Magmatismo Rapakivi en La Cuenca Media Del Río Inírida, Departamento De Guainía, Colombia

Abstract

. 2016. Magmatismo rapakivi en la cuenca media del río Inírida, departamento de Guainía, Colombia. Boletín de Geología, 38 (1): 17-32. RESUMENDurante el Mesoproterozoico varios granitos rapakivi intruyeron el basamento cristalino en el oriente colombiano aflorando en varios sitios como en las comunidades indígenas de Danta y Matraca, en la cuenca media del río Inírida en el departamento de Guainía, donde están cubiertos con rocas sedimentarias del Terciario y depósitos cuaternarios. Análisis petrográficos y geoquímicos revelan que se trata de un cuerpo porfirítico, holocristalino, leucocrático, grosogranular y de composición monzonítica a granodiorítica con textura rapakivi tipo piterlita, indicando afinidad anorogénica. Hemos designado informalmente este cuerpo plutónico como granito rapakivi de Matraca e inicialmente fue asociado con el gran Evento Parguenze descrito en Venezuela (método convencional U/Pb en circones, 1.550 Ma). Sin embargo, las recientes dataciones U/Pb en circones con LA-ICP-MS establecen una edad concordante de 1.343 ± 8 Ma para su cristalización que marca un magmatismo de 100-200 Ma más joven, pero que a su vez representa mayor concordancia con las recientes edades mediante el mismo método para el Granito de Parguaza en Colombia de 1.390-1.400 Ma, lo cual nos permite suponer intrusiones episódicas de granitos tipo "A" emplazados entre 1.300-1.400 Ma y parcialmente enriquecidos en mineralizaciones de Nb, Ta, REE y Sn.

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

“…Also shown are A-type granitoids to the East (Parguaza and Matraca rapakivi granites), Grenvillian-age remnants to the West near and within the Andes, the Ecarian to Cambrian Nepheline Syenite of San Jose de Guaviare, Precambrian (Caranacoa and Naquén) to Phanerozoic covers and ages of some mafic rock outcrops (Table 1). Modified after Cordani et al, 2010;Tassinari and Macambira, 1999;Ibañez et al, 2011Ibañez et al, , 2016Bonilla et al, 2016. Consequently, this belt could represent a separate composite orogeny (Cardona et al, 2010;Ibañez, 2010). Based on drill core sample analyses, Ibañez (2010) suggested the existence of a younger orogenic belt in Colombia called the "Putumayo Orogen" assumed to be coeval with the Sunsás belt.…”

Chapter 4

“…We also make mention of the limited (but relevant) δ 18 O Zrn stable isotope results that have recently become available. Thus, the data used for the purposes of this chapter comes from the following sources (in chronologic order): Tassinari et al (1996), Santos et al (2000), Ibañez-Mejia et al (2011), Bonilla-Pérez et al (2013), Ibañez-Mejia (2014, Ibañez-Mejia et al (2015), Cordani et al (2016b), Veras et al (2018). U-Pb results obtained from this compilation are listed in Table 1, along with the sample coordinates (in degrees, using the WGS84 datum), geographic locality (if known), rock-type that was analyzed, and their unique International Geo Sample Number (IGSN) identifier when available.…”

“…The most extensive outcrops of Precambrian basement in Colombia are located in the eastern and southeastern portions of the Vichada and Guainía Departments (Figure 2), along the Orinoco, Guaviare, Inírida, Atabapo, Guainía, and Negro River basins (Gómez et al, 2017). Samples dated by U-Pb methods in this region, from the studies of Bonilla-Pérez et al (2013), Cordani et al (2016b), andIbañez-Mejia (2014) are mainly from outcrops located around the Orinoco, Inírida, and Atabapo Rivers. From oldest to youngest, the basement in this area is comprised by: (i) Volcanic and intrusive rocks of the Cuchivero magmatic belt (Gibbs, 1987;Teixeira et al, 2002), with crystallization ages ca.…”

Volume 1

“…Although these later authors argued that the Colombian portion of the granite was younger, another possibility is that the conventional method that was used for the Venezuelan sample did not date the intrusion's age. The small Matraca Granite, which is another anorogenic granite near Inírida, was dated at 1343 ± 8 Ma (Bonilla et al, 2016).…”

“…The origin of the granitic rocks in the Mitú Complex has been subjected to different interpretations. The Parguaza and Matraca Granites are generally agreed to be anorogenic granites Bonilla et al, 2016). Based on chemical analyses of the granitic orthogneisses in the Mitú area, Rodríguez et al (2011) showed that these rocks plotted entirely within the field of A-type granites, while considered that these rocks formed during orogenic cycles.…”