar en los Andes colombianos un arco magmático fragmentado con Silurian actividad entre 294 y 260 Ma. Este arco está expuesto a lo largo del flanco suroriental de la cordillera Central en el Valle Superior del Magdalena, la serranía de San Lucas y la Sierra Nevada de Santa Marta. Los fragmentos de arco consisten en plutones localizados en la margen occidental del basamento neoproterozoico y presentan una amplia variación litológica entre ro- Ordovician Citation: Rodríguez–García, G., Correa–Martínez, A.M., Zapata–Villada, J.P. & Obando–Erazo, G. 2019. Frag- ments of a Permian arc on the western margin of the Neoproterozoic basement of Colombia. In: Gómez, J. & Mateus–Zabala, D. (editors), The Geology of Colombia, Volume 1 Proterozoic – Paleozoic. Servicio Geológi- Cambrian co Colombiano, Publicaciones Geológicas Especiales 35, p. 205–239. Bogotá. https://doi.org/10.32685/pub. esp.35.2019.10 205 Proterozoic RODRÍGUEZ–GARCÍA et al. cas ígneas (monzodioritas, cuarzomonzonitas, tonalitas, granodioritas, monzogranitos y sienogranitos) y metamórficas (migmatitas, gneises y gneises miloníticos). Los grani- tos son de carácter metaluminoso a peraluminoso y corresponden a la serie calcoal- calina a calcoalcalina alta en potasio, formados en un ambiente de arco de margen continental. Algunos cuerpos presentan rocas metamórficas asociadas (Granito de La Plata y Complejo Icarco) que pueden corresponder a las raíces del arco, mientras que otros exhiben metamorfismo dinámico sobreimpuesto (Gneis de Nechí y Ortogneis El Encanto). Los plutones pérmicos están dispersos con el basamento neoproterozoico y no se habían identificado en trabajos anteriores debido a sus similitudes litológicas con el magmatismo que ocurrió durante el Jurásico Temprano a Medio. El plutonismo pérmico que intruye el basamento de los Andes del norte posiblemente se originó en una zona de subducción localizada en la margen occidental de Gondwana. Palabras clave: geoquímica, geocronología U–Pb, Andes colombianos, rocas ígneas y metamórficas. 1. Introduction We describe a new unit termed the Ortega Granite and characterize and compare the different Permian plutons using Permian age rocks in Colombia have been described in the core petrographic, whole–rock geochemical, and zircon U–Pb laser of the Central Cordillera, in the serranía de San Lucas and in the ablation inductively coupled plasma mass spectrometry (LA– Sierra Nevada de Santa Marta, without clear differentiation be- ICP–MS) geochronological data. Regional geologic maps have tween metamorphic belts, granitoids, and peraluminous granitic been improved, and the spatial distribution of the Permian arc gneisses (Cardona et al., 2010a, 2010b; Cochrane et al., 2014; blocks was determined. Leal–Mejía, 2011; Restrepo et al., 2011; Spikings et al., 2015; Vinasco et al., 2006). 2. Geologic Setting Different models have been proposed for the formation of these units: (i) a Permian – Triassic collisional orogen (Tahamí The Neoproterozoic basement of the Colombian Andes con- Terrane; Restrepo & Toussaint, 1989; Martens et al., 2014) sists of blocks and tectonically scattered outcrops in the Upper that formed during the development of Pangea (Vinasco et al., Magdalena Valley (UMV), Eastern Cordillera, serranía de San 2006), (ii) a continental arc followed by anatexis during the Lucas, Sierra Nevada de Santa Marta, and La Guajira (Figure Triassic (Spikings et al., 2015), (iii) a post–collisional anatectic 1). These blocks are included in the Chibcha Terrane (Restrepo event that formed granites at 280 Ma (Piraquive, 2017) and 228 & Toussaint, 1989; Restrepo et