Beacon Supergroup

Quality 0.50 · 1 view · Updated 2 months ago

title: "Beacon Supergroup" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["geology-of-antarctica", "geological-supergroups", "fossil-trackways", "trace-fossils"] topic_path: "science/earth-science" source: "https://en.wikipedia.org/wiki/Beacon_Supergroup" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::data[format=table title="Infobox rockunit"]

FieldValue
nameBeacon Supergroup
typeGeologic Supergroup
subunits*Fremouw Formation
ageEmsian - Induan
~
periodDevonian-Triassic
countryRoss Dependency
::

| name = Beacon Supergroup | image = | caption = | type = Geologic Supergroup | subunits = *Fremouw Formation

::figure[src="https://upload.wikimedia.org/wikipedia/commons/a/a3/Taylorglacier_pho_2013_studinger.jpg" caption="Beacon Supergroup in [[Taylor Valley]]. The tan bands are Beacon Sandstone layers and the dark layers are [[diabase]] sills, intruded about 180 million years ago."] ::

The Beacon Supergroup is a geological formation exposed in Antarctica and deposited from the Devonian to the Triassic (). The unit was originally described as either a formation or sandstone, and upgraded to group and supergroup as time passed. It contains a sandy member known as the Beacon Heights Orthoquartzite.

Overview

The base of the Beacon Supergroup is marked by an unconformity and is composed of the Devonian Taylor Group, a quartzose sandstone sequence; and the Late Carboniferous to Early Jurassic Victoria Group, consisting of glacial beds, sandstone, shale, conglomerate, and coal. The Beacon Sandstone was named by Hartley T. Ferrar during Scott's Discovery Expedition (1901–1904), using the Beacon Heights survey points as reference. Glossopteris fossils dated the sandstone to the Permian and linked the lithology to similar sequences on neighboring continents. Generally flat lying, the supergroup is up to 3.2 km thick and is fairly continuous from south Victoria Land to the Beardmore Glacier along the Transantarctic Mountains. The Urfjell Group in Dronning Maud Land and the Neptune Group in the Pensacola Mountains have been correlated with the Taylor Group. Macrofossils and palynomorph assemblages age date Devonian, Late Carboniferous–Early Permian, Late Permian and Triassic strata. The Ferrar Dolerite intrudes at various levels, while the Mawson Formation and Kirkpatrick Basalts within the Ferrar Supergroup cap the Beacon Supergroup.

The location of the formation in a cold, desert environment and the lack of nutrients or soil (due to the purity of the sandstone) has led to the Beacon Sandstone being considered the closest analogue on Earth to Martian conditions; therefore, many studies have been performed on life's survival there, mainly focusing on the lichen communities that form the modern inhabitants.e.g. {{cite journal |author1=Derek Pullan |author2=Frances Westall |author3=Beda A. Hofmann |author4=John Parnell |author5=Charles S. Cockell |author6=Howell G.M. Edwards |author7=Susana E. Jorge Villar |author8=Christian Schroder |author9=Gordon Cressey |author10=Lucia Marinangeli |author11=Lutz Richter |author12=Gostar Klingelhofer. | year = 2008 | title = Identification of Morphological Biosignatures in Martian Analogue Field Specimens Using In Situ Planetary Instrumentation | journal = Astrobiology | volume = 8 | issue = 1 | doi = 10.1089/ast.2006.0037 | pages = 119–56 | pmid = 18211229| bibcode=2008AsBio...8..119P |hdl=1893/17124 |hdl-access=free }}

The supergroup originated in a shallow marine sedimentary depositional environment. The well-sorted nature of the unit suggests that it was probably deposited close to the shoreline, in a high-energy environment. Features such as the presence of coal beds and desiccation cracks suggest that parts of the unit were deposited subaerially, though ripple marks and cross bedding show that shallow water was also commonly present. The rock is low in phosphorus.

Taylor Group

::figure[src="https://upload.wikimedia.org/wikipedia/commons/d/d9/Beacon-crossbedding.jpg" caption="Cross-bedding in sandstone of the Beacon Supergroup suggests a fluvial environment."] ::

The Taylor Group is separated from the overlying Victoria Group by a disconformity called the Maya Erosion Surface. Taylor Group formations in the Darwin Mountains region include the Brown Hills Conglomerate (34 m), which overlies pre-Devonian plutonic rocks of igneous and metamorphic nature, with over 30 m of erosional relief, and igneous and metamorphic clasts. The conglomerate is poorly sorted at the base, with influxes of coarser material. Coarseness is laterally variable, with pebbles in places and sands in others at the same horizon. The conglomerate includes planar beds, trough cross-bedding, flaser bedding, mud-drapes on some ripples, U-shaped burrows and escape structures, with fining-up cycles topped by desiccation cracks in places.

