Serra do Tapa Ophiolite Suite - Araguaia Belt: Geological characterization and Neoproterozoic evolution (central-northern Brazil)

The Araguaia Belt is a Neoproterozoic collisional orogen located in the northern Tocantins tectonic province, North-central Brazil, being one of the most expressive orogens of West Gondwana. The Serra do Tapa Ophiolite Suite is the most important representative of the ophiolitic bodies of the Araguaia Belt, exposed along the low-grade metamorphic domain of the Belt and extending over 80 km in the N-S direction. It constitutes a set of N-S aligned bodies that represent a disrupted ophiolite special sequence comprising serpentinized peridotites and dunites, massive and pillow basaltic lavas, volcanosedimentary rocks, cherts, jaspilites, and their metamorphic products. The serpentinized rocks have protoliths of mantelic harzburgites and dunites, with relict original protogranular texture partially replaced by pseudomorphic texture after olivine and orthopyroxene, and non-pseudomorphic (replacements). Submarine basaltic flows represent the volcanic succession, overlying serpentinized peridotites. The volcanic succession occurs as homogeneous massive basalts or pillow basalts, and locally volcanoclastic breccias (hyaloclastite). The pillow structure shows zoning, where the core consists of homogeneous massive metabasalt with preserved igneous features whereas pillow outer zone consists of hyalobasalt with quenching textures whose pillow surface is transformed into chlorite-rich rocks that appear fine-grained and related to the metasomatic transformations due to interactions with seawater. Geochemically, the massive metabasalts display a subalkaline-tholeiitic affinity, compatible with Middle Oceanic Ridge Basalts types (MORB). The suite evolution is a testimony of an oceanic stage during the Neoproterozoic of the Araguaia Basin that generated an oceanic lithosphere followed by volcanic activity, the interaction between lava flows and pelitic sediments, and deposition of chemical sedimentary rocks (jaspilites and cherts). Subsequently, the detachment of the oceanic lithosphere and the compressional tectonic evolution of the Araguaia Orogen inverted the sequence leading to the obduction of ophiolite bodies along overthrust and transcurrent faults projecting/thrusting a mass toward the Amazonian Craton. The tectonics was accompanied by regional metamorphism from anchymetamorphism to low greenschist facies conditions. All these processes are related to the evolution of the Brasiliano/Pan-African Cycle of the Araguaia Belt. The Serra do Tapa Ophiolite constitutes a