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Use of vertical temperature gradients for prediction of tidal flat sediment characteristics

Journal of Geophysical Research C: Oceans

By:
, , , and
DOI: 10.1029/2011JC007566

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Abstract

Sediment characteristics largely govern tidal flat morphologic evolution; however, conventional methods of investigating spatial variability in lithology on tidal flats are difficult to employ in these highly dynamic regions. In response, a series of laboratory experiments was designed to investigate the use of temperature diffusion toward sediment characterization. A vertical thermistor array was used to quantify temperature gradients in simulated tidal flat sediments of varying compositions. Thermal conductivity estimates derived from these arrays were similar to measurements from a standard heated needle probe, which substantiates the thermistor methodology. While the thermal diffusivities of dry homogeneous sediments were similar, diffusivities for saturated homogeneous sediments ranged approximately one order of magnitude. The thermal diffusivity of saturated sand was five times the thermal diffusivity of saturated kaolin and more than eight times the thermal diffusivity of saturated bentonite. This suggests that vertical temperature gradients can be used for distinguishing homogeneous saturated sands from homogeneous saturated clays and perhaps even between homogeneous saturated clay types. However, experiments with more realistic tidal flat mixtures were less discriminating. Relationships between thermal diffusivity and percent fines for saturated mixtures varied depending upon clay composition, indicating that clay hydration and/or water content controls thermal gradients. Furthermore, existing models for the bulk conductivity of sediment mixtures were improved only through the use of calibrated estimates of homogeneous end-member conductivity and water content values. Our findings suggest that remotely sensed observations of water content and thermal diffusivity could only be used to qualitatively estimate tidal flat sediment characteristics.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Use of vertical temperature gradients for prediction of tidal flat sediment characteristics
Series title:
Journal of Geophysical Research C: Oceans
DOI:
10.1029/2011JC007566
Volume
117
Issue:
C3
Year Published:
2012
Language:
English
Publisher:
American Geophysical Union
Publisher location:
Washington, DC
Contributing office(s):
St. Petersburg Coastal and Marine Science Center
Description:
10 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Geophysical Research C: Oceans
First page:
C03012
Last page:
C03023