From mesoarchean drips to modern–style tectonics in the Carajás Province, Amazonian Craton

Abstract The beginning of modern–style plate tectonics on Earth is not a consensus, but many authors suggest that it happened transitionally, from 3.2 to 2.5 Ga. In the Amazonian Craton, Brazil, the contrasting crustal architecture of the Rio Maria and the Carajas domains is marked by dome–and–keel and linear belt, respectively, which may represent a shift in the tectonic styles along the Mesoarchean to Neoarchean transition. Here, we discuss this hypothesis combining existing literature and an interpretation of airborne geophysical data for the Caracol Dome. This Archean TTG (Trondhjemite–Tonalite–Granodiorite) Dome shows a concentric lithological variation, with older 2.97–2.96 Ga trondhjemites at the edges and younger 2.95–2.92 Ga tonalites within the inner parts. The Caracol Dome exhibits a similar magmatic evolution to other Archean domes worldwide (e.g., Yalgoo and Mt. Edgar Domes), commonly interpreted as the record of vertical tectonics (e.g., drip–tectonics). However, the subsequent geological record in the Carajas Province is more likely related to the onset or transition to modern–style tectonics, such as large continental shelf sedimentation (Carajas Basin), steeply dipping linear shear zones with 2.76–2.73 Ga syn–tectonic intrusions and Neoarchean iron oxide–copper–gold (IOCG) mineralization. Finally, late Neoarchean to Paleoproterozoic tectonic events with new (and/or remobilized) IOCG deposits are also recorded in the Carajas Province.