Geochemical evidence of environmental changes during the quaternary in the Montain range of the southern Espinhaço, Minas Gerais

Abstract

Determination and understanding of the reasons that create certain specific characteristics recorded in organic soils enable to explain the environmental dynamic during their genesis. Soil weathering process, deposition of atmospheric dust, vegetation changing and trophic state can be inferred by analysis of geochemical elements determined in peatlands. Their concentrations reflect if levels are from natural bottom (background), derived from anthropic activities (enrichment factors), or natural catastrophic events. So, the aims of the research project are: A) to determine and characterize the geochemistry (major and minor elements, lithogenic trace elements, metallic trace elements, halogen, and As and Se elements preserved in soil organic matter) of peatlands from Espinhaço Meridional Mountain Range in order to infer on environmental changes (natural or anthropic); b) to correlate bioindicators (pollen grain, fern spores, bryophytes, fungi and chlorococcales algae) and geoindicators (C isotopes - 14C e 13C; N isotopes - 15N) determined in Brazil with geochemical elements (major and minor elements, lithogenic traces, metallic traces, halogen, and Se and As) determined in Spain as well as all data acquired in field work in order to interpret the evolution of this environment since its genesis regarding the main modifying processes and factors (natural and/or anthropic). For this, four peatlands were chosen: Pau-de-fruta (PF), Sempre-Viva (SV) and São João da Chapada (SJC). Analysis of elements contained in soil samples from peatland will be proceeded each 2 cm by X-Ray fluorescence (Energy-dispersive Miniprobe Multielement Analyzer/ FRX EMMA) and vacuum detection X-ray. Statistical techniques such as Factorial Analysis by Principal Components (PC), Correlation Analysis (CA), Association by Hierarchical Analysis of (HCA), and Correspondence Analysis (DCA) will be used for exploration of information contained in biotic and abiotic records. These techniques will be employed in analysis of the geochemical data together with isotopic, physical, chemical and morphological data of the peatlands. (AU)