Walsh River Sediment Dispersal on Continental Margins 2009

8/8/2019 Walsh River Sediment Dispersal on Continental Margins 2009

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Understanding fine-grained river-sediment dispersal on continental margins

J.P. Walsha,, C.A. Nittrouer b

a Department of Geological Sciences and Institute for Coastal Science and Policy, East Carolina University, Greenville, NC 27858, United Statesb School of Oceanography, University of Washington, Seattle, WA 98195-7940, United States

a b s t r a c ta r t i c l e i n f o

Article history:

Received 10 September 2008

Received in revised form 14 March 2009

Accepted 23 March 2009

Communicated by John T. Wells

Keywords:

deltas

rivers

continental margins

sedimentation

Studies of fine-grained sediment dispersal in the marine environment have documented diversity in the

behavior of depositional systems on continental margins with different oceanographic conditions and

morphologies. Based on the pattern and nature of sediment accumulation for twenty-three case studies, we

propose there are five basic types of dispersal systems, and these are related to river, wave, tide and margin

characteristics. Data suggest that the type of dispersal system on any margin can be predicted with

knowledge of sediment load, mean significant wave height, tidal range and continental-shelf width at a river

mouth, and from these, a hierarchical decision tree is developed. Analysis of the dispersal-system type of

more than 100 river mouths reveals that proximal-accumulation-dominated (PAD) and marine-dispersal-

dominated (MDD) systems are most abundant. But, estuarine-accumulation-dominated (EAD) systems also

are anticipated to be numerous globally. Research quantifying marine sediment dynamics in these system

types is needed. Although less common, the size and nature of subaqueous-delta-clinoform (SDC) and

canyon-captured (CC) systems also warrant future attention to their study. Strong correlations between

physical characteristics (i.e., significant wave height and tidal range) and the depth and distance to the

nearest maximum shelf depocenter provide evidence that in reality a continuum exists between the system

types. The process-related partitioning of sediment in the five different types of marine dispersal systems has

important implications for understanding the stratigraphic record and the cycling of carbon.

2009 Elsevier B.V. All rights reserved.

1. Introduction

A river dispersal system is the means and area over which water,

sediments and solutes aregenerated, transferred and stored in a given

drainage basin, from the source through the sea. The components of

dispersal systems (e.g., mountains, floodplains, deltas), their con-

nectivity and their functioning vary dramatically as result of the

tectonic setting, climate, and many other factors. This paper

specifically examines the nature of sedimentation in the marine

portion of dispersal systems, where most sediment emanating from a

source stream will be deposited under the influence of basin

processes.

Marine sedimentary deposits can take a variety of shapes, and can

be characterized by substantial subaqueous deltas (e.g., Amazon;

Nittrouer et al., 1996). It is well understood that the morphology and

stratigraphy of the proximal portion of deltaic systems are regulated

by waves, tides, and sediment supply (Coleman and Wright, 1975;

Galloway,1975; Wright,1985; Orton and Reading,1993). The subaerial

and shallow parts of the delta generally contain a considerable

fraction of sandy sediments. But the bulk of sediment discharged by

rivers consists of silt and clay particles, and these particles generally

accumulate at deeper depths in the ocean, where the strength of

waves and tides are diminished.

Commonly associated with fine-grained particles are organic

materials and other chemical species that may be buried or recycled

in the seabed (Hedges and Keil, 1995). Storage of terrestrial/marine

carbon and anthropogenic pollutants has important implications for

marine ecosystems, climate cycles, and human impacts. Additionally,

the high-resolution record of potentially thick, deltaic deposits may

give new, detailed insights into late Holocene sea-level rise and

climate change. To address these concerns, it is important that we

understand how fine-grained river sediments accumulate under

different oceanographic conditions and morphological configurations

as highlighted by McKee et al. (2004).

Thispaper aims to integrate existingknowledge about marinefine-

sediment dispersal systems, so that insights on individual systems can

be placed in a larger context and further research can be planned. At

this point, a relatively small number of dispersal systems have been

examined thoroughly with sedimentological and geophysical tools.

The goals of this work are threefold: (1) to identify commonality

among the systems that have been examined, (2) to determine how

basic characteristics of dispersal systems distinguish them, and (3) to

use these insights to predict the nature of unknown systems.

Marine Geology 263 (2009) 3445

Corresponding author. Tel.:+ 1 252 328 5431.

E-mail address: [email protected] (J.P. Walsh).

0025-3227/$ see front matter 2009 Elsevier B.V. All rights reserved.

doi:10.1016/j.margeo.2009.03.016

Contents lists available at ScienceDirect

Marine Geology

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / m a r g e o
mailto:[email protected]://dx.doi.org/10.1016/j.margeo.2009.03.016http://www.sciencedirect.com/science/journal/00253227http://www.sciencedirect.com/science/journal/00253227http://dx.doi.org/10.1016/j.margeo.2009.03.016mailto:[email protected]


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2. Background

There are a number of factors affecting the accumulation of river-

derived sediments in the ocean (Orton and Reading, 1993; Nittrouer

and Wright, 1994; Wright and Nittrouer, 1995), and these may be

separated into drainage- and receiving-basin characteristics (see Fig. 5

in Coleman and Wright, 1975). Influential aspects of the drainage

basin include the volume of sediment supply and also the timing and

nature of sediment discharge, e.g., the grain-size distribution, andwater/sediment ratio (Orton and Reading, 1993). The amount of

sediment supply has been shown to be proportional to drainage basin

area and elevation (Milliman and Meade, 1983; Milliman, 1995) and

related to mountain uplift rate (Hovius,1998), but it is also influenced

by a number of other factors including geology, vegetation, rainfall,

and human activities (Pinet and Souriau, 1988; Summerfield and

Hulton, 1994; Syvitski et al., 2005). Wave climate and tidal flows are

critical receiving-basin characteristics that impact marine dispersal,

but other currents (e.g., density-driven transport and geostrophic

circulation) and margin geometry also are important. Because small

(silt and clay) sedimentary particles may be transported easily, they

are extremely sensitive to oceanographic conditions (Orton and

Reading, 1993).

A complete review of shelf-sediment-transport mechanisms is

beyond the scope of this paper; the reader is referred to Nittrouer and

Wright (1994), Nittrouer et al. (2007) and the references therein and

below. There are three primary means in which sediments are

transported across continental margins: (1) surface-plume (or

hypopycnal) transport, (2) dilute-suspension bottom-boundary-

layer dispersal, and (3) sediment gravity flows (e.g., hyperpycnal

plumes and fluid muds). Although impressive from altitude, surface

plumes transport a relatively small amount of the sediment load from

a river, and flocculation is a key process restricting transport distances

(Geyer et al., 2004). Flocculation coupled with estuarine circulation at

river mouths produces the turbidity maximum, a zone characterized

by high suspended-sediment concentrations and commonly rapid

sediment deposition (Geyer et al., 2004). In this way, most sediments

are placed at or near the seabed where rivers meet the coastal ocean.

These sediments can subsequently move across and along continentalmargins in the bottom boundary layer as dilute suspensions,

immediately above the seabed. Research with instrumented tripods

has documented and quantified the frequency, magnitude, and

direction of sediment transport by currents and waves on continental

shelves (Sternberg and Nowell, 1999; Sternberg, 2005; Cacchione

et al., 2006; and the papers therein).

After initial deposition, sediment resuspension is governed by the

threshold of motion for sediments, which is a function of the critical

bed shear stress and the combined wave-current bed shear stress

created by the physical conditions (e.g., waves, tides, wind-driven

circulation). When the combined bed shear stress exceeds the critical

stress, sediments are resuspended, and currents can disperse any

suspended sediment. Eventually, sediments will deposit when (and

where) thewaves and currents arereduced, as particlesflocculate andsettle (Nittrouer and Wright, 1994). Depending on the conditions,

particles (or some fraction of those deposited) can experience

multiple episodes of transport and re-deposition until their ultimate

site of accumulation is reached. Relatively recently, in situ measure-

ments have revealed the importance of sediment gravity flows (dense

suspensions) as a key transport agent on continental shelves (Wright

et al., 1988; Sternberg et. al., 1991; Ogston et al., 2000; Traykovski et

al., 2000; Wright et al., 2001; Puig et al; 2004); however, only on

relatively steep shelves can these flows move by their own weight.

