GSSP Pleistocene / Holocene

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Coordinates: 75 ° 6 ′ 0 ″  N , 42 ° 19 ′ 12 ″  W.

Map: Arctic
marker
GSSP Pleistocene / Holocene​
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Arctic Ocean

The GSSP Pleistocene / Holocene is a stratigraphic reference profile that defines the boundary between the Pleistocene and the Holocene . In contrast to other GSSPs , which are located in marine or terrestrial sediment sequences , in this case the ice core -2 of the North Greenland Ice Core Project ( NGRIP ) serves as the reference profile. The limit was dated 11,700 years before the year 2000 (b2k). The core is kept at the Niels Bohr Institute for Astronomy, Physics and Geophysics at the University of Copenhagen .

history

The GSSP Pleistocene / Holocene, even GSSP Holocene , 2004 was made by a working group of members of the Subcommission on Quaternary Stratigraphy (SQS) and the INTIMATE project ( engl. Abbreviation for Integration of ice-core, marine and terrestrial records - sedimentary integration records in ice cores, marine and terrestrial sequences). This proposal was ratified by the International Union of Geological Sciences (IUGS) in 2008 . The GSSP was scientifically described for the first time by Mike Walker et al. a. in the year 2009.

Description and definition

Curves for the isotope ratios ( δ 18 O , deuterium excess ) and the dust content ( ) in the Pleistocene-Holocene limit interval of the NGRIP2 ice core with marking of the exact position of the limit (dashed line; time runs from right to left)

The NGRIP drilling took place between 1996 and 2003 in the North Greenland ice sheet at 75.10 ° north latitude and 42.3 ° west longitude. The borehole passed a total of 3,085 meters of ice before encountering existing rock . Dating has shown that the two extracted cores document the last 123,000 years BP and thus go back to the last interglacial ( eemium ).

The base of the Holocene is located at 1,492.45 meters in the uppermost section of the NGRIP2 core and is defined as the ice layer from which the ice provides the clearest signals for global warming . This climatic event marks the end of the Younger Dryas or Greenland Stadium 1 at the end of the Pleistocene .

Global warming manifests itself in the following physico-chemical changes in the Greenland Ice Sheet:

These changes reflect a dramatic change in the pattern of atmospheric circulation that was accompanied by a 10 ° C increase in temperature in the Arctic region at the beginning of the Holocene . The observed decrease in the deuterium excess of 2 to 3 ‰ paradoxically points to a drop in ocean temperatures of 2 to 4 ° C in the evaporation area , which can, however, be explained by an abrupt northward shift of the polar front . It documents the shift of the ice age evaporation area in the middle latitudes of the Atlantic to much cooler northern latitudes with the onset of the Holocene.

Absolute dating

The GSSP Pleistocene / Holocene was dated 11,700 years before the year 2000. This dating was done indirectly with the aid of a thin layer of volcanic ash that occurs in all ice cores in Greenland and whose age in the Dye-3 ice core was determined radiometrically to be 8236 ± 47 years b2k. Based on this time stamp ( called the date in stratigraphic terminology ), the age of the GSSP was finally determined by simply counting the annual ice layers, which are on average 20 cm thick.

The GSSP is also flanked by two volcanic ash layers , the younger Saksunarvatn Tephra at a depth of 1,409.83 meters and the older Vedde ash at a depth of 1,506.14 meters. The Saksunarvatn tephra gave an age of 10347 years b2k and the Vedde ashes an age of 12171 years b2k. The two ash layers are spread over the entire North Atlantic area and can be found in marine and terrestrial sediments.

GSSP deputy

The Holzmaar

In addition to the NGRIP drill core profile, several terrestrial and one marine substitutes were proposed:

  • Eifelmaare : Holzmaar and Meerfelder Maar in Germany :
    The two 17 to 18 meter deep maars are characterized by distinct layers of warvas in their     bottom sediment. Boreholes for the transition to the Holocene, which can be recognized in both lake sediments by striking sedimentological and floristic changes in the pollen composition, resulted in an age of 11600 varven years BP for the Holzmaar and 11590 varven years BP for the Meerfelder Maar.
  • Splan Pond (also Basswood Road Lake ) in northeast Canada ( New Brunswick )
    In the 10.8 meter deep lake, several drill profiles up to 6.5 meters long were drawn, in which the Pleistocene / Holocene boundary can be seen very clearly. The Younger Dryas is represented by a gray tone 55 to 80 centimeters thick, which abruptly changes into a dark brown Gyttja at the border to the Holocene . At the same time, there is a significant increase in the organic carbon content C org from <5 to over 30%. The pollen composition of grasses shows a decrease from 30 to 15%, at the same time tree pollen shows a strong increase (in particular the taxon Picea , which increases from 7 to 40%). The diatoms also show a noticeable increase. A sudden transition from cold forms like     Heterotrissocladius to warm forms like Dicrotendipes can be observed in the Chironomids . A temperature model based on the composition of the chironomid taxa suggests a temperature increase of 10 ° C. Radiocarbon dating indicated a time span of 11385 to 11981 years BP for the boundary.
  • Suigetsu Lake in Japan
    The 37 meter deep lake of     tectonic origin , located near Tsuruga on the Japanese Sea , contains a 73.5 meter thick, lacustrine sediment sequence, the top 40 meters of which are annual and document the last 50,000 years. The Pleistocene / Holocene boundary was encountered in the SG3 core at a depth of 13.91 meters. A temperature reconstruction based on pollen data shows a sudden increase at the border, accompanied by a drastic decrease in Fagus pollen from 40 to 20%. The limit was dated to 11552 ± 88 calendar years BP using the radiocarbon method on plant remains.
  • Lake Maratoto in New Zealand
    Lake Maratoto, 12.5 kilometers south of Hamilton , is part of a group of 30 smaller lakes in the Waikato Great Plain that was formed around 20,000 years ago by aggradation of the Waikato River on the North Island of New Zealand. The lake contains a complete series of sediments that go back to the last glacial maximum. The position of the Pleistocene / Holocene boundary can be determined using tephro and pollen stratigraphy. It is located in the immediate vicinity of the Andesite Konini-Tephra of Mount Egmont , which was dated to 11720 ± 220 calendar years BP.
  • Cariaco Basin north of Venezuela
    The Cariaco Basin, located southeast of Isla La Tortuga , is anoxic from a water depth of 300 meters due to restricted deep water circulation and high organic production rates on the surface . The basin sediments are made up of warv-like, laminated alternating layers that document the change from a windy dry season with upwelling close to the coast to a windless rainy season . The thickness of the light layers can be used as a representative for the parameters organic productivity, lift and trade wind strength. It emerged that the changes recorded in the sediment of the Cariaco Basin were almost identical to the changes in parameters in the ice cores in Greenland - the rapid climatic change, which took only 6 years at the turn of the Holocene, was therefore almost synchronous in these two regions, which are far apart . This is possibly explained by a coupling of the trade wind strength with the north-south temperature gradient in the North Atlantic . The climatic reversal in the Cariaco Basin was     dated to 11578 ± 32 calendar years BP in core PL07-58PC .

