Schwelm facies

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The limestones in the Schwelm facies (formerly: Schwelmer Kalk ) are a medium to Upper Devonian mass limestone , which was first described by Werner Paeckelmann in an outcrop in Schwelm east of Wuppertal . The limestones of the Schwelm facies mark the beginning of the actual reef limestone development in many Devonian reef limestone complexes in the northern Rhenoherzynic .

Definition

In 1913 Werner Paeckelmann proposed a division of the Devonian mass limestone into Schwelmer, Dorper and Iberger limestone in the Oberberg area - based on lithological considerations. The most characteristic fossil of the series of layers is the brachiopod Stringocephalus burtini . This is why these limestones were often referred to as Stringocephalic limestone in the past .

In the 1960s, facials began to be taken of the reef limestones around the world. Wolfgang Krebs presented a facial structure for the reef limestone complexes of the Rhenish Slate Mountains . The Devonian mass limestone in the northern Rhenish Slate Mountains can be divided into a flat, reef and cap stage. At the base of the reef limestone development, flat biostreams can be found, which are assigned to the platform stage . In recognition of the services of Paeckelmann, Wolfgang Krebs named the biostromal calcareous facies as Schwelm facies. About of the resulting basal carbonate formed on the Riffrand and isolated in the slowly descending, south offshore marine basin reefs in the form of bioherms from which the reef stage of Dorp facies are attributed. In contrast to the shallow bank reefs of the Schwelm facies, the reef limestone complexes of the Dorp facies tend to grow upwards and are locally overlaid by the youngest reef limestones, the Upper Devonian limestones of the Iberg facies , which were formed in the so-called cap stage .

rocks

Reef organisms in the mass limestone, Rock Sea Hemer

The limestone in Schwelm facies is made up of thick, dark blue-gray to gray-black, dense limestones in which, particularly in the deeper part of the sequence of layers, marly intermediate layers and fibrous limestone are embedded. In the Kettwig area , sandy to conglomerate layers can also be observed at the base , which suggest a deposit in the coastal area. The marly intermediate layers are largely absent further west in the Brilon Reef. There, laterally, at the same time as the Schwelm limestone, a carbonate facies ( Almer facies ) interlocked , which was formed in a lagoon area between the biostreams of the Schwelm facies. The formation of the carbonates is similar to the younger limes in Dorp facies: Banked, light, micritic limestone and dismicrite dominate here . In the Wuppertal area, dark flinz slates are embedded in the limestone of the Schwelm facies in the uppermost Givetium .

The limestones in Schwelm facies are usually clearly stratified and have a bank thickness of a few decimeters to three meters. Like most carbonate rocks, the Schwelm limestones were also intensively karstified - especially during the Upper Cretaceous and Tertiary Periods . The outcrop area of ​​the Schwelm limestone is characterized by the appearance of sinkholes , caves and ponors .

In the Wuppertal and Hagen area , a large part of the limestone was subsequently dolomitized by the influence of magnesium-containing sea ​​and pore waters . The primary sediment structures were often destroyed by recrystallization . Dolomitized Schwelm limestones are mostly characterized by a sugar-grain structure and a brown-gray color.

Fossils

Stringocephalus burtini, Haan , Heinhauser Weg (geological nature trail)

The limestones in Schwelm facies are predominantly rich in fossils . In addition to reef- and rock-forming, spherical, layered or dendroid stromatopores , such as Actinostroma, Amphipora and Stachyodes , numerous corals in particular are involved in rock formation, such as B. Campophyllum , Thamnopora , Alveolites and Heliolites . There are locally accumulations of thick- shelled mussels ( Megalodus ), snails (including Murchisonia , Bellerophon ), crinoids and brachiopods such as spirifers , atrypids and uncites .

The biogens in the mass limestone of the Schwelm facies occur as bioclasts in a micritic base mass or as densely packed layers of unbroken fossils. In marly layers, especially in the Sauerland , accumulations of brachiopod stringocephalic schill can often be observed.

Paleogeographical interpretation

The limestones in Schwelm facies are widespread on the northern edge of today's Rhenish Slate Mountains. The thickness of these facies varies regionally from a few to several hundred meters. The Schwelm limestone forms large parts of the mass limestone ranges from Gruiten - Dornap , Vohwinkel and Elberfeld . In the Wülfrath area , the Schwelm limestone - except for a few meters of fibrous limestone - is largely missing. Reef limestone in Schwelm facies can also be found in the limestone deposits of Warstein , Brilon and Attendorn . West of Brilon , the thickness decreases rapidly.

