Spatiotemporal Constraints On The Western Cauaburi Belt Tectonics - Northwestern Amazon Craton, Brazil

The study of Precambrian tectonics is an intricate task, demanding a holistic approach to take an accurate view of geologic history. Here we attempt to set up the overview of an Orosirian-Statherian continental arc in the northwestern Amazon Craton, the Cauaburi Belt. Field relations, petrological, geochemical, and geochronological data of calc-alkaline metagranitoids, high-grade metasedimentary rocks, and peraluminous metasyenogranites yielded new interpretations about its tectonic evolution. The record of intense and episodic calc-alkaline magmatism between ca. 1805 and 1759 Ma, assign to the Cauaburi Complex, with field evidence of magma mixing and lodgement in a compressional tectonic regime, suggest a continental arc as the tectonic setting. During the magmatic lulls, deformation and metamorphism increase, culminating with the partial fusion of the high-grade metasedimentary rocks of the Taiuacu-Cauera Complex. This succession composes the precursor paleobasin, presenting maximum and minimum depositional ages of 1819 and 1794 Ma, and was a relevant source for the calc-alkaline magmatism. The geochronological record of a low-volume production of peraluminous crustal rocks (Igarape Tocandira Granite), with crystallization age at ca. 1791 Ma and metamorphic age at ca. 1771 Ma, also highlights the time and effect of the magmatic lulls. The Cauaburi Belt structural framework follows a general E-W to ENE-WSW trend, expressed in the Paleoproterozoic rocks as syn-magmatic and solid-state deformation fabrics. Assuming that Columbia Supercontinent nucleus assembled in the late Orosirian, we interpret that this coeval continental arc developed at its border and followed a north-south shortening direction, at current orientation.