Barium and the Late Paleocene δ13C maximum: Evidence of increased marine surface productivity

Abstract

Deep‐sea sediment Ba* (Ba/Al2O3(sample) × 15% ‐ Ba(aluminosilicate) records show increasing values synchronous with the evolution of the late Paleocene global δ13C maximum, reflecting an increase in marine surface primary production and biogenic barite formation at this time. At two oligotrophic locations, Deep Sea Drilling Project (DSDP) Sites 384 and 527 in the North and South Atlantic, respectively, Ba* increases from 160–360 ppm in the early Paleocene to 1100–3000 ppm during the δ13C maximum. At equatorial DSDP Site 577, positioned within or near the high‐productivity zone, Ba* increases from ∼15,500 ppm in the early Paleocene to ∼25,400 ppm in conjunction with late Paleocene maximum δ13C values. Linear fitted correlation plots of sediment Ba* content versus surface water δ13C in all three regions support barite originating in the euphotic zone. The early to late Paleocene relative increase in Ba* illustrates how burial rates of Corg (relative to Al2O3) accelerated by a factor of ∼1.8 and ∼6.0 in the eutrophic and oligotrophic areas, respectively. A tentative estimate, weighing our result for the entire ocean, suggests that accumulation rates of organic carbon increased by a factor of 2 during the late Paleocene δ13C maximum.