/wak"euh/, n.
a poorly sorted sandstone containing fragments of rock and minerals in a clayey matrix. Cf. graywacke.
[1795-1805; < G: a kind of stone]

* * *

also called  dirty sandstone 

      sedimentary rock composed of sand-sized grains (0.063–2 mm [0.0025–0.078 inch]) with a fine-grained clay matrix. The sand-sized grains are frequently composed of rock fragments of wide-ranging mineralogies (e.g., those consisting of pyroxenes, amphiboles, feldspars, and quartz). The grains are angular and poorly sorted with many minerals retaining growth forms that resulted from low abrasion. The matrix, which contains appreciable amounts of clay minerals, may constitute up to 50 percent of the volume. Of the clay minerals, chlorite and biotite are more abundant than muscovite and illite; kaolinite is absent. The abundant matrix tends to bind the grains strongly and form a relatively hard rock.

      Common structural features of wackes include repeated graded bedding and such deformational features as folds and deformed bedding, which appear to have formed soon after deposition; cross bedding is absent. Cyclic sequences of deposition are common within wackes, with basal sandstone followed by laminated sandstone and shale at the top.

      The characteristics of wackes all point to rapid deposition in turbidity currents (density currents resulting from an increase in sediment concentration) in a tectonically active region. Wacke sequences may be several thousand metres thick, strongly suggesting rapid subsidence in geosynclinal regions. They occur in almost all fold mountain belts except those dominated by limestones, such as the Canadian Rockies.

* * *

Universalium. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • Wacke — bezeichnet: Christoph Wacke (1596–1649), deutscher Rechtswissenschaftler Grauwacke, eine Gesteinsart Siehe auch:  Wiktionary: Wacke – Bedeutungserklärungen, Wortherkunft, Synonyme, Übersetzungen …   Deutsch Wikipedia

  • wacke — ou wake (va k ) s. m. Terme de minéralogie. Matière opaque qui tient le milieu entre le basalte et l argile. SUPPLÉMENT AU DICTIONNAIRE    WACKE. Ajoutez : ÉTYM. Angl. wacke ; de l all. Wacke, même sens …   Dictionnaire de la Langue Française d'Émile Littré

  • Wacke — Wack e, Wacky Wack y, n. [G. wacke, MHG. wacke a large stone, OHG. waggo a pebble.] (Geol.) A soft, earthy, dark colored rock or clay derived from the alteration of basalt. [1913 Webster] …   The Collaborative International Dictionary of English

  • wacke — (n.) rock resembling sandstone, 1803, from Ger. Wacke, from M.H.G. wacke a large stone, from O.H.G. wacko gravel, probably from O.H.G. wegan to move. A miner s word, brought into geology by German geologist Abraham Gottlob Werner (1750 1817) …   Etymology dictionary

  • Wacke — Sf (Wacken m.) Flußkiesel per. Wortschatz reg. (13. Jh.), mhd. wacke m. Stammwort Wohl als Geröll, Geschiebe zu bewegen2. ✎ Lüschen (1979), 232; Lühr (1988), 292. deutsch s. bewegen …   Etymologisches Wörterbuch der deutschen sprache

  • Wacke [1] — Wacke, 1) thonsteinartiges Mineral, hat dichte bis erdige, selten feinkörnige Grundmasse, welche porös, blasig od. mandelsteinartig erscheint, von etwa 2,5 specifischem Gewicht; grünlichgrau, aschgrau, braun od. roth, Strich wenig glänzend, Bruch …   Pierer's Universal-Lexikon

  • Wacke [2] — Wacke, 1) so v.w. Wuhne; 2) ein starkes hohes Zugnetz mit einem Sack ohne Spiegel …   Pierer's Universal-Lexikon

  • Wacke — Wacke, zerfetztes Gestein, s. Basaltwacke …   Meyers Großes Konversations-Lexikon

  • Wacke — Wacke, alter Bergmannsausdruck für Gestein, in Zusammensetzungen noch erhalten (Grauwacke u.a.) …   Kleines Konversations-Lexikon

  • Wacke — Wacke, zum Thongeschlechte gehöriges Mineral, 21/2 spec. Gewicht, Grundmasse der Mandelsteine und Porphyre …   Herders Conversations-Lexikon

  • Wacke — Wạ|cke 〈f. 19〉 verwitternder, seine schwarze Farbe verlierender Basalt, aus dem schließlich ein grauer Lehm entsteht [<ahd. wacko <*waggo „Geröll im Flussbett“; → (be)wegen] * * * Wạ|cke, die; , n [mhd. wacke, ahd. wacko, H. u.] (landsch …   Universal-Lexikon

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”