Fortunian
538.8 ± 0.2 – ~529 Ma
Delegates from the Ichnia 2012 conference inspect the Global Boundary Stratotype Section and Point (GSSP) for the Ediacaran-Cambrian boundary at Fortune Head Ecological Reserve, Newfoundland, Canada.
Chronology
Etymology
Name formalityFormal
Name ratified2007[2]
Former name(s)Cambrian Stage 1
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitAge
Stratigraphic unitStage
First proposed byEd Landing, 2007[3]
Time span formalityFormal
Lower boundary definitionAppearance of the Ichnofossil Treptichnus pedum
Lower boundary GSSPFortune Head section, Newfoundland, Canada
47°04′34″N 55°49′52″W / 47.0762°N 55.8310°W / 47.0762; -55.8310
Lower GSSP ratified2007 (as base of Terreneuvian and Fortunian)[2]
Upper boundary definitionNot formally defined
Upper boundary definition candidatesFirst appearance of small shelly fauna or Archaeocyathids
Upper boundary GSSP candidate section(s)None

47°04′34″N 55°49′52″W / 47.0762°N 55.8310°W / 47.0762; -55.8310 The Fortunian age marks the beginning of the Phanerozoic Eon, the Paleozoic Era, and the Cambrian Period. It is the first of the two stages of the Terreneuvian series. Its base is defined as the first appearance of the trace fossil Treptichnus pedum 538.8 million years ago. The top of the Fortunian which is the base of the Stage 2 of the Cambrian has not been formally defined yet, but will correspond to the appearance of an Archeocyatha species or "Small shelly fossils" approximately 529 million years ago.[4]

The name Fortunian is derived from the town of Fortune on the Burin Peninsula, near the GSSP and Fortune Bay.[5]

GSSP

The type locality (GSSP) of the Fortunian stage is in Fortune Head, at the northern edge of the Burin Peninsula, Newfoundland, Canada (47°04′34″N 55°49′52″W / 47.0762°N 55.8310°W / 47.0762; -55.8310). This GSSP coincides with the base of the Terreneuvian series, the Precambrian-Cambrian boundary and the beginning of the Phanerozoic. The outcrops show a carbonate-siliciclastic succession which is mapped as the Chapel Island Formation. The formation is divided into the following members that are composed of peritidal sandstones and shales (Member 1), muddy deltaic and shelf sandstones and mudstones (Member 2A), laminated siltstones (Member 2B and 3) and mudstones and limestones of the inner shelf (Member 4). The Precambrian-Cambrian boundary lies 2.4 m above the base of the 2nd member which is the lowest occurrence of Treptichnus pedum. The traces can be seen on the lower surface of the sandstone layers. The first calcareous shelled skeletal fossils (Ladatheca cylindrica) is 400 m above the boundary. The first trilobites appear 1,400 m above the boundary, which corresponds to the beginning of the Branchian Series.[6]

See also

References

  1. ^ "Chart/Time Scale". stratigraphy.org. International Commission on Stratigraphy.
  2. ^ a b Landing, Ed; Peng, Shanchi; Babcock, Loren; Geyer, Gerd; Moczydlowska-Vidal, Malgorzata (December 2007). "Global standard names for the Lowermost Cambrian Series and Stage". Episodes. 30 (4): 287–289. doi:10.18814/epiiugs/2007/v30i4/004. Retrieved 13 December 2020.
  3. ^ Landing, Ed. "THE BASE OF THE CAMBRIAN: TERRENEUVIAN SERIES AND FORTUNIAN STAGE". International Subcommission on Cambrian Stratigraphy. Retrieved 13 December 2020.
  4. ^ "Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Archived from the original on 15 November 2012. Retrieved 2 November 2012.
  5. ^ Landing, E. "THE BASE OF THE CAMBRIAN: TERRENEUVIAN SERIES AND FORTUNIAN STAGE" (PDF). Retrieved 2 November 2012.
  6. ^ Brasier, Martin; John Cowie; Michael Taylor (1994). "Decision on the Precambrian-Cambrian boundary stratotype" (PDF). Episodes. 17 (1–2): 95–100. doi:10.18814/epiiugs/1994/v17i1.2/002. Retrieved 14 September 2012.

External links


Cambrian Period
Geological history of Earth
Categories