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Sirius Passet

Sirius Passet
Stratigraphic range: Cambrian Series 2
~523–518 Ma
↓
Halkieria evangelista, an iconic fossil of the Sirius Passet
TypeGeological formation
Lithology
PrimaryMudstone
Location
Coordinates82°47.6′N 42°13.7′W / 82.7933°N 42.2283°W / 82.7933; -42.2283
RegionNorthern Greenland
Country Greenland
Type section
Named forSirius sledge patrol
Named byA. Higgins
LocationJ.P. Koch Fjord
Year defined1987
Coordinates82°47.6′N 42°13.7′W / 82.7933°N 42.2283°W / 82.7933; -42.2283
Country Greenland

Geologic Map with the Buen and the Portfjeld formations, and the Polkorridoren Group.

Sirius Passet is a Cambrian Lagerstätte in Peary Land, Greenland. The Sirius Passet Lagerstätte was named after the Sirius sledge patrol that operates in North Greenland. It comprises six places in Nansen Land, on the east shore of J.P. Koch Fjord in the far north of Greenland.[1] It was discovered in 1984 by A. Higgins of the Geological Survey of Greenland. A preliminary account was published by Simon Conway Morris and others in 1987 and expeditions led by J. S. Peel and Conway Morris have returned to the site several times between 1989 and the present. A field collection of perhaps 10,000 fossil specimens has been amassed. It is a part of the Buen Formation.

Age

Location of Sirius Passet during the early Cambrian

The fauna is inevitably compared to that of the Burgess Shale, although it is probably ten to fifteen million years older – 518 million years ago vs. 508 million years ago[2]) – and more closely contemporaneous with the fauna of the Maotianshan shales from Chengjiang, which are dated to 518 million years ago.

Preservation

The preservation of the Sirius Passet is traditionally considered to represent silicification associated with a death mask,[3] recalling the 'Ediacara-type' preservation of the Precambrian Ediacara biota.[4] A 2022 study suggested that the original preservation mode was phosphatisation that was later altered by low-grade metamorphism with a peak temperature of 409 ± 50 °C (768 ± 90 °F) during the Devonian Ellesmerian orogeny, which resulted in widespread mineral replacement.[5]

Geochemical analysis indicates that the fossils lived close to the boundary of an oxygen minimum zone, possibly being preserved in oxygen-starved periods.[6]

IUGS geological heritage site

In respect of the importance of the exceptionally preserved fossils in our understanding of the event, the 'Cambrian Explosion in Sirius Passet' was included by the International Union of Geological Sciences (IUGS) in its assemblage of 100 'geological heritage sites' around the world in a listing published in October 2022. The organisation defines an 'IUGS Geological Heritage Site' as 'a key place with geological elements and/or processes of international scientific relevance, used as a reference, and/or with a substantial contribution to the development of geological sciences through history.'[7]

Fauna

Although the fauna has not yet been fully described, it is known to consist of a moderate number of arthropods and sponges, and rare representatives of other groups. It has yielded the problematic taxon Halkieria, and the Panarthropods Kerygmachela and Pambdelurion, all of which have played prominent roles in discussions about the origins of the modern animal phyla.

Taxa from the Sirius Passet fauna

After[8]

Arthropods

Arthropods
Genus Species Notes Images
Aaveqaspis[9] A. inesoni An arthropod of uncertain affinitiies
Arthroaspis A. bergstroemi A member of Artiopoda
Buenaspis B. forteyi A nektaspid artiopod
Buenellus B. higginsi A trilobite
Campanamuta C. mantoni An artiopod
Kleptothule K. rasmusseni A trilobite
Molaria M. steini An artiopod
Sidneyia? Indeterminate A vicissicaudatan artiopod, later authors have stated that the assignment to the genus is equivocal.[10]
Thulaspis T. tholops A basal artiopodan closely related to Squamacula.
Siriocaris S. trollae A possible member of Lamellipedia
Isoxys I. volucris, I. sp A bivalved, freely swimming arthropod
Kiisortoqia K. soperi A basal arthropod with large frontal appendages
Kerygmachela K. kierkegaardi A "gilled lobopodian" closely related to arthropods
Pambdelurion P. whittingtoni A "gilled lobopodian" closely related to arthropods
Tamisiocaris T. borealis A filter feeding radiodont
Amplectobeluidae[11] Indeterminate Predatory radiodont
Pauloterminus P. spinodorsalis A shrimp-like arthropod, possibly a member of Hymenocarina


Other animals

Non-arthropod animals
Genus Species Notes Images
Ooedigera[12] O. peeli A vetulicolian, another indeterminate vetulicolian is also present
Chordata[11] Indeterminate Vertebrate-like chordate
Hadranax H. augustus A lobopodian
Halkieria H. evangelista A basal mollusc
Xystoscolex X. boreogyrus A palaeoscolecid worm
Chalazoscolex C. pharkus A palaeoscolecid worm
Timorebestia[11] T. koprii A giant stem-group chaetognath
Chaetognatha[11] Indeterminate Small-sized form
Pygocirrus P. butyricampum An annelid worm
Phragmochaeta[13] P. canicularis A polychaete worm
Singuuriqia S. simony A priapulid worm
Sirilorica S. carlsbergi, S. pustulosa a stem-group Loricifera or a scalidophoran
Hyolithus H. cf. tenuis A hyolith
Trapezovitus Indeterminate
Orthothecida
Hyolithida
Archaeocyatha Indeterminate A sponge
Choia C. cf. carteri A sponge
Constellatispongia C. canismajorii A sponge
Crassicoactum C. cucumis A sponge
Demospongiae Indeterminate A sponge
Fieldospongia F. bellineata A sponge
Hamptonia H. limatula A sponge
Lenica L. cf. unica L. hindei, L. perverse A sponge
Saetaspongia S. cf. densa S. procera A sponge
Salactiniella S. cf. plumata A sponge
Stephanella? Indeterminate A sponge

