Data on Holocene Tephra (Volcanic Ash) Deposits in the Alaska Peninsula and Lower Cook Inlet Region of the Aleutian Volcanic Arc, Alaska

ByJ.R. Riehle1, C.E. Meyer2, and R.T. Miyaoka1

Open-File Report 99-135


This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code.  Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.


1U.S. Geological Survey, 4200 University Drive, Anchorage Alaska 99508;
2U.S. Geological Survey, retired 

Introduction -- This site provides information about the number, thickness, and grainsize of Holocene volcanic ash deposits at 50 localities in the eastern Aleutian volcanic arc. In addition, the major-element compositions of the glasses separated from more than 350 samples of tephra from these localities, determined by electron microprobe, are presented as a basis for correlating samples. Where known with reasonable certainty, the source of an analyzed sample is also identified for use in comparative studies of magma chemistry.

How to Use this Site -- Sample localities are shown on an index map of the Alaska Peninsula and lower Cook Inlet, eastern Aleutian volcanic arc, Alaska. Each locality is linked to its own page, on which are shown a stratigraphic column for the site, the sampled deposits, and analytical results. Volcanoes that have been active during the past 10,000 years and other geographic features are also shown on the index map.

A methods description, tabulated analytical and location data, and a list of samples with known source vents are also included as part of this site.

The rest of the project can be found following the links which are below and on each second-level page:

  Index Map: links to stratigraphic columns and data for individual sites

  Methods: history and goals of the project, and analytical proceedures

  Data:tabulated chemical data in the following formats:
          browser readable
                   normalized to 100% anhydrous
                   unnormalized, with std. deviations of multiple analyses and mineralogical data
          MS Excel v5.0/95 spreadsheet
                   normalized to 100% anhydrous
                   unnormalized, with std. deviations of multiple analyses and mineralogical data
         PDF file (requires Adobe Acrobat Reader)

  Sample Localities: location and brief description of each field site

  Sample Sources: list of samples whose source vent is know with reasonable certainty

go to: Alaska Volcano Observatory HomePage
The URL for this site is
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