Flinz - Flinz

Variscally folded succession of Loughshinny layers similar to the Palaeozoic Flinz of Central Europe ( Karbon , Ireland)

In German-speaking countries, various sedimentary rocks or sequences of sedimentary rocks are referred to as Flinz .

In the Central European Varisticum, the term stands for an alternating layer of carbonate and dark, clayey sediments that were deposited in a sea basin by turbid currents . [1] Thus, there is a special turbidite - facies . [2]

In addition, the term is used for fine-grain, laminated limestone layers of the Solnhofen limestone (Upper Jura). [1]

In addition, the sandy to clayey sediments of the Upper Freshwater Molasse (Miocene) in Upper Bavaria are so called. [1]

Flint effects of the varisticum

Genesis and structure

Flinzschiefer in Wuppertal-Dorrenberg

The Palaeozoic Flinz of the Rhenish Slate Mountains and the Harz Mountains are limestone-mudstone alternations that were deposited in the deeper sea regions of the Rhenohercynian Basin in the vicinity of submarine thresholds with the processing of older carbonatic rocks such as reef limestone . The carbonate was carried into the storage area by turbid currents. Similar to clastic turbidites, this led to cyclically layered sediment sequences, with a single cycle corresponding to a so-called Bouma sequence . A complete Bouma sequence comprises the following sections, from the lying to the hanging wall:

  • A - Graduated Section:
    • Deposition through sedimentation at very high flow speeds, often associated with erosion of the top of the underlying layer
    • Base consists of limestone with coarse biodetritus and / or breccia , grain size decreasing upwards (graduation)
  • B - Lower Laminated Section:
    • Deposits when the flow velocity is still high
    • parallel, laminated layers of coarser and finer carbonate particles
  • C - Section with cross and wound bedding (convolute bedding), plate structures and flow ripples (deposits at reduced flow velocity)
  • D - Upper Laminated Section:
    • Deposition at the end of the pouring event
    • relatively fine-grain, laminated limestone
  • E - clayey section
    • Suspended load of normal basin sedimentation (background sediment): clays and silts

Complete Bouma cycles can only rarely be observed in nature, especially in sections A – D, the actual turbidite locations. The pitches (section E) each separate two successive turbidites and, after solidification, form what are known as Flinzschists . The calcareous bidites themselves are called Flinzkalke . While the Flinz limestone is deposited in a relatively short time (a few hours to days), the sedimentation of the Flinz slate takes many years to many thousands or tens of thousands of years, depending on its thickness. The material for the Flinzkalke mostly comes from reef bodies or other submarine threshold or platform limestones.

The distance from the delivery area can be derived from the ratio of the thickness of the strata and the completeness of a Bouma sequence: While flint sequences that were deposited in the vicinity of the area of ​​origin ( proximal ) are characterized by largely complete cycles and a relatively high thickness of the limestone, In the case of flinz sequences formed far away ( distally ), the coarser sections are usually missing , the flinz limestones are relatively thin and a large part of the sequence consists of slate. The thickness of a Flinz sequence varies from a few centimeters to several meters.

Occurrence

In the Oberdevon of the Rhenish Slate Mountains, flinzschichten are known around the Velberter saddle . Here they overlay the central Devonian mass limestone in the northern Bergisches Land . Up to 20 m of flinz limestone are stored there in 35 m of flinz slate. In this room, at the top of the sequence of layers, is the Frasne - Famenne boundary. [3]

In 1928 Walter Schriel also introduced the term for the Upper Devonian layer sequences in the Harz Mountains. Flinzschichten are known from the area around Wernigerode and St. Andreasberg . [4] [5]

All over the world, rock sequences that correspond genetically and facially to the Flinz des Varistikum are widespread. Examples include the Shady Dolomite (Cambrian, Virginia, USA) or the Prong Creek Formation (Devon, Yukon Territory, Canada). [2]

