Multiscale Brazil nut effects in bioturbated sediment

Abstract

Size segregation in granular materials is a universal phenomenon popularly known as the Brazil nut effect (BNE), from the tendency of larger nuts to end on the top of a shaken container. In nature, fast granular flows bear many similarities with well-studied mixing processes. Instead, much slower phenomena, such as the accumulation of ferromanganese nodules (FN) on the seafloor, have been attributed to the BNE but remain essentially unexplained. Here we document, for the first time, the BNE on sub-millimetre particles in pelagic sediment and propose a size segregation model for the surface mixed layer of bioturbated sediments. Our model explains the size distribution of FN seeds, pointing to a uniform segregation mechanism over sizes ranging from < 1 mm to > 1 cm, which does not depend on selective ingestion by feeding organisms. In addition to explaining FN nucleation, our model has important implications for microfossil dating and the mechanism underlying sedimentary records of the Earth’s magnetic field.

Continuous measurement of ferrous sinter size distributions using an optical sensor system

“…There is convincing correlation between the sieve data and the camera data for different bin sizes, for each of the four samples. The discrepancies for the 0–5, 25–40, and 40+ mm bins were attributed to a bias in the size of sinter on the top layer of the belt, via the ‘brazil nut effect’ [24]. There is also some algorithmic bias introduced, especially in the 0–5 mm bin, where smoothing induced by the topographical functions may obscure smaller areas.…”

Estimating Post‐Depositional Detrital Remanent Magnetization (pDRM) Effects for Several Lacustrine and Marine Sediment Records Using a Flexible Lock‐In Function Approach

“…The depositional ages depend on additional lithological factors and may be influenced by bioturbation (Egli & Zhao, 2015), the so‐called Brazil nut effect (Savnranskaia et al., 2022) and other processes like differential dissolution (Barker et al., 2007). Including these effects in the age‐depth modeling procedure is difficult due to many unknowns related to the processes.…”

“…Some use paleo secular variations to complement radiocarbon dates. Further, most of them are constructed using out-dated radiocarbon calibration curves that is, older versions of IntCal for Northern Hemisphere, SHCal for Southern Hemisphere and/or Marine for oceanic records; see Reimer et al (2020) The depositional ages depend on additional lithological factors and may be influenced by bioturbation (Egli & Zhao, 2015), the so-called Brazil nut effect (Savnranskaia et al, 2022) and other processes like differential dissolution (Barker et al, 2007). Including these effects in the age-depth modeling procedure is difficult due to many unknowns related to the processes.…”

A downcore increase in time averaging is the null expectation from the transit of death assemblages through a mixed layer

“…Burial is the combined effect of new sediment added to the sediment–water interface (deposition) as well as the downward movement of shells to the underlying increments associated with mixing by burrowers (e.g., conveyor-belt species that preferentially move fine sediment upward and shells downward; Tudhope and Scoffin 1984; Bradshaw and Scoffin 2001). Exhumation is the combined effect of the physical erosion or winnowing of fines, leaving shells behind, as well as the upward movement of shells to overlying increments by bioturbators (e.g., granola or nut effect preferentially moving fines downward; Rhoads and Stanley 1965; McCave 1988; Savranskaia et al 2022). Disintegration is the combined effect of physical, chemical, and biological agents of shell destruction, leading to the loss of a taxonomically identifiable shells.…”