Catharpin Creek Formation

Last updated
Bull Run Formation
Stratigraphic range: Late Triassic,
late Norian to Rhaetian
Type Geological formation
Unit of Chatham Group
Sub-unitsGoose Creek Member
Underlies Mount Zion Church Basalt
Overlies Bull Run Formation
Lithology
Primary sandstone, conglomerate
Other shale, siltstone
Location
Region Maryland, Virginia
CountryFlag of the United States (23px).png  United States
Extent Culpeper Basin
Type section
Named forCatharpin Creek, Virginia
Named byLee & Froelich, 1989

The Catharpin Creek Formation is a Late Triassic (late Norian to Rhaetian) geologic formation in Maryland and Virginia. It is found along the western edge of the Culpeper Basin, one of the largest sedimentary basins in the Newark Supergroup. Compared to the underlying Bull Run Formation, the Catharpin Creek Formation is dominated by much coarser sedimentary rocks such as sandstone and conglomerate. [1] The base of the formation is reddish arkosic sandstone, which grades into drabber thin-bedded siltstone and shale in cyclical sequences. [2]

The general depositional environment is reconstructed as a system of active streams running down from alluvial fans which developed along highlands further west of the basin. A few outcrops contain lenses of a conglomerate unit known as the Goose Creek Member. This unit preserves a diverse array of reddish brown to grayish green pebbles and cobbles derived from metamorphic rocks, alongside some sandstone and sandy siltstone. The pebbles and cobbles would have originated from the Proterozoic and Cambrian Catoctin Formation and Chilhowee Group exposed along the Blue Ridge Mountains. [3] [2]

The Catharpin Creek Formation is the youngest fully Triassic unit in the Culpeper Basin, before the occurrence of Triassic-Jurassic basalts associated with eruptions of the Central Atlantic Magmatic Province (CAMP). [1] Based on general stratigraphic characteristics, it is typically considered to be equivalent to the Passaic Formation of the Newark Basin. [4] The estimated age of the Catharpin Creek Formation is late Norian to Rhaetian according to fossils of conchostracans such as Shipingia olseni and Euestheria brodieana . [5]

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<span class="mw-page-title-main">Culpeper Basin</span> Triassic rift basin in the United States

The Culpeper Basin is one of the Newark Supergroup's Triassic rift basins. It lies east of the Appalachian Mountains and extends from the Madison County—Orange County line in Virginia to Frederick, Maryland. A diverse group of sedimentary rocks including siltstone, sandstone, and conglomerate within the basin were intruded by igneous rocks, which caused thermal metamorphism at the contact with sedimentary rock.

The Midland Formation is a Mesozoic geological formation in the Culpeper Basin of Virginia. It is a sedimentary unit which formed in a short period of time between the first two basalt flows in the basin: the Hickory Grove and Mount Zion Church basalts. The most common rocks in the formation are dark reddish interbedded sandstones and siltstones, representative of fluvial (stream) environments. Rare but fossiliferous calcareous shale and limestone also occurs, representing recurring lacustrine (lake) conditions. The Midland Formation is considered equivalent to the Shuttle Meadow Formation of the Hartford Basin, the Feltville Formation of the Newark Basin, and the Bendersville Formation of the Gettysburg Basin. Some sources prefer to classify the Midland Formation as part of the Shuttle Meadow Formation.

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The Meriden Group is a geologic group, part of the Newark Supergroup, in Connecticut. It preserves fossils dating back to the Jurassic period.

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<i>Oncodella</i> Extinct genus of jawless fishes

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The Sanford Formation is a Late Triassic (Norian)-age geologic formation in North Carolina. It is mainly found in the Sanford sub-basin of the Deep River Basin, the southernmost of the large Mesozoic basins forming the Newark Supergroup. It is the highest unit of the Chatham Group, overlying the dark lake and swamp sediments of the Cumnock Formation. The Sanford Formation is composed primarily of coarse red sediments such as conglomerates, sandstones, and mudstones. The conglomerate layers contain pebbles of schist and slate, with the occasional large boulders of granite.

References

  1. 1 2 Weems, Robert E.; Olsen, Paul E. (1997-02-01). "Synthesis and revision of groups within the Newark Supergroup, eastern North America". GSA Bulletin. 109 (2): 195–209. Bibcode:1997GSAB..109..195W. doi:10.1130/0016-7606(1997)109<0195:SAROGW>2.3.CO;2. ISSN   0016-7606.
  2. 1 2 Lee, K.Y.; Froelich, A.J. (1989). "Triassic- Jurassic Stratigraphy of the Culpeper and Barboursville Basins, Virginia and Maryland". U.S. Geological Survey Professional Paper. 1472: 1–52. doi:10.3133/pp1472.
  3. Lindholm, R.C. (1979). "Geologic history and stratigraphy of the Triassic–Jurassic Culpeper basin, Virginia". Geological Society of America Bulletin. 90 (2): 1702–1736. Bibcode:1979GSAB...90.1702L. doi:10.1130/GSAB-P2-90-1702.
  4. Weems, Robert E.; Tanner, Lawrence H.; Lucas, Spencer G. (2016). "Synthesis and revision of the lithostratigraphic groups and formations in the Upper Permian?–Lower Jurassic Newark Supergroup of eastern North America". Stratigraphy. 13 (2): 111–153. doi:10.29041/strat.13.2.03.
  5. Kozur, Heinz W.; Weems, Robert E. (2010-01-01). "The biostratigraphic importance of conchostracans in the continental Triassic of the northern hemisphere" (PDF). Geological Society, London, Special Publications. 334 (1): 315–417. Bibcode:2010GSLSP.334..315K. doi:10.1144/SP334.13. ISSN   0305-8719. S2CID   131224365.