See also

References

  1. ^ Peel, J. S.; Ineson, J. R. (2011). "The extent of the Sirius Passet Lagerstätte (early Cambrian) of North Greenland". Bulletin of Geosciences: 535–543. doi:10.3140/bull.geosci.1269.
  2. ^ Stein, Martin (March 2010). "A new arthropod from the Early Cambrian of North Greenland, with a 'great appendage'-like antennula". Zoological Journal of the Linnean Society. 158 (3): 477–500. doi:10.1111/j.1096-3642.2009.00562.x.
  3. ^ Strang, Katie M.; Armstrong, Howard A.; Harper, David A. T.; Trabucho-Alexandre, João P. (2016). "The Sirius Passet Lagerstätte: Silica death masking opens the window on the earliest matground community of the Cambrian explosion". Lethaia. 49 (4): 631–643. doi:10.1111/let.12174.
  4. ^ Tarhan, LG; Hood, A V. S; Droser, ML; Gehling, JG; Briggs, DEG (2016). "Exceptional preservation of soft-bodied Ediacara Biota promoted by silica-rich oceans". Geology. 44 (11): G38542.1. Bibcode:2016Geo....44..951T. doi:10.1130/G38542.1.
  5. ^ Nielsen, Morten Lunde; Lee, Mirinae; Ng, Hong Chin; Rushton, Jeremy C.; Hendry, Katharine R.; Kihm, Ji-Hoon; Nielsen, Arne T.; Park, Tae-Yoon S.; Vinther, Jakob; Wilby, Philip R. (2022-01-01). "Metamorphism obscures primary taphonomic pathways in the early Cambrian Sirius Passet Lagerstätte, North Greenland". Geology. 50 (1): 4–9. Bibcode:2022Geo....50....4N. doi:10.1130/G48906.1. ISSN 0091-7613.
  6. ^ Hammarlund, Emma U.; Smith, M. Paul; Rasmussen, Jan A.; Nielsen, Arne T.; Canfield, Donald E.; Harper, David A. T. (2019). "The Sirius Passet Lagerstätte of North Greenland-A geochemical window on early Cambrian low-oxygen environments and ecosystems". Geobiology. 17 (1): 12–26. doi:10.1111/gbi.12315. PMC 6586032. PMID 30264482.
  7. ^ "The First 100 IUGS Geological Heritage Sites" (PDF). IUGS International Commission on Geoheritage. IUGS. Retrieved 10 November 2022.
  8. ^ Harper, David A. T.; Hammarlund, Emma U.; Topper, Timothy P.; Nielsen, Arne T.; Rasmussen, Jan A.; Park, Tae-Yoon S.; Smith, M. Paul (2019). "The Sirius Passet Lagerstätte of North Greenland: a remote window on the Cambrian Explosion". Journal of the Geological Society. 176 (6): 1023–1037. doi:10.1144/jgs2019-043. ISSN 0016-7649.
  9. ^ Peel, J.S.; Stein, M. "A new Arthropod from the Lower Cambrian Sirius Passet Fossil-Lagerstätten of North Greenland" (PDF). Bulletin of Geosciences. 84 (4): 1158.
  10. ^ Sun, Zhixin; Zeng, Han; Zhao, Fangchen (March 2020). "First occurrence of the Cambrian arthropod Sidneyia Walcott, 1911 outside of Laurentia". Geological Magazine. 157 (3): 405–410. doi:10.1017/S0016756819000864. ISSN 0016-7568.
  11. ^ a b c d Park, Tae-Yoon S.; Nielsen, Morten Lunde; Parry, Luke A.; Sørensen, Martin Vinther; Lee, Mirinae; Kihm, Ji-Hoon; Ahn, Inhye; Park, Changkun; de Vivo, Giacinto; Smith, M. Paul; Harper, David A. T.; Nielsen, Arne T.; Vinther, Jakob (2024-01-05). "A giant stem-group chaetognath". Science Advances. 10 (1). doi:10.1126/sciadv.adi6678. ISSN 2375-2548. PMC 10796117.
  12. ^ Vinther, J.; Smith, M. P.; Harper, D. A. T. (2011). "Vetulicolians from the Lower Cambrian Sirius Passet Lagerstätte, North Greenland, and the polarity of morphological characters in basal deuterostomes". Palaeontology. 54 (3): 711–719. doi:10.1111/j.1475-4983.2011.01034.x. S2CID 85602402.
  13. ^ Conway Morris, S.; Peel, J. S. (2008). "The Earliest Annelids: Lower Cambrian Polychaetes from the Sirius Passet Lagerstätte, Peary Land, North Greenland". Acta Palaeontologica Polonica. 53: 137–148. doi:10.4202/app.2008.0110.

Further reading
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