A new approach to isotopic modelling of the variation of atmospheric oxygen through the Phanerozoic

Abstract

The use of stable isotopes as inputs to modelling the redox geochemical cycles is analyzed. A major correction to earlier models arises from the need to use the time derivatives of δ (obtained from the measured δ versus time data) directly in the calculations. This correction is much more important for the sulfur system than for the carbon system. The rise of an "oxygen catastrophe' in earlier isotope models of the redox cycles leads to a new method of handling the dynamics of geochemical cycles that is based on minimization of a statistical function. The statistical function not only incorporates the usual mass balance expressions but also includes constraints on geochemical fluxes. This statistical model not only solves the "oxygen catastrophe' but also can be generalized to many other future applications. -Author