Neoarchean-Paleoproterozoic metallogenesis associated with plate tectonics in early Earth: Insights from the North China Craton

Abstract

Precambrian cratons are archives of several precious metallic deposits that significantly contribute to our planet’s resources and habitability and also provide key information on plate tectonics on Earth. The North China Craton (NCC) preserves important records of Neoarchean to Paleoproterozoic tectonic processes and associated episodes of metallogenic pulses that generated five major types of mineral deposits including banded iron formations (BIFs), volcanogenic massive sulfide (VMS) Cu–Pb–Zn deposits, orogenic Au deposits, magmatic sulfide Cu-Ni deposits and porphyry Cu deposits. These deposits are distributed in Neoarchean granite-greenstone belts and Paleoproterozoic orogenic belts, and show dominant mineralization ages of 2.6–2.5 Ga and two subordinate age groups of 2.7–2.6 Ga and 2.3–1.95 Ga. The Neoarchean metallogenic events generated BIFs, VMSs, Au and magmatic sulfide Cu-Ni deposits and the tectonic framework correlates with the microblock amalgamation and plate subduction possibly also aided by mantle plumes. The BIFs representing the dominant mineral deposits in Neoarchean are mainly Algoma-type with few examples of Superior-type. Meta-basaltic rocks associated with the Algoma-type BIF deposits in the granite-greenstone belts of the NCC display highly variable trace element compositions and LREE-depleted and LREE-enriched. The REE distribution patterns and high field-strength element characteristics of meta-basaltic rocks suggest the formation of BIF and VMS deposits in mid-ocean ridge, island arc and back-arc settings. The formation of VMS, Au and magmatic Cu-Ni deposits correspond to plate subduction and collision in a convergent continental margin setting during the late Neoarchean. The Paleoproterozoic deposits are represented by BIFs and porphyry Cu deposits. The Paleoproterozoic BIFs and meta-basaltic rocks correspond to magmatic-hydrothermal activities in passive continental margin or island arc settings, whereas the porphyry Cu deposits were formed in an extensional environment, corresponding to the Paleoproterozoic subduction-rifting events in the Trans-North China Orogen. The variation of δ⁵⁶Fe, Ce anomalies and Y/Ho ratios in BIFs from Neoarchean to Paleoproterozoic indicate the initial increase of oxygen in late Neoarchean and the change of ambient marine environment from anoxic to oxic during the Great Oxidation Event. The multi-stage Neoarchean to Paleoproterozoic metallogenic systems of the NCC were intrinsically linked to the plate subduction along with arc-plume interaction and rifting-subduction-collision activities. The contemporaneous increasing in weathering of exposed continental crust due to plate subduction potentially controlled the atmosphere-hydrosphere oxidation state and formation of BIF deposits in the NCC.