Sedimentary Facies of the Outcrop Rocks From of the North of the Espírito Santo State, Onshore of the Espírito Santo Basin

Sedimentary facies of the outcrop rocks from the North of the Espírito Santo State, onshore portion of the Espírito Santo Sedimentary Basin

Abstract

In the current study, an attempt was made to contribute to the understanding of the geology of the onshore portion of the Espírito Santo basin, which is a region with few studies in the literature. The most common sedimentary facies were identified, such as rudaceous, arenitic, and mud facies, with white to light gray colors, forming tabular deposits with normal grading and interbedding. Lateral accretion features, channel excavation, and filling were also observed. The arenitic and rudaceous facies are poorly sorted, matrix-supported, mainly composed of quartz, feldspar (some well-preserved), and diagenetic clay minerals, also containing basement fragments, sedimentary rocks, and a possible contribution of volcanosedimentary material. The mud facies are few, tabular, and rarely bioturbated. In addition to these facies, a thick conglomeratic deposit was identified, possibly from a high-density fluid, containing scattered blocks of claystone in a sandy-clay matrix at the base, and, higher up, oriented pebbles and parallel stratification, indicating a high-velocity unidirectional current. It makes erosive contact at the base with a fine, well-sorted sandstone, which is deposited on the basement. However, the evolution of part of the studied onshore portion is suggested to be from a fluvial system with a slightly humid to arid climate, under a supply and base level condition that allows continental deposition.