Weitendorf basalt quarry

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Weitendorf basalt quarry (2018), with grit crusher and sorting system

The Weitendorf basalt quarry is a quarry in the market towns of Wildon and Dobl-Zwaring in the Austrian state of Styria . The basalt deposits go back to the Weitendorf volcano , a middle Miocene shield volcano . It gained fame as a mineral deposit and location of numerous fossils . Parts of the quarry have been designated as natural monuments since 1985 .

Location and surroundings

The quarry is located in the lower Kainach valley at the southern end of the Kaiserwald . The top of the quarry directly on Weitendorferstrasse (L603) is at an altitude of 305  m above sea level. A. on the left bank of the river. At this point, the valley bordered by the quarry bar ( 369  m ) on the south side - before its confluence with the Grazer Feld - shows a geological narrowing compared to the wide Kainachboden upstream. The eponymous village of Weitendorf , an independent municipality until the end of 2014, belongs to the market town of Wildon and is located a good 1 km east of the basalt quarry. About 700 m northwest of the edge of the quarry is the village of Steindorf, the name of which is probably associated with the basalt deposits. The provincial capital Graz is around 19 km away.

Weitendorf volcano

geology

Weitendorfer basalt set as "Steindorfer Stein" in 2000 near Steindorf

About 18 million years ago the Styrian Basin began to sink in the course of tectonic processes . With the progressive subsidence, the water of the Paratethys penetrated the basin from the southeast and a sea bay with active volcanism was formed . Earthquakes and hot springs occurring on the seabed allowed glowing magma to reach the surface of the earth through crevices and crevices and cover the seabed around Weitendorf and Wundschuh on an area of ​​10 km² with a basalt layer up to 40 m thick. The volcano, whose existence was first suspected in the 1830s , was only active for a short time and recorded few eruptions. As in Eastern Styria , the thinning of the crust on the edge of the Pannonian Basin with simultaneous uplift of the Alps is assumed to be the trigger. With the help of radiometry an age of 14.5 to 15 million years could be determined, based on the thin liquid lava , similar to the Hawaiian volcanoes, the type of shield volcano can be determined. A consequence of volcanism is the recognized Sauerbrunn mineral spring near Hengsberg .

Shift sequence in the quarry

The Weitendorfer Basalt is, strictly speaking, a potassium- accentuated basaltic trachy andesite (Shoshonite, field S2 in the TAS diagram ). This dark gray to black igneous rock forms the lower two-thirds of the quarry wall and partially shows a columnar segregation , the surface is weathered 2 to 3 m deep. The hanging wall is formed by blue-gray marl and sands of the lower Badenium , which in turn are overlaid 4 to 5 m thick by the ice-age gravel and clay of the Kaiserwald terrace. Under the basalt there is a layer of fossil-bearing clay marl, which is also underground, which was first exposed in the course of the lowering of the quarry floor in the 1950s .

Mineralogy and Paleontology

Finds of particularly shapely and colorful minerals as well as rare fossils brought the Weitendorfer volcano international renown among scientists and mineral collectors from the early 20th century.

The rapid solidification of the lava under water and the resulting gas seal created geodes in the basalt, which are characterized by rich mineral deposits. Crystals of various carbonates and some silicon dioxide modifications, sulfides and rare zeolites formed on the walls from mixed aqueous phases . Different colored calcites and over 10 cm long aragonites in connection with chalcedony and / or quartz crystal lawns were of interest as well as citrine-colored quartz made of sepiolite fibers , banded agates and intensely blue colored crusts of CT opal with small pyrite crystals distributed on them . The latter were given the name "Weitendorfer Sternenhimmel" by collectors. The minerals hyalite , clinoptilolite and harmotome as well as - in microscopic doses - deep cristobalite , pseudobrookite , garnet , malachite , brochantite and antlerite were found less frequently .

The area between Weitendorf, Pöls, Preding and Groß Sankt Florian presented itself as a tropical lagoon in the Middle Miocene , which was shielded from the open sea by the Central Styrian Threshold . This created a habitat for mussels , snails , crabs and sea ​​urchins . More than 100 different species have been detected in the clay marls of the quarry, of which the tower snail species Turritella badensis appears almost rock-forming in a horizon up to 50 cm thick. The Long-beaked screw tibia dentata and the conch Strombus schröckingeri were in Austria only in Weitendorf and Wetzelsdorf be found. In addition, the discovery of a tooth found the giant shark species Otodus megalodon, which is over 15 m long . The fossil discoveries not only enabled a biostratigraphic classification of the rock layers in the Lageniden zone of the Badenium (Florian layers), but also provided evidence of the connection between Paratethys and the Indian Ocean , where the closest relatives of the fossilized species live today.

history

Finds of spindle whorls show that the Weitendorf basalt deposit was already actively used in the Neolithic . From the 16th century there was a regular quarry operation, with the Weitendorfer basalt initially serving primarily as building stone and paving stone . While the foundations of the Wildon Castle were built from the stone in the vicinity , it was in demand in Graz as a particularly wear-resistant pavement .

