Reappraising the Elatina series: What if the Solar Interpretation Were Correct?

Abstract

We revisit the sedimentary laminae from the Neoproterozoic Elatina Formation of South Australia. These were first interpreted as varves driven by solar activity and later as tidalites formed by tidal processes, although the debate has remained open. This series exhibits remarkably consistent periodicities, including a primary and a secondary period of approximately 12 and 314 laminae, respectively. Our present analysis reveals a statistically significant negative correlation between the length of a cycle and the amplitude of the subsequent cycle. By analyzing the residuals of the series' minima with respect to a linear trend and calculating Dicke's ratio, we show that this series exhibits a high degree of phase stability, except for a single break-point which possibly indicates a 90° phase shift. As these findings are difficult to reconcile with the tidal model, we reconsider the original interpretation as solar-driven sedimentation and tentatively discuss it in terms of a recently developed synchronization model of the solar dynamo. This model is used to calculate the orbital periods of Venus, Earth, Jupiter and Saturn that would be required to explain the 12-year cycle, when interpreted as a modified solar Schwabe cycle, and the 314-year cycle, when interpreted as a prolonged Suess-de Vries cycle. Assuming that the sums of the angular momenta of Jupiter and Saturn and Venus and Earth are pairwise conserved, we find that the planetary orbits change surprisingly little. The plausibility of such changes over a period of seven hundred million years is discussed in light of solar system dynamics.