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U.S. Geological Survey Open-File Report 03-221
A Pictorial Survey of the Bedrock Beneath Western Cape Cod, Massachusetts

 Detailed Bedrock Photographskip navbar

82MW0008

SAMPLE_ID:  82MW0008

DATE: 4/5/2001

Sample: 82MW0008 - Orthogneiss

ORTHOGNEISS

Sample 82MW0008, an orthogneiss, is composed of the minerals K-feldspar (35%), plagioclase (32%), quartz (25%), biotite (3%), epidote (2%), chlorite (2%), and trace sphene and oxides. This foliated rock is characterized by porphyroclasts of K-feldspar (up to 8 mm) wrapped by biotite, chlorite, and quartz aggregates. Plagioclase occurs mainly as recrystallized matrix grains, though some severely altered porphyroclasts are present. Shearing is evidenced by quartz subgrains and undulose extinction, as well as by mica texture. Chlorite partially replaces biotite.

Latitude: 41.64103

Longitude: -70.57682

Elevation of well site (m): 35.43

Elevation of the upper
bedrock surface (m):
 -56.01

Elevation of the
top of casing (m):
 35.32

Total thickness of strata
penetrated by the well (m):
 94.49

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