Nitrogen isotopes of released gas from rock crushing and implications to origins of molecular nitrogen in Lower Cambrian overmature shale gas in South China

Both methods—high-vacuum-pulsed electromagnetic rock-crushing and degassing and helium-filled ball-mill rock-crushing and degassing—are developed to measure the contents, chemical compositions and nitrogen isotopes of N2 in shale-crushed gas from Lower Cambrian organic-rich shales in South China. Using the shale-crushed gas geochemistry, thermal maturity, mineral composition and nitrogen species of the Lower Cambrian overmature shale, we examined the key factors causing N2 enrichment in the Cambrian shale gas, and we investigated the origins of N2.