High-resolution δ13C stratigraphy through the early Aptian "Livello Selli" of the Alpine Tethys

Very similar high-resolution delta(13)Ccarb and delta(13)Corg curves are reported for the early Aptian "Livello Selli" (LS, oceanic anoxic subevent la) at two pelagic successions of the Alpine Tethys: "Roter Sattel" (Swiss Prealpes), deposited along the northwest margin, and "Cismon" (southern Alps of northern Italy), deposited along the southeast margin. The delta(13)Ccarb and delta(13)Corg curves are both divided into eight segments, six of which occur within the early Aptian Globigerinelloides blowi foraminiferal zone, indicating significant subzonal resolution. Most of the LS coincides with a chemostratigraphically defined "Selli event": a period of constant isotopic values (mean values of delta(13)Ccarb and delta(13)Corg approximate to+2.6% and -25% respectively) lasting 500 kyr to 1 Myr, rather than of positive excursion as previously supposed. This uniformity may reflect an equilibrium between Corg burial and increased recycling rates of C-12 and nutrient-rich intermediate water resulting from the intensification of oceanic thermohaline circulation.