They were formed in the middle of Devon on a reef platform on a slowly sinking shelf that was off a continental land mass, the Old Red continent in the southwest. The edge of the shelf lay in the middle of the Devon, roughly on the Bonn - Olpe - Marsberg line . The biostromal reefs in Schwelm facies developed on the north-west of it on an adjoining external shelf about 100 kilometers wide. The coral stromatopore lawns of the Schwelm limestone represent in-situ reef formations that were formed in shallow water. Redistributed limestones tend to be subordinate in this facies area. In the Wuppertal area, dark flinz slate (Osterholz layers) are formed within the carbonate formations, which were deposited in a clayey facies area between the biostrivers. On the Brilon and Warsteiner reefs , the Central Devonian Sparganophyllum limestone with its flat biostromal formations represents the basal reef limestone facies.

Age rating

The age of the limestone is usually determined with microfossils , the so-called conodonts . In the limestone of the Schwelm facies, however, there is usually only a reduced conodont fauna due to their formation area. It was unanimously determined that the majority of the carbonates of the Schwelm facies were formed from the lower varcus to the lowest asymmetricus conodont zone ( Givetium to Frasnium ).

use

Limestone quarry near Rösenbeck

The pure limestones are a sought-after raw material and are mined in various large quarries on the northern edge of the Rhenish Slate Mountains for the chemical and building materials industry. They are characterized by an average calcium carbonate content of 94 to 98% and are therefore somewhat more impure than the reef limestone of the younger Dorp facies.

The partially dolomitized limestones of the Schwelm facies are mined in Dornap and Osterholz , among others . Although this facies is also widespread west of the Hönnetal , they are currently not mined there due to the higher proportion of non-carbonate components. In the Warstein area , mainly limestone from the Schwelm facies is mined in various quarries ( Kallenhardt , Hohe Lieth , Warstein ) for the production of gravel , fine chippings and armourstones. The carbonate rocks are also used industrially in the Brilon reef limestone complex. In several quarries ( Thülen , Kirchloh , Rösenbeck , Mühlenbein , Madfeld and Bleireinigung ) both the carbonate rocks of the Schwelm and Dorp facies are extracted. In the Attendorn area , the reefs developed on a threshold region at the shelf edge are also developed in Schwelm and Dorp facies. The Schwelm limestone is currently not being mined.

Individual evidence

  1. ^ Wolfgang Krebs: Reef development in the Devonian of the eastern Slate Mountains, Germany . In: Alberta Society Petrol. Geologists . tape 2 . Calgary 1968, p. 295-306 .
  2. ^ A b Wolfgang Krebs: The Devonian reefs in Central Europe . In: Communications from the TU Carolo-Wilhelmina in Braunschweig . tape 6 , no. 2/3 . Braunschweig 1971, p. 23 ff .
  3. ^ A b Karl-Heinz Ribbert, Klaus Skupin, Béatrice Oesterreich: Explanations for sheet 4518 Madfeld . In: Geological Service NRW (Hrsg.): Geological map of North Rhine-Westphalia 1: 25,000 . 2nd, completely revised edition. Krefeld 2006, ISBN 3-86029-155-6 , p. 26 .
  4. ↑ a b c d Werner Paeckelmann: Explanations for sheet 4708 Wuppertal-Elberfeld . In: Geologisches Landesamt NRW (Ed.): Geological map of North Rhine-Westphalia 1: 25,000 . 2nd Edition. Krefeld 1979, p. 24 ff .
  5. ↑ Wilfried Rosendahl, Volker Wrede: Karst phenomena and geotope protection in the northern Sauerland. Excursion 4 . In: Scriptum - work results from the geological service - North Rhine-Westphalia . tape 8 . Krefeld 2001, p. 85-98 .
  6. ↑ Götz Ebhardt, Peter Meiburg: Relationship between tectonics and karst in the Warsteiner area (northeastern Rheinisches Schiefergebirge) . In: Association of Friends of Mineralogy and Geology [VFMG] e. V. (Ed.): Geology and mineralogy of the Warsteiner area . Aufschluss - special volume 29. Heidelberg 1979, p. 93-112 .
  7. ↑ a b c Wolfgang Paeckelmann, Fritz Kühne: Explanations on sheet 2585 (4517) Alme . In: Prussian Geological State Institute (Hrsg.): Geological map of Prussia and neighboring German countries 1: 25,000 . 1st edition. Berlin 1936, p. 12 ff .
  8. ^ Claus-Dieter Clausen, Klaus Leuteritz: Overview of the geology of the Warsteiner saddle and its immediate surroundings . In: Association of Friends of Mineralogy and Geology [VFMG] eV (Ed.): Aufschluss . Special volume 29. Heidelberg 1979, p. 1-32 .
  9. ↑ Willi Ziegler : Explanations to sheet 4813 Attendorn . In: Geologisches Landesamt NRW (Ed.): Geological map of North Rhine-Westphalia 1: 25,000 . Krefeld 1978, p. 230 .
  10. ^ A b Karl-Heinz Ribbert: Geology in the Rhenish Slate Mountains . Ed .: Geological Service NRW. Part 2 Bergisches Land. Krefeld 2012, ISBN 978-3-86029-935-7 , p. 48 ff .
  11. ↑ Claus-Dieter Clausen, Klaus Leuteritz: Explanations for sheet 4516 Warstein . In: Geologisches Landesamt NRW (Ed.): Geological map of North Rhine-Westphalia 1: 25,000 . 2nd Edition. Krefeld 1984, p. 24 .
  12. ↑ a b Günter Drozdzewski: Deposits of usable solid rock in North Rhine-Westphalia . Ed .: Geological Service NRW. Krefeld 2007, ISBN 978-3-86029-933-3 , p. 90 ff .

