Cyclic anoxia and organic rich carbonate sediments within a drowned carbonate platform linked to Antarctic ice volume changes: Late Oligocene-early Miocene Maldives

•Four myr sequence of sapropels in an atoll 1000 s of m above the ocean floor.•Anoxia related to the development of a shallow sill resulting in decreased ventilation.•TOC controlled by cyclic anoxia related to changes in Antarctic ice volume.•IODP Expedition 359 drills sapropel sequence of Late Oligocene-Early Miocene in age.