DGRN

Abstract

As anomalias de gadolínio são reconhecidas atualmente como bons marcadores de poluição causada por água residuária. Apesar disso, ainda não existe um método padronizado para a sua estimativa. Neste artigo são comparadas quatro equações, diferentes limiarese diferentes valores de normalização para estimativa das anomalias de Gd em um estudo de caso realizado em um aquífero aluvionar onde existem sistemas de saneamento in-situ.

Recognizing the deposits of linear megadunes in ancient aeolian successions is challenging when the original bedform topography is not preserved. The present study provides a detailed analysis of the depositional architecture of an ∼ 80 m-thick interval of the Mesoproterozoic Galho do Miguel Formation (SE Brazil) to reconstruct the original morphologies of linear megadunes and to understand their dynamics. The depositional architecture reveals compound cross-bedded sets, which transition laterally into thick low-angle cross-stratified sets and planar-parallel sandstone beds.

The Neoproterozoic phosphogenic event records biotic and biogeochemical changes that seem to indicate intrinsic relationships between phosphogenesis and phosphatic fossil preservation. However, chemo-litho and biostratigraphic correlations conducted on fossiliferous, phosphatic successions of the Doushantuo Formation, South China, evidence a highly heterogeneous record, featuring diachronic depositional ages, variable taxonomic diversity and inconsistent, “noisy” δ13C records.