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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:  03MW2620

DATE: 7/22/2000

Sample: 03MW2620 - Granite


Sample 03MW2620 is a porphyritic foliated granite composed of plagioclase (36%), K-feldspar (30%), quartz (25%), chlorite (5%), epidote (1%), oxides (1%), sericite (1%), and trace hornblende, muscovite, garnet, and biotite. This rock is characterized by coarse porphyries of K-feldspar (17 mm) and plagioclase (14 mm) in a matrix of quartz and micas. Perthitic K-feldspar grains show plagioclase inclusions. Feldspar alteration to sericite and epidote is common. Quartz grains are mostly equigranular, and some show serrated grain boundaries. Irregular hornblende grains are rimmed by oxides and epidote, suggesting replacement. Biotite is nearly all replaced by finer-grained chlorite.

Latitude: 41.62934

Longitude: -70.52784

Elevation of well site (m): 25.83

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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OFR03-221 Home | Introduction | Bedrock Photographs | GIS Data Catalog

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