Timing of Proterozoic magmatism in the Sunsas belt, Bolivian Precambrian Shield, SW Amazonian Craton
Date
2021-06-05
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier B.V.
Abstract
We present new U–Pb zircon and monazite ages from the Sunsas belt granitic magmatism in Bolivia, SW
Amazonian Craton. The geochronological results revealed four major magmatic events recorded along the
Sunsas belt domains. The older igneous event formed a granitic basement coeval to the Rio Apa Terrane
(1.95 – 1.85 Ga) in the southern domain. The second magmatic episode is represented by 1.68 Ga granites
associated to the Paraguá Terrane (1.69–1.66 Ga) in the northern domain. The 1.37–1.34 Ga granites
related to San Ignacio orogeny represent the third and more pervasive magmatic event, recorded
throughout the Sunsas belt. Moreover, magmatic ages of ~1.42 Ga revealed that the granitogenesis associated
to the Santa Helena orogeny also affected the Sunsas belt, indicating that it was not restricted to
the Jauru Terrane. Lastly, the 1.10–1.04 Ga youngest magmatism was developed during the Sunsas orogeny
and represents the final magmatic evolution related to Rodinia assembly. Likewise, the 1.95–1.85
and 1.68 Ga inherited zircon cores obtained in the ~1.3 Ga and 1.0 Ga granite samples suggest strong partial
melting of the Paleoproterozoic sources. The 1079 ± 14 Ma and 1018 ± 6 Ma monazite crystallization
ages can be correlated to the collisional tectono-thermal event of the Sunsas orogeny, associated to reactions
of medium- to high-grade metamorphism. Thus, the Sunsas belt was built by heterogeneous 1.95–
1.85 Ga and 1.68 Ga crustal fragments that were reworked at 1.37–1.34 Ga and 1.10–1.04 Ga related to
orogenic collages. Furthermore, the 1.01 Ga monazite age suggests that granites previously dated by zircon
can bear evidence of a younger thermal history. Therefore, the geochronological evolution of the
Sunsas belt may have been more complex than previously thought.
Description
CITATION: Nedel. I. M. et al. 2021. Timing of Proterozoic magmatism in the Sunsas belt, Bolivian Precambrian Shield, SW Amazonian Craton. Geoscience Frontiers 12:(2021) 101247. doi.10.1016/j.gsf.2021.101247
The original publication is available at: elsevier.com
The original publication is available at: elsevier.com
Keywords
Sunsas belt -- Southwestern Amazonian Craton, Bolivian Precambrian Shield, U–Pb geochronology, Zircon -- Bolivia, Monazite -- Bolivia, Geology, Stratigraphic -- Proterozoic, Magmatism -- Southwestern Amazonian Craton
Citation
Nedel. I. M. et al. 2021. Timing of Proterozoic magmatism in the Sunsas belt, Bolivian Precambrian Shield, SW Amazonian Craton. Geoscience Frontiers 12:(2021) 101247. doi.10.1016/j.gsf.2021.101247