High-resolution speleothem record of precipitation from the Yucatan Peninsula spanning the Maya Preclassic Period

摘要

We produced a new high-resolution absolute U-Th dated stalagmite oxygen isotope record (delta O-18) 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 delta O-18 on seasonal time scales, we characterized the amount effect between precipitation amount (P) and precipitation delta O-18 (delta P). We found that precipitation 8180 in the Yucatan Peninsula is controlled by the amount effect on seasonal scales (delta P/Delta P = -0.0137 +/- 0.0031 parts per thousand per mm, r = 0.9), as suspected but never before demonstrated. Cave drip delta O-18 is consistent with the annual amount-weighted delta O-18 composition of precipitation. Multiple lines of evidence suggest that stalagmite delta O-18 reflects isotopic equilibrium conditions and thus stalagmite delta O-18 changes are interpreted to reflect precipitation amount. We determined quantitative precipitation changes from the stalagmite delta O-18 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. (C) 2015 Elsevier B.V. All rights reserved.