literature

  • Werner Paeckelmann : The Upper Devon of the Bergisches Land. Treatises of the Royal Prussian Geological State Institute, New Series, Volume 70, Berlin 1913.
  • Werner Paeckelmann: The central Devonian mass limestone of the Bergisches Land. Treatises of the Royal Prussian State Geological Institute, New Series, Volume 91, Berlin 1922.
  • Werner Paeckelmann, Fritz Kühne: Geological map of Prussia and neighboring German countries, explanations for sheet 2585 (4517) Alme. 1st edition. Prussian Geological State Institute, Berlin 1936, p. 11 ff.
  • Wolfgang Krebs: The Devonian reefs in Central Europe. In: Communications from the TU Carolo-Wilhelmina in Braunschweig. 6, 1971, issue 2/3, Braunschweig, pp. 22-33.
  • Wolfgang Krebs: Devonian carbonate complexes of central Europe. In: Léo F. Laporte (Ed.): Reefs in Time ans Space - Selected Examples from the recent and ancient. Society of Economic Paleontoligists and Mineralogists, Special Publication, 18, Tulsa 1974, pp. 155-208.
  • Wolfgang Eder, Wolfgang Engel, Wolfgang Franke : Facies distribution of the Middle / Upper Devonian Reef and contemporaneous limestone-turbidites. In: Erik Flügel (Ed.): International Sympos. Fossil Algae, Erlangen 1975, pp. 37-43.
  • Wolfgang Eder, Wolfgang Engel, Wolfgang Franke: Paleogeography at the turn of the Middle-Upper Devonian (Facies transition shelf / basin using the example of Brilon mass limestone, Padberger Kalk and Flinz: outcrops 4 to 6). Excursion guide Geotagung '77, Göttingen 1977, pp. 22–29.
  • Association of Friends of Mineralogy and Geology (VFMG) e. V. (Ed.): Geology and mineralogy of the Warsteiner area. Aufschluss, special volume 29, Heidelberg 1979.
  • Werner Paeckelmann: Geological map of North Rhine-Westphalia 1: 25,000, explanations for sheet 4708 Wuppertal-Elberfeld. 2nd Edition. Geological State Office of North Rhine-Westphalia, Krefeld 1979.
  • Alexander Fuchs, Werner Paeckelmann: Geological map of North Rhine-Westphalia 1: 25,000, explanations for sheet 4709 Wuppertal-Barmen. 2nd Edition. Geological State Office of North Rhine-Westphalia, Krefeld 1979.
  • Claus-Dieter Clausen, Klaus Leuteritz: Geological map of North Rhine-Westphalia 1: 25,000, explanations for sheet 4516 Warstein. 2nd Edition. Geological State Office of North Rhine-Westphalia, Krefeld 1984.
  • Wilfried Rosendahl, Volker Wrede: Karst phenomena and geotope protection in the northern Sauerland. Excursion 4, Scriptum - work results from the geological service - North Rhine-Westphalia 8, Krefeld 2001, pp. 85–98.
  • Karl-Heinz Ribbert, Klaus Skupin, Béatrice Austria: Geological map of North Rhine-Westphalia 1: 25,000, explanations for sheet 4518 Madfeld. 2nd, completely revised edition. Geological Service NRW, Krefeld 2006, ISBN 3-86029-155-6 .
  • Karl-Heinz Ribbert: Geology in the Rhenish Slate Mountains. Part 2 Bergisches Land, Geological Service NRW, Krefeld 2012, ISBN 978-3-86029-935-7 .