A GIANT SEDIMENT TRAP IN THE FLORIDA KEYS

Aerial photography, high-resolution seismic profiling, coring and jet probing have revealed a large sediment-filled sinkhole in the Key Larg e National Marine Sanctuary off Key Large, Florida. The 600-m-diameter feature straddles coral reef and carbonate-sand facies and contains > 55 m of marine lime sand and aragonite mud. Bulb C-14 age determinatio ns of mud from a 30-m sediment core indicate infilling rates exceeding 20 m/ka between 3 and 5.6 ka. The total thickness and nature of the s ediment near the base of the sinkhole are not known.