Old stone crushing plant on the L603, wooden construction with cyclone dust separator

In 1943 the quarry was the largest basalt mine in Austria. In 1977 the Leibnitz District Commission approved an in-house diesel tank system and issued provisions on employee protection . There were two serious explosions in the quarry: In 1972 the explosives depot with 227 kg of explosives and over 600 detonators exploded for unexplained reasons, in 1984 two burglars were killed while trying to open the factory safe with the help of a welding torch and oxygen bottles . In the same year the designation of the quarry as a natural monument was discussed. The community of Weitendorf saw this as an opportunity to prevent a planned landfill for the city of Graz, but demanded the maintenance of the quarry as a condition. In March 1985, the BH finally placed 0.6 hectares in the southern pit area under monument protection, whereby it was decreed that the fossil-bearing clay marl, in order to remain accessible, must not be buried. The appeal by the Graz magistrate against the decision was rejected.

The quarry is owned by the city of Graz and is operated as one of three Styrian basalt works (next to Mühldorf bei Feldbach and Hochstraden ) by Appel Steinbruch GmbH & Co. KG. Use finds the wide basalt villages as chippings , asphalt - aggregate and particularly weathering resistant armor stone .

literature

  • Fritz Ebner & Walter Gräf: The fauna of Weitendorf. In: Annual Report 1976 , Landesmuseum Joanneum , Graz 1977, pp. 157–183.
  • Helmut Flügel , Alois Hauser & Adolf Papp: New observations on the basalt deposit in Weitendorf near Graz. In: Meeting report of the Academy of Sciences , Math. Naturwiss. Kl., Abt. 1, 161, Vienna 1952, pp. 173-184.
  • Hartmut Hiden: The Weitendorf volcano. In: Hengist Magazin. Journal for archeology, history and culture of Central Styria. Issue 2 (2006), pp. 4-9. Online PDF
  • Bernhard Krainer: Sedimentation and Shoshonite from Weitendorf, Badenien, Styrian Basin. In: Communications from the Austrian Geological Society, Volume 80, Vienna 1987, pp. 143–155. Online PDF

Web links

Commons : Weitendorf basalt quarry  - Collection of images, videos and audio files

Individual evidence

  1. ^ Fritz Lochner von Hüttenbach: Styrian place names. On the origin and interpretation of names of settlements, mountains, waters and fields. Graz comparative works, Leykam 2008, ISBN 978-3-7011-0116-0 , p. 123.
  2. ↑ Plaque on the "Steindorfer Stein". Steindorf 2000. Photo
  3. ↑ a b c d e f Hartmut Hiden: The volcano of Weitendorf. In: Hengist Magazin. Journal for archeology, history and culture of Central Styria. Issue 2 (2006), pp. 4-9. Online PDF , accessed November 29, 2018.
  4. ↑ Hilmar Zetinigg: The mineral and thermal springs of Styria. In: Communications from the Department of Geology and Paleontology at the Landesmuseum Joanneum , Issue 50/51 (1992/93), pp. 186–188. Online PDF , accessed November 29, 2018.
  5. ↑ a b c Herbert Paschinger: Styria. Styrian Randgebirge, Grazer Bergland, Styrian Riedelland. Collection of Geographical Guides Volume 10. Gebrüder Borntraeger , Berlin - Stuttgart 1974, ISBN 3-443-16006-9 , p. 146.
  6. ↑ Styrian basalt, the hardest rock in the Ostmark. In: Kleine Zeitung , issue of August 16, 1943, p. 4.
  7. ↑ Leibnitz district administration : Decision of October 6, 1977. GZ 4, Scha 4/1977, p. 1.
  8. ↑ Leibnitz district administration: Decision of December 6, 1977. GZ 4, Scha 10/1977, p. 1.
  9. ^ Doris Nager: Community of Weitendorf - An economic historical analysis. Master's thesis at the Institute for Economic, Social and Corporate History of the University of Graz 2009, p. 18 u. 21st
  10. ^ Community of Weitendorf : Circular of July 26, 1984, p. 2.
  11. ↑ Leibnitz District Authority: Decision of March 4, 1985. GZ 6.0 B 10, p. 1.
  12. ↑ works. Appel Steinbruch GmbH, accessed on November 29, 2018 .

Coordinates: 46 ° 53 ′ 43.2 "  N , 15 ° 26 ′ 43.5"  E