High resolution speleothem record of precipitation from the Yucatan Peninsula spanning the Maya Preclassic Period
Abstract We produced a new high resolution absolute U Th dated stalagmite oxygen isotope record (d 18 O) from Rio Secreto, Playa del Carmen, Yucatan Peninsula (YP) This new 1434 year stalagmite record (named Itzamna after the Maya god of creation) spans the time interval between BCE 1037 and CE 397 with an average resolution of 8 2 years. It provides a novel view of climate evolution over the Preclassic and early Classic periods in Maya history. To understand the controls of regional precipitation d 18 O on seasonal time scales, we characterized the amount effect between precipitation amount P and precipitation d 18 O (d P We found that precipitation d 18 O in the Yucatan Peninsula is controlled by the amount effect on seasonal scales (d P /D P 0.0137 0.0031%0 per mm, r 0.9) as suspected but never before demonstrated. Cave drip d 18 O is consistent with the annual amount weighted d 18 O composition of precipitation. Multiple lines of evidence suggest that stalagmite d 18 O reflects isotopic equilibrium conditions and thus stalagmite d 18 O changes are interpreted to reflect precipitation amount. We determined quantitative precipitation changes from the stalagmite d 18 O record following previous methods (Medina Elizalde and Rohling, 2012) The stalagmite precipitation record suggests twelve periods of anomalous precipitation reductions ranging between about 30 and 70% below mean conditions at the time and with durations from 6 years to 31 years. Between BCE 520 and 166, the speleothem precipitation record suggests that the YP experienced an interval of high precipitation labeled the Late Preclassic Humid Period (LPHP) with precipitation maxima of up to 86 20% Preclassic Maya cultural expansion in El Mirador Basin, located in northern Guatemala, took place while the peninsula transitioned from the LPHP to an interval with below average precipitation. We find that the Preclassic abandonment of major centers in the Mirador Basin and others around the Maya Lowlands was synchronous with two unprecedented multi decadal events of severe precipitation reduction with magnitudes of 55 13% and 49 12 and centered at CE 186 and 234, respectively. We also find evidence that centennial scale precipitation variability in the YP during the Preclassic Period may have been associated with shifts in rainfall fluxes from Atlantic tropical cyclones.