Wright et al. (2001) calculate that sediment gravity flows with

Richardson numbers ofb0.25 canbecome autosuspending at slopesof

0.7 or greater. Elsewhere, waves and/or currents must assist

transport. In fact, most shelves have gradients much less than 0.7.

For this reason, wave- and current-assisted gravity-driven transport

can be important on portions of some margins. Geyer et al. (2004)

states Notwithstanding the recent progress in identifying new

mechanisms of sediment transport on the continental shelf, we are

a long way from the point at which sediment fluxes and deposition

patterns can be predicted, given knowledge of the supply, the

geometry and forcing conditions. This is a reasonable statement,

and thus we note here that this paper is not intended to predict the

locations or rates of sediment deposition in different systems. Rather,

the analysis aims to identify commonalities in the nature ofsedimentation in the diversity of marine dispersal systems.

Based on quantitative studies of the marine sediment dispersal

systems, a range in sedimentation behavior is evident. Many rivers

have relatively small sediment loads and large estuaries, such that

little fluvial sediment reaches the continental shelf (Dalrymple et al.,

1992). But, many others with substantial loads have filled their

estuaries, and these are actively supplying most of their sediment to

the shelf. For the Po River, largest accumulation rates (13 cm/y) are

found only ~2 km from the mouth (Frignani and Langone, 1991;

Palinkas and Nittrouer, 2007). In contrast, foreset beds of the Amazon

subaqueous delta clinoform experience very high rates of sediment

accumulation (N10 cm/y) approximately 250 km from the Amazon

River mouth (Dukat and Kuehl, 1995; Kuehl et al., 1996). In fact, a

number of studies have documented subaqueous delta clinoforms

seaward of river mouths (e.g., Amazon, Nittrouer et al., 1986; Kuehl

et al., 1989; Kuehl et al., 1996; Nittrouer et al., 1996; Ganges

Brahmaputra, Kuehl et al., 1997; Michels et al., 1998; Yellow

(Huanghe), Alexander et al., 1991; Liu et al., 2002, 2004; Yangtze

(Changjiang), McKee et al., 1983, 1984; Nittrouer et al., 1984; Fly,

Harris et al., 1993; Walsh et al., 2004; Indus, Giosan et al., 2006), and

this body of work indicates similarity in the processes and products of

these systems. However, other research shows subaqueous delta

clinoforms are not formed everywhere. For example, along the Eel

River margin in northern California, flood deposits and large

accumulation rates (0.50.8 cm/y, over a 100-year timescale) are

found on the shelf in water depths of ~60 m about 15 km from the

fluvial source, without a notable subaqueous delta clinoform

(Wheatcroft et al., 1997; Sommerfield and Nittrouer, 1999). Despite

large sediment loads, a subaqueous delta clinoform is also absentseaward of the Copper and Columbia rivers (Nittrouer and Sternberg,

1981; Jaeger et al., 1998). In Papua New Guinea, the Sepik River

discharges its load essentially into a submarine canyon, and excep-

tional rates of sediment deposition and accumulation (N2.5 cm/y) are

evident at 650 m water depth (Walsh and Nittrouer, 2003). Similar

sedimentation is evident in the Congo system (Heezen et al., 1964;

Droz et al., 1996). Examination of the range in the amountof sediment

carried to and off the shelf by various marine dispersal systems

suggests a continuum exists that is related to the width of the

continental shelf and the dominant dispersal processes (Walsh and

Nittrouer, 2003).

Although primarily oriented towards sequence stratigraphic

modeling, Swift and Thorne (1991) provide a conceptual framework

for shelf sedimentation, referred to as regime theory, which isrelevant to the research presented here. They suggest that four

variables regulate shelf depositional behavior: sediment input rate

(Q), relative sea-level change (R), the delivered grain size (M), and

dispersive sediment transport (D) which is a function offluid power

from waves, tides and currents (P). Their Concept of the Equilibrium

Shelf, which is based on earlier work (see references therein), argues

that sediments will accumulate vertically until reaching wave base,

the theoretical depth above which physical transport processes

preclude accumulation. They discuss how the Q/P relationship is

fundamental in controlling sedimentation on shelves. Swift and

Thorne (1991) further explain that systems where Q MNR D are

deltaic while those in which Q MbR D are estuarine. In the

latter case, sufficient accommodation space is available for storage. In

essence, the present paper investigates Qand Pvariability (but waves

35 J.P. Walsh, C.A. Nittrouer / Marine Geology 263 (2009) 3445


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indicating rivers with relatively small sediment loads, shelf widths,

and tidal ranges are more common in this dataset. In total, twentyfive

of the systems have a shelf width b40 km. A number of systems have

no wave data; the remaining data range from 0.7 to 3 m and have a

mode at 1.1 m. Two scatter plots of these data are created to show

distribution of the variables with respect to others and to illustrate

how the well-studied systems in Table 1 are distributed (Fig. 3). Note,

neither of the graphs exhibits a simple relationship between the

variables. The only strong relationships observed in the data collected

are shown in Fig. 4.

By comparing sediment accumulation patterns from previous

studies, we have identified five basic types of fine-grained marine

dispersal systems (Fig. 5). Each system that has been studied in some

detail is classified using this scheme (Table 1). Theexamplesystemsin

Fig. 5 (right) are not end-members, and it is likely that true end-

members do not exist. Most, if not all, systems probably lose a fraction

of their load to various segments of a continental margin. The system

types proposed in Fig. 5 are designed to explain how the majority of

sediment supplied by a river is stored in the marine setting. The

Delaware and Susquehanna rivers with relatively low sediment loads

(b2 Mt y1) drain into large, unfilled estuaries, which capture the

majority of the sediment load (Fig. 3A; Fletcher et al., 1992; Langland

and Cronin, 2000); these systems are classified as Estuarine

Accumulation Dominated (EAD) (Table 1; Fig. 5). Deltaic systems

with rapid rates of sediment accumulation very close to their mouth

(e.g., Po and Mississippi rivers) are referred to as Proximal

Fig. 1. Magnitude of sediment discharge (A), and tidal range and shelf width (B) at many large river mouths. Size and color of symbols are scaled as indicated. Sediment discharge

units are megatons per year (Mt y1), and data are adopted from Milliman and Syvitski (1992) and Hovius (1998). Background data are elevations from ETOPO2 (Smith and

Sandwell, 1997; Jakobsson et al., 2000). Rivers are the following: 1=Amazon, 2=Yellow (Huanghe), 3 and 4=GangesBrahmaputra, 5=Yangtze (Changjiang), 6=Mississippi,

7= Irrawaddy, 8= Indus, 9= Magdalena, 10=Godavari, 11= Mekong, 12= Orinoco,13= Red,14= Colorado, 15=Nile, 16=Fly, 17= Orange, 18=Purari,19= Sepik, 20= Parana,

21=Copper, 22=Pearl, 23=Danube, 24=Krishna, 25=Choshui, 26=Mahanadi, 27=Yukon, 28=TigrisEuphrates, 29=Amur, 30=Zambezi, 31=Zaire, 32=Mackenzie,

33=Liao He, 34=Niger, 35=Daling, 36=Kaoping, 37=Limpopo, 38=Tana, 39=Rhone, 40=Tsengwen, 41=Kikori, 42=Murray, 43=Damodar, 44=Waiapu, 45=Susitna,

46=Eel,47= Peinan, 48=KizilIrmak, 49=Semani,50= Chira,51=Fraser, 52=Hsiukuluan,53= Hualien, 54=Ord,55 =Rio Grande, 56=Ebro, 57=Rufiji, 58=Brazos, 59=Ob,

60=Columbia, 61=Drini, 62=Huaihe, 63=Indigirka, 64=Haast, 65=Negro, 66=Po, 67=Rio Negro, 68=Yenisey, 69=Lena, 70=Chao Phraya, 71=Uruguay, 72=Kuskok-

wim, 73=Waiapoa, 74=Rio Colorado, 75=Pechora, 76=Colville, 77=Kolyma, 78=Sao Francisco, 79=Severnaya, 80=St. Lawrence, 81=Burdekin, 82=Jana, 83=Sanaga,

84=Waiau, 85=Dnestr, 86=Vistula, 87=Mobile, 88=Garonne, 89=Dnepr, 90=Colorado, 91=Senegal, 92=Susquehanna, 93=Loire, 94=Seine, 95=Hudson, 96=Elbe,

97= Don, 98= Rhein, 99= Meuse, 100= Delaware, 101= Rio Grande, 102= Weser, 103=Apalachicola, 104= Kemijoki, 105=Oder.



