A high-resolution reconstruction of paleo-hurricane strikes from the Blue Hole, Belize

Annually laminated sediments are one of the most valuable sources of paleo-climatic proxy records. Sediment cores collected from the Blue Hole of Lighthouse Reef, Belize provide a continuous, high-resolution proxy record for hurricane strikes spanning the past ca. 1200 years. This record is based on the identification of anomalous graded beds, interpreted as event layers that are deposited as overwash material under the influence of tropical storms and hurricanes. These beds are found interbedded with normal background sediments that consist of annually laminated biogenic carbonate muds that, in combination with 14C AMS dating, allow for the development of an absolute storm chronology. In order to facilitate the recognition and counting of these not always well-developed laminations, a new quantitative method was developed for use with the widely-used Geoscan line scanning camera system. The hurricane signal at the Blue Hole was found to exhibit multi-centennial frequency variability, with periods of increased activity occurring between ∼1100 and 600 yBP and ∼100 yBP to present, and a period of decreased activity occurring between ∼600 and 100 yBP. These frequency shifts correspond other North Atlantic Basin paleoclimatic features, in particular sea surface temperature variations observed during the Medieval Warm Period and the Little Ice Age and known migration patterns of the Inter-tropical Convergence Zone.