Proposed type sections for Upper Silurian and Lower Devonian subsurface units in Permian Basin, West Texas
Proposed type sections for Upper Silurian and Lower Devonian subsurface units in Permian Basin, West Texas
AAPG Bulletin (September 1979) 63 (9): 1510-1521
- biostratigraphy
- correlation
- Crane County Texas
- Devonian
- Lower Devonian
- new names
- nomenclature
- Paleozoic
- Pecos County Texas
- Permian Basin
- Silurian
- Southwestern U.S.
- stratigraphic units
- stratigraphy
- Texas
- Thirtyone Formation
- type sections
- United States
- Upper Silurian
- Ward County Texas
- Winkler County Texas
- Wristen Formation
- Wink Member
- Frame Member
The name Wristen Formation is proposed for the formation in the Permian basin known as the "Silurian shale," "Upper Silurian," or "Green Silurian" with a type section in Ward County, Texas. Two members are designated in the Wristen Formation-the Wink and Frame Members. The lower, Wink Member, consists principally of gray limestone, and the upper, Frame Member, consists principally of greenish-gray shale and limestone. These members grade into a thick carbonate facies in Andrews County, Texas. The Wristen Formation is assumed to be of late Middle and Late Silurian age, and correlative with part of both the Hunton Group of Oklahoma and perhaps the Caballos Novaculite of the Marathon region. The name Thirtyone Formation is proposed for the unit known as the "Lower Devonian cherty limestone" in the subsurface of the Permian basin. The type section is in Crane County, Texas. The three lithofacies of the Thirtyone are: (1) a chert facies in the southwest; (2) a carbonate facies in the north; and (3) a siliceous limestone facies in the center of the study area. The Thirtyone is of Early and Middle Devonian age, and is also correlative with part of both the Hunton Group of Oklahoma and the Caballos Novaculite of the Marathon region.