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K. C. Stewart

Publications and source records attributed to K. C. Stewart.

17 recordsLinked to original sources
USGS2006

Genesis of marine terrace soils, Barbados, West Indies: evidence from mineralogy and geochemistry

Well-developed, clay-rich soils dominated by interstratified kaolinite-smectite are found on the uplifted coral reef terraces on the island of Barbados. The reef limestone is unlikely to have been the soil parent material however, because it is 98% CaCO 3 and geomorphic evidence argues against the 20 m of reef solution required to produce the soils by this process. The mineralogy of the sand, silt, and clay fractions of the soils, and trace element geochemistry, suggest that aeolian materials carried on the trade winds from Africa, volcanic ash from the island of St. Vincent, and quartz from Tertiary bedrock on the island itself are the parent materials for the soils. -Authors

Earth Surface Processes and Landforms↗
USGS1995

Sagebrush as a sampling medium for gold exploration in the Great Basin - evaluation from a greenhouse study

Seedlings (Artemisia tridentata subsp, tridentata germinated from seed collected near Preble, Nevada were grown in soils containing Carlin-type disseminated gold ore. After 4 months growth leaves, twigs and stems were combined and analyzed by INAA. Plants grown in soils containing Carlin ore did not accumulate significantly more gold than those growing in control soil. On the other hand, sagebrush grown in soils containing Carlin ores accumulated significantly more arsenic and antimony compared to those grown in control soils. Results suggest that sagebrush would be a good prospecting medium for detecting concealed Carlin-type deposits in the Great Basin if arsenic and antimony are used as the pathfinder elements. Results also suggest that true gold anomalies in sagebrush will be more difficult to separate from aeolian contamination than those for arsenic and antimony in arid environments. -from Authors

Journal of Geochemical Exploration↗
USGS1984

Chemical analyses of soils and other surficial materials, Alaska

Introduction: The favorable response to the reports on the geochemistry of unconsolidated surficial materials of the conterminous United States (informally called the '50-mile geochemical survey,' Shacklette and others, 1971a, 1971b, 1973, and 1974) led us, in 1975, to initiate a somewhat similar survey of Alaska. The principal objective of studies of this type is to establish estimates of the abundance of elements in soils and other surficial materials. Such information is useful in the evaluation of geochemical data for (1) mineral resources, (2) environmental appraisals, and (3) the definition of broad-scale geochemical patterns. For about six years this effort progressed slowly on a non-funded, time-available basis. During fiscal years 1982 and 1983, however, some funds were made available through the USGS Energy Lands and Alaska Mineral Surveys programs which allowed for the completion of the field-work phase of the project. The sampling plan was kept simple because, as with the 50-mile study, the acquisition of samples depended on the voluntary cooperation of field personnel (only about 40 percent of the total number of samples was obtained by the authors).

Open-File Report↗