The late Holocene, high-resolution storm and climate archive of the Blue Hole, Lighthouse Reef, Belize (Central America)

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In the second phase of the proj2ect (2 years), a continuous, 30 m long sediment core was retrieved from the bottom of the Belize Blue Hole, which was subsequently investigated at high resolution with regard to sedimentology, paleontology, and geochronology. The core encompasses some 12.5 ka, i.e., the complete Holocene into the latest, postglacial Pleistocene (Younger Dryas). The sedimentological succession may be subdivided in three units from top to base including (1) a varved marine unit with well-developed event beds (<5.7 ka BP), (2) a restricted marine to brackish unit (5.7-7.2 ka BP), and (3) an organic-rich lacustrine unit (7.2-12.5 ka BP). In total, 694 event (cylone) layers were identified that were used to prepare a unique, exceptionally long, annually resolved storm archive of the western Atlantic. The record indicates that storm activity was relatively low from 12-3.5 ka BP, with the exception of two short intervals during the Holocene Climate Optimum (6.8-5.9 ka BP), and high since 3.5 ka, with two maxima during the Medieval Warm Period (MWP) and the recent time of Industrial Warming (IW). Based on comparisons with historical storm records, it was possible to quantitatively relate storm bed thickness and texture to reported max. wind speed, i.e., to calibrate sedimentological characteristics of event beds based on storm intensity. Given the unexpected, great length of the retrieved core and the uniqueness of this record, we ask for a final year of funding for the project in order to conduct geochemical analyses (d18O, d13C, TEX86) at annual resolution. The objectives of the final funding period include (1) the extension of the annually resolved SST-record to the Younger Dryas and (2) the development of a d13C-record of equal length. Objective 1 will allow to assemble an exceptional Holocene SST-record, which will enable a comprehensive interpretation of the new storm record in the light of Holocene climate variability, including the influence of the Atlantic Multidecadal Oscillation (AMO). Based on objective 2, manifestations of climate variability such as cyclone frequency, precipitation, and soil-erosion may be deciphered, which in turn enable an evaluation as to how Mesoamerican hydro-climate changes operated as a catalyst for the regional cultural development and eventual collapse of the Maya high culture during the past ca. 3 ka.