Middlesex Formation

Middlesex Formation
Middlesex Formation
Stratigraphic range: Frasnian
Type	Formation
Unit of	Sonyea Group
Underlies	Cashaqua Shale or Pulteney shale
Overlies	Genesee Group
Thickness	6–75 feet (23 m)
Lithology
Primary	Black Shale
Location
Region	Maryland, New York, Ohio, Pennsylvania, West Virginia
Country	United States
Type section
Named for	Town of Middlesex, NY

The Middlesex Formation is a carbon rich black shale geologic formation found in the Appalachian Basin. It represents one of several transgressive events (rising sea levels) during the Late Devonian.^[1]

Description

The Middlesex is a laminated, dark grey to black formation comprising mudstone and siltstone. It developed in an anoxic environment. Further evidence of this is the lack of bioturbation. There are also sparse sand and silt layers, suggesting that they were single event deposits.^[2]

References

^ KIRCHGASSER, WILLIAM T.; OVER, D. JEFFREY (9 December 2023). "FRASNIAN (UPPER DEVONIAN) STRATA OF THE GENESEE RIVER VALLEY, WESTERN NEW YORK STATE" (PDF). Otto's Website. Retrieved 9 December 2023.
^ Schieber, J. (1999-07-01). "Distribution and deposition of mudstone facies in the Upper Devonian Sonyea Group of New York". Journal of Sedimentary Research. 69 (4): 909–925. doi:10.2110/jsr.69.909. ISSN 1527-1404.

"Cashaqua and Middlesex Shales". USGS. Retrieved 2015-09-17.
Bergin, M. J. (1964). "Bedrock Geology of the Penn Yan and Keuka Park Quadrangles New York". Geological Survey Bulletin (1161-G). USGS. Retrieved 22 September 2015.
"Middlesex Shale Formation – Sonyea Group". Shanan E. Peters & Noel A. Heim. Archived from the original on 2015-09-23. Retrieved 2015-09-17.
Schieber, J. (1999). "Distribution and deposition of mudstone facies in the Upper Devonian Sonyea Group of New York". Journal of Sedimentary Research. 69 (4). SEPM Society for Sedimentary Geology: 909–925. doi:10.2110/jsr.69.909. Retrieved 22 September 2015.

[1] KIRCHGASSER, WILLIAM T.; OVER, D. JEFFREY (9 December 2023). "FRASNIAN (UPPER DEVONIAN) STRATA OF THE GENESEE RIVER VALLEY, WESTERN NEW YORK STATE" (PDF). Otto's Website. Retrieved 9 December 2023.

[2] Schieber, J. (1999-07-01). "Distribution and deposition of mudstone facies in the Upper Devonian Sonyea Group of New York". Journal of Sedimentary Research. 69 (4): 909–925. doi:10.2110/jsr.69.909. ISSN 1527-1404.

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