Back المرحلة 2 (الكمبري) Arabic Камбрий етаж 2 Bulgarian Segon estatge del Cambrià Catalan Piso 2 (Cámbrico) Spanish اشکوب ۲ کامبرین FA Étage 2 (époque) French Kambrium Tahap 2 ID カンブリア紀第二期 Japanese Tầng 2 (kỷ Cambri) VI 寒武纪第二期 Chinese
| Cambrian Stage 2 | ||||||||||||||||||||||||||||||||||||||
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| Chronology | ||||||||||||||||||||||||||||||||||||||
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| Etymology | ||||||||||||||||||||||||||||||||||||||
| Name formality | Informal | |||||||||||||||||||||||||||||||||||||
| Usage information | ||||||||||||||||||||||||||||||||||||||
| Celestial body | Earth | |||||||||||||||||||||||||||||||||||||
| Regional usage | Global (ICS) | |||||||||||||||||||||||||||||||||||||
| Time scale(s) used | ICS Time Scale | |||||||||||||||||||||||||||||||||||||
| Definition | ||||||||||||||||||||||||||||||||||||||
| Chronological unit | Age | |||||||||||||||||||||||||||||||||||||
| Stratigraphic unit | Stage | |||||||||||||||||||||||||||||||||||||
| Time span formality | Formal | |||||||||||||||||||||||||||||||||||||
| Lower boundary definition | Not formally defined | |||||||||||||||||||||||||||||||||||||
| Lower boundary definition candidates | First appearance of small shelly fauna or Archaeocyathids | |||||||||||||||||||||||||||||||||||||
| Lower boundary GSSP candidate section(s) | None | |||||||||||||||||||||||||||||||||||||
| Upper boundary definition | Not formally defined | |||||||||||||||||||||||||||||||||||||
| Upper boundary definition candidates | FAD of Trilobites | |||||||||||||||||||||||||||||||||||||
| Upper boundary GSSP candidate section(s) | None | |||||||||||||||||||||||||||||||||||||
Stage 2 of the Cambrian is the unnamed upper stage of the Terreneuvian Series. It lies atop the Fortunian and below Stage 3 of the Cambrian. It is commonly referred to as the Tommotian, after the Cambrian stratigraphy of Siberia.[2] Neither the upper nor lower boundary has yet been defined by the International Commission on Stratigraphy.[3] The preferred definitions for the lower boundary are the first appearance of the molluscs Watsonella crosbyi or Aldanella attleborensis around 529 million years ago.[4] The proposed upper boundary might be the first appearance of trilobites around 521 million years ago.[3]
Possible candidates for a GSSP include the first appearance of Watsonella crosbyi in the Zhujiaqing Formation (朱家庆组) in Yunnan, China or the Pestrotsvet Formation near the Aldan River on the Siberian Platform.[5]
- ^ "Chart/Time Scale". stratigraphy.org. International Commission on Stratigraphy.
- ^ Kouchinsky, Artem; Bengtson, Stefan; Missarzhevsky, Vladimir V.; Pelechaty, Shane; Torssander, Peter; Val'kov, Anatolij K. (24 September 2001). "Carbon isotope stratigraphy and the problem of a pre-Tommotian stage in Siberia". Geological Magazine. 138 (4): 387–396. Bibcode:2001GeoM..138..387K. doi:10.1017/S0016756801005684. S2CID 3884375.
- ^ a b "GSSP List ICS". ICS. Archived from the original on 15 November 2012. Retrieved 9 November 2012.
- ^ "International Commission on Stratigraphy".
- ^ Li, Guoxiang; Zhao, Xin; Gubanov, Alexander; Zhu, Maoyan; Na, Lin (1 April 2011). "Early Cambrian Mollusc Watsonella crosbyi: A Potential GSSP Index Fossil for the Base of the Cambrian Stage 2". Acta Geologica Sinica - English Edition. 85 (2): 309–319. doi:10.1111/j.1755-6724.2011.00400.x. S2CID 129506892.