Rheological boundaries of mud: Where are the limits?

Abstract

Mud" includes a rheological criterion that implies it exhibits a particular consistency state, the lower boundary of which can be specified through the use of the Atterberg plastic limit, but the upper boundary remains undefined. A relationship between the water content of a hindered settling suspension when its structure changes from fluid-supported to body-supported and its Atterberg liquid limit appears capable of predicting the physical conditions at the moment when the suspension acquires a rheotogical character sufficient to define the upper surface of mud. This relationship appears consistent and predictable within various marine and estuarine environments.

Sedimentology of a tidal point-bar within the fluvial–tidal transition

“…Deposition of the thicker mud layers noted higher in the bar sequence could be due to fluid muds, but this is unlikely as in the Severn Estuary these flows are bottomhugging with a fines concentration >10 g l À1 (Faas, 1991) and occur mainly in the outer estuary (Kirby and Parker, 1983). Thus, it is unlikely that major lutoclines form in the transitional zone.…”

Palaeo-Orinoco (Pliocene) channels on the tide-dominated Morne L'Enfer delta lobes and estuaries, SW Trinidad

“…In a growing number of documented cases (Harris et al, 1993;Ichaso and Dalrymple, 2009;Jaeger and Nittrouer, 1995;Kineke et al, 1996), and as emphasized recently by Dalrymple and Choi (2007) and MacKay and Dalrymple (2011), the distinguishing features for fluid mud as a strong tidal dominance indicator include (1) High suspended-sediment concentration (SSC): fluid mud is defined as any aqueous suspension in which the concentration of particles exceeds 10 g/L (Dalrymple and Choi, 2007;Faas, 1991;MacKay and Dalrymple, 2011); (2) The zone in which they are generated: "fluid muds" are generated in the turbidity maximum zone of estuaries and deltas, where the SSC is sufficiently high. The high SSC is facilitated by the mixing of fresh and marine water in the tidal zone and results in rapid mud flocculation (Dalrymple and Choi, 2007); (3) Sedimentary generation processes: the characteristics of fluid mud are still poorly known, but they have rheological properties intermediate between dirty water and a stationary, deposited mud layer.…”

“…7.20). Although the sand in the channel succession tends to fine upward, the abundance of fluid mud layers that formed by high-concentration suspensions (defined as suspension concentrations >10 g/L) (Dalrymple and Choi, 2007;Faas, 1991) of fine-grained sediments at the channel base produces an apparent upwardcoarsening trend in the lower part of each channel succession (see also Dalrymple et al, 2003;Harris et al, 2004;Ichaso and Dalrymple, 2009;Kineke and Sternberg, 1995;MacKay and Dalrymple, 2011). 7.18A) and between the upwardcoarsening delta-front packages (yellow (white in the print version) arrows in Fig.…”

Hydrodynamics in a Mud Bank Regime during Nonmonsoon and Monsoon Seasons

“…Although a number of studies attempted to explain the formation, sustenance, and disappearance of the mud banks off Kerala, the phenomenon still remains an enigma (for reviews see FAAS, 1991FAAS, , 1995LI and PARCHURE, 1998;MATHEW, BABA, and KURIEN, 1995;MEHTA and JIANG, 1993;NAIR, 1976;SILAS, 1984;WELLS and KEMP, 1986). In hindsight this is not surprising, as most of the earlier studies on the Kerala mud banks covered basically their hydrographic features and the physical processes involved in their formation, but did not include real time, nearshore ocean monitoring.…”