U-Pb zircon ages of rocks from the Amazonas Territory of Colombia and their bearing on the tectonic history of the NW sector of the Amazonian Craton

Cordani, Umberto G.; Sato, Kei; Sproessner, Walter; Fernandes, Fernando

doi:10.1590/2317-4889201620150012

Cited by 39 publications

(66 citation statements)

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“…In 1996, the first SHRIMP U-Pb analyses on zircons from the region were published by Tassinari et al (1996), marking the beginning of what we here consider as 'modern methods' from a U-Pb geochronology standpoint. As mentioned previously, this chapter will not take into consideration the Rb-Sr and K-Ar databases, because a comprehensive compilation and careful analysis of these results was recently done by Cordani et al (2016b), and because these databases have not been expanded since then. The U-Pb, Lu-Hf, and Sm-Nd datasets, on the other hand, have been moderately or significantly expanded, so the discussion provided in this chapter focuses on the data produced using these three isotopic systems as produced since 1996.…”

Section: Figurementioning

confidence: 99%

“…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.…”

Section: Figurementioning

confidence: 99%

“…All igneous/metaigneous units are pervasively intruded by granitic dikes and sills, many of which have coarsely pegmatitic textures (e.g., Figure 4g), and a later generation of dikes and sills of doleritic composition (e.g., Figure 4h). Samples from this uplift have been dated using zircon U-Pb geochronology by Cordani et al (2016b), Ibañez-Mejia (2014), andIbañez-Mejia et al (2011), who have analyzed the (meta)granitoids outcropping along the Yarí River (sample PR-3215), the Caquetá River near the Sumaeta (J-263 and 11MIAr-22), and Yarí (11MIAr-18) islands, as well as samples taken along the Caquetá River closer to the town of Araracuara, collected from ortho-(EP-2 and 11MIAr-07) and paragneisses (11MIAr-02, -06, and -08) of the Araracuara Gneiss unit in the Cañón del Diablo gorge. These studies have found the orthogneisses in the region to yield exclusively Paleoproterozoic (ca.…”

Section: Geology Of the Araracuara Basement High Caquetá Rivermentioning

confidence: 99%

“…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.…”

Section: Geology Of Guainía and Vichada Near The Colombia-venezuela Bmentioning

confidence: 99%

“…In this chapter, we provide a brief synthesis of the current state of knowledge on the geology of the Precambrian basement of the westernmost Guiana Shield, particularly focusing on the geochronologic and isotopic data obtained in Colombian territory over the last decade using modern U-Pb, Lu-Hf, and Sm-Nd methods. For a discussion of other available data using the Rb-Sr and K-Ar isotopic systems, the reader is referred to the recent comprehensive discussion provided by Cordani et al (2016b).…”

Section: Introductionmentioning

confidence: 99%

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Chapter 4

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2019

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The crystalline basement of eastern Colombia, east of the frontal deformation zone of the north Andean Eastern Cordillera, is comprised by Precambrian igneous, metamorphic, and sedimentary rocks of the western Guiana Shield. Designated in the late seventies with the all-embracing stratigraphic name of 'Mitú Migmatitic Complex', the age, petrology, and tectonic history of the Precambrian basement in eastern Colombia has remained one of the least explored issues in South American geology. This chapter aims to present a brief overview of recent advances made to improve our general understanding of the geology of this wide region, using a compilation of the available U-Pb, Sm-Nd, Lu-Hf, and δ 18 O isotopic data obtained using modern methods. Using all the available U-Pb geochronologic data we show that, in general: (i) The Precambrian basement of the western Guiana Shield exhibits magmatic crystallization ages in the range from ca. 1.99 to ca. 1.38 Ga, and (ii) that four broad periods of magmatic activity, two in the mid-to late-Paleoproterozoic (ca. 1.99 and ca. 1.81-1.72 Ga), one in the early Mesoproterozoic (ca. 1.59-1.50 Ga), and one in the mid Mesoproterozoic (ca. 1.41-1.39 Ga) dominate the geology of the area. The (whole-rock) Nd and combined (zircon) Hf-O datasets indicate a general lack of 'depleted mantle' like mid-Paleoproterozoic or Mesoproterozoic crust, thus indicating that either the Proterozoic sub-continental mantle in the region was not as radiogenic as global mantle evolution models would suggest, or that reworking of older crust might have played an important role in the geological and geochemical evolution of the western Guiana Shield. Therefore, although the geochronologic results confirm that most of the exposed basement in eastern Colombia can be broadly considered to be of Rio Negro-Juruena-like affinity, this belt exhibits some distinct isotopic characteristics relative to similar age domains exposed south of the Amazon Basin. Furthermore, we note that the geochronologic data obtained to this date has failed to clearly identify an early-to mid-Mesoproterozoic terrane boundary in the Colombian basement, thus opening the possibility that a Rondonian-San Ignacio-like province is not represented in the Guiana Shield. Based on these recent field, geochemical, and geochronological observations, we consider the long and extensively used term 'Mitú Migmatitic Complex' to be now inadequate and obsolete, and argue that the current state of the knowledge of the Colombian Precambrian basement is such that the community should move towards adopting Proterozoic

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Section: Figurementioning

confidence: 99%