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Accumulation Dominated (PAD). In these cases, the delta-front

(essentially the foreset of a proximal, shallow clinoform; Giosan

et al., 2006) lies only kilometers from the distributary mouth. The

Yellow (Huanghe) River is most appropriately classified as PAD

because 90% of the Yellow River sediment load accumulates very close

to the river mouth in the Bohai Sea (Bornhold et al.,1986). Note, these

systems haverelatively low mean significant wave height (b2 m)and/

or tidal range (b2 m) (Table 1; Figs. 3 and 5). Subaqueous delta

clinoforms (SDC) are shelf sedimentary deposits displaced from the

river sediment source (i.e., part of the deeper prodelta; Giosan et al.,

2006), with notable relief above thetransgressive surface (e.g., Fly and

Amazon rivers). In this case, the foreset region of the SDC is located

tens to hundreds of kilometers seaward. These pronounced features

account for a significant fraction of the sediment budget in several

dispersal systems (Table 1) and are characterized by large sediment

loads and tidal ranges (Table 1; Figs. 3 and 5). The sediment loaddischarged from marine-dispersal-dominated (MDD) rivers is more

efficiently dispersed in the ocean, precluding the development of a

PAD or SDC (i.e., no clinoforms are present). MDD systems have high

mean significant wave heights and/or tidal ranges (both N2 m;

Table 1; Figs. 3B and 5). In MDD systems, areas of high sediment

accumulation can be located in tectonic basins on the shelf, slope or in

canyons (e.g.,Eel andColumbiarivers). Even duringhigh-standsin sea

level, the majority (N50%) of sediment discharged by some rivers is

transported rapidly to the deep sea via a submarine canyon, and such

systems are classified here as canyon captured (CC; e.g., Sepik and

Congo rivers). These systems have narrow shelf widths (Table 1;

Fig. 3A).

Data from systems studied quantitatively (i.e., to define sediment

accumulation rates and patterns) reveal two important relationships

(Fig. 4). Mean significant wave height is well correlated with the

depth of NMSD, and a strong non-linear relationship exists between

tidal range and the distance to the NMSD. Both of these plots have

high correlation coefficients (r2=0.82 and 0.76, respectively; Fig. 4),

suggesting a strong association between the variables.

5. Discussion

5.1. Sediment partitioning and fluvial dispersal systems

There is great disparity in how processes affect the partitioning of

fine-grained sediment between different sinks (e.g., estuarine sedi-

ment trapping versus turbidity-current transport to the deep sea;

Heezen et al., 1964; Fletcher et al., 1992; Kineke et al., 2000; Langland

Fig. 2. Mean significant wave height for dispersal systems (left) and histograms of the data in this study (right). Note, circles indicate systems where mean significant wave heights

are b2m, and squares arethose systems where mean significant wave heights areN2m. Also, the large areas of white in the ArcticOcean, Mediterranean Sea, and elsewhere are sites

of no data. A scale bar for the mean significant wave height data (gray shading) is provided. The percent occurrence of systems for the specified variables is shown at right.

Fig. 3. Scatter plots of shelf width and sediment load (A) and tidal range and mean significant wave height for classified and all systems (B). EAD and CC systems plot in the darker

blue and lighter green patterns of A, respectively. In B, yellowand whiteshading indicates areas anticipated to be MDDand PADsystems,respectively; however, systems in B that fall

within the hachured pattern are expected to SDC, if their load exceeds 100 Mt y1

. The small black dots are the unclassified dispersal systems (i.e., those in Fig.1 but not in Table 1).



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and Cronin, 2000; Walsh and Nittrouer, 2003). A scatter plot of mean

significant wave height versus mean tidal range is a simple, objective

way to compare processes affecting coastal and shelf systems (Davis

and Hayes, 1984), and rivers classified in this study (Table 1) are

plotted in Fig. 3B to illustrate how physical processes may relate to the

dispersal-system classifications. The scatter plot in Fig. 3A can be used

as a similar tool to examine the shelf width and sediment load of a

system. Shown on these plots is an interpretation of where the five

system types are anticipated to plot; this interpretation will be

discussed further.

5.1.1. Estuarine-accumulation-dominated (EAD) systems

EAD systems are characterized by flocculation and estuarine

circulation, and these are commonly the most critical processes

regulating the nature of sediment accumulation. EADs represent the

simplest scenario of marine dispersal, where the load of a system is

sufficiently small that the estuary into which it drains remains

unfilled. Sediments generally are rapidly deposited, and, even if

resuspended, only a small portion might escape. As a result, regardless

of other characteristics (shelf width, waves, or tides, as indicated in

Fig. 3A), most river sediments accumulate within the estuary. The

Fig. 4. Scatterplots of meansignificantwaveheightversus depth to nearestmaximumshelf depocenter (NMSD) (A) andtidal range versus distanceto NMSD (B).These plots use data

from quantitatively studied systems listed in Table 1. Note, the x-axis in A is linear, but is logarithmic in B.

Fig. 5. Major types of marine river-sediment dispersal systems (left side) and representative examples of each type (except EAD, right side). Examples for the PAD (B), CC (C), MDD

(D) and SDC (E) are the Po, Sepik, Eel and Fly rivers, respectively (right). These example systems do not reflect end-members. The distribution of 100-y sediment accumulation rates

are shown in small figures for each example system. Locations of maximum fine-grained sediment accumulation in each system type (left) and examples (right) are shown in red.

Isobath positions are noted on right. See Table 1 for references.



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Delaware and Susquehanna rivers are two examples of EAD systems,

but numerous others are found along the west and east sides of the

Atlantic Ocean and elsewhere. Based on these two systems, the

sediment load criterion for an EAD system is assumed to beb2 M t y1

(Fig. 3A). However, quantitative knowledge about the sediment

budgets from more systems may shift this boundary. Sediment load

is not expected to be the sole factor regulating this system type, but it

isused hereas a first-orderproxy. The size of thereceivingestuary, the

timing of the discharge, and the oceanographic conditions also can beimportant.

5.1.2. Proximal-accumulation-dominated (PAD) systems

As in the EAD case, PAD systems are also characterized by

flocculation and rapid deposition offine-grained sediments. In these

cases, however, the sediments supplied by source streams have filled

the estuaries and presently enter coastal water bodies experiencing

relatively small wavesand a lowtidal range (Fig.3B). With diminished

stream-transport capacity from effluent spreading and insufficient

bed shear stresses for sediment movement by marine processes, the

majority (N50%) of fine-grained sediments flocculate and deposit

close to (within a few kilometers of) the coastline (e.g., Fisk et al.,

1954; Scruton, 1960; Frignani and Langone, 1991; Fox et al., 2004;

Frignani et al., 2005; Corbett et al., 2006; Palinkas and Nittrouer,

2007). A significant portion of the load also can be advected in the

direction of prevailing currents (e.g., 3540% for the Po River, Fig. 5;

Frignani et al., 2005). This rapid proximal sediment accumulation

forms the depositional bulge where each distributary reaches the

coastline (Fisk et al., 1954). Like the Mississippi delta, these systems

can build to unstable relief onto the surrounding shelf, and thus be

prone to mass-failure events (e.g., Coleman and Prior, 1988). Due to

the nature of PAD systems (i.e., sediments accumulate rapidly near

their discharge location), channel migration and switching are

common. For this reason, sediment may be discharged by more than

one distributary channel, and several foci of sediment accumulation

can occur on the continental shelf adjacent to each distributary

channel (Fig. 5, right).

