Paleoenvironmental catastrophies on the Peruvian coast revealed in lagoon sediment cores from Pachacamac

摘要

Paleoenvironmental reconstruction combining data from diatom, pollen, macrophytic, and archaeologicalanalyses had not been attempted previously for coastal Peru. We analyzed two radiocarbondatedsediment cores extracted from the “sacred” Urpi Kocha Lagoon at the pre-Hispanic religiouscenter of Pachacamac (ca. AD 350-1533), near Lima, to characterize the paleoenvironment of the site.The data reveal an environmental history characterized by alternating periods of severe drought andcatastrophic flood. Recurrent pulses with distinctive sediment, diatom, pollen, and macrophyticcharacteristics reflecting variations in water depth, substrate, turbidity and salinity, usually containa thick basal sandy storm deposit overlain by thin organic accumulations of peat, gyttja, and snails. Themost intense of these disturbance pulses, when correlated with pollen, plant macrofossils, radiocarbondates, and regional proxy data, provide local evidence of four major floods associated with sustained,catastrophic El Ni?o events, tsunamis and/or severe storms in the Andean highlands over the last 2000 years.