Within the Darwin Mountains region, the Junction Sandstone (290 m) overlies the Brown Hills Conglomerate, with abundant Skolithos. This is followed by the Hatherton Sandstone (330 m), with brachiopod and bivalve shell fragments in places. Trough cross beds and current rippling are present, with abundant ichnofauna.

The Beacon Heights Orthoquartzite (330 m) is found in the South Victoria Land region between the Arena Sandstone and the overlying Devonian Aztec Siltstone. It is well sorted and cemented, with medium to coarse grain sizes and trough cross-beds, with Haplostigma and Beaconites remnants.

The Aztec Siltstone (125–220 m) is found both in South Victoria Land and the Darwin Mountains. The siltstone includes interbedded sandstones, fish-bearing shales, conchostracans, and paleosols implying subaerial periods within an alluvial plain sequence.{{cite journal | author1 = Isbell, J.L. | author2 = Lenaker, P.A. | author3 = Askin, R.A. | author4 = Miller, M.F. | author5 = Babcock, L.E. | year = 2003 | title = Reevaluation of the timing and extent of late Paleozoic glaciation in Gondwana: Role of the Transantarctic Mountains | journal = Geology | volume = 31 | issue = 11 | pages = 977–980 | doi = 10.1130/G19810.1|bibcode = 2003Geo....31..977I}}

Within the Beardmore Glacier region, the Devonian Alexandra Formation (0–320 m), which constitutes the entire Taylor Group, is a quartz sandstone to siltstone.

Victoria Group

The Victoria Group begins with a diamictite-bearing unit known as the Metschel Tillite (0–70 m) in South Victoria Land and continues with the Darwin Tillite (82 m) in the Darwin Mountains, the Pagoda Tillite (395 m) at the Beardmore Glacier, the Scott Glacier Formation (93 m) on the Nilsen Plateau, and the Buckeye Tillite (140–308 m) in the Wisconsin Range and Ohio Range.

Paleontology

Body fossils

The Aztec sandstone contains units bearing body fossils of fish:{{cite journal | author = Woolfe, K.J. | year = 2004 | title = Cycles of erosion and deposition during the Permo-Carboniferous glaciation in the Transantarctic Mountains | journal = Antarctic Science | volume = 6 | issue = 1 | pages = 93–104 | doi = 10.1017/S095410209400012X | bibcode = 1994AntSc...6...93W | author = Turner, S. |author2= Young, G.C. | year = 2004 | title = Thelodont scales from the Middle-Late Devonian Aztec Siltstone, southern Victoria Land, Antarctica | journal = Antarctic Science | volume = 4 | issue = 1 | pages = 89–105 | doi = 10.1017/S0954102092000142 | bibcode = 1992AntSc...4...89T

Trace fossils

::figure[src="https://upload.wikimedia.org/wikipedia/commons/c/ce/Beacon-burrows.jpg" caption="Burrows in the Beacon Supergroup."] ::

Trace fossils are sparse below, but become common in the Hatherton Sandstone. They change from Skolithos-dominated facies to wide diversity and abundance, including vertical and horizontal burrows and huge arthropod trackways. The size of the arthropod tracks (less than 91 cm) is taken to imply that water must have been required for support.

  • Fodinichnia: feeding burrows, probably of marine polychaetes, featuring evidence of rhythmic defecation.

    • Narrow, sinuous, near-surface forms on flat bedding surfaces
    • Longer, larger forms, reaching 13 cm across and 1 m in length.

  • Walking trackways of arthropods (Repichnia).{{cite journal | author = Gevers, T.W. |author2= Frakes, L.A.|author3= Edwards, L.N.|author4= Marzolf, J.E. | year = 1971 | title = Trace Fossils in the Lower Beacon Sediments (Devonian), Darwin Mountains, Southern Victoria Land, Antarctica | journal = Journal of Paleontology | volume = 45 | issue = 1 | pages = 81–94 | jstor=1302754