5.1.3. Canyon-captured (CC) systemsAt CC river mouths, the majority of the sediment load moves

rapidly down a canyon immediately seaward of the river mouth;

sediment gravity flows (e.g., turbidity currents) are the primary

means of sediment transport to the deep sea in such systems (Heezen

et al., 1964; Kineke et al., 2000; Walsh and Nittrouer, 2003). The

proximity of a submarine canyon is the most important factor

determining the degree to which, the load of a system is lost to a

canyon. At river mouths where the shelf is narrow (and steep),

canyons can be more closely positioned to a fluvial source, or may

form the natural extensions of river valleys. As a first approach, the

minimum gradient for an autosuspending gravity flow (0.7; Wright

et al., 2001) is used to identify margins where this form of transport

will dominate. This criterion suggests that shelves b12 km in width

(assuming a shelf break depth of 150 m) are locations where CCsystems should be anticipated. The two examples described here, the

Sepik and Congo rivers, match this description. Because CC systems

are most likely found in areas with narrow continental shelves that

typically have small tidal ranges, they should plot near the abscissa in

Fig. 3B. Other types of modern dispersal systems can lose a portion of

their sediment load to the deep sea (e.g., Eel: Mullenbach and

Nittrouer, 2000; Columbia: Baker and Hickey, 1986; Mississippi:

Coleman et al., 1998; GangesBrahmaputra: Kuehl et al., 1989), yet

these arenot classified asCC systems as the majority (N50%) isnot lost

to a canyon.

Many studies of modern dispersal systems have documented the

transport offluvial sediment through canyons. These incised features

may extend very close to river mouths, thereby intercepting the shelf

dispersal pathway of river sediments. A significant portion of the

sediment from the Sepik, Eel, Congo, and GangesBrahmaputra River

is transported regularly and rapidly by sediment gravityflows through

submarine canyons (Heezen et al., 1964; Kudrass et al., 1998;

Mullenbach and Nittrouer, 2000; Puig et al., 2003; Walsh and

Nittrouer, 2003; Puig et al., 2004). All of these systems have shelves

narrower than 50 km adjacent to the canyon head. These examples

provide good evidence for the impact of shelf width on off-shelf

sediment transport (Walsh and Nittrouer, 2003). In the CC systems

(Sepik and CongoRivers), a submarine canyon extends essentially intothe river mouth; in other cases, a canyon is incised into the

surrounding margin near the discharge location. The Ganges

Brahmaputra system highlights how a canyon may capture a

significant part (~1/3) of the river sediment budget, although not

being immediately adjacent to the river mouth (Goodbred and Kuehl,

1999). The Swatch of No Ground (a submarine canyon) is situated

over 200 km from the river mouth, yet sediment is actively

transported into and through this canyon because of strong along-

shelf transport and the very narrow shelf at the canyon head (Kudrass

et al., 1998). Numerous aspects of sedimentary dynamics (e.g., bottom

Ekman veering, internal waves) and their coupling canalso impact the

extent of off-shelf sediment transport.

5.1.4. Marine-dispersal-dominated (MDD) systems

Bottom-boundary layer transport and sediment gravity flows

efficiently disperse most river sediments on the continental margin

surrounding an MDD system. The cartoon of a MDD system implies

one large area of greatest sediment accumulation (Fig. 5, left). But, as

depicted for the Eel River system, several isolated foci of sediment

accumulation may exist; these distorted bulls-eye patterns may be

related to dominant currents, fluid-mud transport pathways, and

structural controls allowing sediment accumulation to be locally

elevated at several sites over the same time scale (Fig. 5, right;

Nittrouer and Sternberg, 1981; Jaeger et al., 1998; Alexander and

Simoneau., 1999; Sommerfield and Nittrouer, 1999; Mullenbach and

Nittrouer, 2000). MDD systems develop where rivers discharge their

sediment load into an oceanographic environment with moderate to

large waves and/or currents (gray area in Fig. 3B). Because of

energetic receiving-basin conditions, the majority of the fine-grainedsediment load cannot accumulate at shallow water depths proximal to

the river mouth; only a fraction (up to 10%) may be sequestered

among proximal sandy sediments (e.g., the Eel River shelf; Crockett

and Nittrouer, 2004). The development offluid muds during flooding

can allow deposition of discrete beds at a consistent location on the

continental shelf (Wheatcroft et al., 1997; Sommerfield and Nittrouer,

1999). Nevertheless, a considerable portion of the load is advected

across and along the margin (tens to hundreds of kilometers) as a

result of efficient dispersal by bottom and intermediate nepheloid

layers (Alexander and Simoneau, 1999; Walsh and Nittrouer, 1999;

Mullenbach and Nittrouer, 2000; Puig et al., 2003, 2004). The impact

of the mean significiant wave height and tidal range on the nearest

maximum shelf depocenter suggests their critical control on MDD

development (Fig. 4). These relationships reflect the importance ofwave orbitals and tidal currents on the depth and distances,

respectively, where fine sediment can accumulate. The data suggest

that both waves and tides are important to continental-margin

sediment dispersal and, specifically, MDD-system functioning.

5.1.5. Subaqueous-delta-clinoform (SDC) systems

SDC systems are different from EAD and PAD systems in that their

coastline is characterized by a tide-dominated delta (triangular-

shaped) as a result of strong astronomical tidal flow (Coleman and

Wright, 1975; Galloway; 1975), and tidal flows are important in

carrying the fine-sediment load greater distances from the shoreline

(Figs. 3B and 5). In dispersal systems with a SDC, at least two

important areas (including the SDC) of marine sediment storage are

identified (Fig. 5, left). Expansive coastal wetlands and floodplains are



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common to these systems, and a significant fraction of the river

sediment load may be stored in these regularly (marine) or

episodically (freshwater) flooded areas. These characteristics result

from the broad, low-gradient margins where SDC systems are located.

In the Amazon and GangesBrahmaputra systems, it is estimated that

about one third of the load is sequestered in the region between the

beginning of tidal influence and the river mouth (Nittrouer et al.,

1996; Goodbred and Kuehl, 1998). Coastal areas of the Gulf of Papua

may store 14% of the load from several large rivers including the Fly,Kikori, and Purari Rivers (Walsh and Nittrouer, 2004). The separation

of coastal and shelf sinks (Fig. 5, left) is accomplished through

energetic tidal flow and wave action (Figs. 3B and 4). The pattern of

sediment accumulation on a SDC is generally aligned with bathy-

metric isobaths, and is parallel to but significantly displaced (tens to

hundreds of kilometers) from the shoreline (Fig. 5, right). This pattern

reflects the impact of waves and tides on the depth and distance of

sediment accumulation (Fig. 4). A subaqueous delta clinoform

accretes vertically to the depth (known as the rollover point) above

which fine sediments in the topset region are in disequilibrium with

the oceanographic conditions (Walsh et al., 2004). Energetic flows

gradually or episodically move sediment seaward. Ultimately, greatest

accumulation rates are situated on the more steeply dipping foreset

region, where combined (wave and current) bed shear stresses are

diminished, due to deeper water depths (Fig. 2, right; Harris et al.,

1993; Kuehlet al., 1996; Walsh et al., 2004). Therolloverpoint(i.e., the

shallow boundary of the foreset region, where sediments accumulate

most rapidly) may be better regarded as the wave-current base

(Walsh et al., 2004).

Large tidal range (N2 m), inparticular, is a key trait of SDC systems,

as tidal flows enable the separation between the river mouth and the

region of high sediment accumulation rates on the subaqueuos delta

clinoform (Fig. 3B). But, the amount of sediment supplied to the

margin seaward of a river mouth also is hypothesized to be important

(Fig. 3A). SDC systems listed in Table 1 have sediment loads that cover

a broad range,115

1200 Mty

1

. SDCs havenot been found seaward ofany rivers with smaller sediment loads, e.g., Eel, Columbia. Based on

this information, we infer that any river or group of rivers with

appropriate physical conditions (i.e., large tidal range and modest

wave climate) and a load N100Mt y1 could develop a SDC. TheKikori

River (which discharges 30 Mt y1) empties into the northwestern

Gulf of Papua along with the larger Fly and Purari Riversamong others

(Walsh et al., 2004), and the combined loads (N300Mty1; Milliman,

1995) coalesce toforma SDC inthisregion.The rationale for needing a

large sediment load for SDC development is based on the observation

that as the distance to the nearest maximum shelf deposition

increases non-linearly with tidal range (Fig. 4B), the area over

which sediments must accumulate to produce a subaqueous delta

clinoform also increases non-linearly because of effluent spreading.

