Katian is the second stage of the Upper Ordovician. It is preceded by the Sandbian and succeeded by the Hirnantian stage. The Katian began 453.0 ± 0.7 million years ago and lasted for about 7.8 million years until the beginning of the Hirnantian 445.2 ± 1.4 million years ago. [3 ]
The name Katian is derived from
Katy Lake ( Oklahoma, USA). [4 ]
The GSSP of the Katian stage is the Black Knob Ridge Section in southeastern
Oklahoma ( USA). It is an outcrop of the Womble Shale and the Bigfork Chert, the latter containing the lower boundary of the Katian. The lower boundary is defined as the first appearance datum of the graptolite species . This horizon is 4.0 m above the base of the Bigfork Chert. Diplacanthograptus caudatus [5 ] [6 ]
References [ edit ]
^ Wellman, C.H., Gray, J. (2000). "The microfossil record of early land plants". Phil. Trans. R. Soc. B 355 (1398): 717–732. doi: 10.1098/rstb.2000.0612. PMC 1692785. PMID 10905606.
^ Gradstein, F. M., ed. (2012). . Elsevier Science Ltd. p. 504. The Geologic Time Scale 2012 ISBN 978-0444594259.
^ "GSSP Table - Paleozoic Era". Geologic Timescale Foundation . Retrieved 2 December 2012.
^ Bergström, Stig; Finney, Stanley; Xu, Chen; Goldman, Daniel; Leslie, Stephen (31 August 2006). "Three new Ordovician global stage names". Lethaia 39 (3): 287–288. doi: 10.1080/00241160600847439.
^ Goldman, Daniel; Stephen A. Leslie, Jaak Nõlvak, Seth Young, Stig M. Bergström, Warren D. Huff (2007). "The Global Stratotype Section and Point (GSSP) for the base of the Katian Stage of the Upper Ordovician Series at Black Knob Ridge, Southeastern Oklahoma, USA". Episodes 30 (4): 258–270 . Retrieved 20 September 2012.
^ "GSSP for Katian Stage". Geologic Timescale Foundation . Retrieved 2 December 2012.