Blockhorizont von Bernhardzell

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Representation and status

Color CMYK
N/A
Color RGB
R: 250 G: 225 B: 225
Rank
lithostratigraphic Bed
Validity
Unit is in Use
Status
local name (informal)
Status discussion

Nomenclature

Deutsch
Blockhorizont von Bernhardzell
Français
Horizon à blocs de Bernhardzell
English
Bernhardzell Block Horizon
Origin of the Name

Bernhardzell (SG)

Historical Variants

Blockhorizont (Hofmann 1951, Hofmann 1973, Kälin & Kempf 2009), vulkanischer Blockhorizont (Hofmann 1949 und 1956), Rotmergelhorizont mit exotischen Geröllen (Hofmann 1973c), Horizont mit Impaktphänomenen (Büchi & Schlanke 1977), Malmkalk-Blockhorizont (Habicht 1987), Blockhorizont of Bernhardzell (Letsch 2018)

Description

Thickness
10-15 cm (Letsch 2018)

Age

Age at top
  • Langhian
Age at base
  • Langhian

Geography

Geographical extent
Ostschweiz.
Type locality
  • Bernhardzell (SG), an der Sitter
    Site particularities
    • Obergrenze
    • Untergrenze
    • typische Fazies
    Site accessibility
    • Bachprofil
    Coordinates
    • (2743140 / 1260530)
    Note
    • Hofmann 1951
Point of interest

Palaenography and tectonic

  • OSM-II
Kind of protolith
  • sedimentary
Conditions of formation

Very distally located ejecta-layer resulting from the Ries meteorite impact (Hofmann 1973b, which caused the impact structures of the Nördlinger Ries and Steinheim craters in southern Germany (SHOEMAKER & CHAO 1961, HÜTTNER & SCHMIDT-KALER 1999).

References

Definition
Kälin Daniel, Kempf Oliver (2009) : High-resolution stratigraphy from the continental record of the Middle Miocene Northern Alpine Foreland Basin of Switzerland. N. Jb. Geol. Paläont. Abh. 254/1-2, 177-235

HOFMANN (1951) described an exotic horizon within the OSM deposits of eastern Switzerland, which comprises angular Jurassic limestone blocks of Swabian lithofacies with a size of up to 20 cm, within greenish freshwater marl. Later, HOFMANN (1973b) identified this layer as a very distally located ejecta-layer resulting from the Ries meteorite impact, which caused the impact structures of the Nördlinger Ries and Steinheim craters in southern Germany (SHOEMAKER & CHAO 1961, HÜTTNER & SCHMIDT-KALER 1999). HOFMANN (1973b) also pictured typical, impact-related shatter-cone structures. Near Bischofszell, the Ries ejecta-layer is situated approx. 80-100 m below the Schoosstobel [= Leimbach] bentonite, and approx. 180-200 m below the Waldkirch/Mollen bentonite (Fig. 5).

Numerical ages of the Ries meteorite impact range from 14.4–14.9 Ma (GENTNER & WAGNER 1969, STORZER et al. 1995, REICHENBACHER et al. 1998). A detailed discussion of these ages, however, is beyond the scope of our study since the age of the Ries impact is not crucial to our correlations.
Important Publications
Letsch Dominik (2018) : Diamictites and soft sediment deformation related to the Ries (ca. 14.9 Ma) meteorite impact: the "Blockhorizont" of Bernhardzell (Eastern Switzerland). Int. J. Earth Sci. (Geol. Rundschau) 107, 1379-1380
Habicht J. K. A. (1987) : Schweizerisches Mittelland (Molasse). Internationales Stratigraphisches Lexikon Vol.1 Fasc.7b
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