Sirius Passet is a

Cambrian The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago ...

Lagerstätte A Lagerstätte (, from '' Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that exhibits extraordinary fossils with exceptional preservation—sometimes including preserved soft tissues. These f ...

in Peary Land,

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland ...

. The Sirius Passet Lagerstätte was named after the Sirius sledge patrol that operates in North Greenland. It comprises six places in

Nansen Land Nansen Land is a peninsula in far northwestern Greenland. It is a part of the Northeast Greenland National Park. The Arctic wolf is present in the peninsula. The northern shore facing the Lincoln sea slopes evenly and is fertile for the area, bei ...

, on the east shore of

J.P. Koch Fjord J.P. Koch Fjord is a fjord in Peary Land, northern Greenland. To the west, the fjord opens into the Lincoln Sea of the Arctic Ocean. It is named after Danish captain and explorer of the Arctic Johan Peter Koch (1870 – 1928), Geography The fjord ...

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

Age

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

Preservation

The preservation of the Sirius Passet is traditionally considered to represent silicification associated with a death mask, recalling the 'Ediacara-type' preservation of the Precambrian Ediacara biota. A 2022 study suggested that the original preservation mode was phosphatisation that was later altered by low-grade

metamorphism Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of ch ...

with a peak temperature of during the

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wh ...

Ellesmerian orogeny, which resulted in widespread mineral replacement. Geochemical analysis indicates that the fossils lived close to the boundary of an oxygen minimum zone, possibly being preserved in oxygen-starved periods.

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 The International Union of Geological Sciences (IUGS) is an international non-governmental organization devoted to international cooperation in the field of geology. About The IUGS was founded in 1961 and is a Scientific Union member of the Int ...

(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.'

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 ''Kerygmachela kierkegaardi'' is a gilled lobopodian from the Cambrian Stage 3 aged Sirius Passet Lagerstätte in northern Greenland. Its anatomy strongly suggests that it, along with its relative ''Pambdelurion whittingtoni'', was a close rela ...

'' and ''

Pambdelurion ''Pambdelurion'' is an extinct genus of panarthropod from the Cambrian aged Sirius Passet site in northern Greenland. Like the morphologically similar ''Kerygmachela'' from the same locality, ''Pambdelurion'' is thought to be closely related to ...

'', all of which have played prominent roles in discussions about the origins of the modern animal phyla.

Taxa from the Sirius Passet fauna

After

Arthropods

Other animals

References

External links

Palaeos.com: Cambrian ''Sirius Passet''
{{Burgess shale type preservation Geologic formations of Greenland Cambrian Greenland Cambrian paleontological sites Paleontology in Greenland Lagerstätten * Peary Land First 100 IUGS Geological Heritage Sites

Age