For this reason, systems with sediment loads b100 Mt y1 but large

tides (N2 m) arehypothesized to be unableto form a subaqueous delta

clinoform (Fig. 3A). For the same reason, systems with large loads but

N2 m mean significant wave heights also will not create subaqueous

Fig. 6. The hierarchical decision tree developed in this study. This hierarchical decision tree is designed to predict the marine dispersal system at a river mouth using basic

oceanographic and morphologic characteristics. The tool was constructed by evaluating the factors controlling well-studied dispersal systems ( Table 1; Fig. 3).



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delta clinoforms (Fig. 3B).More data areneeded to better establishthe

boundaries between SDC and MDD systems, but undoubtedly,

sediment load is a key factor. Given the available data, a 100 Mt y1

limit is assumed based on the Fly River in the westernmost (updrift)

portion of the Gulf of Papua (Fig. 3A).

5.2. A prediction tool

A reasonable prediction of the sediment dispersal type at any rivermouth can be made with knowledge of tidal range, significant wave

height, sediment supply and shelf width (Fig. 3). A hierarchical

decision tree is developed here to predict the type of marine dispersal

systemat any river mouth (Fig. 6). This approach successfully predicts

all the system classifications listed in Table 1, except the Kikori and

Purari rivers which act as SDC systems as a result of their enhanced

load. With the basicinformation available (sediment load, shelf width,

mean significant wave height and tidal range) for a given system, one

can use the decision tree to predict the type of marine dispersal

system at a river mouth. The predictions for each system with

available (or assumed) data are plotted in Fig. 7. The prediction totals

for each system are the following: 16 EAD, 39 PAD, 9 CC, 32 MDD, and

8 SDC. In these data, PAD and MDD systems are most abundant, but, as

pointed out earlier, this study is heavily biased towards large river

systems. In reality, the number of EAD systems (i.e., those with a load

b2 Mt y1) should be significantly larger than the other classes, while

thenumber of SDC systems would be modified the least.The literature

on EAD systems is indeed extensive, but process-oriented sediment

dynamics studies and sediment budgets are needed for more EAD

systems, to better quantify trapping efficiencies. PAD and MDD

systems also are likely to be more numerous, as these are produced

by rivers with moderatesedimentloads. Thesesystems also have been

relatively understudied (Table 1). Although SDC and CC systems are

rarer, their size and nature (dominated by gravity-driven flows)

requires further research to quantify and, ultimately, model these

systems.

The research presented here attempts to find order within the

complexity of nature, and, in so doing, disregards important subtleties

in terrestrial and marine processes that have impacts on fine-grainedsediment dispersal of specific river systems. This is the bane of such

approaches. Nevertheless, this research is valuable in that it helps

explain and evaluate which and why some systems behave similarly,

and this is accomplished using data that are readily available for many

dispersal systems. Regional currents undoubtedly also play an

important role in regulating the nature of fine-sediment dispersal

on continental margins, but to the knowledge of the authors, these

data do not exist in a form that can be easily accounted for globally.

Additionally, this classification highlights the existence of distinctly

different types of dispersal systems, and this is relevant not only to

modern studies but also to interpretation of ancient strata.

5.3. A continuum of systems

The observed relationships between marine processes and the

depth and distance of the NMSD have significant implications for the

proposed classification system (Fig. 4), as they suggest that fine-

grained sediment dispersal responds over a predictable scale to mean

significant wave height and tidal range (linear and logarithmic,

respectively). It is hypothesized that the former relationship is related

to thewaveorbital control on thewater depth at whichfine sediments

can accumulate, and the latteris caused by the distancefine-sediment

must be transported to reach these water depths on continental

shelves, which is a consequence of their shelf width. These relation-

ships imply that dispersal systems lie more in a continuum than as

discrete types (e.g., there is no exact boundary between PAD and

SDC systems). The modeling work of Swenson et al. (2005) nicely

illustrates this concept, highlighting how the changes in the distance

between the shoreline and rollover point are impacted by the physical

conditions. With these comments in mind, thereader should be aware

that the thresholds used in the decision tree (Fig. 6) are not well

defined and probably do not represent absolute boundaries (Fig. 3).

Nonetheless, the hierarchical decision tree is valuable as it provides

direction for using process-related factors to understand the diversity

in dispersal systems. Future research can test, refine and refute the

ideas presented.

5.4. System types through geologic time

It must be mentioned that the type of marine sediment dispersalfor many river systems certainly has changed with time. During low

stands of sea level, when rivers debouched at the modern shelf break,

Fig. 7. Predictions for the type of marine dispersal system characterizing N100 rivers in this study. These predictions were made using the available data (Figs. 1 and 2) and the

hierarchical decision tree in Fig. 6. Data are available upon request.



10/12

CC systems would have been considerably more common than today

(Milliman and Syvitski, 1992), and wave and tide conditions were

likely different as climate and shelf width (and, therefore, fetch) were

altered. As sea level rose rapidly after the Last Glacial Maximum, most

rivers systems stored their sediment loads in estuarine valleys

crossing the shelf (i.e., were EAD systems). When sea-level rise

slowed around 86 ky BP and where sediment overwhelmed the

holding capacity of some estuaries, deltas began to form around the

world (Warne and Stanley, 1995). In this way, the modern dispersalsystems presented in Fig. 7 reflect the transition of former estuaries to

non-EAD systems (i.e., a balance between sediment fill and initial

size). This evolution in system behavior must be kept in mind when

interpreting the geologic record.

5.5. Implications

Variability in the process-related partitioning of sediments in the

five fundamental typesof dispersal systems identifiedin thisstudy has

significant implications for the fate of carbon; a detailed discussion

with specific focus on large river margins is provided in McKee et al.

(2004). Rapid deposition and accumulation of sediment, particularly

in thick beds from sediment gravity flows (e.g., fluid muds or turbidity

currents) can minimize biological mixing and carbon respiration.Continued remobilization of sediment allows multiple opportunities

for carbon respiration by oxygen-, iron-, and manganese-based

electron-receptor systems for bacterial decomposition (Aller et al.,

2004). Particularly in EAD, PAD and CC cases, terrestrially supplied

carbon can have little opportunity for oxidation in the marine

environment; rapid transport and thick accumulation of sediment

likely minimizes oxygen exposure times, and enhances carbon burial

(Hedges and Keil, 1995; Harnett et al., 1998). Fluid muds also can

transport sediment in MDD and SDC systems, but much of this

sediment experiences multiple episodes of sediment movement, and

carbon has repeated opportunities for incineration in such systems

(Aller, 1998). Dynamics and complexities in carbon loading (e.g., Goni

et al., 1997; Leithold and Blair, 2001) and respiration with multiple

electron receptors (e.g., Aller,1998) needto be betterunderstood in alltypes of dispersal systems for the development of realistic global

carbon budgets (Keil et al., 1997; McKee et al., 2004).

6. Conclusions

The conclusions of this research are the following:

1) Fine-grained fluvial sediment dispersal systems can be divided

into five basic types: estuarine accumulation dominated (EAD),

canyon captured (CC), proximal accumulation dominated (PAD),

marine dispersal dominated (MDD), and subaqueous delta clino-

form (SDC).

2) These divisions are based on the dominant mode and pattern of

sedimentation anticipated from eachtype. EAD and PAD systems areregulated byflocculation, and immediate deposition. CC systems are

dominated by gravity-driven off-shelf sediment transport, and MDD

andSDC arecontrolled by dilutesuspension transportin thebenthic-

boundary-layer and sediment gravity flows.

3) Basic characteristics of these systems (mean significant wave

height, tidal range, shelf width and sediment load) can be used to

predict the dispersal system using a hierarchical decision tree.

4) Strong relationships between the meansignificantwave height and

the depth and distance of the nearest maximum shelf depocenter

suggest that a continuum exists between the systems types.

