GSSP
A GSSP, more fully a Global Boundary Stratotype Section and Point, is an internationally agreed point which defines the start of a stage on the geologic time scale.
The work is done by the International Commission on Stratigraphy, a part of the International Union of Geological Sciences. As of 2012, 64 of the 101 stages that need a GSSP have been decided.[1]
Rules for GSSP
A geologic section has to follow the rules to be adapted as a GSSP by the ICS. The list below are the rules:[2][3]
- A GSSP has to decide the lower boundary (start of a geological period) of a geologic stage.
- The lower boundary (start of a geological period) has to be decided using a primary (main) marker (usually first appearance datum of a fossil specie).
- There should also be secondary markers (other fossils, chemical, geomagnetic reversal).
- The horizon in which the marker appears should have minerals that can be radiometrically dated.
- The marker has to have regional and global correlation in outcrops of the same age
- The marker should be independent of facies.
- The outcrop has to have an acceptable thickness
- Sedimentation has to be constant without any changes in facies
- The outcrop should not be affected by tectonic and sedimentary movements, and metamorphism
- The outcrop has to be accessible to research and free to access.
- This includes that the outcrop has to be located where it can be visited quickly (International airport and good roads), has to be kept in good condition (Ideally a national reserve), in accessible terrain, extensive enough to allow repeated sampling and open to researchers of all nationalities.
List
This list shows some of the GSSPs.
Global Standard Stratigraphic Age (GSSAs)
Because defining a GSSP depends on finding well-preserved geologic sections and identifying key events, this task becomes more harder as one goes farther back in time. Before 640 million years ago, boundaries on the geologic timescale are defined simply by reference to fixed dates, known as "Global Standard Stratigraphic Ages". The oldest GSSP is the one that marks the start of the Ediacaran at 635 million years ago.
GSSP Media
The 'golden spike' (bronze disk in the lower section of the image) or 'type section' of the Global Boundary Stratotype Section and Point (GSSP) for the base of Ediacaran period (Ediacara, South Australia)
References
- ↑ "International Chronostratigraphic Chart 2012" (PDF). ICS. Retrieved 28 November 2012.
- ↑ Remane J. et al 1996. "Guidelines for the establishment of global chronostratigraphic standards by the International Commission on Stratigraphy (ICS)". Episodes. 19: 77–81. doi:10.18814/epiiugs/1996/v19i3/007.
- ↑ "GSSP Rules". Geologic Timescale Foundation.
- ↑ Walker, Mike et al 2009 (2009). "Formal definition and dating of the GSSP (Global Stratotype Section and Point) for the base of the Holocene using the Greenland NGRIP ice core, and selected auxiliary records". Journal of Quaternary Science. 24 (1): 3–17. Bibcode:2009JQS....24....3W. doi:10.1002/jqs.1227. S2CID 40380068.
- ↑ Rio, Domenico et al 1998 (1998). "The Gelasian Stage (Upper Pliocene): a new unit of the global standard chronostratigraphic scale". Episodes. 21 (2): 82–87. doi:10.18814/epiiugs/1998/v21i2/002.
- ↑ Couvering John A. Van et al 2000 (2000). "The base of the Zanclean Stage and of the Pliocene Series". Episodes. 23 (3): 179–187. doi:10.18814/epiiugs/2000/v23i3/005. S2CID 10836910.
- ↑ Steininger, Fritz F. et al 1997 (1997). "The Global Stratotype Section and Point (GSSP) for the base of the Neogene". Episodes. 20 (1): 23–28. doi:10.18814/epiiugs/1997/v20i1/005.
- ↑ Silva, Isabella Premoli; Jenkins, D Graham (1993). "Decision on the Eocene-Oligocene boundary stratotype". Episodes. 16 (3): 379–382. doi:10.18814/epiiugs/1993/v16i3/002.
