![]() ![]() Texture, Carbonate Content, and Preliminary Maps of Surficial Sediments, Flower Garden Banks Area, Northwest Gulf of Mexico Outer Shelf, USGS Open-File Report 03-002 Home / Contents / Introduction / Setting / Methods / Previous Work / Discussion / Conclusions / Acknowledgments / References Appendices: I. Field Report / II. Sediment Analysis / III. Table / Graphic / IV. Figures / V. Fig. Summary / VI. GIS/Metadata
Sediment Texture Analysis TechniquesIf the sediment sample contained gravel, the entire sample was
analyzed. If the sample was composed of only sand, silt, and clay, an approximately
50-gram, representative split was analyzed. The sample to be analyzed was
placed in a pre-weighed 100-ml beaker, weighed, and dried in a convection
oven set at 75°C. When dried, the samples were placed in a desiccator
to cool and then weighed. The decrease in weight due to water loss was used
to correct for salt. The weight of the sample and beaker less the weight of
the beaker and the salt correction gave the sample weight. The sand fraction was dry-sieved at whole phi intervals using
a Ro-Tap shaker. The fine fraction was analyzed by Coulter Counter. To mitigate
biologic or chemical changes, storage in the Mason jars prior to analysis
never exceeded five days. The gravel, sand, and fine fraction data were processed
by computer to generate the distributions, statistics, and data base (Poppe
and others, 1985). One limitation of using a Coulter Counter to perform fine
fraction analyses is that it has only the ability to "see" those
particles for which it has been calibrated. Calibration for this study allowed
us to determine the distribution down to 0.7µ or about two-thirds of
the 11ø fraction. Because clay particles finer than this diameter and
all of the colloidal fraction were not determined, a slight decrease in the
11ø (and finer) fraction is present in the size distributions. References Poppe, L. J., Eliason, A. H., and Fredericks, J. J., 1985, APSAS:
An automated particle-size analysis system: U.S. Geological Survey Circular
963, 77 p.
![]() Home / Contents / Introduction / Setting / Methods / Previous Work / Discussion / Conclusions / Acknowledgments / References Appendices: I. Field Report / II. Sediment Analysis / III. Table / Graphic / IV. Figures / V. Fig. Summary / VI. GIS/Metadata
U.S. Department of the Interior, U.S. Geological Survey |