al., 2009), recently described as Ma (Vinasco et al., 2006), and (iv) a continental arc that was the Putumayo Orogen (Ibañez–Mejia et al., 2011, 2015). Paleo- along the western boundary of the Neoproterozoic basement zoic marine sedimentary sequences overlie this basement. These (Cardona et al., 2010b; Rodríguez et al., 2014, 2017). rocks are intruded by Carboniferous arc plutons, such as the The description of plutons that comprise the Permian arc Carmen Stock (Leal–Mejía, 2011), and by Permian arc plutons, on the western boundary of the Chibcha Terrane presented in such as La Plata Granite (Leal–Mejía, 2011; Rodríguez et al., this study was conducted by the Servicio Geológico Colombia- 2017), the Nechí Gneiss (Restrepo et al., 2011; Rodríguez et al., no (SGC) and from a compilation of previous studies (Cardo- 2014), and the mylonitic granitoids of the Sierra Nevada de San- na et al., 2010b; Leal–Mejía, 2011; Piraquive, 2017; Restrepo ta Marta (Cardona et al., 2010b; Piraquive, 2017). The available et al., 2011; Rodríguez et al., 2014, 2017; Villagómez, 2010). geochronological data of the Permian magmatism in Colombia The plutons that form the Permian arc defined in this study are outlined in Table 1. Subsequent to intrusion, local continental are along the eastern margin of the Central Cordillera and in and marine sequences were deposited during the Triassic. the Upper Magdalena Valley (La Plata Granite sensu Rodrí- guez, 1995a; Leal–Mejía, 2011; Rodríguez et al., 1998, 2017; Velandia et al., 1999, 2001a; the Ortega Granite, this study), Figure 1. (a) Occurrences of Permian igneous rocks in the Colom- serranía de San Lucas (Nechí Gneiss sensu Restrepo et al., bian Andes. Modified from Gómez et al. (2015a). Data source: U–Pb zircon ages from Cardona et al. (2010b), Cochrane (2013), Cochrane 2011; Leal–Mejía, 2011; Rodríguez et al., 2014), and Sierra et al. (2014), Gómez et al. (2015b), Leal–Mejía (2011), Piraquive, Nevada de Santa Marta (mylonitic granitoids sensu Cardona (2017), Restrepo et al. (2011), Rodríguez et al. (2017), Villagómez et al., 2010b, subsequently named El Encanto Orthogneiss (2010), and this study. (b) Proposed distribution of metamorphic sensu Piraquive, 2017). basement units in the regions related to Permian magmatism. 206 Fragments of a Permian Arc on the Western Margin of the Neoproterozoic Basement of Colombia a GGuajirauajira 78° W 75° W 72° W RegionRegion Caribbean Sea Cuisa Fault 2276.576.5 ± 55.1.1 Oca Fault 2274.874.8 ± 22.1.1 SSanta Marta–Bucaramanga Fault 2238.6738.67 ± 66.1.1 a 10° N n 10° N t a M a r Sierra Nevada de t a – Venezuela Santa Marta B u c Panamá a r a m a n g a F a 2277.377.3 ± 33.0.0 u l Upper Magdalena Valley t ++4.44.4 281.5281.5--4.54.5 and Ibagué 2262.762.7 ± 22.1.1 274.0274.0 ± 22.3.3 293.8293.8 ± 22.7.7 277.6277.6 ± 22.4.4 2277.877.8 ± 22.2.2 280.1280.1 ± 22.0.0 2274.574.5 ± 55.3.3 t l u a F Permian a n ti s le a Serranía de San Lucas 5° N P 5° N 274.8274.8 ± 22.3.3 2274.874.8 ± 44.6.6 2277.977.9 ± 22.1.1 0 50 100 150 200 250 km 2272.072.0 ± 66.8.8 lt b u a Colombian metamorphic basement F ta la Algeciras Fault P 1 a SNSM L 2 – Pacic Ocean a 3 m s u h CChusma–La Plata Fault 5 MMedellínedellín 4 6 BBogotáogotá 7 Ecuador 78° W 75° W 72° W Jurassic units Triassic – Jurassic Central Faults 4 Bucaramanga Fault U–Pb in this work (plutons and volcanic units) Cordillera basement 1 Cuisa Fault 5 Otu–Pericos Fault Paleozoic metamorphic Permian arc U–Pb others authors basement 2 Oca Fault 6 Palestina Fault Precambrian basement Neoproterozoic basement 3 Santa Marta Fault 7 Algeciras Fault 207 RODRÍGUEZ–GARCÍA et al.