The Early Proterozoic Matachewan Large Igneous Province: Geochemistry, Petrogenesis, and Implications for Earth Evolution

摘要: The Matachewan Large Igneous Province (LIP) is interpreted to have formed during the early stages of mantle plume-induced continental break-up in Proterozoic. When LIP reconstructed its original configuration with units from Superior Craton and other formerly adjacent blocks (Karelia, Kola, Wyoming Hearne), dyke swarms, layered intrusions flood basalts, emplaced over lifetime province, form one most extensive magmatic provinces recognized geological record. New geochemical data allow, for first time, be considered as a single, coherent entity show that rocks share common tholeiitic composition trace element geochemistry, characterized by enrichment incompatible elements depletion less elements. This signature, ubiquitous Proterozoic rocks, may indicate through contamination primary magmas lithospheric material or had fundamentally different modern mantle. In addition radiating geometry plume origin consistent geochemistry some suites; these suites are used constrain source potential temperature c. 1500–1550°C. Comparison temperatures estimated upper indicates they hot magmatism. Geochemical coeval suggest head was compositionally heterogeneous sampled both depleted enriched As has been documented ancient but similarly vast LIPs, emplacement probably significant impact on global environment. Compilation best age estimates various shows occurred synchronously Great Oxidation Event. We explore eruption this emission associated volcanic gases driver irreversible oxygenation Earth.