Gzhelian

System Subsystem/
Series		 Stage Age
(Ma)
Permian Cisuralian Asselian younger
Carboniferous Pennsylvanian Gzhelian 299.0–303.9
Kasimovian 303.9–306.5
Moscovian 306.5–311.7
Bashkirian 311.7–318.1
Mississippian Serpukhovian 318.1–328.3
Viséan 328.3–345.3
Tournaisian 345.3–359.2
Devonian Upper Famennian older
Subdivision of the Carboniferous system according to the ICS.[1]

The Gzhelian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the youngest stage of the Pennsylvanian, the youngest subsystem of the Carboniferous. The Gzhelian lasted from 303.9 ± 0.9 to 299.0 ± 0.8 Ma.[2] It follows the Kasimovian age/stage and is followed by the Asselian age/stage, the oldest subdivision of the Permian system.

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

Contents

Name and definition

The Gzhelian is named after the Russian village of Gzhel (Russian: Гжель), nearby Ramenskoye, not far from Moscow. 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 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 isolatus within the Streptognathus "wabaunsensis" chronocline.[3] Six meters higher in the reference profile, the Fusulinida species Sphaeroschwagerina vulgaris aktjubensis appears.

At the moment (2008), a golden spike for the Gzhelian stage is yet lacking. A candidate is a section along the Ussolka river (a tributary of the Belaya river) at the edge of the hamlet of Krasnoussolsky, about 120 kilometres south-east of Ufa and 60 kilometres north-east of Sterlitamak (in Bashkortostan).[4]

Biozones

The Gzhelian stage is subdivided into five biozones, based on the conodont genus Streptognathodus:

Sources

  1. ^ Gradstein et al. (2004)
  2. ^ Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press
  3. ^ Davydov, V.I.; Glenister, B.F.; Spinosa, C.; Ritter, S.M.; Chernykh, V.V.; Wardlaw, B.R. & Snyder, W.S.; 1998: Proposal of Aidaralash as Global Stratotype Section and Point (GSSP) for base of the Permian System, Episodes 21(1): pp 11-18, [1]
  4. ^ Chernykh, V.V.; Chuvashov, B.I.; Davydov, V.I.; Schmitz, M. & Snyder, W.S.; 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, [2]

External links
 
In horizontal bars are eras; in left column are periods; right column: bold are epochs; not bold not italic are ages; italic are chrons:
 
Cambrian
(542 – 488.3 Mya)
Terreneuvian (542 – 521 Mya) (de): Fortunian (542 – 528 Mya) (de) · Age 2* (528 – 521 Mya)
Epoch 2* (521 – 510 Mya): Age 3* (521 – 515 Mya) · Age 4* (515 – 510 Mya)
Epoch 3* (510 – 499 Mya): Age 5* (510 – 506.5 Mya) · Drumian (506.5 – 503 Mya) (de) · Guzhangian (503 – 499 Mya) (de)
Furongian (499 – 488.3 Mya): Paibian (499 – 496 Mya) · Jiangshanian (496 – 492 Mya) (de) · Age 10* (492 – 488.3 Mya)
Ordovician
(488.3 – 443.7 Mya)
Silurian
(443.7 – 416 Mya)
Devonian
(416 – 359.2 Mya)
Carboniferous
(359.2 – 299 Mya)
Permian
(299 – 251 Mya)
kya = thousands years ago. Mya = millions years ago. * Not officially recognized by the I.C.S.