Diamictite

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Type of sedimentary rock

title: "Diamictite" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["sedimentary-rocks"] description: "Type of sedimentary rock" topic_path: "general/sedimentary-rocks" source: "https://en.wikipedia.org/wiki/Diamictite" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Type of sedimentary rock ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/2/20/Geschiebemergel.JPG" caption="Diamictite from Stolpe, eastern Germany"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/0/00/PocatelloFm.JPG" caption="'[[Snowball Earth]]'-type diamictite from the Pocatello Formation, [[Idaho]], United States"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/b/b8/Diamictite_Mineral_Fork.JPG" caption="Boulder of diamictite of the [[Mineral Fork Formation]], [[Antelope Island]], [[Utah]], United States"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/8/86/Elatina_Fm_diamictite.JPG" caption="Flinders Ranges NP]], South Australia. A$1 coin for scale."] ::

Diamictite (; from Ancient Greek grc (): 'through' and grc (): 'mixed') is a type of lithified sedimentary rock that consists of unsorted to poorly sorted terrigenous sediment containing particles that range in size from clay to boulders, suspended in a matrix of mudstone or sandstone. The term was coined by Richard Foster Flint and others as a purely descriptive term, devoid of any reference to a particular origin. Some geologists restrict the usage to unsorted or poorly sorted conglomerate or breccia that consists of sparse, terrigenous gravel suspended in either a mud or sand matrix.

Unlithified diamictite is referred to as diamicton.

The term diamictite is often applied to unsorted or poorly sorted, lithified glacial deposits such as glacial tillite and boulder clay, and diamictites are often mistakenly interpreted as having an essentially glacial origin (see Snowball Earth). The most common origin for diamictites, however, is deposition by submarine mass flows like turbidites and olistostromes in tectonically active areas, and they can be produced in a wide range of other geological conditions. Possible origins include:

There are two Neoproterozoic diamictite layers in Namibia, the Chuos and Ghaub formations, which have been extensively studied in support of the snowball earth hypothesis. The Chuos diamictite is marked the Sturtian glaciation around 710 Mya, while the Ghaub is the result of Marinoan glaciation (630 Mya). Both diamictites are deposited within continuous carbonate formations that imply a tropical marine environment. It is postulated that thick ice-sheets were developed during two phases in the Neoproterozoic that covered almost the entire Earth, including the tropical seas.

References

References

  1. Flint, R.F., J.E. Sanders, and J. Rodgers (1960) ''Diamictite, a substitute term for symmictite'' Geological Society of America Bulletin. 71(12):1809–1810.
  2. [[Tucker, M.E.]] (2003) ''Sedimentary Rocks in the Field'' John Wiley & Sons, Ltd., New York, New York. 244 pp. {{ISBN. 978-0-470-85123-4
  3. [http://courses.eas.ualberta.ca/eas457/Eyles_2004.pdf Eyles, N.; Januszczak, N. (2004). "’Zipper-rift’: A tectonic model for Neoproterozoic glaciations during the breakup of Rodinia after 750 Ma". Earth-Science Reviews 65 (1-2): 1-73. (pdf 4 Mb)] {{webarchive. link. (2007-11-28)
  4. [http://www.univie.ac.at/geochemistry/koeberl/publication_list/184-Dwyka-geochem-GCA2001.pdf Huber, H., Koeberl, C., McDonald, I., Reimold, W.U.: ''Geochemistry and petrology of Witwatersrand and Dwyka diamictites from South Africa: Search for an extraterrestrial component.'' Geochimica et Cosmochimica Acta, Vol. 65, No. 12, pp. 2007–2016, 2001. (pdf 470 Kb)]

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