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Phosphorite and other apatite-bearing sedimentary rocks in the Precambrian of northern Michigan

Circular 746

By:
,

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Abstract

Phosphatic pebbles are widespread in basal units of the Marquette Range Supergroup (Precambrian X) in the central part of the Upper Peninsula of Michigan. At one locality, a conglomeratic bed about 15 m thick averages about 15 percent P2O5, and many thinner beds are of comparable grade. This occurrence is believed to be the richest sedimentary phosphate deposit known in the Precambrian of the United States, as well as one of the oldest. Although outcrops are generally scarce, similar material has been found at four other localities in the Upper Peninsula of Michigan.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Phosphorite and other apatite-bearing sedimentary rocks in the Precambrian of northern Michigan
Series title:
Circular
Series number:
746
Edition:
-
Year Published:
1976
Language:
ENGLISH
Publisher:
Dept. of the Interior, Geological Survey : distributed by Branch of Distribution, U.S. Geological Survey,
Description:
iii, 6 p. :maps ;26 cm.