What feeds shelf‐edge clinoforms over margins deprived of adjacent land sources? An example from southeastern Brazil

Abstract

In southeastern Brazil, the Serra do Mar coastal mountain range blocks the sediment influx from arriving at a ca. 1,500 km long continental margin comprising Santos and Pelotas basins. Despite this deprivation, the margin accumulated a ca. 1 km thick sedimentary succession since the Mid‐Miocene. Examination of seismic reflection and oceanographic data indicates that shelf‐margin clinoform formation exhibits a regional variability, with major sigmoidal clinoforms developed in the transitional area between both basins. Laterally, poorly developed oblique clinoforms constitute isolated depocenters along the shelf margin. The continuous clinoform development in the transitional area is attributed to the major influence on sediment transport patterns of several ocean bottom currents flowing along the margin, such as the Brazil Coastal Current, the Brazil Current and the Intermediate Water Brazil Current. These currents erode, transport and distribute sediments across the shelf break and upper slope from distant sediment sources located either north or south of the study area. The progressive southward strengthening of the Brazil Current could be responsible for a major southward sediment redistribution from the northern Campos Basin, and/or for sediment entrainment from northward‐induced transport by the Brazil Coastal Current, originally derived from the De la Plata Estuary. In the transition between Santos and Pelotas basins, the Intermediate Water Brazil Current splits forming the Santos Bifurcation, allowing for a continuous depositional process and clinoform generation. We suggest that ocean bottom currents may shape other shelf‐edge ‘contouritic clinoforms’ in continental margins mainly constructed by along‐strike sediment transport largely driven by long‐term geostrophic currents.

Clinoforms and clinothems: Fundamental elements of basin infill

“…Gong, Blum, Wang, Lin, & Xu, 2018) (Figure 3). In keeping with the current upsurge of interest in oceanic contour currents and drift deposits, this special issue also emphasizes how important the action of these bottom-hugging currents are in supplying and reshaping some segments of clinothems (Cattaneo et al, 2007;Gamberi et al, 2019;Schattner et al, 2019).…”

“…Process-regime reconstructions show that river-dominated delta fronts are controlled by hyperpycnal flows and are significantly steeper than their wave-dominated counterparts. Schattner et al, 2019, based on seismic and oceanographic data, stress the importance of the impact of oceanic bottom currents on clinothem formation from the post-Mid-Miocene succession of the south-eastern Brazilian margin. Currents flowing along-strike, both northeast and southwest along the 1,500-km-long continental margin, were able to erode, transport and deposit a 1-km-thick clinoform succession.…”

“…Clinothems with their high rates of accumulation have a similar tendency to preserve a good record of sedimentary processes and are excellent aids to reconstruct palaeo‐environmental regimes and oceanographic configurations through time (e.g. Amorosi et al, 2019; Anderson et al, 2004; Anderson, Wallace, Simms, Rodriguez, & Milliken, 2014; Bahr, Arz, Lamy, & Wefer, 2006; Cattaneo & Trincardi, 1999; Fanget et al, 2014; Gamberi et al, 2019; Jouet et al, 2006; Korus & Fielding, 2015; Li, Chen, Zhang, Yang, & Fan, 2000; Patruno et al, 2019; Pellegrini et al, 2015; Rodriguez, Simms, & Anderson, 2010; Schattner et al, 2019; Simms, Lambeck, Purcell, Anderson, & Rodriguez, 2007; Stanley & Warne, 1994; Trincardi, Asioli, Cattaneo, Correggiari, & Langone, 1996). For instance, recent publications have shown Quaternary climatic reconstruction extracted from shelf mud‐belts (e.g.…”

“…As a consequence, care is needed when interpreting the palaeophysiographic significance of ancient rollover points, to pinpoint the shelf break, to identify the shoreline and to estimate palaeo‐water depths from clinoforms (Bryn et al, 2019; Gamberi et al, 2019; Patruno et al, 2015; Patruno et al, 2019; Schattner et al, 2019; Steel et al, 2019; Trincardi et al, 2019).…”

“…Their basinward migration is also a testimony of deposition outpacing destructive processes, such as erosion from nearshore and shelfal oceanographic currents (e.g. Lobo & Ridente, 2014; Nittrouer et al, 2007; Patruno et al, 2019; Pellegrini et al, 2018; Pellegrini, Bohacs, et al, 2017; Pellegrini, Maselli, et al, 2017; Schattner, José Lobo, López‐Quirós, Passos Nascimento, & Mahiques, 2019; Steel, Olariu, Zhang, & Chen, 2019). In a similar way, clinothems also result from the biological growth (upbuilding and/or outbuilding) of carbonate and/or sulphate platforms (e.g.…”