Deep-sea hiatuses track the vigor of Cenozoic ocean bottom currents

Abstract

Abstract The deep-sea stratigraphic record is full of gaps. These hiatuses track changes in ocean circulation and chemistry, but determining their timing and causes has been limited by sparse data and incomplete knowledge of ocean gateway evolution in earlier studies. We combine a significantly expanded, age-calibrated deep-sea stratigraphic database with a global tectonic and paleo–water depth model to investigate the distribution of >400 Cenozoic hiatuses longer than ~0.2 m.y. We find that only a small number of hiatuses are due to carbonate dissolution. The majority of hiatuses were, by implication, caused by mechanical erosion and redistribution of sediments by bottom currents into regions of increased sedimentation such as contourite drifts. We link peaks in regional hiatuses to changes in ocean circulation and intensification of deep-water formation. Widespread hiatuses in the South Atlantic, South Pacific, and southern Indian oceans between ca. 34 Ma and 30 Ma are attributed to the coeval widening and deepening of the Drake Passage and the opening of the deep Tasman Gateway. A peak in hiatuses in the Atlantic in the early Miocene is linked to the initiation of a proto–Atlantic Meridional Overturning Circulation driven by the complete opening of the deep Drake Passage and the progressive closure of the Tethys seaway. A long-term 30% decline in hiatus frequency since ca. 14 Ma is synchronous with post–Miocene Climate Optimum cooling, suggesting the slowing of abyssal circulation. Our synthesis of deep-sea hiatuses could be used to track the fate of deep-sea sediments and to ground-truth deep-ocean circulation models.