Flinze des Solnhofener Plattenkalks

Solnhofener Plattenkalk, Steinbruch Frauenberg

Those layers of Solnhofen limestone ( Tithonium of the Franconian Alb ), which consist of very fine-grained, internally laminated limestone, are also called "Flinz" or "Flinze". [6] [7] They reach average thicknesses between 0.5 and 1 cm and a maximum thickness of up to 30 cm in the area around Solnhofen. [7] The Flinzen are layers of clay that are richer in clay, so-called rot , temporarily stored . [6] [7] Flint and rot contain the same microfossils ( coccoliths and rarely foraminifera ). [7] The rest of the carbonate was passively precipitated from the water column.[6] Since the Flinz rot packets split along the layer surfaces, but not along the internal lamination of the Flinze, most of the fossils of the Solnhofen limestone are known from the upper layers of the flinz layers. [7] The Solnhofen limestone was probablydepositedin a water depth of about 30 to 80 m in smaller, possibly hypersalinear lagoons that stretched between sponge-algae reefs. [7]

Flinz of the Upper Freshwater Molasse

Flinz of the Upper Freshwater Molasse in the Aubinger Lohe, trained as clay marl

In Upper Bavaria, Miocene fluviatil-limnic sediments of the Molasse basin (Upper Freshwater Molasse ) are called "Flinz" . These are fine sandy to clayey , sometimes marly deposits with a high proportion of mica . [8] In the Munich gravel plain , they form the base for the ice age deposits. The Isar , the Lech , [9] the Würm and the Hachinger Bach have partly cut into these layers of flax.

literature

  • H. Füchtbauer: Sediments and sedimentary rocks . Schweizerbart'sche Verlagsbuchhandlung, Stuttgart 1988, p. 821.
  • A. H. Bouma, W. R. Normark & N. E. Barnes (Hrsg.): Submarine Fans and Related Turbidite Systems. Springer Verlag, New York 1986, S. 351.
  • Maurice E. Tucker, V. P. Wright: Carbonate Sedimentology. Blackwell Science, S. 482
  • K.-D. Meischner: Allodapic limestones, turbidites in sedimentation basins near reefs .- In: AH Bouma & A. Brouwer (eds.): Tubidites. Developments in Sedimentology, 3, Amsterdam (Elsevier) 1964, pp. 156-191
  • E. Rutte: Bavaria's geological history - The geological guide through Bavaria . Ehrenwirth Verlag, Munich 1992, ISBN 3-431-02348-7 .
  • Rolf KF Meyer, H. Schmidt-Kaler: Walks into the history of the earth - On the trail of the Ice Age south of Munich , Verlag Pfeil, Munich 1997, ISBN 3-931516-09-1 .

Individual evidence

  1. a b c Author collective: Lexicon of Geosciences , Volume II, Spectrum Academic Publishing House, Heidelberg / Berlin 2000, ISBN 3-8274-0421-5 , p. 180
  2. a b H. E. Cook, H. T. Mullins: Basin Margin Environment. In: Peter A. Scholle, Don G. Bebout, Clyde H. Moore (Hrsg.): Carbonate Depositional Environments. AAPG Memoir. Bd. 33, 1983, S. 540–617, ISBN 0-89181-310-1
  3. K.-H. Ribbert: Geology in the Rhenish Slate Mountains, Part II: Bergisches Land. Krefeld 2012, ISBN 978-3-86029-935-7 , pp. 65-67.
  4. ^ H. Zellmer: Stratigraphy and sedimentology of the Flinz facies south of St. Andreasberg (Harz) , TU Braunschweig 1989, 93 pp.
  5. P. Junge: Sedimentology and stratigraphy of the Flinzkalke south of Wernigerode (Harz). Zentralblatt für Geologie und Paläontologie, Part I (General and applied geology including deposit geology). Jhrg. 1990, No. 13, pp. 1545-1554.
  6. a b c Helmut Keupp: Aspects of the origin of the Solnhofen lithographic limestone facies based on a new core drilling in the Maxberg quarry. Geobios. Suppl.-Nr. 16 (Bd. 27, Suppl.-Nr. 1), 1994, S. 71–80, doi:10.1016/S0016-6995(94)80022-7
  7. a b c d e f Hans Hesse: Upper Jurassic Solnhofen Plattenkalk of Bavaria, Germany. In: Hans Hess, William I. Ausich, Carlton E. Brett, Michael J. Simms (Hrsg.): Fossil Crinoids. Cambridge University Press, Cambridge, UK, 1999, S. 216–224, ISBN 0-521-45024-1
  8. ^ Entry "Flinz" at geo-glossar.de
  9. StadtZeitung Augsburg, 23. August 2012 (Memento des Originals vom 8. Mai 2014 im Internet Archive) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.@1@2Template: Webachiv / IABot / www.stadtzeitung.de