Gschnitz Stadium

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The Gschnitz Stadium is the first significant ice advance in the late glacial of the Alps . He found in the period 13,000 to 14,200 years BC. Chr. Instead.

Naming and conceptual history

Trins with the terminal moraine of the Gschnitz stadium above the local church, cut from the Gschnitzbach

The Gschnitz stage (or Gschnitz stage), sometimes also referred to as the Schlern stage or just S stage , was named after its type of locality , the Gschnitztal in the Stubai Alps . The term was first used in 1901/1909 by Albrecht Penck and Eduard Brückner . They had recognized that the ice retreat from the high ice age maximum in the Alpine foothills was not continuous, but was interrupted by a series of renewed glacier advances , which they termed the Bühl , Gschnitz and Daun stages .

Location description

The Gschnitz stage is well marked by its type locality by its terminal moraine near Trins in the Gschnitztal. The terminal moraine, which is up to 30 meters high, suggests that the glacier stagnated at this position for several decades or more. The Gschnitz Stadium can usually be seen quite well in the Austrian Alps on small and medium-sized glaciers. However, there is a lack of large ice flows such as the Inn Glacier , the Rhone Glacier or the Aare Glacier .

characterization

At the time of the Gschnitz stage, the glaciers had retreated far into the interior of the Alps and around 80 to 90% of the maximum ice mass had already melted. Geomorphological findings show that the stage does not mark a retreat, but a clear advance that took place over ice-free terrain. The steep-walled, rubble-rich, several tens of meters high moraines appear as very sediment-rich and distinctive individual forms. They mainly girdled valley glaciers and some large dendritic glaciers. It can be assumed that the large side valleys were then glaciated again and that the main valleys were also reached by glacier tongues in favorable positions. At higher altitudes, even larger connected glaciers are likely to have existed.

Below 1400 meters the moraines show no solifluction overprint . The lowering of the equilibrium line ( engl. Equilibrium Line Altitude or ELA ) was during the Gschnitz-stage (as opposed to 1850) between 650 and 700 meters of the type locality, 800 meters on the Alpine northern edge 900 meters in the Maritime Alps and up to 1000 meters in adriatic south.

Stratigraphic position and correlation

The Gschnitz stage follows the late glacial ice decay or the Steinach stage according to Heuberger or the Bühl stage by Penck and Brückner. It is in turn superseded by the Clavadel / Sender stage . It correlates with the Heinrich event 1 ( H 1 or HE 1 ).

Compared to the Vistula glacial period in Northern Europe, the Gschnitz Stadium is located before the start of the Meiendorf Interstadial and towards the end of the Mecklenburg phase .

The Gschnitz stage falls within the Greenland stage 2a ( GS-2a ).

Dating

The stabilization of the terminal moraine in the Gschnitztal was in 2006 by Ivy-Ochs and others with about 13450 to 14150 BC. Chr. Determined. This minimum age is also underpinned by other radiocarbon ages (also minimum ages ), such as the San Bernardino with 13,000 to 14,700 BC. And from Sempione with 12,300 to 13,500 BC. Chr.

The actual ice advance began with the Heinrich event 1, which dates back to 15,000 ± 1000 years BC. Is set. Dating on the moss of Rödschitz in the valley of the Traun resulted in a (quite high) maximum age for Gschnitz-stadial deposits of 16,070 to 17,150 years BC. Chr. Ponte Murato in the Gessotal of the Italian Maritime Alps finally delivered the age 14,600 ± 1000 years BC. Chr.

All in all, the average ages for the Gschnitz stage accumulate in the period 13,000 to 14,200 years BC. Chr.

Connection with the Heinrich event H 1

The ages for the Gschnitz stage accumulate towards the end of the first Heinrich event ( H 1 ), which in turn dates from 16000 to 14000 BC using radiocarbon. BC, a correlation is therefore obvious. During this event there was a massive iceberg calving on the Laurentide Ice Sheet combined with a drift of the icebergs into the North Atlantic . The melting impaired the thermohaline circulation in the North Atlantic, which was driven by density differences , which in turn led to a very rapid cooling of the surrounding areas and of Europe, which was in downdraft. But not only in Europe, but generally across the entire northern hemisphere, a very direct reaction of the valley glaciers and ice sheets to the prevailing cooling can be demonstrated.

Individual evidence

  1. ^ A. Penck, E. Brückner: The Alps in the Ice Age . 3 volumes 1901–1909. Tauchnitz, Leipzig.
  2. ↑ Hanns Kerschner, Susan Ivy-Ochs: Palaeoclimate from glaciers: Examples from the Eastern Alps during the Alpine Lateglacial and early Holocene . In: Global and Planetary Change . tape 60 , no. 1–2 , January 2008, pp. 58-71 , doi : 10.1016 / j.gloplacha.2006.07.034 .
  3. ^ S. Ivy-Ochs, H. Kerschner, PW Kubik, C. Schlüchter: Glacier response in the European Alps to Heinrich event 1 cooling: the Gschnitz stadial . In: Journal of Quaternary Science . tape 21 , 2006, p. 115-130 .
  4. ↑ H. Zoller, H. Kleiber: Vegetation-historical studies in the montane and subalpine level of the Ticino valleys . In: Negotiations of the Natural Research Society Basel . tape 81 , 1971, p. 90-154 .
  5. ↑ M. Welten: Vegetation-historical studies in the western Swiss Alps: Bern-Wallis . In: Memoranda of the Swiss Natural Research Society . tape 95 , 1982, pp. 1-105 .
  6. ↑ S. Hemming: Heinrich events: massive late Pleistocene detritus layers of the North Atlantic and their global climate imprint . In: Reviews of Geophysics . tape 42 , 2004, p. 1-43 .
  7. ^ I. Draxler: On the vegetation history and stratigraphy of the Würm late glacial of the Traungletscher area . In: D. Van Husen (Ed.): The area of ​​the Traungletscher, Upper Austria: A type region of the Würm Glacial (=  communications from the Commission for Quaternary Research of the Austrian Academy of Sciences . Volume 7 ). 1987, ISBN 3-7001-1075-8 , pp. 19-35 .
  8. ^ PR Federici, among others: Last Glacial Maximum and the Gschnitz stadial in the Maritime Alps according to 10 Be cosmogenic dating . In: Boreas . 2011, p. 1–15 , doi : 10.1111 / j.1502-3885.2011.00233.x .
  9. ^ Sidney R. Hemming: Heinrich events: Massive late Pleistocene detritus layers of the North Atlantic and their global climate imprint . In: Review of Geophysics . tape 42 , no. 1 , March 2004, p. RG1005 , doi : 10.1029 / 2003RG000128 .
  10. ^ JF McManus, R. Francois, JM Gherardi, LD Keigwin, S. Brown-Leger: Collapse and rapid resumption of Atlantic meridional circulation linked to deglacial climate changes . In: Nature . tape 428 , 2004, p. 834-837 .
  11. ↑ JM Licciardi, PU Clark, EJ Brook, D. Elmore, P. Sharma: Variable responses of western US glaciers during the last deglaciation . In: Geology . tape 32 , 2004, p. 81-84 .