Oceanography, Ocean Technology and Marine Biology

This study focuses on the last 1500 yr. precipitation record and tropical storm occurrence, archived in the sediments from the Belize Central Shelf and the Blue Hole of Lighthouse Reef, proximal to the land areas where the Mayan Urban Civilization thrived and then abruptly collapsed. Cores were retrieved in 30 and 19 mbsl (meters below sea level) from Elbow Caye Lagoon and English Caye Channel, respectively, in addition to cores retrieved from the anoxic bottom sediment of the Blue Hole at 120 mbsl. The core timeframe is constrained by AMS radiocarbon dating of benthic foraminifera and organic residues, in addition to varve counts. Element (Ti, Si, K, Fe, Al, Ca, and Sr) counts were quantified via X-Ray Fluorescence. The records of Ti and K counts, and Ti/Al in these two cores have recorded, in the past 1500 years, the variable weathering rates of the adjacent Maya Mountain, defining alternating periods of high precipitation and droughts, linked to large climate fluctuations and extreme events, highly influenced by the ITCZ latitudinal migration. Coarse sediment layers in the upper part of the Blue Hole cores were correlated with historical tropical cyclones. The CE 800-900 century just preceding the Medieval Climate Anomaly (MCA), characterized by unusually low Ti counts and Ti/Al, and tropical cyclone scarcity, is interpreted to represent a time of low precipitation and resulting severe droughts in the Yucatan Peninsula, contemporaneous with the Mayan Terminal Classic Collapse. High Ti counts and Ti/Al, although highly variable, during the MCA (CE 900-1350), are interpreted as an unusually warm period characterized by two 100-to-250 years-long intervals of higher precipitation when the number of tropical cyclones peaked. These intervals of high precipitation are separated by a century (CE 1000 -1100) of severe droughts and rare tropical storm coinciding with the collapse of Chichen Itza (CE 1040-1100).