Abstract
The Guaviare Complex is a new unit defined in the Colombian Amazonian Craton, which is part of the Precambrian basement located in southeastern Colombia. It is divided into three units according to their textural and compositional characteristics, termed Termales Gneiss, Unilla Amphibolite, and La Rompida Quartzite.
 Termales Gneiss rocks are petrographically classified as gneisses and quartz-feldspar granofels, with the local formation of blastomylonite-like dynamic rocks. The Unilla Amphibolite consists of only amphibolites, and La Rompida Quartzite consists of muscovite quartzites, quartz-feldspar granofels, and quartz-muscovite schists.
 The protoliths of Termales Gneiss and Unilla Amphibolite were formed in the Mesoproterozoic at 1.3 Ga due to bimodal magmatism (felsic and mafic) derived from mantle material, with some crust contamination that was probably related to the formation of extensional arcs associated with trans-arc basins in the NW section of the Amazon Craton. La Rompida Quartzite rocks originated from sediments derived from granite rocks and from other, older areas of the craton. These rocks have a maximum age of 1.28 Ga.
 The low-to-medium grade metamorphism that affected these units occurred from 1.28 to 0.6 Ga, most likely concurrently with the Putumayo orogeny of approximately 1.0 Ga, although it may have been an independent event.
Highlights
M ethodIn addition to the primary reference material and to zircons from the Guaviare Complex, during our analytical session, several zircon fragments from Plešovice and FC-1 (Duluth gabbro, Minnesota, USA) were analyzed to evaluate the precision, accuracy, and reproducibility of the method
The Guaviare Complex is a new unit defined in the Colombian Amazonian Craton, which is part of the Precambrian basement located in southeastern Colombia
In the primitive mantle-normalized multielement plots of McDonough et al (1992) (Figure 6), the pattern of the main group of the Termales Gneiss is homogeneous, and the samples cluster around the same values, except for rare earth elements (REEs) (La, Ce, Nd and Sm), whose values show variable enrichments in light (LREEs) and intermediate rare earth elements (IREEs) (Figure 6a)
Summary
In addition to the primary reference material and to zircons from the Guaviare Complex, during our analytical session, several zircon fragments from Plešovice and FC-1 (Duluth gabbro, Minnesota, USA) were analyzed to evaluate the precision, accuracy, and reproducibility of the method These secondary materials yielded weighted mean ages of 206Pb/238U = 335.0 ± 1.2/3.9 (2σ, n = 21, mean squared weighted deviation (MSWD) = 0.8) for Plešovice and 207Pb/206Pb = 1098 ± 8/11 (2σ, n = 23, MSWD = 0.3) for FC-1, where the first level of uncertainty reported represents only internal analytical uncertainties, and the second level of uncertainty includes the propagation of systematic and standardization-related sources of uncertainty. 0.58 Ma for FC-1 (Ibáñez Mejía and Tissot, 2019), assessed following the Chemical Abrasion - Isotope Dilution - Thermal Ionization Mass Spectrometry reference, which confirms that the geochronological results reported in this study are accurate and that the analytical uncertainties have been correctly assigned
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
