Holocene environmental change recorded in lagoonal sediment proxies at Huaca Prieta, north coastal Peru

Abstract

This study attempts to define the early to mid-Holocene paleoenvironment at Huaca Prieta, an archaeological site on the north coast of Peru, through a combination of sedimentological, paleoecological, and stable isotope analyses. This research is part of a larger collaborative study drawing on many disciplines, and the interpretations of the results presented here are solely from a geological perspective. Multiple studies point to a severely diminished or even absent El Niño in the region during the mid-Holocene, but the Chicama River valley is a relatively unstudied location. Sediment coring from the upper 6 m reveals laminated to thinly bedded carbonates, organic sediments, and fine-grained clays deposited within larger intervals of sands and silts. These finer-grained sediments evidence a coastal lagoon 3 km in length which existed approximately 7300-6200 cal ybp. Stratigraphic analysis of the upper 6 m of sediments reveals a marked decrease in siliciclastic material delivered to the floodplain during this time, with potential implications for the mid-Holocene El Niño frequency debate and human-environment linkages during this time.