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Opaque minerals as aids in distinguishing between source and sorting effects on beach sand mineralogy in southwestern Oregon

Journal of Sedimentary Petrology
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https://doi.org/10.1306/212F7A36-2B24-11D7-8648000102C1865D

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Abstract

Both source area and wave sorting affect the heavy-mineral distributions of beach sands. Although source and sorting effects are difficult to distinguish, they can be separated on four Oregon beaches by studying the magnetic fraction of the sand. Prominent headlands bound the four beaches, which are located on the southwestern Oregon coast. On three beaches the percentage of magnetite in the sand from the upper swash zone consistently increases toward the north end of each beach, apparently owing to selective sorting during littoral transport. However, the percentages of chromium and titanium in the magnetite are generally independent of the relative location of the samples along the beach and therefore independent of sorting effects. Each beach appears to be characterized by a fairly distinct range of Ti/Cr in the magnetic fraction, and the range differs from beach to beach. The magnetite percentage and the Ti/Cr range suggest that sorting and source effects can be distinguished on beaches rich in "black" sands, and that sand transport around headlands in this area is not extensive enough to mask source differences. The results of this study suggest that sorting and source effects can be distinguished wherever there are chemical or mineralogical differences in a restricted density fraction.

Publication type Article
Publication Subtype Journal Article
Title Opaque minerals as aids in distinguishing between source and sorting effects on beach sand mineralogy in southwestern Oregon
Series title Journal of Sedimentary Petrology
DOI 10.1306/212F7A36-2B24-11D7-8648000102C1865D
Volume 50
Issue 2
Year Published 1980
Language English
Publisher SEPM
Description 8 p.
First page 489
Last page 496
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