5) More research is needed to verify or improve the definition of the

boundaries between the dispersal system types, and develop a

better understanding how sedimentological and geochemical

processes affect the quality and quantityof sedimentaccumulation.

Acknowledgements

The authors thank the National Science Foundation (grants OCE

9904167, OCE 0203351 and OCE 0452166), the National Geographic

Society (grant 6573-99) and the Office of Naval Research (ONR

N00014-00-1-0846) for funding this research. Neal Driscoll gave

helpful support for this paper. The work was inspired by discussions

with many past lab mates and other colleagues. Liviu Giosanand other

anonymous reviewers are acknowledged for suggestions whichimproved the manuscript.

References

Alexander, C.R., Simoneau, A.M., 1999. Spatial variability in sedimentary processes onthe Eel continental slope. Mar. Geol. 154 (14), 243254.

Alexander,C.R., DeMaster, D.J.,Nittrouer, C.A.,1991. Sediment accumulation in a modernepicontinental-shelf settingthe Yellow Sea. Mar. Geol. 98 (1), 5172.

Allen, J.R.L., 1964. Sedimentation in the modern delta of the river Niger, west Africa,Deltaic and shallow marine deposits. In: Van Straaten, L.M.J.U. (Ed.), Deltaic andShallow Marine Deposits: Proceedings of the 6th International SedimentologicalCongress. Developments in Sedimentology 1. Elsevier, Amsterdam, pp. 2634.

Aller, R.C., 1998. Mobile deltaic and continental shelf muds as suboxic, fluidized bedreactors. Mar. Chem. 61 (34),143155.

Aller, R.C., Hannides, A., Heilbrun, C., Panzeca, C., 2004. Coupling of early diageneticprocesses and sedimentary dynamics in tropical shelf environments: the Gulf ofPapua deltaic complex. Cont. Shelf Res. 24, 24552486.

Allison, M.A., Neill, C.F., 2002. Accumulation rates and stratigraphic character of themodern Atchafalaya River prodelta,Louisiana. Trans. Gulf Coast Assoc. Geol. Soc.52,10311040.

Aloisi, J.C., Monaco, A., Thommeret, J., Thommeret, Y., 1975. Evolution paleogeographi-que du plateau continental languedocien dans le cadre du golfe du Lyon; Analysecomparee des donnees sismiques, sedimentologiques et radiometriques concer-nant le Quaternaire recent. (Paleogeographical evolution of the Languedoccontinental shelf in the framework of the Gulf of Lion; comparative analysis fromseismic, sedimentologic and radiometric data concerning the upper Quaternary).Rev. Geogr. Phys. Geol. Dyn. 17 (1), 1322.

Baker, E.T., Hickey, B.M.,1986. Contemporarysedimentation processesin and around anactive West-Coast submarine-canyon. Mar. Geol. 71, 1534.

Bornhold, B.D., Yang, Z.S., Keller, G.H., Prior, D.B., Wiseman, W.J., Wang, Q., Wright, L.D.,Xu, W.D., Zhuang, Z.Y., 1986. Sedimentary framework of the modern Huanghe(Yellow-River) Delta. Geo-Mar. Lett. 6 (2), 7783.

British Oceanographic Data Center, 1994. GEBCO Digital Atlas. British OceanographicData Center, Birkenhead, Merseyside, United Kingdom.

Cacchione, D., Sternberg, R.W., Ogston, A.S., 2006. Bottom instrumented tripods:history, applications, and impacts. Cont. Shelf Res. 26 (1718), 23192334.

Coleman, J.M., Wright, L.D., 1975. Modern river deltas: variability of processes and sandbodies. In:Broussard, M.L.(Ed.), Deltas, Models for Exploration.HoustonGeologicalSociety, Houston, pp. 99149.

Coleman, J.M., Prior, D.B., 1988. Mass-wasting on continental margins. Annu. Rev. EarthPlanet. Sci. 16, 101119.

Coleman, J.M., Roberts, H.H., Murray, S.P., Salama, M., 1981. Morphology and dynamicsedimentology of the Eastern Nile Delta Shelf. Mar. Geol. 42 (14), 301326.

Coleman, J.M., Roberts, H.H., Stone, G.W., 1998. Mississippi River delta: an overview. J.Coast. Res. 14 (3), 698716.

Corbett, D.R., Mckee, B., Allison, M., 2006. Nature of decadal-scale sedimentaccumulation on the western shelf of the Mississippi River delta. Cont. Shelf Res.26, 21252140.

Correggiari, A., Trincardi, F., Langone, L., Roveri, M., 2001. Styles of failure in lateHolocene highstand prodelta wedges on the Adriatic shelf. J. Sediment. Res. 71 (2),218236.

Crockett, J.S., Nittrouer, C.A., 2004. The sandy inner shelf as a repository for muddysediment: an example from Northern California. Cont. Shelf Res. 24 (1), 5573.

Dalrymple, R.W., Zaitlin, B.A., Boyd, R., 1992. Estuarine facies models: conceptual basisand stratigraphic implications. J. Sediment. Petrol. 62, 11301146.

Davis, R.A., Hayes, M.O., 1984. Whatis a wave-dominatedcoast? Mar. Geol. 60, 313329.Droz, L., Rigaut, F., Cochonat, P., Tofani, R., 1996. Morphology and recent evolution of the

Zaire turbidite system (Gulf of Guinea). Geol. Soc. Amer. Bull. 108 (3), 253 269.Dukat, D.A., Kuehl, S.A., 1995. Non-steady-state Pb-210 flux and the use of Ra-228/Ra-

226 as a geochronometer on the Amazon Continental-Shelf. Mar. Geol. 125 (34),329350.

Fisk, H.N., McFarlan, E.J., Kolb, C.R., Wilbert, L.J., 1954. Sedimentary framework of themodern Mississippi delta. J. Sediment. Petrol. 24, 7699.

Fletcher, C.H., Knebel, H.J., Kraft, J.C., 1992. Holocene depocenter migration andsediment accumulation in Delaware Baya submerging marginal marine sedi-mentary basin. Mar. Geol. 103 (13), 165183.

Fox, J.M., Hill, P.S., Milligan, T.G., Boldrin, A., 2004. Flocculation and sedimentation onthe Po River Delta. Mar. Geol. 203 (12), 95107.

Frignani, M., Langone, L.,1991. Accumulation rates and Cs-137 distribution in sedimentsoff the Po River Delta and the Emilia-Romagna Coast (Northwestern Adriatic Sea,Italy). Cont. Shelf Res. 11 (6), 525542.

Frignani, M., Langone, L., Ravaioli, M., Sorgente, D., Alvisi, F., Albertazzi, S., 2005. Fine-sediment mass balance in the western Adriatic continental shelf over a century

time scale. Mar. Geol. 222

223, 113

133.



11/12

Galloway, W.E., 1975. Process framework for describing the morphologic andstratigraphic evolution of deltaic depositional systems. In: Broussard, M.L. (Ed.),Deltas, Models for Exploration. Houston Geological Society, Houston, pp. 8798.

Geyer, W.R., Hill, P.S., Kineke, G.C., 2004. The transport, transformation and dispersal ofsediment by buoyant coastal flows. Cont. Shelf Res. 24, 927949.

Giosan, L., Constantinescu, S., Clift, P.D., Tabrez, A.R., Danish, M., Inam, A., 2006. Recentmorphodynamics of the Indus delta shoreans shelf. Cont. Shelf Res. 26,16681684.

Goni, M.A., Ruttenberg, K.C., Eglinton, T.I., 1997. Source and contribution of terrigenousorganiccarbonto surface sedimentsin theGulf ofMexico.Nature389 (6648),275278.

Goodbred, S.L., Kuehl, S.A., 1998. Floodplain processes in the Bengal Basin and thestorage of GangesBrahmaputra river sediment: an accretion study using Cs-137

and Pb-210 geochronology. Sediment. Geol. 121 (3

4), 239

258.Goodbred, S.L., Kuehl, S.A., 1999. Holocene and modern sediment budgets for theGangesBrahmaputra river system: evidence forhighstand dispersal toflood-plain,shelf, and deep-sea depocenters. Geology 27 (6), 559562.

