Biogenic opals in the identification of lacustrine and marine sediments

Abstract

This study aimed to identify lacustrine or marine sediments based on biogenic opals (also known as spicules). The layers and horizons of a Humic Gley Thiomorphic soil in the Riacho catchment area, Aracruz, state of Espirito Santo, Brazil, were analyzed. Each soil sample was specifically treated to isolate the spicules, which were then identified by an electronic microscope. It was possible to verify the presence of lacustrine as well as marine spicules. Moreover, the shape of the opals provided information on the conditions of the geochemical environment and transport distance of the sediments.

environmental indicators; hydromorphic soils; Gleysoils