    • Beaconites antarcticus: narrow, parallel grooves, about an inch apart, disappearing into elliptical pits; created by shovelling the surface sediment aside before burrowing into the sediment. Occasionally branch.
    • Perhaps B. barretti: more widely spaced grooves (~3 cm); small footprints visible. Implies many walking limbs and an approximately rectangular shape — reminiscent of trilobites. Extend laterally up to ; burrow deeply into sediment.{{cite conference | author1 = Bradshaw, M.A. | author2= Harmsen, F.J. | year = 2007 | title = The paleoenvironmental significance of trace fossils in Devonian sediments (Taylor Group), Darwin Mountains to the Dry Valleys, southern Victoria Land | conference = 10th International Symposium on Antarctic Earth Sciences | volume = 1047 | url = https://pubs.usgs.gov/of/2007/1047/ea/of2007-1047ea133.pdf | access-date = 2008-04-22
    • Large (~30 cm wide) trails with a scrape mark from a central tail. Three to four footprint pits diverge from these tracks at a high angle. The feet making the footprints had spines on their rears. These may have been formed by eurypterids but are not a perfect match to known eurypterid trails; they may also have been formed by xiphosurans

  • Diplichnites trackways: double rows of fossils previously attributed to marine trilobites but now thought to perhaps be formed by annelids or myriapods. Here they appear on metre-scale crossbeds that may represent sub-fluvial dunes.

  • Cruziana and Rusophycus: thought to be formed by trilobites, whose body fossils are found only in marine assemblages. Could also have been made by other arthropods, or the lower parts of the Beacon Sandstone may have been marine. They have been found in many other non-marine instances.

  • Skolithos: traditionally thought to be marine; however, there are many counterexamples.

References

References

  1. Bradshaw, Margaret A.. (August 6, 2013). "The Taylor Group (Beacon Supergroup): the Devonian sediments of Antarctica". Geological Society of London, Special Publications.
  2. Stewart, Duncan Jr.. "The Petrography of the Beacon Sandstone of the South Victoria Land". The American Mineralogist.
  3. (August 2025). "Type section of the Beacon Sandstone of Antarctica". US Geol Survey Prof Paper.
  4. "Scott's Terra Nova Antarctic Expedition".
  5. Friedmann, E.I.. (1987). "Microbial trace-fossil formation, biogenous, and abiotic weathering in the Antarctic cold desert". Science.
  6. Elliott, R.B.. (1963). "A Beacon Sandstone: its Petrology and Hydrocarbon Content". Nature.
  7. (1982). "Geology and terrestrial age of the Derrick Peak meteorite occurrence, Antarctica". Meteoritics.
  8. (1991). "The Devonian to Jurassic Beacon Supergroup of the Transantarctic Mountains and correlatives in other parts of Antarctica, in The Geology of Antarctica". Clarendon Press.
  9. (1986). "Antarctica-Geology and Hydrocarbon Potential, in Future Petroleum Provinces of the World". American Association of Petroleum Geologists.
  10. Bernet, M.. (2005). "Diagenetic history of Triassic sandstone from the Beacon Supergroup in central Victoria Land, Antarctica". New Zealand Journal of Geology and Geophysics.
  11. Banerjee, M.. (2000). "Phosphatase Activities of Endolithic Communities in Rocks of the Antarctic Dry Valleys". Microbial Ecology.
  12. Woolfe, K.J.. (1993). "Devonian depositional environments in the Darwin Mountains: Marine or non-marine?". Antarctic Science.
  13. Angino, E.E.. (1962). "Sedimentologic Study of Two Members of the Beacon Formation, Windy Gully, Victoria Land, Antarctica". Transactions of the Kansas Academy of Science.
  14. Woolfe, K.J.. (1994). "Cycles of erosion and deposition during the Permo-Carboniferous glaciation in the Transantarctic Mountains". Antarctic Science.
  15. Woolfe, K.J.. (1990). "Trace fossils as paleoenvironmental indicators in the Taylor Group (Devonian) of Antarctica". Palaeogeography, Palaeoclimatology, Palaeoecology.
  16. (1991). "The palaeo-Pacific margin as seen from East Antarctica, in Geological Evolution of Antarctica". Cambridge University Press.
  17. (1971). "An Upper Paleozoic Tillite in the Dry Valleys, South Victoria Land, Antarctica: NOTES". Journal of Sedimentary Research.
  18. (1991). "Evidence for a low-gradient alluvial fan from the palaeo-Pacific margin in the Upper Permian Buckley Formation, Beardmore Glacier area, Antarctica, in Geological Evolution of Antarctica". Cambridge University Press.
  19. (1991). "Provenance and tectonic implications of sandstones within the Permian Mackellar Formation, Beacon Supergroup of East Antarctica, in Geological Evolution of Antarctica". Cambridge University Press.

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::

geology-of-antarcticageological-supergroupsfossil-trackwaystrace-fossils