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    • Source: Minaret Formation

      • The Minaret Formation is a Late Cambrian limestone formation of the Heritage Group of Antarctica. The age of the formation is established to be Guzhangian to Cambrian Stage 10 (or Merioneth to Dresbachian in the regional stratigraphy), dated at ranging from 500 to 488 Ma.
      The formation has provided the first known Late Cambrian archaeocyathid, and Knightoconus antarcticus, an ancestor to the cephalopods.


      Description


      The Minaret Formation forms a discontinuous limestone unit exposed from Webers Peaks in the northern Heritage Range to the Independence Hills in Horseshoe Valley of the Ellsworth Mountains. At Mount Rosenthal, at the head of Horseshoe Valley, the Minaret Formation is formed predominantly of white to pale grey micritic limestone with thin, discrete interbeds of oolitic and oncolithic grainstones.
      The Minaret Formation is the uppermost formation of the Heritage Group, overlying the Liberty Hills and Springer Peak Formations. The formation is overlain by the Howard Nunataks Formation of the Crashsite Group. The formation reaches a thickness of 600 metres (2,000 ft) in the south of its extent. The formation ranges from shallow to deep marine. The Minaret fauna contains the first known Late Cambrian archaeocyathid. During the final stages of Gondwanian deformation, structureless and stratified post-cleavage breccia bodies formed in the carbonate lithologies of the Minaret Formation, due to cave-like dissolution processes and contemporaneous low temperature hydrothermal activity.


      Fossil content


      The reefal limestones of the formation have provided fossils:

      Antarcticocyathus webersi
      Gastropods
      Strepsodiscus splettstoesseri
      Conodonts
      Furnishina furnishi
      F. quadrata
      F. ?asymmetrica
      Proacodus tenuis
      Phakelodus sp.
      Westergaardodina bicuspidata
      W. moessebergensis
      W. tricuspidata
      Tergomya
      Aremellia batteni
      Ellsworthoconus andersoni
      Kirengella pyramidalis
      Knightoconus antarcticus
      Proconus incertis
      Proplina rutfordi
      Rostroconchia
      Apoptopegma craddocki
      Cosminoconella runnegari
      Paragastropoda
      Matherella antarctica
      Ribeiria australiensis
      Scaevogyra thompsoni
      ?Kobayashiella heritagensis


      See also


      List of fossiliferous stratigraphic units in Antarctica
      Geology of Antarctica
      Shackleton Limestone, Cambrian fossiliferous limestone of Antarctica


      References




      = Bibliography

      =
      Webers, G.F.; Splettstoesser, J.F. (2007), "Review of the geology and paleontology of the Ellsworth Mountains, Antarctica" (PDF), USGS and the National Academies; USGS OF-2007-1047, Short Research Paper, 107: 1–5, retrieved 2020-07-11
      Curtis, Michael L.; Lomas, Simon A. (1999), "Late Cambrian stratigraphy of the Heritage Range, Ellsworth Mountains: implications for basin evolution", Antarctic Science, 11 (1): 63–77, Bibcode:1999AntSc..11...63C, doi:10.1017/S0954102099000103, retrieved 2020-07-11
      Buggisch, Werner; Webers, Gerald F.; Repetski, John E.; Glenister, Linda (1992), "Cambrian conodonts from the Springer Peak and Minaret Formations, Ellsworth Mountains, West Antarctica", Geological Society of America Memoir, 170: 169–179, doi:10.1130/MEM170-p169, retrieved 2020-07-11
      Webers, G.F.; Pojeta, J.; Yochelson, E.L. (1992), "Cambrian Mollusca from the Minaret Formation, Ellsworth Mountains, West Antarctica", Geological Society of America Memoir, 170: 181–248, doi:10.1130/MEM170-p181
      Debrenne, F.; Rozanov, A. Y.; Webers, G. F. (1984), "Upper Cambrian archaeocyatha from Antarctica", Geological Magazine, 121 (4): 291–299, Bibcode:1984GeoM..121..291D, doi:10.1017/S0016756800029186
      Yochelson, E.L.; Flower, R.H.; Webers, G.F. (1973), "The bearing of the new Late Cambrian monoplacophoran genus Knightoconus upon the origin of the Cephalopoda", Lethaia, 6 (3): 275–309, Bibcode:1973Letha...6..275Y, doi:10.1111/j.1502-3931.1973.tb01199.x

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