Zircon U-Pb geochronology and Lu-Hf isotope systematics of the Araguaia Belt basement Rocks: Evidence of links with the southeastern Amazonian Craton, Brazil

Author(s)

Assis, Clauber R. F. ^[1] ; Moura, V, Candido A. ; Milhomem Neto, Joao M. ^[2] ; Gorayeb, Paulo S. S. ^[2] ; Dias, Airton N. C. ^[3]

Affiliation

^[1] V, IG UFPA, Programa Posgrad Geol & Geoquim PPGG, BR-66075110 Belem, Para - Brazil

^[2] Moura, Candido A., V, Univ Fed UFPA, Inst Geociencias IG, BR-66075110 Belem, Para - Brazil

^[3] Univ Fed Sao Carlos UFSCar, Dept Fis Quim & Matemat, BR-18052780 Sorocaba, SP - Brazil

• Document type: Journal article
• Source: Precambrian Research; v. 356, MAY 2021.
• Web of Science Citations: 1

Abstract

Archean and Paleoproterozoic basement rocks are exposed in the Araguaia Belt, a Neoproterozoic orogen bordering the eastern portion of the Amazonian Craton. Zircon LA-MC-ICPMS U-Pb and Lu-Hf isotopic systematics allowed a more accurate dating of the basement rocks and investigating the evolution of this large Archean/Paleoproterozoic crustal segment and discuss the relationship with the southeastern Amazonian Craton. Archean TTG orthogneisses (2.93 to 2.87 Ga) prevail in the northern belt while distinct magmatic events generated their protoliths in approximately 60 Ma. Zircon Hf model ages (similar to 3.0 to 3.4 Ga) and epsilon(Hf(2.87-2.93)) from -4.3 to +5.3 suggest crustal reworking of Mesoarchean juvenile sources, with the subordinated contribution of older crust. A Mesoarchean source is also indicated by the Hf model ages (2.93-3.25 Ga) and epsilon(Hf(-1.86 Ga)) from -4.8 to -1.6 of a 1.86 Ga granitic gneiss intrusive in the Archean TTG. An orthogneiss and an intrusive granitoid from southern segment of the belt were dated 2.06 Ga and 1.87 Ga, respectively. The Hf model ages (2.65-2.86 Ga) determined for these rocks, the epsilon(Hf(-2.06 Ga)) (-4.8 to -1.6) for the orthogneiss and the epsilon(Hf(1.87 Ga)) (-15.8 to -9.7) found for the granitoid reveal a dominant crustal source for the southern basement rocks. The Archean and Paleoproterozoic basement constituted a single crustal segment by the Orosirian, since both segments present intrusive granites of this geological period. The Archean orthogneisses of the Araguaia Belt and the granitoids of the Carajas Province Mesoarchean domains in southeastern Amazonian Craton share some similarities, such as the TTG affinity magmatism formed in a relatively similar time interval, the Orosirian intrusive granites, and the Mesoarchean juvenile source. Therefore, the basement rocks cropping out in the northern segment of the Araguaia Belt may represent portions of the adjacent Amazonian Craton. (AU)

• FAPESP's process: 17/12208-6 - THERMOCRONOLOGICAL STUDIES APPLIED TO ALMAS GREENSTONE/TTG, TOCANTINS, BRAZIL
• Grantee: Airton Natanael Coelho Dias
• Support Opportunities: Regular Research Grants