Got, H., Aloesi, J.-C., Monaco, A., 1985. Sedimentary processes in Mediterranean deltasand shelves. In: Stanley, D.J., Wezel, F.-C. (Eds.), Springer-Verlag, New York.

Harris, P.T., Baker,E.K., Cole, A.R.,Short, S.A.,1993. A preliminary-studyof sedimentationin the tidally dominated Fly River Delta, Gulf of Papua. Cont. Shelf Res. 13 (4),441472.

Hartnett, H.E., Keil, R.G., Hedges, J.I., Devol, A.H., 1998. Influence of oxygen exposuretime on organic carbon preservation in continental margin sediments. Nature 391(6667), 572574.

Hedges, J.I., Keil, R.G., 1995. Sedimentary organic-matter preservationan assessmentand speculative synthesis. Mar. Chem. 49 (23), 81115.

Heezen, B.C., Ewing, M., Granelli, N.C.L., Menzies, R.J., Schneider, E.D., 1964. Congosubmarine canyon. Am. Assoc. Petroleum Geol. 48 (7), 11261149.

Hori, K., et al., 2001. Sedimentary facies of the tide-dominated paleo-Changjiang(Yangtze) estuary during the last transgression. Mar. Geol. 177 (34), 331351.

Hori, K., Saito, Y., Zhao, Q., Wang, P., 2002. Architecture and evolution of the tide-

dominated Changjiang (Yangtze) River delta, China. Sediment. Geol. 146 (34),249264.

Hovius, N., 1998. Controls on sediment supply by large rivers. SEPM Spec. Publ. 42,4769.

Jakobsson, M., et al., 2000. New grid of Arctic bathymetry aids scientists andmapmakers. Eos Trans. Am. Geophys. Union 81 (9), 89, 93, 96.

Jaeger, J.M., Nittrouer, C.A., Scott, N.D., Milliman, J.D., 1998. Sediment accumulationalong a glacially impacted mountainous coastline: North-east Gulf of Alaska. BasinRes. 10 (1), 155173.

Keil, R.G., Mayer, L.M., Quay, P.D., Richey, J.E., Hedges, J.I., 1997. Loss of organic matterfrom riverine particles in deltas. Geochim. Cosmochim. Acta 61 (7), 15071511.

Kineke, G.C.,Woolfe, K.J.,Kuehl,S.A., Milliman,J.D., Dellapenna, T.M., Purdon,R.G., 2000.Sediment export from the Sepik River, Papua New Guinea: evidence for a divergentsediment plume. Cont. Shelf Res. 20, 22392266.

Kudrass, H.R., Michels, K.H., Wiedicke, M., Suckow, A., 1998. Cyclones and tides asfeeders of a submarine canyon off Bangladesh. Geology 26, 715718.

Kuehl, S.A., Hariu, T.M., Moore, W.S., 1989. Shelf sedimentation off the GangesBrahmaputra River systemevidence for sediment bypassing to the Bengal fan.Geology 17 (12), 11321135.

Kuehl,S.A., Nittrouer,C.A., Allison, M.A.,Faria,L.E.C.,Dukat,D.A., Jaeger, J.M., Pacioni,T.D.,Figueiredo, A.G., Underkoffler, E.C., 1996. Sediment deposition, accumulation, andseabed dynamics in areenergeticfine-grained coastal environment. Cont. Shelf Res.16 (56), 787815.

Kuehl, S.A.,Levy, B.M., Moore, W.S., Allison, M.A.,1997. Subaqueous deltaof the GangesBrahmaputra river system. Mar. Geol. 144 (13), 8196.

Langland, M., Cronin, T. (Eds.), 2000. A Summary Report of Sediment Processes inChesapeake Bay and Watershed. USGS Water Resources Investigations Report 03-4123. U.S. Geological Survey, p. 122.

Leithold, E.L., Blair, N.E., 2001. Watershed control on the carbon loading of marinesedimentary particles. Geochim. Cosmochim. Acta 65, 22312240.

Liu, J.P., Milliman, J.D., Gao, S., 2002. The Shandong mud wedge and post-glacialsediment accumulation in the Yellow Sea. Geo-Mar. Lett. 21 (4), 212 218.

Liu, J.P., Milliman, J.D., Gao, S., Cheng, P., 2004. Holocene development of the YellowRiver's subaqueous delta, North Yellow Sea. Mar. Geol. 209 (14), 4567.

Maldonado, A., Serra, J., Martrous, F., Verdaguer, A., Aloisi, J.C., Got, H., Monaco, A.,Mirabile, L., 1980. La plateforme continentale de l'Ebre dans le cadre de l'evolutionrecentedu delta. Thecontinentalshelf of theEbro regionin theframeworkof Recent

delta evolution. Abstracts-International Geological Congress 26, Paris, p. 508.McCave, I.N., 1972. Transport and escape offine-grained sediment from shelf areas. In:

Swift, D.J.P., Duane, D., Pilkey, O.H. (Eds.), Shelf Sediment Transport. DowdenHutchinson and Ross, Stroudsburg, PA, pp. 225248.

McKee, B.A., Nittrouer, C.A., DeMaster, D.J., 1983. Concepts of sediment deposition andaccumulation applied to the continental-shelf nearthe mouth of the Yangtze-River.Geology 11 (11), 631633.

McKee, B.A., DeMaster, D.J., Nittrouer, C.A., 1984. The use of Th-234/U-238 disequili-brium to examine the fate of particle-reactive species on the Yangtze continental-shelf. Earth Planet. Sci. Lett. 68 (3), 431442.

McKee, B.A., Aller, R.C., Allison, M.A., Bianchi, T.S., Kineke, G.C., 2004. Transport andtransformation of dissolved and particulate materials on continental marginsinfluenced by major rivers: benthic boundary layer and seabed processes. Cont.Shelf Res. 24 (78), 899926.

Michels,K.H., Kudrass,H.R., Hubscher, C., Suckow, A., Wiedicke, M.,1998. The submarinedelta of the GangesBrahmaputra: cyclone-dominated sedimentation patterns.Mar. Geol. 149 (14), 133154.

Milliman, J.D., 1995. Sediment discharge to the ocean from small mountainous rivers:the New Guinea example. Geo-Mar. Lett. 15 (34),127133.

Milliman,J.D., Meade, R.H.,1983. World-wide deliveryof river sediment to the oceans. J.Geol. 91 (1), 121.

Milliman, J.D., Syvitski, J.P.M., 1992. Geomorphic tectonic control of sediment dischargeto the oceanthe importance of small mountainous rivers. J. Geol. 100 (5),525544.

Mullenbach, B.L., Nittrouer, C.A., 2000. Rapid deposition offluvial sediment in the EelCanyon, northern California. Cont. Shelf Res. 20 (16), 21912212.

Nelson, H., Creager, J.S., 1977. Displacement of Yukon-derived sediment from Bering Seato Chukchi Sea during Holocene time. Geology 5 (3), 141146.

Nelson, C.H., Rowland, R.W., Stoker, S.W., Bradley, B.R., 1980. Interplay of physical andbiological sedimentary structiures of the Bering epicontinental shelf. In: Larsen, M.

C., Nelson, C.H., Thor, D.R. (Eds.), Geological, Geochemical, and GeotechinicalObservation on the Bering Shelf, Open-File Report 80-979. U.S. Geological Survey,Reston, VA.

Nittrouer, C.A., Sternberg, R.W., 1981. The formation of sedimentary strata in anallochthonous shelf environmentthe Washington continental-shelf. Mar. Geol. 42(14), 201232.

Nittrouer, C.A., Wright, L.D., 1994. Transport of particles across continental shelves. Rev.Geophys. 32 (1), 85113.

Nittrouer, C.A.,DeMaster,D.J., McKee, B.A.,1984. Fine-scale stratigraphyin proximalanddistal deposits of sediment dispersal systems in the East China Sea. Mar. Geol. 61(1), 1324.

Nittrouer, C.A., Kuehl, S.A., DeMaster, D.J., Kowsmann, R.O., 1986. The deltaic nature ofAmazon shelf sedimentation. Geol. Soc. Amer. Bull. 97 (4), 444458.

