Event stratigraphy

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Actuogeological observations allow conclusions to be drawn about the past: When the Pinatubo erupted in 1991 in the Philippines, an ash fall covered a huge area in a short time

The Eventstratigraphie (of English. Event , Event 'and stratigraphy , stratigraphy') is a sub-discipline of stratigraphy is divided in geosciences and compares and rock sequences with the help of short-term in the geological sense events (so-called events).

content

The subject of event stratigraphy is - on a geological scale - short-term external events such as pole reversals , storm surges , tsunamis , volcanic eruptions , impact events or alternations between cold and warm periods that can be seen in the stratified body.

Correspondences in archeology are incendiary layers , suspected earthquake horizons or warlike destruction, or the well-known lava and ash strata of Pompeii and Herculaneum .

Such guiding layers become significant for event stratigraphy when their effects can be recognized locally, regionally, supra-regionally or even globally in several stratigraphic profiles. Due to the nature of the event, the trace left in the rock or soil can correspond to a time interval of a few hours to a few million years.

meaning

The particular importance lies in the precise temporal parallelization of the smallest stratigraphic units over a large spatial distance.

The submarine or continental volcanic ash layers examined in tephrostratigraphy form deposits that can be sedimented in a period of a few hours to a few weeks and can sometimes be identified over thousands of kilometers. The accuracy of the temporal parallelization of such positions cannot be achieved with any other method for events many million years ago. In the case of the example of a volcanic ash layer described here, the absolute age can be determined even under favorable conditions by means of a radiometric determination of the age . An example of such a horizon, which is almost always clearly recognizable in Central and Northern Europe, is the ash layers of the Laacher See volcano , which erupted around 13,000 years ago and whose ash was drifted as far as Scandinavia by the wind . Several such events can be used as reliable reference points for the absolute dating of the stratigraphic boundaries between them (method of "graphic correlation").

Individual evidence

  1. ^ Stanley 2001: 665

literature

  • H. Murawski & W. Meyer: Geological dictionary . 10th ed .; Enke, Stuttgart 1998, ISBN 3-432-84100-0
  • PM Sadler & RA Cooper: Best-Fit Intervals and Consensus Sequences . In: PJ Harries (Ed.): High-Resolution Approaches in Stratigraphic Paleontology . Topics in Geobiology, Vol. 21; Kluwer, Dordrecht, 2003. ISBN 1-4020-1443-0
  • AB Shaw: Time in Stratigraphy . McGraw-Hill, 1964
  • St. M. Stanley: Historical Geology . 2nd ed.; Spectrum Academic Publishing House, Heidelberg u. Berlin 2001, ISBN 3-8274-0569-6
  • OH Walliser (Ed.): Global Events and event stratigraphy in the Phanerozoic . Berlin (Springer), 1995. ISBN 3-540-59056-0