The Lunde Formation is a geologic formation in Norway. The formation was known to preserve

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...

of '' Plateosaurus'' sp. in the Norwegian offshore ( Snorre Field well 34/4-9S), dating back to the

Rhaetian The Rhaetian is the latest age of the Triassic Period (in geochronology) or the uppermost stage of the Triassic System (in chronostratigraphy). It was preceded by the Norian and succeeded by the Hettangian (the lowermost stage or earliest age ...

period. The formation comprises dry floodplain; paleosol/pedogenic, concretionary, brown, red, calcareous

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...

s.Snorre Field well 34/4-9S
at

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.org

Description

The Lunde Formation occurs in the northern part of a Late Triassic continental basin that covered most of the present North Sea area. Several thousands of meters of

fluvial In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluviog ...

sediments were deposited in this basin during a thermal subsidence phase following Late Permian to Early Triassic rifting. With an approximate width of between present mainland Norway and the Shetland Platform, the continental post-rift basin contains the Teist, Lomvi and Lunde Formations, and lasted throughout the Triassic until the final depositional stages of the overlying latest Triassic to Early Jurassic

Statfjord Formation The Statfjord oil field is a large oil and gas field covering 580 km2 in the U.K.-Norwegian boundary of the North Sea at a water depth of 145 m, discovered in 1974 by Mobil and since 1987 operated by Equinor. It is a trans-median field cros ...

, when the whole area was flooded during a marine

transgression Transgression may refer to: Legal, religious and social *Sin, a violation of God's Ten Commandments or other elements of God's moral law *Crime, legal transgression, usually created by a violation of social or economic boundary **In civil law ju ...

from the north and south in late Sinemurian to early Pliensbachian times. The climate during deposition of the Lunde Formation was semiarid and highly seasonal, typical for the contemporary palaeogeographic position at 40-50 degrees North paleolatitude. The basin was linked to a marine borealic seaway, probably located some tens to hundreds of kilometers to the north and to

provenance Provenance (from the French ''provenir'', 'to come from/forth') is the chronology of the ownership, custody or location of a historical object. The term was originally mostly used in relation to works of art but is now used in similar senses i ...

areas composed of Archean gneisses, Caledonian metamorphic rocks and

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, whe ...

sandstones. These sources located on the Shetland Platform and in the southwestern area of Norway and deposited into a vast

alluvial plain An alluvial plain is a largely flat landform created by the deposition of sediment over a long period of time by one or more rivers coming from highland regions, from which alluvial soil forms. A floodplain is part of the process, being the sma ...

in the Triassic of what is now the North Sea.Hurum et al., 2006, p.117 The bone slice of ''Plateosaurus'' was discovered during the description of a core retrieved in February 1997 from well 34/4-9S in the north-western part of the Snorre Field. It occurs in a reddish-brown, mudstone interval referred to as the upper member of the Lunde Formation. The mudstone is composed of dominantly compound and cumulative paleosols that formed in distal to

fluvial channel In physical geography, a channel is a type of landform consisting of the outline of a path of relatively shallow and narrow body of water or of other fluids (e.g., lava), most commonly the confine of a river, river delta or strait. The word is ...

s in a floodplain forming the uppermost part of the upper member of the Lunde Formation. The paleosols are characterized by carbonate nodules, pedogenic mud aggregates and slickensides, mottling, root traces and mud cracks. The paleosol type is similar to modern vertisols forming in semi-arid areas with seasonal precipitation, commonly with dry periods lasting 4–8 months. The presence of root traces suggests that the floodplain was covered with small trees and bushes, vegetation suitable for herbivorous animals living on the alluvial plain. Beds containing the bone specimen belong to the younger of two palynomorph assemblages containing the spore '' Kreuselisporites reissingeri'' thought to indicate an early Rhaetian rather than a Norian age, corresponding approximately to an age of 203-202 Ma according to the time scale of Gradstein et al. (2005).Hurum et al., 2006, p.118

References

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* {{citation , last=Hurum , first=J.H. , first2=M. , last2=Bergan , first3=R. , last3=Müller , first4=J.P. , last4=Nystuen , first5=N. , last5=Klein , year=2006 , title=A Late Triassic dinosaur bone, offshore Norway , url=http://www.geologi.no/images/NJG_articles/117-123_NGT_print-3.pdf , journal= Norwegian Journal of Geology , volume=86 , pages=117–123 , accessdate=2019-10-12 Geologic formations of Norway Geologic formations of Scotland Triassic System of Europe Triassic Norway Triassic Scotland Rhaetian Stage Mudstone formations Alluvial deposits Fluvial deposits Paleontology in Norway Formations

Description

See also

References

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