Nittrouer, C.A., et al., 1996. The geological record preserved by Amazon shelfsedimentation. Cont. Shelf Res. 16 (56), 817841.

Nittrouer, C.A., Austin, J.A., Field, M.E., Kravitz, J.H., Syvitski, J.P.M., Wiberg, P.L., 2007.Writing a Rosetta Stone: Insights into Continental-Margin Sedimentary Processesand Strata, Special Publication 37 of the International Association of Sedimentol-ogists. Blackwell Publishing, Malden, MA. 549 pp.

Ogston, A.S., Cacchione, D.A., Sternberg, R.W., Kineke, G.C., 2000. Observations of stormand river flood-driven sediment transport on the northern california continentalshelf. Cont. Shelf Res. 20, 21412162.

Orton, G.J., Reading, H.G., 1993. Variability of deltaic processes in terms of sedimentsupply, with particular emphasis on grain size. Sedimentology 40, 475512.

Palanques, A., Puig, P., Guillen, J., Jimenez, J., Gracia, V., Sanchez-Arcilla, A., Madsen, O.,2002. Near-bottom suspended sediment fluxes on the microtidal low-energy Ebrocontinental shelf (NW Mediterranean). Cont. Shelf Res. 22 (2), 285303.

Palinkas, C.M., Nittrouer, C.A., 2007. Modern sediment accumulation on the Po shelf,Adriatic Sea. Cont. Shelf Res. 27, 489505.

Pinet, P., Souriau, M., 1988. Continental erosion and large-scale relief. Tectonics 7,563582.

Puig, P., Ogston, A.S., Mullenbach, B.L., Nittrouer, C.A., Sternberg, R.W., 2003. Shelf-to-canyon sediment-transport processes on the Eel continental margin (northernCalifornia). Mar. Geol. 193 (12),129149.

Puig, P., Ogston, A.S., Mullenbach, B.L., Nittrouer, C.A., Parsons, J.D., Sternberg, R.W.,2004. Storm-induced sediment gravity flows at the head of the Eel submarinecanyon, northern California margin. J. Geophys. Res. Oceans 109 (C3).

Rodriguez, A.B., Hamilton, M.D., Anderson, J.B., 2000. Facies and evolution of themodern Brazos Delta, Texas; wave versus flood influence. J. Sediment. Res. 70 (2),283295.

Scruton,P.C.,1960.Delta buildingand thedeltaicsequence.In: Shepard,F.P., Phleger, F.B.,van Andel, T.H. (Eds.), Recent Sediments, northwest Gulf of Mexico. AmericanAssociation of Petroleum Geologists, Tulsa, OK.

Smith, W.H.F., Sandwell, D.T., 1997. Global sea floor topography from satellite altimetryand ship depth soundings. Science 277, 19561962.

Sommerfield, C.K., Nittrouer, C.A., 1999. Modern accumulation rates and a sedimentbudget for the Eel shelf: a flood-dominated depositional environment. Mar. Geol.154 (14), 227241.

Sternberg, R., 2005. Sediment transport in the coastal ocean: a retrospective evaluationof the benthic tripod and its impact, past, present and future. Sci. Mar. 69, 4354.

Sternberg, R.W., Nowell, A.R.M., 1999. Continental shelf sedimentology: scales ofinvestigation define future research opportunities. J. Sea Res. 41 (12), 5571.

Sternberg, R.W., Kineke, G.C., Johnson, R., 1991. An instrument system for profilingsuspended sediment, fluid, and flow conditions in shallow marine environments.Cont. Shelf Res. 11 (2), 109122.

Summerfield, M.A., Hulton, N.J., 1994. Natural controls of fluvial denudation rates

in major world drainage basins. J. Geophys. Res. B Solid Earth Planets 99,1387113883.

Summerhayes, C.P., Sestini, G., Misdorp, R., Marks, N., 1978. Nile Delta; nature andevolution of continental shelf sediments. Mar. Geol. 27 (12), 4365.

Swenson, J.B., Paola, C., Pratson, L., Voller, V.R., Murray, A.B., 2005. Fluvial and marinecontrols on combined subaerial and subaqueous delta progradation: morphody-namic modeling of compound-clinoform development. J. Geophys. Res. Earth Surf.110, 116.

Swift, D.J.P., Thorne,J.A., 1991. Sedimentationon continental margins:I. A generalmodelfor shelf sedimentation. In: Swift, D.J.P., Tillman, R.W., Oertel, G.F., Thorne, J.A.(Eds.), Shelf Sand and Sandstone Bodies, Geometry, Facies and SequenceStratigraphy: International Association of Sedimentologists Special Publication,vol.14, pp. 331.

Syvitski,J.P.M., Vrsmarty, C.J.,Kettner, A.J., Green, P.A., 2005. Impact of humans on theflux of terrestrial sediment to the global coastal ocean. Science 308, 376380.

Ta,T.K.O., Nguyen,V.L., Tateishi, M.,Kobayashi,I., Saito, Y., Nakamura,T.,2002a. Sedimentfacies andLate Holoceneprogradation of theMekongRiverDeltain BentreProvince,southern Vietnam: an example of evolution from a tide-dominated to a tide- andwave-dominated delta. Sediment. Geol. 152 (34), 313325.



12/12

Ta, T.K.O., Nguyen, V.L., Tateishi, M., Kobayashi, I., Tanabe, S., Saito, Y., 2002b. Holocenedelta evolution and sediment discharge of the Mekong River southern Vietnam.Quat. Sci. Rev. 21 (1617), 18071819.

Tolman, H.L.,2002. Usermanualand system documentation of WAVEWATCH-IIIversion2.22. NOAA/NWS/NCEP/OMB technical note, 222: 133 pp.

Traykovski, P., Geyer,W.R., Irish, J.D.,Lynch, J.F., 2000. Therole of wave-induced density-driven fluid mud flows for cross-shelf transport on the Eel River continental shelf.Cont. Shelf Res. 20, 21132140.

Walsh, J.P., Nittrouer, C.A., 1999. Observations of sediment flux to the Eel continentalslope, northern California. Mar. Geol. 154 (14), 5568.

Walsh, J.P., Nittrouer, C.A., 2003. Contrasting styles of off-shelf sediment accumulation

in New Guinea. Mar. Geol. 196 (3

4), 105

125.Walsh, J.P., Nittrouer, C.A., 2004. Mangrove sedimentation in the Gulf of Papua, PapuaNew Guinea. Mar. Geol. 208, 225248.

Walsh, J.P., et al., 2004. Clinoform mechanics in the Gulf of Papua, New Guinea. Cont.Shelf Res. 24 (19), 24872510.

Wang, X.H., Pinardi, N., 2002. Modeling the dynamics of sediment transport andresuspension in the northern Adriatic Sea. J. Geophys. Res. Oceans 107 (C12), 3225.

Warne, A.G., Stanley, D.J., 1995. Sea-level change as critical factor in development ofbasin margin sequences: new evidence from late Quaternary record. J. Coast. Res.Spec. Issue 17, 231240.

Wheatcroft, R.A., Sommerfield, C.K., Drake, D.E., Borgeld, J.C., Nittrouer, C.A., 1997. Rapidand widespread dispersal of flood sediment on the northern California margin.Geology 25 (2), 163166.

Wright, L.D., 1985. River deltas, In: Davis, R.A. (Ed.), Coastal Sedimentary Environments,2nd ed. Springer-Verlag, New York, pp. 175.

Wright, L.D., Nittrouer, C.A., 1995. Dispersal of river sediments in coastal seassixcontrasting cases. Estuaries 18 (3), 494508.

Wright, L.D., Wiseman, W.J., Bornhold, B.D., Prior, D.B., Suhayda, J.N., Keller, G.H., Yang,

Z.S., Fan, Y.B.,1988. Marine dispersal and deposition of Yellow-River silts by gravity-driven underflows. Nature 332, 629632.Wright, L.D., Friedrichs, C.T., Kim, S.C., Scully, M.E., 2001. Effects of ambient currents and

waves on gravity-driven sediment transport on continental shelves. Mar. Geol. 175(14), 2545.


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Walsh River Sediment Dispersal on Continental Margins 2009