Ice-core evidence of earliest extensive copper metallurgy in the Andes 2700 years ago

M. Schwikowski,T. Kellerhals,Th. Rehren,L. Tobler,A. Eichler,G. Gramlich

doi:10.1038/srep41855

Abstract

The importance of metallurgy for social and economic development is indisputable. Although copper (Cu) was essential for the wealth of pre- and post-colonial societies in the Andes, the onset of extensive Cu metallurgy in South America is still debated. Comprehensive archaeological findings point to first sophisticated Cu metallurgy during the Moche culture ~200–800 AD, whereas peat-bog records from southern South America suggest earliest pollution potentially from Cu smelting as far back as ~2000 BC. Here we present a 6500-years Cu emission history for the Andean Altiplano, based on ice-core records from Illimani glacier in Bolivia, providing the first complete history of large-scale Cu smelting activities in South America. We find earliest anthropogenic Cu pollution during the Early Horizon period ~700–50 BC, and attribute the onset of intensified Cu smelting in South America to the activities of the central Andean Chiripa and Chavin cultures ~2700 years ago. This study provides for the first time substantial evidence for extensive Cu metallurgy already during these early cultures.

Highlights

Complementary to archaeological artefacts, natural archives such as ice cores, peat bogs or lake sediment cores contain independent information about the smelting history by recording a metallurgy-related air pollution signal
In this study we present a 6500-year history of Cu emissions in the central Andes based on a continuous, highly time-resolved ice core record from the Illimani glacier, located at the north-eastern margin of the Bolivian Altiplano[18]
The Cu record allowed us to constrain the earliest stages of extensive prehistoric Cu metallurgy in South America and to document the complete history, including timing and intensity of Cu smelting activities

Summary

Introduction

Complementary to archaeological artefacts, natural archives such as ice cores, peat bogs or lake sediment cores contain independent information about the smelting history by recording a metallurgy-related air pollution signal. The record suggested that earliest anthropogenic air pollution potentially originating from Cu metallurgy occurred already around ~2000 BC, thereby considerably preceding any archaeological evidence. A sediment core record from Lake Pirhuacocha in the central Peruvian Andes provided evidence for earliest extensive Cu smelting around 1000 AD, coinciding with the fall of the Wari Empire and decentralization of local populations[17]. Potential source regions of air pollution arriving at the Illimani include main parts of Peru, Bolivia, northern Chile, and north-western Brazil as shown by the 5-day back-trajectory analysis (Fig. 1), encompassing the cradle of New World metallurgy in the Central Andes[19,20,21]. The Cu record allowed us to constrain the earliest stages of extensive prehistoric Cu metallurgy in South America and to document the complete history, including timing and intensity of Cu smelting activities

Methods

Results

Conclusion