Mount Zion Church Basalt

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Mount Zion Church Basalt
Stratigraphic range: 201.8 ± 0.7 Ma [1]
Basalt from Mount Zion Church Basalt.jpg
A basalt rock from the Mount Zion Church Basalt
Type Half Graben
Unit of Newark Supergroup
Overlies Midland Formation
Thicknessup to 100 metres (330 ft)
Lithology
Primary Basalt
Location
Location Virginia
Coordinates 38°23′27″N77°25′18″W / 38.3908°N 77.4217°W / 38.3908; -77.4217
Region Culpeper Basin
Country United States
Extent30 miles (48 km)
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Mount Zion Church Basalt
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Location within the United States in Virginia

The Mount Zion Church Basalt is a large volume flood basalt lava field located in the Culpeper Basin in the US state of Virginia. It was associated with the rifting and initial break-up of the ancient supercontinent Pangea. Part of the larger Newark Supergroup formation which is a part of the Central Atlantic magmatic province (CAMP) large igneous province which erupted ~201 Ma. [2]

Contents

Pangea

The ancient supercontient of Pangea existed between 300 and 200 Ma. This includes the continents known today as North America, South America, (Laurentia), Europe, and Africa (Gondwana) which all collided together to form the supercontient. [3]

Around 230 Ma, Pangea showed its first signs of break up. Subduction zones lined Pangea on both side which began to cause extension in Pangea's interior. [4] Along with orogenic collapse and thermal mantle heating caused by the enormous size of Pangea, were the main factors that led to continental breakup. [5]

Between 250 and 200 Ma, Pangea underwent a counter-clockwise rotation focused on Laurentia, and a clockwise rotation focused on Gondwana, due to subduction zones. This further weakened Pangea's pre existing weaknesses from its formation. This caused rift valleys to form which gradually grew deeper and wider over time. [6]

Geology

The Mount Zion Church Basalt is the oldest of 3 eruptive cycles in the Culpeper Basin with the other 2 being the Hickory Grove Basalt and the Sander Basalt. Throughout the Newark Supergroup, the Mount Zion Church Basalt is equivalent to the Aspers Basalt in Pennsylvania and the Orange Mountain Basalt in New Jersey. The greater Culpeper Basin is made up to Sediment to igneous basalt layers that alternate between eruptive cycles. [7]

The basalt found in the Mount Zion Church Basalt are generally aphanitic fine-grained and micro-porphyritic, high-titanium, normative tholeiitic basalt The main mineral phases are idiomorphic or sub-idiomorphic plagioclase and augitic clinopyroxene. During post eruption, the basalts contain calcite, prehnite, and zeolites. [1] [8]

There are at least 2 different lava flows that have been identified. The exposed basalt is quite narrow due to lava that settled inside a western border fault. Eruptions were characterized by long eruptive fissures that erupted large volumes of lava. [9]

See also

References

  1. 1 2 Marzoli, Andrea; Jourdan, Fred; Puffer, John H.; Cuppone, Tiberio; Tanner, Lawrence H.; Weems, Robert E.; Bertrand, Hervé; Cirilli, Simonetta; Bellieni, Giuliano; De Min, Angelo (March 2011). "Timing and duration of the Central Atlantic magmatic province in the Newark and Culpeper basins, eastern U.S.A." Lithos. 122 (3–4): 175–188. doi:10.1016/j.lithos.2010.12.013 . Retrieved 27 November 2025.
  2. ↑ Marzoli, Andrea; Callegaro, Sara; Dal Corso, Jacopo; Davies, Joshua H. F. L.; Chiaradia, Massimo; Youbi, Nassrrdine; Bertrand, Hervé; Reisberg, Laurie; Merle, Renaud; Jourdan, Fred (2018). "The Central Atlantic Magmatic Province (CAMP): A Review". The Late Triassic World. 46: 91–125. doi:10.1007/978-3-319-68009-5_4 . Retrieved 27 November 2025.
  3. ↑ "What was Pangea?". www.usgs.gov. United States Geological Survey. 31 December 2021. Retrieved 27 November 2025.
  4. ↑ Keppie, Fraser (January 2016). "How subduction broke up Pangaea with implications for the supercontinent cycle". Geological Society, London, Special Publications. 424 (1). Special Publications: 265–288. doi:10.1144/SP424.8 . Retrieved 27 November 2025.
  5. ↑ Gianni, Guido M.; Navarrete, César R. (4 February 2022). "Catastrophic slab loss in southwestern Pangea preserved in the mantle and igneous record". Nature Communications. 13 (1): 698. doi:10.1038/s41467-022-28290-z. ISSN   2041-1723 . Retrieved 27 November 2025.
  6. ↑ Le Pichon, Xavier; Şengör, A. M. Celal; Jellinek, Mark; Lenardic, Adrian; İmren, Caner (17 January 2023). "Breakup of Pangea and the Cretaceous Revolution". Tectonics. 42 (2). doi:10.1029/2022TC007489 . Retrieved 27 November 2025.
  7. ↑ Weems, Robert; Olsen, Paul (February 1997). "Synthesis and revision of groups within the Newark Supergroup, eastern North America" (PDF). ldeo.columbia.edu. Geological Society of America Bulletin. Retrieved 27 November 2025.
  8. ↑ Davis, Adam; Southworth, Scott; Reddy, James; Schindler, J. Stephen (January 2001). "USGS Open-File Report 01-227". pubs.usgs.gov. United States Geological Survey. Retrieved 27 November 2025.
  9. ↑ Lee, K.Y.; FROELICH, A.J. (1989). "Triassic- Jurassic Stratigraphy of the Culpeper and Barboursville Basins, Virginia and Maryland" (PDF). pubs.usgs.gov. United States Geological Survey. Retrieved 27 November 2025.
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