Individual evidence

  1. ↑ M. Walker et al. a .: 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 . In: Journal of Quaternary Science . tape 24 , no. 1 , 2009, p. 3-17 .
  2. ↑ D. Dahl-Jensen et al. a .: The North-GRIP deep drilling program . In: Annals of Glaciology . tape 35 , 2002, pp. 1-4 .
  3. ↑ JP Steffensen u. a .: High-resolution Greenland ice core data show abrupt climate change happens in a few years . In: Science . tape 321 , 2008, p. 680-684 .
  4. ↑ AM Grachev, JP Severinghaus: A revised +10 ± 4 ° C magnitude of the abrupt change in Greenland temperature at the Younger Dryas termination using published GISP2 gas isotope data and air thermal diffusion constants . In: Quaternary Science Reviews . tape 24 , 2005, pp. 513-519 .
  5. ↑ Masson-Delmotte et al. a .: GRIP deuterium excess reveals rapid and orbital-scale changes in Greenland moisture origin . In: Science . tape 209 , 2005, pp. 118-121 .
  6. ↑ BM Vinther u. a .: A synchronized dating of three Greenland ice cores throughout the Holocene . In: Journal of Geophysical Research . tape 111 , 2006, p. D13102 , doi : 10.1029 / 2005JD006921 .
  7. ↑ B. Zolitschka: Paleoclimatic importance of laminated sediments . In: Relief, Soil. Paleoclimate . tape 13 . Bornträger, Berlin / Stuttgart 1998.
  8. ↑ T. Litt, H.-U. Schmincke, B. Kromer: Environmental response to climate and volcanic events in central Europe during the Weichselian Lateglacial . In: Quaternary Science Reviews . tape 22 , 2003, p. 7-32 .
  9. ↑ AJ Levesque, LC Cwynar, IR Walker: Exceptionally steep north south gradients in lake Temperatures during the load deglaciation . In: Nature . tape 385 , 1997, pp. 423-426 .
  10. ↑ PJ Reimer et al. a .: INTCAL04 Terrestrial radiocarbon age calibration, 0-26 cal kyr BP . In: Radiocarbon . tape 46 , 2004, p. 1029-1058 .
  11. ↑ T. Nakagawa et al. a .: Pollen / event stratigraphy of the varved sediment of Lake Suigetsu, central Japan from 15,701 to 10,217 SG vyr BP (Suigetsu varve years before present): description, interpretation, and correlation with other regions . In: Quaternary Science Reviews . tape 24 , 2005, pp. 1691-1701 .
  12. ↑ H. Kitagawa, J. van der Plicht: A 40,000-year varve chronology from Lake Suigetsu, Japan: extension of the C-14 calibration curve . In: Radiocarbon . tape 40 , no. 1 , 1998, p. 505-515 .
  13. ^ MJ Selby, DJ Lowe: The middle Waikato Basin and hills . In: JM Soons, MJ Selby (Eds.): Landforms of New Zealand . 2nd Edition. Auckland-Longman-Paul, Auckland 1992, p. 233-255 .
  14. ↑ DJ Lowe, PAR Shane, BV Alloway, RM Newnham: Fingerprints and age models for widespread New Zealand tephra marker beds erupted since 30,000 years ago: a framework for NZ-INTIMATE . In: Quaternary Science Reviews . tape 27 , 2008, p. 95-126 .
  15. ↑ KA Hughen et al. a .: Rapid climate changes in the tropical Atlantic region during the last deglaciation . In: Nature . tape 380 , 1996, pp. 51-54 .
  16. ↑ KA Hughen et al. a .: Synchronous radiocarbon and climate shifts during the last deglaciation . In: Science . tape 290 , 2000, pp. 1951-1954 .