GEOLEX

Summary of Citation: Coamo

Publication:
Glover, Lynn, III, 1961, Preliminary report on the geology of
   the Coamo Quadrangle, Puerto Rico: U.S. Geological Survey
   Miscellaneous Investigations Series Map, I-335, 1 sheet,
   scale 1:20,000

Usage in Publication:
Coamo Formation*

Modifications:	Geologic Province:	Dominant Lithology:
Named	Caribbean region	Tuff Breccia Conglomerate

Summary:
The Coamo Formation, here named, consists of massive volcanic rocks including tuff breccia, lapilli tuff, and tuffaceous conglomerate overlying several bedded units. The San Diego Lapilli Tuff Member, the Santa Ana Limestone Member, and a tuff breccia unit are named in the lower part. Conformably overlies the Cariblanco Formation; underlies the Cuevas Limestone with erosional unconformity. Maximum thickness is 1,599 m. Age is Late Cretaceous.

Summary of Citation: Coamo

Publication:
Mattson, P.H., 1967, Cretaceous and lower Tertiary stratigraphy
   in west-central Puerto Rico, IN Contributions to stratigraphy:
   U.S. Geological Survey Bulletin, 1254-B, p. B1-B35

Usage in Publication:
Coamo Formation*

Modifications:	Geologic Province:	Dominant Lithology:
Revised	Caribbean region

Summary:
In west-central PR the Coamo Formation is restricted to the massive volcanic rocks, excluding the bedded units (San Diego Lapilli Tuff Member, Santa Ana Limestone Member, and unnamed conglomerate and sandstone and siltstone units) below the massive volcanic units. The conformably underlying Maravillas Formation has been defined to include the sequence below the restricted Coamo and limestone blocks and lenses in the Maravillas may be correlative with the Santa Ana Member and lapilli tuff and tuff lenses in the Jayuya quadrangle may be correlative with the San Diego Member. In the Jayuya quadrangle, the Coamo consists of coarse-grained tuff, lapilli tuff, and fine-grained volcanic breccia. Upper contact of the Coamo is removed by erosion. Thickness is 300 m. Age is Campanian to Maastrichtian based on fossils.

Summary of Citation: Coamo

Publication:
Briggs, R.P., 1969, Changes in stratigraphic nomenclature in
   the Cretaceous System, east-central Puerto Rico, IN Contributions
   to stratigraphy, 1968: U.S. Geological Survey Bulletin,
   1274-O, p. O1-O31, Prepared in cooperation with the Commonwealth
   of Puerto Rico Economic Development Administration.

Usage in Publication:
Coamo Formation*

Modifications:	Geologic Province:	Dominant Lithology:
Revised	Caribbean region

Summary:
Mapping in the Orocovis quadrangle has shown that the Pozas Formation of the Ciales quadrangle is continuous with the so-called Coamo Formation of the Barranquitas quadrangle; therefore those rocks in the northwest Barranquitas are reassigned to the Pozas. The Rio Bauta Member is named at the base of Pozas in the Orocovis quadrangle. The Botijas Limestone and Reves Members are reassigned from the Coamo to the Pozas. Age is late Campanian to early Maastrichtian.

Summary of Citation: Coamo

Publication:
Glover, Lynn, III, 1971, Geology of the Coamo area, Puerto Rico,
   and its relation to the volcanic arc-trench association: U.S.
   Geological Survey Professional Paper, 636, 102 p.

Usage in Publication:
Coamo Formation*

Modifications:	Geologic Province:	Dominant Lithology:
Revised	Caribbean region

Summary:
The heterogeneous lower part of the Coamo Formation is here included in the underlying Maravillas Formation and the massive upper 70% of the sequence is restricted to the Coamo. The part assigned to the Maravillas includes the San Diego and Santa Ana Members, leaving no members in the Coamo.

Summary of Citation: Coamo

Publication:
Krushensky, R.K., in press, Geologic map of Puerto Rico: U.S.
   Geological Survey Miscellaneous Investigations Series Map,
   I-__

Usage in Publication:
Coamo Formation*

Modifications:	Geologic Province:	Dominant Lithology:
Overview	Caribbean region

Summary:
The Coamo Formation occurs in central Puerto Rico and consists of tuff and volcanic breccia with locally occurring andesitic lava flows and lenses of calcarenite. Maximum estimated thickness is 300 meters. The Coamo is of Late Cretaceous age.