CARBON-ISOTOPE STRATIGRAPHY OF THE MOROCCAN ANTI-ATLAS: EARLY CAMBRIAN CARBON CYCLING AND THE IMPORTANCE OF PHYSICALLY BUFFERED METAZOA

We present a δ¹³C record from the Anti-Atlas mountains of Morocco and calibrate the curve using precision U-Pb zircon geochronology of ash beds in the same section. The variations in δ¹³C of carbonate occur on a wide range of time scales, suggesting that different mechanisms are involved, including methane clathrate destabilization on short (<100 kyr) time scales and changes in nutrient recycling and organic carbon burial on longer (>1 myr) time scales. Through a correlation with more fossiliferous, albeit condensed, sections in Siberia, we examine the pattern of cyclic δ¹³C variation in the context of the reappearance and diversification of skeletonized metazoa during the Early Cambrian.