The Minaret Formation is a

Late Cambrian The Furongian is the fourth and final Epoch (geology), epoch and Series (stratigraphy), series of the Cambrian. It lasted from to million years ago. It succeeds the Miaolingian series of the Cambrian and precedes the Lower Ordovician Tremadocia ...

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondary ...

of the Heritage Group of

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

. The age of the formation is established to be

Guzhangian The Guzhangian is an uppermost stage of the Miaolingian Series of the Cambrian. It follows the Drumian Stage and precedes the Paibian Stage of the Furongian Series. The base is defined as the first appearance of the trilobite '' Lejopyge laevi ...

Cambrian Stage 10 Stage 10 of the Cambrian is the still unnamed third and final stage of the Furongian series. It follows the Jiangshanian and precedes the Ordovician Tremadocian Stage. The proposed lower boundary is the first appearance of the trilobite '' Lotagno ...

(or

Merioneth Merionethshire, or Merioneth ( or '), was one of the thirteen counties of Wales that existed from 1536 until their abolishment in 1974. It was located in the north-west of Wales. Name 'Merioneth' is an anglicisation of the Welsh placename ''Mei ...

Dresbachian The Dresbachian is a Maentwrogian regional stage of North America, lasting from 501 to 497 million years ago. It is part of the Upper Cambrian and is defined by four trilobite zones. It overlaps with the ICS-stages Guzhangian, Paibian and the ...

in the regional stratigraphy), dated at ranging from 500 to 488 Ma.Minaret Formation
at

Fossilworks Fossilworks was a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cr ...

.org The formation has provided the first known Late Cambrian archaeocyathid, and '' Knightoconus antarcticus'', an ancestor to the

cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

s.Yochelson et al., 1973

Description

The Minaret Formation forms a discontinuous limestone unit exposed from Webers Peaks in the northern

Heritage Range The Heritage Range is a major mountain range, long and wide, situated southward of Minnesota Glacier and forming the southern half of the Ellsworth Mountains in Antarctica. The range is complex, consisting of scattered ridges and peaks of mo ...

to the

Independence Hills The Independence Hills () are a line of rugged hills and peaks, long, with mainly bare rock eastern slopes. They lie southeast of the Marble Hills and form the southern segment of the west wall of Horseshoe Valley, in the Heritage Range of Anta ...

Horseshoe Valley Horseshoe Valley may refer to: * Horseshoe Valley (Antarctica) * Horseshoe Valley (Peleliu) * Horseshoe Valley (Missouri) * Horseshoe Valley (North Dakota) * Horseshoe Valley (Nebraska) * Horseshoe Valley, North Dakota * Horseshoe Resort, formerly ...

of the

Ellsworth Mountains The Ellsworth Mountains are the highest mountain ranges in Antarctica, forming a long and wide chain of mountains in a north to south configuration on the western margin of the Ronne Ice Shelf in Marie Byrd Land. They are bisected by Minneso ...

. 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

grainstone Under the Dunham classification (Dunham, 1962) system of limestones, a grainstone is defined as a grain-supported carbonate rock that contains less than 1% mud-grade material. This definition has recently been clarified as ''a carbonate-dominated ...

s.Curtis & Lomas, 1999, p.66 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.Curtis & Lomas, 1999, p.65 The formation reaches a thickness of in the south of its extent.Webers & Splettstoesser, 2007, p.3 The formation ranges from shallow to deep marine.Curtis & Lomas, 1999, p.71 The Minaret fauna contains the first known Late Cambrian archaeocyathid.Webers & Splettstoesser, 2007, p.5 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 Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...

activity.Curtis & Lomas, 1999, p.64

Fossil content

The

reef A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic component, abiotic (non-living) processes such as deposition (geol ...

al limestones of the formation have provided fossils: * '' Antarcticocyathus webersi''Debrenne et al., 1984 *

Gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

s ** '' Strepsodiscus splettstoesseri''Webers et al., 1992 *

Conodont Conodonts, are an extinct group of marine jawless vertebrates belonging to the class Conodonta (from Ancient Greek κῶνος (''kōnos''), meaning " cone", and ὀδούς (''odoús''), meaning "tooth"). They are primarily known from their hard ...

s ** '' Furnishina furnishi'' ** '' F. quadrata''Buggisch et al., 1992, p.172 ** '' F. ?asymmetrica''Buggisch et al., 1992, p.170 ** '' Proacodus tenuis'' ** '' Phakelodus sp.'' ** '' Westergaardodina bicuspidata'' ** '' W. moessebergensis''Buggisch et al., 1992, p.173 ** '' W. tricuspidata'' * Tergomya ** '' Aremellia batteni'' ** '' Ellsworthoconus andersoni'' ** '' Kirengella pyramidalis'' ** '' Knightoconus antarcticus'' ** '' Proconus incertis'' ** '' Proplina rutfordi'' *

Rostroconchia The Rostroconchia is a class of extinct molluscs dating from the early Cambrian to the Late Permian. They were initially thought to be bivalves, but were later given their own class. They have a single shell in their larval stage, and the adult ...

** '' Apoptopegma craddocki'' ** '' Cosminoconella runnegari'' * Paragastropoda ** '' Matherella antarctica'' ** '' Ribeiria australiensis'' ** '' Scaevogyra thompsoni'' ** '' ?Kobayashiella heritagensis''

References

Bibliography

* * * * * * {{citation , first1=E.L. , last1=Yochelson , first2=R.H. , last2=Flower , first3=G.F. , last3=Webers , year=1973 , title=The bearing of the new Late Cambrian monoplacophoran genus ''Knightoconus'' upon the origin of the Cephalopoda , journal=

Lethaia ''Lethaia'' is a quarterly peer-reviewed scientific journal of Earth science, covering research on palaeontology and stratigraphy. Now published by Scandinavian University Press, it was originally published by the International Commission on Strat ...

, volume=6 , issue=3 , pages=275–309 , doi=10.1111/j.1502-3931.1973.tb01199.x, bibcode=1973Letha...6..275Y Geologic formations of Antarctica Paleozoic Antarctica Furongian Guzhangian Limestone formations Shallow marine deposits Deep marine deposits Cambrian southern paleotemperate deposits Paleontology in Antarctica

Description

Fossil content

See also

References

Bibliography