U.S. Geological Survey Home AASG Logo USGS HOME CONTACT USGS SEARCH USGS
National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Minguillo Tuff Member*
  • Modifications:
    • Named
    • Biostratigraphic dating
  • Dominant lithology:
    • Tuff
Publication:

Berryhill, H.L., Jr., 1965, Geology of the Ciales quadrangle, Puerto Rico: U.S. Geological Survey Bulletin, 1184, 116 p.


Summary:

The Minguillo Tuff Member of the Pozas Formation, here named, forms a lens of brecciated lava at the base of the Pozas in west-central Ciales quadrangle. Member varies from oxidized murky-red flow breccia to gray porphyritic lava with plagioclase phenocrysts to dark-greenish-gray dense porphyritic rock with pyroxene phenocrysts. Conformably overlies the Manicaboa Formation; underlies the Blacho Tuff Member of the Pozas. Maximum thickness is 300 m. Age is Late Cretaceous (Maastrichtian) based on rudistids in similar rocks.

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 does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).