The Gzhelian ( ) is an age in the ICS

geologic timescale The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochr ...

or a

stage Stage or stages may refer to: Acting * Stage (theatre), a space for the performance of theatrical productions * Theatre, a branch of the performing arts, often referred to as "the stage" * ''The Stage'', a weekly British theatre newspaper * Sta ...

in the

stratigraphic column A stratigraphic column is a representation used in geology and its subfield of stratigraphy to describe the vertical location of rock units in a particular area. A typical stratigraphic column shows a sequence of sedimentary rocks, with the oldest ...

. It is the youngest stage of the Pennsylvanian, the youngest

subsystem A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and expresse ...

of the Carboniferous. The Gzhelian lasted from to Ma. It follows the Kasimovian age/stage and is followed by the

Asselian In the geologic timescale, the Asselian is the earliest geochronologic age or lowermost chronostratigraphic stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Asselian lasted between and million years ago (Ma) ...

age/stage, the oldest subdivision of the

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last ...

system. The Gzhelian is more or less coeval with the Stephanian Stage of the regional stratigraphy of Europe.

Name and definition

The Gzhelian is named after the

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ...

n village of

Gzhel Gzhel is a Russian style of blue and white ceramics which takes its name from the village of Gzhel and surrounding area, where it has been produced since 1802. Overview About thirty villages located southeast of Moscow produce pottery and shi ...

(russian: Гжель), nearby Ramenskoye, not far from

Moscow Moscow ( , US chiefly ; rus, links=no, Москва, r=Moskva, p=mɐskˈva, a=Москва.ogg) is the capital and largest city of Russia. The city stands on the Moskva River in Central Russia, with a population estimated at 13.0 millio ...

. The name and type locality were defined by Sergei Nikitin (1850–1909) in 1890. The base of the Gzhelian is at the first appearance of the

Fusulinida The Fusulinida is an extinct order within the Foraminifera in which the tests are traditionally considered to have been composed of microgranular calcite. Like all forams, they were single-celled organisms. In advanced forms the test wall was dif ...

genera '' Daixina'', '' Jigulites'' and '' Rugosofusulina'', or at the first appearance of the conodont ''Streptognathodus zethus''. The top of the stage (the base of the Permian system) is at the first appearance of the conodont ''

Streptognathodus ''Streptognathodus'' is an extinct genus of conodonts from the Late Carboniferous to Early Permian. Use in stratigraphy Late Carboniferous The top of the Kasimovian stage is close to the first appearance of ''Streptognathodus zethus''. T ...

isolatus'' within the ''Streptognathus "wabaunsensis"'' chronocline. Six meters higher in the reference profile, the Fusulinida species '' Sphaeroschwagerina vulgaris aktjubensis'' appears. At the moment (2008), a

golden spike The golden spike (also known as The Last Spike) is the ceremonial 17.6- karat gold final spike driven by Leland Stanford to join the rails of the first transcontinental railroad across the United States connecting the Central Pacific Railroad ...

for the Gzhelian Stage is yet lacking. A candidate is a section along the Ussolka river (a

tributary A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drai ...

of the Belaya river) at the edge of the hamlet of Krasnoussolsky, about 120 kilometres south-east of

Ufa Ufa ( ba, Өфө , Öfö; russian: Уфа́, r=Ufá, p=ʊˈfa) is the largest city and capital city, capital of Bashkortostan, Russia. The city lies at the confluence of the Belaya River (Kama), Belaya and Ufa River, Ufa rivers, in the centre-n ...

and 60 kilometres north-east of Sterlitamak (in

Bashkortostan The Republic of Bashkortostan or Bashkortostan ( ba, Башҡортостан Республикаһы, Bashqortostan Respublikahy; russian: Республика Башкортостан, Respublika Bashkortostan),; russian: Респу́блик� ...

).; 2006: ''Usolka section (southern Urals, Russia): a potential candidate for GSSP to define the base of the Gzhelian Stage in the global chronostratigraphic scale'' Geologija 49(2): pp 205–217,

Biozones

The Gzhelian Stage is subdivided into five

biozone In biostratigraphy, biostratigraphic units or biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa, as opposed to a lithostratigraphic unit which is defined by the lithological properties ...

s, based on the conodont genus ''

'': * ''Streptognathodus wabaunsensis'' and ''Streptognathodus bellus'' Zone * ''Streptognathodus simplex'' Zone * ''Streptognathodus virgilicus'' Zone * ''Streptognathodus vitali'' Zone * ''Streptognathodus simulator'' Zone

References

External links

Carboniferous timescale
at the website of the Norwegian network of offshore records of geology and stratigraphy

{{Geological history, p, p, state=collapsed Pennsylvanian geochronology Geological ages