Open AccessRheology of Natural Sediments and Its Influence on the Settling of Dropstones in Hemipelagic Marine Sediment
Author(s) -
Knappe E.,
Manga M.,
Le Friant A.
Publication year - 2020
Publication title -
earth and space science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.843
H-Index - 23
ISSN - 2333-5084
DOI - 10.1029/2019ea000876
Subject(s) - geology , sediment , rheology , clastic rock , settling , rheometer , mineralogy , shear stress , geomorphology , pumice , shear (geology) , geotechnical engineering , sedimentary rock , geochemistry , petrology , volcano , materials science , environmental engineering , engineering , composite material
We investigate the rheology of naturally occurring hemipelagic marine sediment and compare measurements to another naturally occurring sediment from a terrestrial mud volcano and literature values. The hemipelagic marine sediment, collected by IODP 340, has a median grain size of 5.5 microns, is poorly sorted, and contains 31% clay, including smectite. The yield stresses and consistency are calculated by applying a range of shear stresses and shear rates using a cone‐and‐plate rheometer. A Herschel‐Bulkley model is fit to measured shear stresses and shear rates to calculate the yield stress and consistency. These measurements are performed at a range of particle concentrations and show that the hemipelagic sediment has a yield stress at particle concentrations as low as 10%. Increasing particle concentration increases the yield stress and consistency. We apply our results to show that natural pumice clasts need to have a radius greater than about 1 cm in order to settle through hemipelagic sediment on the sea floor. Most recovered pumice clasts from IODP 340 are thus preserved in the same horizon in which they were deposited.