Spatio-temporal evolution of Statherian intraplate magmatism in the SW Amazon Craton: Insights from magmatism, sedimentation and geochemistry

The Statherian period was critical for the assembly of the Columbia supercontinent and is widely recorded in the Amazon Craton. The Western Amazonia Igneous Belt (WAIB) was formed by silicic-dominated magmatic events between ~1815 Ma and 1740 Ma. By combining literature geochemical-isotopic data with new results, we refine the spatio-temporal framework of the WAIB. The igneous record is subdivided into three bimodal (basalt-ferroan silicic rocks) associations: Event 1 (1815-1780 Ma), the most voluminous, consists of OIB-like tholeiitic basalts and silicic rocks with variable Ga/Al ratios, interbedded with fluvial-lacustrine sedimentary rocks. This event reflects hotter and deeper basaltic sources contemporaneous with high-temperature silicic magmatism; its peak (1790-1780 Ma) coincides with the emplacement of the Avanavero Large Igneous Province (LIP). Event 2 (1780-1760 Ma), less voluminous and restricted to the southwestern WAIB, comprises E-MORB-like basalts derived from cooler and shallower sources, along with lower-temperature silicic rocks showing low Ga/Al ratios, and is associated with marine and fluvial sedimentation. Event 3 (1760-1740 Ma) marks a decline in igneous activity and the onset of rifting, with small-volume volcanism interbedded with deltaic to coastal sediments. The high volumes, short duration, and intraplate affinities of Events 1 and 2 are consistent with a silicic LIP emplaced as a LIP-shirker event. WAIB evolution shows no evidence of arc-related magmatism and was not followed by continental breakup. Instead, it suggests that LIP activity was the main driver of crustal growth and contributed significantly to continental stabilization during Columbia’s assembly.