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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


SAMPLE_ID:  95MW0207

DATE: 8/13/1998

Sample: 95MW0207 - Tonalite


A coarse-grained tonalite, sample 95MW0207 contains plagioclase (57%), quartz (40%), muscovite (2%), K-feldspar (1%), and trace oxides. Seritized plagioclase shows a range of grain sizes, though grains reach 9 mm. Plagioclase is albite and carlsbad twinned and shows interlocking grain boundaries. Serrated quartz grains exhibiting undulose extinction and subgrain development commonly fill "gaps" between large plagioclase phenocrysts. Muscovite rims plagioclase and in some places replaces plagioclase along twin planes. K-feldspar, a very minor constituent of this rock, is partially altered and fills gaps between plagioclase porphyries.

Latitude: 41.62102

Longitude: -70.547124

Elevation of well site (m): 14.81

Elevation of the upper
bedrock surface (m):

Elevation of the
top of casing (m):

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

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