Les biosphéroïdes calcitiques de vers de terre

Abstract

Earthworm calcite granules (Ecg) are secreted by several species of earthworms that majoritarily release them in the upper part of the soil. Ecg have been found in different Quaternary calcareous deposits, and particularly in loess sequences. In this article, we present the variations of Ecg abundance from a Weichselian Pleniglacial sequence of northern France. These variations will then be compared to the stratigraphy, the malacology and sedimentological data to assess the potential of this new palaeo-environmental proxy in a loess context. Variations in Ecg reveal a link between their abundance and the nature of pedostratigraphic units with a peak in the tundra gleys and paleosols horizons and absence in the loess units. These variations are also similar to those of molluscs. In addition, the application of isotopic analyses on the granules will be exposed in order to quantify the palaeotemperatures. The Ecg can be used as new paleoclimatic and paleoenvironmental proxy.

Keywords

• earthworm calcite granules
• Last Glacial
• loess
• northern France
• palaeoenvironment