Quartz latite explained

Quartz latite
Type:Volcanic
Composition:Intermediate
Major minerals: plagioclase, alkali feldspar, quartz

A quartz latite is a volcanic rock or fine grained extrusive rock composed mostly of alkali feldspar and plagioclase with some quartz. It forms from the rapid cooling of magma of intermediate composition but moderately enriched in alkali metal oxides.

Quartz latite is intermediate between latite and rhyolite in its mineralogy.

Description

Quartz latite is the fine-grained equivalent of a quartz monzonite, containing approximately equal amounts of plagioclase and alkali feldspar and between 5% and 20% quartz and with plagioclase making up 35% to 65% of its total feldspar content. Quartz latite is not a recognized rock type in the TAS classification used to chemically classify glassy or very fine-grained volcanic rock.[1] [2] [3] [4]

Occurrence

Quartz latite is found in the 130-135 Mya Etendeka Formation of Namibia, where it forms extensive sheets in association with tholeiitic basalt. These are interpreted as densely welded ash flow tuffs.[5] Some of the quartz latite flows were enormous, with estimated volumes of 2320km3 and 6340km3 for two of the flows.[6]

Paleoproterozoic quartz latite is abundant in the Roxby Downs area of Australia, and may have been a source rock for younger granitoids.[7]

Quartz latite is found at the Bingham mine in Utah in association with its plutonic counterpart, quartz monzonite.[8]

Notes and References

  1. Le Bas. M. J.. Streckeisen. A. L.. The IUGS systematics of igneous rocks. Journal of the Geological Society. 148. 5. 825–833. 10.1144/gsjgs.148.5.0825. 1991JGSoc.148..825L. 1991. 10.1.1.692.4446. 28548230.
  2. 1999. Rock Classification Scheme - Vol 1 - Igneous. British Geological Survey: Rock Classification Scheme. 1. 1–52.
  3. Web site: CLASSIFICATION OF IGNEOUS ROCKS. https://web.archive.org/web/20110930102012/http://geology.csupomona.edu/alert/igneous/igclass.htm. 30 September 2011. dead.
  4. Book: Philpotts . Anthony R. . Ague . Jay J. . Principles of igneous and metamorphic petrology . 2009 . Cambridge University Press . Cambridge, UK . 9780521880060 . 2nd . 139–143.
  5. Milner . Sc . Duncan . Ar . Ewart . A . Quartz latite rheoignimbrite flows of the Etendeka Formation, north-western Namibia . Bulletin of Volcanology . February 1992 . 54 . 3 . 200–219 . 10.1007/BF00278389. 1992BVol...54..200M . 54998997 .
  6. Ewart . A. . Milner . S.C. . Armstrong . R.A. . Duncan . A.R. . Etendeka Volcanism of the Goboboseb Mountains and Messum Igneous Complex, Namibia. Part II: Voluminous Quartz Latite Volcanism of the Awahab Magma System . Journal of Petrology . 1 February 1998 . 39 . 2 . 227–253 . 10.1093/petroj/39.2.227. free .
  7. Creaser . Robert A. . Petrogenesis of a Mesoproterozoic quartz latite-granitoid suite from the Roxby Downs area, South Australia . Precambrian Research . September 1996 . 79 . 3–4 . 371–394 . 10.1016/S0301-9268(96)00002-2. 1996PreR...79..371C .
  8. Parry . W. T. . Ballantyne . G. H. . Wilson . J. C. . Chemistry of biotite and apatite from a vesicular quartz latite porphyry plug at Bingham, Utah . Economic Geology . 1 November 1978 . 73 . 7 . 1308–1314 . 10.2113/gsecongeo.73.7.1308. 1978EcGeo..73.1308P .