Hurricane‐Driven Transport of Bermuda Reef Carbonate Platform Sediments to the Deep Ocean

Tropical cyclones erode and remobilize coastal sediments but their impact on the deep ocean remains unclear. Hurricane‐driven transport of carbonates and associated materials from reef carbonate platforms to the deep ocean has important implications for carbon storage, deep ecosystems and ocean chemistry as carbonate platform reef‐sourced aragonite and high‐Mg calcite (HMC) may dissolve and contribute to deep water total alkalinity. Here we describe two hurricane‐driven resuspension events where deep sediment plumes from the Bermuda Pedestal (NW Atlantic) were advected to deep waters surrounding the Oceanic Flux Program (OFP) mooring site, ∼75 km southeast of Bermuda. Hurricanes Fabian (Cat. 3, 2003) and Igor (Cat. 1, 2010) generated large near‐inertial waves propagating to >750 m depths, leading to widespread sediment resuspension from the Pedestal. Following Fabian, carbonate fluxes at the OFP site increased 15‐fold, 32‐fold, and 6‐fold at 500, 1,500 and 3,200 m, respectively, with the 1,500 m flux equivalent to the total annual carbonate flux. OFP traps similarly captured a large detrital carbonate plume following Igor; here, the plume was shallower and persisted longer. Microscopy, geochemistry, and mineralogy confirmed that both plumes consisted of fine‐grained shallow‐water detrital carbonates alongside other materials accumulated on the Pedestal including phosphorus, lithogenic, authigenic, and pollutant elements. Clay‐sized particles (<4 μm) in both plumes exhibited high contents of lithogenic and authigenic elements, and Zn, Cd, and V, facilitating their transport over long distances. Grain‐size, elemental, and lipid composition indicated that plumes intercepted at different depths originated from different source areas on the Pedestal.