Palaeoenvironmental context and significance of ferruginous tubular bioforms and other authigenic mineral formations in source-to-sink sedimentary systems

Abstract

Surficial sediments on the seafloor from passive continental margins can provide insight into recent Late Quaternary sedimentary dynamics acting over offshore sedimentary systems. This work focuses on the study of some particular ferruginous tubular structures resembling bioforms (FTB) located in the distal Galician Continental Margin (NW Iberian Margin) at water depths between ~ 1550 and ~ 2200 m. The characterisation of these structures made it possible to study in depth their formation environment and subsequent sedimentary evolution during the Late Pleistocene and Holocene. The FTB consist of goethite with a framboidal texture. They were interpreted as formed by an initial pyrite precipitation in reducing microenvironments conditioned by the activity of sediment-dwelling organisms during the early diagenesis. This is followed by the oxidation of pyrite by a combination of hydrothermal fluids and erosional processes, which triggers the formation of the framboidal oxyhydroxides. The data allowed obtaining a comprehensive understanding of the environmental context and the significance of these ferruginous tubules, as there are no previous studies in the scientific literature that describe these structures in a source-to-sink sedimentary system.

Increasing impact of North Atlantic Ocean circulation on sedimentary processes along the passive Galicia Margin (NW Spain) over the past 40 million years

“…The Galicia Continental Margin is characterized by the presence of an intra-slope basin, the Galicia Interior Basin (GIB; Figure 1; Murillas et al, 1990;Munoz et al, 2003;Druet et al, 2018). This structural basin of almost 3,000 m water depth is separated from the Iberian Abyssal Plain by the Galicia Bank, a structural high peaking up to less than 700 m water depth (Ercilla et al, 2008;López-Pérez et al, 2021). The Galicia continental margin represents the eastern flank of GIB and extends from 100 to 2,800 m water depth (Figure 1A).…”