Palaeoenvironmental changes in the Vaitea region (Easter Island) through a trace element record from Rano Aroi

Abstract

Easter Island is a remote Island located 3000 km far from the west-coast of Chile and it is considered the most isolated place on Earth. First humans arrived in the island likely during the 10th century. After their arrival the Rapa Nui people used the environmental resources available and created a complex society that lead to the building of the famous statues named Moai. However, between the 15th – 16th century, the Rapa Nui society declined. This decline has been ascribed to several climatic and environmental factors combined with a mismanagement of the resources available that lead to the deforestation of the island. Nevertheless, nowadays, past environmental reconstructions and archaeological evidence do not provide a clear description of the dynamics that lead to the aforementioned decline. In this thesis, a sediment core collected in 2017 (2 m length) at the crater lake named Rano Aroi located in the Vaitea region (Easter Island) was analyzed. Trace and rare earth elements were determined in about 100 samples corresponding to a time period that covers the last 2 millennia. Several diagnostic elemental ratios and their concentrations were used to evaluate the dynamics and the timing of the main environmental changes that can be ascribed to a combination of natural, climatic and anthropogenic factors and that can be related to the Rapa Nui collapse.