Rhenium variations in molybdenite (MoS2): Evidence for progressive subsurface oxidation

Temporal trends in Earth's near-surface mineralogy correlate with major events in Earth's geochemical and tectonic history. New and published analyses of 422 molybdenite (MoS2) specimens from 135 localities with known ages from 2.91 billion years (Ga) to 6.3 million years (Ma) reveal two statistically significant trends. First, systematic increases in average and maximum trace concentrations of Re in molybdenite since 3.0 Ga point to enhanced oxidative weathering by subsurface fluids. In addition, episodic molybdenum mineralization correlates with five intervals of supercontinent assembly from ∼2.7 Ga (Kenorland) to 300 Ma (Pangaea).

► Trace element concentrations through time reveal Earth's changing redox state. ► Trace Re in molybdenite (MoS2) has increased dramatically over the past 3 Ga. ► These increases reflect progressive oxidation of Earth's near-surface environment. ► Most molybdenite was deposited during 5 major pulses of mineralization. ► These pulses correlate with 5 intervals of supercontinent assembly.