- Usage in publication:
-
- Perchas Lava Member*
- Modifications:
-
- Named
- Dominant lithology:
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- Lava
- Tuff
- Sandstone
- AAPG geologic province:
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- Caribbean region
Summary:
The Perchas Lava Member of the Rio Orocovis Formation, here adopted by the USGS, consists of massive amygdaloidal pillow lavas and thin lenticular layers of tuff, sandstone, and breccia. Gradationally overlies the Magueyes Member of the Rio Orocovis; unconformably underlies the Avispa Member in the south-central Ciales quadrangle. Thickness is 1,500 m. Age is Turonian(?) to late Santonian(?) or early Campanian.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
-
- Perchas Formation*
- Modifications:
-
- Revised
- AAPG geologic province:
-
- Caribbean region
Summary:
Rio Orocovis Formation redefined Rio Orocovis Group and Perchas Lava Member redefined Perchas Formation. Overlies the Magueyes Formation; conformably underlies the Avispa Formation.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
-
- Perchas Formation*
- Modifications:
-
- Overview
- AAPG geologic province:
-
- Caribbean region
Summary:
The Perchas Formation occurs in central Puerto Rico and consists of pillowed basaltic lava interbedded with basaltic tuff, volcanic sandstone, and minor hyaloclastite breccia. Unit is lithologically similar to the Magueyes Formation. Maximum estimated thickness is 1500 meters. The Perchas is of Cretaceous age.
Source: GNU records (USGS DDS-6; Reston GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).