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.
Bibliographical noteFunding Information:
The authors acknowledge the support of the Laboratório de Geocronologia (Universidade de Brasília) and the Grupo de Pesquisa em Evolução Crustal e Tectônica (Guaporé). This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. The authors also acknowledge Fundação de Apoio à Pesquisa do Distrito Federal ( FAPDF ) and INCT Estudos Tectônicos (CNPq-CAPES-FAPDF) for financial support. IMN thanks CAPES and Programa de Excelência Acadêmica (PROEX, Edital - 0487) for granting the Doctorate scholarship. RAF and ASR acknowledge CNPq for research fellowship.
The authors acknowledge the support of the Laborat?rio de Geocronologia (Universidade de Bras?lia) and the Grupo de Pesquisa em Evolu??o Crustal e Tect?nica (Guapor?). This study was financed in part by the Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - Brasil (CAPES) - Finance Code 001. The authors also acknowledge Funda??o de Apoio ? Pesquisa do Distrito Federal (FAPDF) and INCT Estudos Tect?nicos (CNPq-CAPES-FAPDF) for financial support. IMN thanks CAPES and Programa de Excel?ncia Acad?mica (PROEX, Edital - 0487) for granting the Doctorate scholarship. RAF and ASR acknowledge CNPq for research fellowship.
© 2021 China University of Geosciences (Beijing) and Peking University
- Sunsas belt
- SW Amazonian Craton
- U–Pb geochronology