First discovery of Holocene cryptotephra in Amazonia.

Elizabeth J Watson,Ivan P Savov,Graeme T Swindles,Karen L Bacon

doi:10.1038/srep15579

Abstract

The use of volcanic ash layers for dating and correlation (tephrochronology) is widely applied in the study of past environmental changes. We describe the first cryptotephra (non-visible volcanic ash horizon) to be identified in the Amazon basin, which is tentatively attributed to a source in the Ecuadorian Eastern Cordillera (0–1°S, 78-79°W), some 500-600 km away from our field site in the Peruvian Amazon. Our discovery 1) indicates that the Amazon basin has been subject to volcanic ash fallout during the recent past; 2) highlights the opportunities for using cryptotephras to date palaeoenvironmental records in the Amazon basin and 3) indicates that cryptotephra layers are preserved in a dynamic Amazonian peatland, suggesting that similar layers are likely to be present in other peat sequences that are important for palaeoenvironmental reconstruction. The discovery of cryptotephra in an Amazonian peatland provides a baseline for further investigation of Amazonian tephrochronology and the potential impacts of volcanism on vegetation.

Highlights

The use of volcanic ash layers for dating and correlation is widely applied in the study of past environmental changes
Our discovery 1) indicates that the Amazon basin has been subject to volcanic ash fallout during the recent past; 2) highlights the opportunities for using cryptotephras to date palaeoenvironmental records in the Amazon basin and 3) indicates that cryptotephra layers are preserved in a dynamic Amazonian peatland, suggesting that similar layers are likely to be present in other peat sequences that are important for palaeoenvironmental reconstruction
There have been a small number of studies of the ecology and paleoecology of Amazonia peatlands owing to their potential as archives of past environmental change[28,31,32,33]

Summary

Introduction

The use of volcanic ash layers for dating and correlation (tephrochronology) is widely applied in the study of past environmental changes. There have been a small number of studies of the ecology and paleoecology of Amazonia peatlands owing to their potential as archives of past environmental change[28,31,32,33]. Such studies are rare and important as they can provide a long-term baseline for recent climate changes in tropical Amazonia and globally. Tropical peats are notoriously difficult to date due to the presence of large roots leading to deep biological alteration[32]

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Discussion

Conclusion