Bar B Formation

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Bar B Formation
Stratigraphic range: middle Pennsylvanian–late Pennsylvanian
Type Formation
Underlies Bursum Formation
Overlies Nakaye Formation
Thickness339 ft (103 m)
Lithology
Primary Limestone, shale
Location
Coordinates 33°01′07″N107°14′20″W / 33.0185°N 107.2390°W / 33.0185; -107.2390
Region New Mexico
Country United States
Type section
Named forBarbee Draw (drainage)
Named byV.C. Kelley and Caswell Silver
Year defined1952
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Bar B Formation (the United States)
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Bar B Formation (New Mexico)

The Bar B Formation is a geologic formation found the Caballo Mountains of New Mexico. It preserves fossils showing it was deposited in the middle to late Pennsylvanian. [1] [2]

Contents

Description

The Bar B formation is mostly cyclic [2] beds of shale and limestone, with shale making up about 80% of the formation and limestone the other 20%. Chert is present in some of the limestone. The upper 50 feet (15 m) include reddish-brown siltstone, limestone conglomerate, and calcareous siltstone. The total thickness is about 339 ft (103 m). [3] The formation rests on the Nakaye Formation and is unconformably overlain by the Bursum Formation. [2]

The formation likely correlates with the Panther Seep Formation in the San Andres Mountains. [1] [2]

Fossils

The formation contains abundant bryozoan fossils. [3]

History of investigation

The formation was first defined by V.C.Kelley and Caswell Silver in 1952. [3] Bachman and Myers criticized its definition in 1975, [1] but it is accepted by Kues and Giles, though they restrict it to the Caballo Mountains. [2]

See also

References

  1. 1 2 3 Bachman, G.O.; Myers, D.A. (1975). "The Lead Camp Limestone and its correlatives in south-central New Mexico" (PDF). New Mexico Geological Society Field Conference Guidebook. 26: 105–108. Retrieved 30 July 2020.
  2. 1 2 3 4 5 Kues, B.S.; Giles, K.A. (2004). "The late Paleozoic Ancestral Rocky Mountain system in New Mexico". In Mack, G.H.; Giles, K.A. (eds.). The geology of New Mexico. A geologic history: New Mexico Geological Society Special Volume 11. pp. 95–136. ISBN   9781585460106.
  3. 1 2 3 Kelley, V.C.; Silver, Caswell (1952). "Geology of the Caballo Mountains; with special reference to regional stratigraphy and structure and to mineral resources, including oil and gas". University of New Mexico Publications in Geology. 4.
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