Lagerstätte

Lagerstätte

A Lagerstätte (German; literally place of storage; plural Lagerstätten) is a sedimentary deposit that exhibits extraordinary fossil richness or completeness. Palaeontologists distinguish two kinds.

Konzentrat-Lagerstätten (concentration Lagerstätten) are deposits with a particular concentration of disarticulated organic hard parts, such as a bone bed. These Lagerstätten are less spectacular than the more famous Konservat-Lagerstätten. Their contents invariably display a large degree of time averaging, as the accumulation of bones in the absence of other sediment takes some time. Deposits with a high concentration of fossils that represent an in-situ community, such as reefs or oyster beds, are not considered Lagerstätten.

Konservat-Lagerstätten (conservation Lagerstätten) are deposits known for the exceptional preservation of fossilized organisms, where the soft parts are preserved in the form of impressions or casts. This is caused by incompleteness of biological recycling, for example where anoxic conditions, as in oxygen-free mud, has suppressed common bacterial decomposition long enough for the initial casts of soft body parts to register. The individual taphonomy of the fossils varies with the sites. Conservation Lagerstätten are crucial in providing answers to important moments in the history and evolution of life, for example the Burgess Shale of British Columbia is associated with the Cambrian explosion, and the Solnhofen limestone with the earliest known bird, Archaeopteryx.

Preservation

Lagerstätten preserve lightly sclerotized and soft-bodied organisms that are not otherwise preserved in the usual shelly and bony fossil record; thus they offer a more complete record of ancient biodiversity and enable some reconstruction of the paleoecology of ancient aquatic communities. In 1986 Simon Conway Morris calculated that only about 14% of genera in the Burgess Shale had possessed biomineralized tissues in life. The affinities of the shelly elements of conodonts were mysterious until the associated soft tissues were discovered near Edinburgh, Scotland, in the Granton Lower Oil Shale of the Carboniferous. Information from the broader range of organisms found in Lagerstätten have contributed to recent phylogenetic reconstructions of some major metazoan groups.

A number of taphonomic pathways may produce lagerstatten. Here's an incomplete list:

Important Lagerstätten

The world's major Lagerstätten include:
Pre-Cambrian
    Bitter Springs 1000-850 mya South Australia
    Doushantuo Formation 600–555 mya Guizhou Province, China
Cambrian
    Maotianshan shales (Chengjiang) 525 mya Yunnan Province, China
    Emu Bay shale 525 mya South Australia
    Sirius Passet 518 mya Greenland
    Kaili Formation 513-501 mya Guizhou province, southwest China
    House Range Middle Cambrian Western Utah, USA
    Burgess Shale 505 mya British Columbia, Canada
    Kinnekulle Orsten and Alum Shale 500 mya Sweden
    Öland Orsten and Alum Shale 500 mya Sweden
Ordovician
    Soom Shale 435 mya South Africa
Silurian
    Wenlock Series 420 mya England
Devonian
    Rhynie chert 400 mya Scotland
    Hunsrück Slates 390 mya Rheinland-Pfalz, Germany
    Canowindra, New South Wales 360mya Australia
    Gogo Formation 350 mya Western Australia
Carboniferous
    Bear Gulch Limestone 320 mya Montana, USA
    Joggins Fossil Cliffs 315 mya Nova Scotia, Canada
    Mazon Creek 300 mya Illinois, USA
    Hamilton Quarry 295 mya Kansas, USA
Triassic
    Karatau 213–144 mya Kazakhstan
    Ghost Ranch 185–155 mya New Mexico, USA
Jurassic
    Holzmaden 160 mya Württemberg, Germany
    La Voulte-sur-Rhone 160 mya Ardèche, France
    Solnhofen limestone 145 mya Bavaria, Germany
Cretaceous
     Yixian Formation ca 135 mya Liaoning, China
    Crato Formation ca 117 mya (Aptian) northeast Brazil
    Xiagou Formation ca 110 mya Gansu, China
    Santana Formation 108–92 mya Brazil
    Ingersoll Shale 85 mya Alabama, USA
    Auca Mahuevo 80 mya Patagonia, Argentina
Eocene
    Green River Formation 50 mya Colorado/Utah/Wyoming, USA
    Monte Bolca 49 mya Italy
    Messel Oil Shale 49 mya Hessen, Germany
    London Clay 54–48 mya UK
OligoceneMiocene
    Dominican amber 30–10 mya Dominican Republic
    Riversleigh 25–15 mya Queensland, Australia
Miocene
    Clarkia fossil beds 20–17 mya Idaho, USA
    Ashfall Fossil Beds 10 mya Nebraska, USA
Pleistocene
    Rancho La Brea Tar Pits 20,000 yrs bp California, USA

References

See also

References

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