Can the magnetic signatures from inorganic fly ash be used to mark the onset of the Anthropocene?

Abstract

Three possible candidates are considered as markers in lake sediments and peat for the onset of the Anthropocene. The artificial radioisotopes Americium 241 and Caesium 137, as well as Spherical Carbonaceous Particles, the by-product of fossil fuel combustion, are considered only briefly. They are possible markers for the onset of the Great Acceleration in the mid 20th century. More attention is given to Inorganic Ash Spheres which are mainly by-products of solid fuel combustion, iron and steel manufacture and metal smelting. Their changing contributions to the stratigraphic record can be detected by means of magnetic measurements. The date at which the deposition of inorganic fly ash is recorded varies from the 16th to the mid 20th centuries, depending mainly on location. In evaluating the prospects for using the magnetic record in recent peat and lake sediments as a marker for the start of the Anthropocene, special attention is given to the importance of developing and testing chronologies of deposition, the choice of appropriate locations and the problems posed by dissolution of magnetic minerals over time especially in acid peat.