- ↑ Dupuis C. et al 2003 (2003). "The Dababiya Quarry section: lithostratigraphy, clay mineralogy, geochemistry and paleontology". Micropaleontology. 49 (1): 41–59. doi:10.2113/49.Suppl_1.41. hdl:1912/5251.
- ↑ Aubry, Marie-Pierre et al 2007 (2007). "The Global Standard Stratotype-section and Point (GSSP) for the base of the Eocene Series in the Dababiya section (Egypt)". Episodes. 30 (4): 271–286. doi:10.18814/epiiugs/2007/v30i4/003.
- ↑ Molina, Eustoquio 2006; et al. "The Global Boundary Stratotype Section and Point for the base of the Danian Stage (Paleocene, Paleogene, "Tertiary", Cenozoic) at El Kef, Tunisia - Original definition and revision". Episodes. 29 (4): 263–278. doi:10.18814/epiiugs/2006/v29i4/004.
- ↑ Kennedy, W.J.; Gale, A.S.; Lees, J.A.; Caron, M. (2004). "The Global Boundary Stratotype Section and Point (GSSP) for the base of the Cenomanian Stage, Mont Risou, Hautes-Alpes, France". Episodes. 27 (1): 21–32. doi:10.18814/epiiugs/2004/v27i1/003.
- ↑ Cresta S. et al 2001 (2001). "The Global Boundary Stratotype Section and Point (GSSP) of the Toarcian-Aalenian Boundary (Lower-Middle Jurassic)". Episodes. 24 (3): 166–175. doi:10.18814/epiiugs/2001/v24i3/003.
- ↑ Mietto P. et al 2012 (2012). "The Global Boundary Stratotype Section and Point (GSSP) of the Carnian stage (Late Triassic) at Prati di Stuores/Stuores Wiesen section (Southern Alps, NE Italy)". Episodes. 35 (3): 414–430. doi:10.18814/epiiugs/2012/v35i3/003.
- ↑ Davydov, Vladimir I. et al 1998 (1998). "Proposal of Aidaralash as Global Stratotype Section and Point (GSSP) for base of the Permian System". Episodes. 21 (1): 11–18. doi:10.18814/epiiugs/1998/v21i1/003.
- ↑ Lane, H. Richard et al 1999. (1999). "The IUGS boundary in the middle of the Carboniferous: Arrow Canyon, Nevada, USA". Episodes. 22 (4): 272–283. doi:10.18814/epiiugs/1999/v22i4/003.
- ↑ Paproth, Eva et al 1991 (1991). "Decision on the Devonian - Carboniferous boundary stratotype". Episodes. 14 (4): 331–336. doi:10.18814/epiiugs/1991/v14i4/004.
- ↑ "Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Retrieved 14 September 2012.}
- ↑ Holland C.H. 1985 (1985). "Series and Stages of the Silurian System". Episodes. 8 (2): 101–103. doi:10.18814/epiiugs/1985/v8i2/005.
- ↑ Cooper R.A. et al 2001 (2001). "Global Stratotype Section and Point for base of the Ordovician System". Episodes. 24 (1): 19–28. doi:10.18814/epiiugs/2001/v24i1/005.
- ↑ Brasier, Martin; Cowie, John; Taylor, Michael (1994). "Decision on the Precambrian-Cambrian boundary stratotype". Episodes. 17 (1–2): 3–8. doi:10.18814/epiiugs/1994/v17i1.2/002.
- ↑ Knoll, Andrew et al 2006 (2006). "The Ediacaran Period: a new addition to the geologic time scale". Lethaia. 39 (1): 13–30. doi:10.1080/00241160500409223.
- ↑ 23.00 23.01 23.02 23.03 23.04 23.05 23.06 23.07 23.08 23.09 23.10 23.11 23.12 23.13 Plumb, K. A. (1991). "New Precambrian timescale". Episodes. 14 (2): 139–140. doi:10.18814/epiiugs/1991/v14i2/005.