Buen Formation

The Buen Formation is a geologic formation and Lagerstätte in the north of Greenland. The shale preserves fossils dating back to the Early Cambrian period (Atdabanian in the local timescale, about 520 to 513 Ma).[1]

Buen Formation
Stratigraphic range: Cambrian Series 2 (Atdabanian)
~520–513 Ma
TypeFormation
Unit ofSirius Passet
Sub-unitsUpper & lower members
UnderliesHans Tavsen icecap
OverliesPortfjeld Formation
ThicknessUp to 700 m (2,300 ft)
Lithology
PrimaryMudstone
OtherSandstone, shale
Location
Coordinates83.1°N 33.8°W / 83.1; -33.8
Approximate paleocoordinates22.1°S 49.0°W / -22.1; -49.0
RegionPeary Land
CountryGreenland
ExtentFranklinian Basin
Type section
LocationSouthern Peary Land
Buen Formation (Greenland)

Description
Geologic map of Sirius Passet with the Buen Formation shown in black

The oldest Cambrian series of the area was deposited in the Franklinian Basin and is poorly exposed in fragmentary, heavily metamorphosed outcrops in Peary Land. It was emplaced during the Ellesmerian orogeny.[2][3]

Paleogeography
Cambrian paleogeography with the Buen Formation in orange

During the Cambrian, Greenland was located in the southern tropical to temperate region. The Buen Formation forms part of the southern shelf succession of the Franklinian Basin of North Greenland and the Canadian Arctic Islands. The formation, approximately 325 metres (1,066 ft) thick, consists of a lower, sand−dominated, member overlain by an upper member dominated by dark grey−green mudstones and siltstones in its type area in southern Peary Land. It thickens to around 700 metres (2,300 ft) in northern Peary Land where it comprises a mud−rich transitional succession into deep water trough deposits of the Polkorridoren Group. Dark grey to black mudstones form part of this transitional succession from the shelf to the slope. To the south they lie in faulted contact with pale dolomites of the underlying Portfjeld Formation, and to the north with bioturbated mudstones and sandstones of the Buen Formation.[4]

Fossil content

The following fossils have been reported from the formation:[1]

Fossils from the Buen Formation, Sirius Passet, Greenland
GroupTaxonImageNotes
AnnelidsPhragmochaeta canicularis
[5]
ArthropodsBuenaspis forteyi
[6]
Buenellus
[1]
Aaveqaspis
Kerygmachela
Tamisiocaris
Limniphacos
Waptia
Kleptothule rasmusseni
[6]
Isoxys volucris
Hadranax augustus
Pauloterminus spinodorsalis
MolluscsHalkieria evangelista
DemospongesChoia hindei
OthersHeliosphaeridium dissimilare
Trapezovitus malinkyi[1]
Kalaallitia myliuserichseni
Nasaaraqia hyptiotheciformis
Nevadotheca boerglumensis
Sullulika broenlundi
Alutella siku[7]
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See also

References
  1. Buen Formation at Fossilworks.org
  2. Geyer & Peel, 2011, p.466
  3. Higgins et al., 2000, p.141
  4. Conway Morris & Peel, 2008, p.138
  5. Conway Morris & Peel, 2008, p.144
  6. Sirius Passet, Buen Formation at Fossilworks.org
  7. Peel & Willman, 2018, p.381

Bibliography

Further reading
  • A. C. Daley and J. S. Peel. 2010. A Possible Anomalocaridid from the Cambrian Sirius Passet Lagerstätte, North Greenland. Journal of Paleontology 84(2):352-355
  • C. B. Skovsted and J. S. Peel. 2011. Hyolithellus in life position from the Lower Cambrian of north Greenland. Journal of Paleontology 85(1):37-47
  • G. E. Budd and J. S. Peel. 1998. A new xenusiid lobopod from the Early Cambrian Sirius Passet fauna of North Greenland. Palaeontology 41(6):1201-1213
  • J. K. Rigby. 1986. Cambrian and Silurian sponges from North Greenland. Rapport Groenlands Geologiske Undersoegelse 132:51-63
  • M. Williams, D. J. Siveter, and J. S. Peel. 1996. Isoxys (arthropoda) from the Early Cambrian Sirius Passet Lagerstaette, North Greenland. Journal of Paleontology 70(6):947-954
  • S. Conway Morris and J. S. Peel. 1990. Articulated halkieriids from the Lower Cambrian of north Greenland. Nature 345(28):802-805
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