Possible Tsunami Deposits at the Cretaceous-Tertiary Boundary in the Western Straits of Florida: High Resolution Seismic Reflection Profile Evidence

High resolution single channel seismic reflection profiles obtained in the western Straits of Florida near the Florida Escarpment show a sedimentary unit overlying the Cretaceous-Tertiary (K/T) boundary that likely formed as a result of the tsunami generated by the bolide impact in the Yucatan Peninsula, located 600-700 km away. The deposit extends as much as 35 km back from the Florida Escarpment and is about 25 km wide. Maximum sediment thickness is approximately 150 m. Average thickness is about 100 m in the portion of the unit extending 15 km back from the escarpment, although thickness varies significantly. The top of the deposit is undulatory and reflects the varying thickness of the unit, because the underlying Cretaceous sedimentary unit is relatively flat. The deposit pinches out at its updip edge. Little internal stratification is evident. The distribution of the deposit appears to be controlled by the presence of a reef that extends above the prominent Mid-Cretaceous Unconformity (MCU) reflector. Elsewhere along the Florida Escarpment, reef growth terminated at the MCU. This reef presented a barrier to movement of the tsunami radiating out from the impact site. The tsunami broke across the reef and formed a deposit in the lee of the reef. Sediment may have been stripped from the top and back of the reef.