Origin of the isotopic composition of natural perchlorate: Experimental results for the impact of reaction pathway and initial ClOx reactant

Natural perchlorate (ClO₄⁻) exists in many places on Earth, in lunar regolith, meteorites, and on the surface of Mars. Terrestrial natural ClO₄⁻ has widely variable Cl and O stable isotopic compositions (δ³⁷Cl, δ¹⁸O, Δ¹⁷O). The δ¹⁸O and Δ¹⁷O values of ClO₄⁻ from the most hyper-arid locations co-vary. ClO₄⁻ from less arid areas has relatively little ¹⁷O excess and poor Δ¹⁷O-δ¹⁸O correlation. ClO₄⁻ from the Atacama Desert has unusually low δ³⁷Cl (