Monzonite

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Monzonite
alkali feldspar
Not to be confused with the rare earth-bearing phosphate mineral Monazite.

Monzonite is an

alkali feldspar
.

Syenodiorite is an obsolescent term for monzonite[1] or for monzodiorite.[2] Larvikite is a particular form of monzonite.[3]

Description

QAPF diagram for classification of intrusive igneous rocks, with the monzonite field highlighted
Photomicrograph of thin section of monzonite (in cross polarised
light)
Photomicrograph of thin section of monzonite (in plane polarised light)
The Notch Peak monzonite intrusion in Utah inter-fingers (partly as a dike) with highly metamorphosed Cambrian carbonate host rocks

Monzonite is a coarse-grained (

volcanic equivalent of monzonite is latite.[2][4]

The plagioclase in monzonite is sodium-rich, ranging from

euhedral).[5] The alkali feldspar is typically orthoclase. Monzonite may also contain minor amounts of hornblende, biotite and other minerals.[2][4]

Occurrence

Monzonite is found in association with

ocean crust slab.[6][7] Monzonite can also form in extensional crustal settings[3][8] or by partial melting of lower crust of alkali basalt composition.[9]

Diorite, monzonite, and syenite are found together on the margins of the

North China craton. These likely formed during the assembly of Columbia and suggest the North China craton was in the interior of Columbia, between Laurentia and Siberia.[10]

The

Bingham mine consists of porphyry copper deposits hosted in altered monzonite. Alteration has converted some of the monzonite to compositions resembling quartz monzonite or granite, by altering plagioclase to potassium feldspar and emplacing hydrothermal quartz.[11]

Fragments of monzonite have been found on the surface of the

immiscibility. This is a process in which high-silica and low-silica components of a magma separate like oil and vinegar.[12]

Etymology

Monzonite was originally named after the Monzoni range in

Val di Fassa (Trento Province, Italy) where it is abundant. As rock definitions have been systematized and codified, this association has lost any relevance to the rock's definition.[2]

References

  1. ISBN 9780199653065
    .
  2. ^
    ISBN 0-521-66215-X
  3. ^
    doi:10.1016/0024-4937(84)90016-1
    .
  4. ^
    ISBN 0-471-80580-7
  5. ISBN 0716724383
    .
  6. doi:10.1016/j.jseaes.2010.01.002
    .
  7. doi:10.1016/j.lithos.2013.08.003
    .
  8. doi:10.1016/j.jog.2012.06.003
    .
  9. doi:10.1017/S0016756800010219
    .
  10. doi:10.1016/j.lithos.2013.01.005
    .
  11. doi:10.2113/gsecongeo.73.7.1270
    .
  12. Bibcode:1976LPSC....7.1723R
    .
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