Size sorting in marine muds: Processes, pitfalls, and prospects for paleoflow-speed proxies

McCave, I. N. and Hall, Ian Robert ORCID: https://orcid.org/0000-0001-6960-1419 2006. Size sorting in marine muds: Processes, pitfalls, and prospects for paleoflow-speed proxies. Geochemistry Geophysics Geosystems 7 (10) , Q10N05. 10.1029/2006GC001284

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Abstract

The basis for, and use of, fine grain size parameters for inference of paleoflow speeds is reviewed here. The basis resides in data on deposited sediment taken in conjunction with flow speed measurements in the field, experimental data on suspended sediment transport and deposition, and theoretical treatments of the generation of size distributions of deposits from suspension controlled by particle settling velocity and flow speed. In the deep sea, sorting events occur under resuspension/deposition events in benthic storms. At flow speeds below 10–15 cm s−1, size in the noncohesive “sortable silt” (10–63 μm) range is controlled by selective deposition, whereas above that range, removal of finer material by winnowing also plays a role. The best particle size instruments to measure a flow speed–related grain size employ the settling velocity method, while laser diffraction sizers can yield misleading results because of particle shape effects. Potential problems, including source effects, downslope supply on continental margins, spatial variability of flow over bedforms, and influence of ice-rafted detritus, are examined. A number of studies using the sortable silt flow speed proxy are reviewed, and inverse modeling of grain size distributions is examined. Outstanding problems are that corroboration is sparse because almost no studies have yet used the full range of proxies for flow rate and water mass identification and that the sortable silt mean size is not yet properly calibrated in terms of flow speed.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Subjects:	G Geography. Anthropology. Recreation > GC Oceanography
Uncontrolled Keywords:	sortable silt; grain size; paleocurrent; flow speed; ocean circulation; contourite; sediment drift
Additional Information:	Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/1525-2027/ (accessed 20/02/2014).
Publisher:	American Geophysical Union.
ISSN:	1525-2027
Date of First Compliant Deposit:	30 March 2016
Last Modified:	03 May 2023 15:51
URI:	https://orca.cardiff.ac.uk/id/eprint/30517

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