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Open-File Report 01-153

Heavy Minerals from the Palos Verdes Margin, Southern California: Data and Factor Analysis

By Florence L. Wong

Thumbnail of and link to report PDF (1.2 MB)Introduction

Heavy or high-density minerals in the 63-250-_m (micron) size fraction (very fine and fine sand) were analyzed from 36 beach and offshore sites (38 samples) of the Palos Verdes margin to determine the areal and temporal mineralogic distributions and the relation of those distributions to the deposit affected by material discharged from the Los Angeles County Sanitation District sewage system (Lee, 1994) (Figure 1). Data presented here were tabulated for a report to the Department of Justice (Wong, 1994). The results of the data analysis are discussed in Wong (in press).

The study of heavy minerals is a common method of determining sources (provenance) and distributions of sediments (e.g., Van Andel and Poole, 1960). The choice of grain size is governed by ease of sample preparation, examination by optical microscopy, and comparability to previous studies. How representative the 63-250-_m heavy minerals are of the whole sample can be approximated by the amount of sand in the sample. Lee and others (1994) mapped a pre-effluent, effluent-affected, and surface layer in the study area off Palos Verdes. The amount of sand in the top and pre-effluent layers ranges from about 20 to 80 percent; in the middle of the effluent body, sand is less than 20 percent (Figure 2; MacArthur and others, 1994). Qualitatively, the 63-250-_m heavy minerals are more representative of the top and pre-effluent layer, but these minerals will also provide useful information about the middle layer.

First posted June 11, 2001

Download the Data as Excel spreadsheets

For additional information, contact:
Pacific Coastal & Marine Science Center
U.S. Geological Survey
400 Natural Bridges Drive
Santa Cruz, CA 95060

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Suggested citation:

Wong, Florence L., 2001, Heavy Minerals from the Palos Verdes Margin, Southern California: Data and Factor Analysis: U.S. Geological Survey Open-File Report 01-153, 31 pp., http://pubs.usgs.gov/of/2001/0153/.



 


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