Petrografía, geoquímica y geocronología U/Pb en circones de rocas ígneas y metamórficas a lo largo del Río Cuiarí en el sur del Departamento de Guainía, Colombia

Abstract

55Petrografía, geoquímica y geocronología U/Pb en circones de rocas ígneas y metamórficas a lo largo del Río Cuiarí en el sur del Departamento de Guainía, Colombia . (2019). Petrografía, geoquímica y geocronología U/Pb en circones de rocas ígneas y metamórficas a lo largo del Río Cuiarí en el sur del Departamento de Guainía, Colombia. Petrography, geochemistry and zircon U/Pb geochronology in igneous and metamorphic rocks, Cuiarí River, south of Guainía department, Colombia ABSTRACTIn order to archive a better understanding of the Rio Negro-Juruena Geochronological Province (1.55-1.8 Ga) of the Amazonian Craton in SE-Colombia, we performed analyses of metamorphic, igneous and metasedimentary rocks outcropping in vicinity of the Cuiarí-River in the south of Guainía Department, near the Brazilian border. Based on field observations, mineralogical, geochemical and U/Pb LA-ICP-MS analysis in zircons, we could identify in the study area a Statherian basement which forms the Mitú Complex. It is composed by Petrografía, geoquímica y geocronología U/Pb en circones de rocas ígneas y metamórficas a lo largo del Río Cuiarí en el sur del Departamento de Guainía, Colombia

Apatite LA-ICP-MS U–Pb and fission-track geochronology of the Caño Viejita gabbro in E-Colombia: Evidence for Grenvillian intraplate rifting and Jurassic exhumation in the NW Amazonian Craton

“…Departamento Nacional da Producäo Mineral, 1976;Huguett, 1977;Kroonenberg and de Roever, 2010;PRORADAM, 1979;Putzer, 1984) and dedicated field work produced a wealth of new data. These studies have led in the 70th to the recognition of the Mitú Migmatitic Complex (Galvis et al, 1979;Rodríguez et al, 2011), later called the Mitú Complex (Bonilla et al, 2019;López et al, 2007) as part of the 1.80-1.55 Ga Rio Negro-Juruena Geochronological Province (Figure 2) in Colombia (Tassinari et al, 1996;Tassinari and Macambira, 1999). Large parts of the Mitú Complex (Figure 3) are composed of monzogranites with calc-alkaline characteristics, and meta-to peraluminous affinity with an U-Pb LA-MC-ICPMS age for the Mitú granite of 1574 ± 10 Ma (Ibáñez-Mejía et al 2011), as well as of other granites: Among the clearly metamorphic rocks prevail quartzo-feldspathic gneisses with zircon U-Pb ages between 1800-1760 Ma (Bonilla et al, 2019;Cordani et al, 2016;Kroonenberg, 2019;López et al, 2007).…”

“…These studies have led in the 70th to the recognition of the Mitú Migmatitic Complex (Galvis et al, 1979;Rodríguez et al, 2011), later called the Mitú Complex (Bonilla et al, 2019;López et al, 2007) as part of the 1.80-1.55 Ga Rio Negro-Juruena Geochronological Province (Figure 2) in Colombia (Tassinari et al, 1996;Tassinari and Macambira, 1999). Large parts of the Mitú Complex (Figure 3) are composed of monzogranites with calc-alkaline characteristics, and meta-to peraluminous affinity with an U-Pb LA-MC-ICPMS age for the Mitú granite of 1574 ± 10 Ma (Ibáñez-Mejía et al 2011), as well as of other granites: Among the clearly metamorphic rocks prevail quartzo-feldspathic gneisses with zircon U-Pb ages between 1800-1760 Ma (Bonilla et al, 2019;Cordani et al, 2016;Kroonenberg, 2019;López et al, 2007). Medium grade amphibolite facies metamorphic rocks within a series of essentially juvenile magmatic arcs in the Rio Negro Juruena province are interpreted as subductionrelated by several workers (Cordani et al, 2016;Tassinari and Macambira, 1999).…”

“…Younger granitoids in its SE-part (especially Guainia Department) exhibit variable compositions, porphyritic textures and may contain ovoid feldspar phenocrysts that crystallized some 1750 Ma ago during the Statherian (Bonilla et al, 2019).…”

“…On this Statherian basement, a metasedimentary sequence, associated with the Tunui Group in Brazil (Almeida et al, 2004;Santos et al, 2003) was deposited about 1720 -1600 Ma ago (Bonilla et al, 2019) and extends to the north into the Naquen and Caranacoa mountains (Figure 2). This Precambrian cover in the south of Guainia Department contains an upper quartzite facies, partly tourmalinized, locally influenced by metasomatism which may be responsible for gold deposits in this area and associated with a two-mica granite intrusion some 1600-1550 Ma ago (Bonilla et al, 2019). The latter is probably part of the Rio Içana Intrusive Suite described in Brazil (Almeida et al, 2004;Almeida and Larizzatti, 1996;Carneiro et al, 2017aCarneiro et al, , 2017bVeras, 2012), and evolved by partial melting of cratonic protoliths (Almeida et al, 1997).…”

“…These provinces have been (re)defined and refined over the last years and the exact positions of their boundaries is still a matter of debate (Cordani et al, 2009(Cordani et al, , 1979Kroonenberg, 2019;Santos et al, 2000;Tassinari and Macambira, 1999;Teixeira et al, 1989). The NW Amazonian Craton that outcrops in Eastern Colombia yields ages between ~1.86-1.70 Ga and is defined as part of the Mitú Migmatitic Complex (Galvis et al, 1979;Rodríguez et al, 2011) or better the Mitú Complex (Bonilla et al, 2019;López et al, 2007). This Mitú Complex is itself a portion of the 1.86-1.55 Ga Rio Negro-Juruena Geochronological Province (Tassinari et al, 1996;Tassinari and Macambira, 1999).…”