Sea-Level Controls on the Facies Architecture of the Trinity/Sabine Incised-Valley System, Texas Continental Shelf

Thomas, Mark A.; Anderson, John B.

doi:10.2110/pec.94.12.0063

Cited by 98 publications

(156 citation statements)

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“…The oldest and highest is the Beaumont terrace, into which the study rivers began incising about 100 ka (Thomas and Anderson, 1994;Blum et al, 1995;Otvos, 2005). Below the Beaumont surface and often merging into the modern floodplain are a series of up to three alluvial terraces.…”

Section: Study Areamentioning

confidence: 99%

Avulsion regimes in southeast Texas rivers

Phillips

2008

Earth Surf Processes Landf

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Avulsions -relatively sudden changes in course, or establishment of new anabranches -are an important process in alluvial rivers. Their key role in floodplain construction and alluvial architecture, and the general conditions favouring avulsions, are well known. However, avulsion processes and evolution, and the factors controlling avulsion regimes, are poorly understood. In the southeast Texas coastal plain, where avulsions are common features of the river valleys, avulsions were studied on the lower Brazos, Navasota, Trinity, Neches and Sabine rivers using a combination of aerial imagery, digital elevation models and field surveys. Avulsions have important influences on the surface morphology and contemporary processes in all five rivers. Features associated with avulsions are active and distinct throughout the study area, and all the rivers have experienced geologically (if not historically) recent avulsions. However, no two of the study rivers have the same contemporary avulsion regime. First-order differences in avulsion style are controlled by the stage of valley filling, and within the three rivers characterized by an unfilled incised valley, antecedent morphology associated with late Quaternary and Holocene coastal and fluvial-deltaic processes accounts for the major differences. In the Navasota (27 avulsions in 185 km) and Neches (21 in 340 km) rivers, subchannels associated with avulsions exist in all stages of development from active to infilled, and some have occurred in recent decades. The other rivers have fewer avulsions, but both the Sabine and Trinity have experienced historic channel shifts. Only the Brazos River has experienced no avulsions within the past c. 300 years. Results show that even within a region of similar environmental controls and geological history local variations in inherited morphology can result in different avulsion regimes.

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Section: Study Areamentioning

confidence: 99%

Avulsion regimes in southeast Texas rivers

Phillips

2008

Earth Surf Processes Landf

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“…Thus the lower river is an actively migrating channel and has been throughout the Quaternary. The alluvial morphology and stratigraphy of the lower Trinity (and the nearby and similar Sabine River), and the deposits and paleochannels now submerged in Trinity and Galveston Bays and the Gulf of Mexico preserve evidence of climate, sea level and upstream sediment delivery changes Anderson et al, 1992;Blum et al, 1995;Phillips, 2003;Phillips and Musselman, 2003;Rodriguez and Anderson, 2000;Rodriguez et al, 2001;Thomas and Anderson, 1994). Thus one task is to disentangle dam effects from other factors influencing the geomorphology of the lower Trinity.…”

Section: Study Areamentioning

confidence: 99%

Channel adjustments of the lower Trinity River, Texas, downstream of Livingston Dam

Phillips

Slattery

Musselman

2005

Earth Surf Processes Landf

138

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Channel cross-sectional changes since construction of Livingston Dam and Lake Livingston in 1968 were studied in the lower Trinity River, Texas, to test theoretical models of channel adjustment, and to determine controls on the spatial extent of channel response. High and average flows were not significantly modified by the dam, but sediment transport is greatly reduced. The study is treated as an opportunistic experiment to examine the effects of a reduction in sediment supply when discharge regime is unchanged. Channel scour is evident for about 60 km downstream, and the general phenomena of incision, widening, coarsening of channel sediment and a decrease in channel slope are successfully predicted, in a qualitative sense, by standard models of channel response. However, there is no consistent channel response within this reach, as various qualitatively different combinations of increases, decreases or no change in width, depth, slope and roughness occur. These multiple modes of adjustment are predicted by the unstable hydraulic geometry model. Between about 60 km and the Trinity delta 175 km downstream of the dam, no morphological response to the dam is observed. Rather than a diminution of the dam's effects on fluvial processes, this is due to a fundamental change in controls of the fluvial system. The downstream end of the scour zone corresponds to the upstream extent of channel response to Holocene sea level rise. Beyond 60 km downstream, the Trinity River is characterized by extensive sediment storage and reduced conveyance capacity, so that even after dam construction sediment supply still exceeds transport capacity. The channel bed of much of this reach is near or below sea level, so that sea level rise and backwater effects from the estuary are more important controls on the fluvial system than upstream inputs.

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“…For example, stratigraphie reconstructions in several estuaries on the Gulf of Mexico (United States) coast reveal buried Pleistocene fluvial terraces along the valley margins that extend onto the continental shelf (Thomas & Anderson 1994;Nichol et al 1996;Rodriguez et al 2005). Vibracore data from these estuaries show the Pleistocene terraces to comprise stiff, weathered mud overlain by soft estuarine mud of Holocene age (Rodriguez et al 2005).…”

Section: Discussionmentioning

confidence: 99%

Preservation of a Late Glacial terrestrial and Holocene estuarine record on the margins of Kaipara Harbour, Northland, New Zealand

Nichol

Deng²,

Horrocks

et al. 2009

Journal of the Royal Society of New Zealand

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Subtidal to intertidal deposits from the margins of Kaipara Harbour in Northland preserve a c. 23 000 year incomplete sedimentary record of the transition from terrestrial to estuarine conditions. Cores are used to reconstruct the depositional setting for this transition, interpreted as a succession from dune and freshwater wetland to shallow estuarine environments. The fossil pollen record provides a proxy of Last Glacial Maximum and Late Glacial vegetation for the area. Stability of the Pleistocene dune landscape during the postglacial marine transgression is interpreted on the basis of strong dominance of tall forest taxa (Dacrydium) in the pollen record and soil development in dune sands, with preservation aided by location along the estuary margin. During the Holocene, reworking of the buried dune and wetland sediments has only reached to a depth of 1.5 m below the modern tidal flat. As such, the site provides a rare example of good preservation of Pleistocene deposits at the coast, where extensive reworking and loss of record are more typical.

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Sea-Level Controls on the Facies Architecture of the Trinity/Sabine Incised-Valley System, Texas Continental Shelf

Cited by 98 publications

References 0 publications

Avulsion regimes in southeast Texas rivers

Avulsion regimes in southeast Texas rivers

Channel adjustments of the lower Trinity River, Texas, downstream of Livingston Dam

Preservation of a Late Glacial terrestrial and Holocene estuarine record on the margins of Kaipara Harbour, Northland, New Zealand

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