Shoshonite

<h2 id="chemical-characteristics">Chemical characteristics</h2>
<a href="/facts/Igneous/xeMJhUah">Igneous</a> rocks with shoshonitic chemical characteristics must be:<a class="footnote-ref" id="fnref:5" href="#fn:5">5</a>

<ol><li>Near-saturated in silica;</li>
<li>Low iron enrichment;</li>
<li>High total alkalies (Na2O + K2O > 5%);</li>
<li>High K2O/Na2O;</li>
<li>Steep positive slope for K2O versus SiO2 at low SiO2;</li>
<li>Enrichment in P, Rb, Sr, Ba, Pb, light rare earth elements;</li>
<li>Low TiO2;</li>
<li>High but variable Al2O3;</li>
<li>High Fe2O3/FeO.</li></ol>
<h2 id="tectonic-settings-and-examples">Tectonic settings and examples</h2>
Shoshonitic rocks tend to be associated with <a href="/facts/Calc-alkaline/fW9qn0oc">calc-alkaline</a> <a href="/facts/Island_arc/J7FIJPmy">island-arc</a> <a href="/facts/Subduction/rkasNdTo">subduction</a> <a href="/facts/Volcanism/0s6p1eFJ">volcanism</a>, but the K-rich shoshonites are generally younger and above deeper, steeper parts or the <a href="/facts/Benioff_zone/SWy7E56r">Benioff zone</a>.<a class="footnote-ref" id="fnref:6" href="#fn:6">6</a><a class="footnote-ref" id="fnref:7" href="#fn:7">7</a>
<a href="/facts/Volcanic_rock/ID3oPwtM">Volcanic rocks</a> of the absarokite-shoshonite-banakite series described from <a href="/facts/Yellowstone_Park/NnavuSNu">Yellowstone Park</a> by Iddings and the similar ciminite-toscanite series described from western <a href="/facts/Italy/tUf0PDYF">Italy</a> by Washington are associated with <a href="/facts/Leucite/l1uVJHtm">leucite</a>-bearing rocks, potassium-rich <a href="/facts/Trachyte/TNz4oTQA">trachytes</a> and andesitic rocks. Similar associations are described from several other regions including Indonesia and the <a href="/facts/East_African_Rift/o82Q47Uc">East African Rift</a>.<a class="footnote-ref" id="fnref:8" href="#fn:8">8</a>
In the <a href="/facts/Aeolian_Islands/PpbmDyA5">Aeolian Arc</a> in the southern <a href="/facts/Tyrrhenian_Sea/akx6f83B">Tyrrhenian Sea</a> (between the Eurasian and African <a href="/facts/Tectonic_plates/CvbfSfeC">tectonic plates</a>), volcanism has changed between <a href="/facts/Calc-alkaline/fW9qn0oc">calc-alkaline</a> to high-K calc-alkaline to shoshonitic with the last one million years, possibly due to the progressive steepening of the <a href="/facts/Benioff_zone/SWy7E56r">Benioff zone</a>, which is inclined at 50-60°.<a class="footnote-ref" id="fnref:9" href="#fn:9">9</a> An example of shoshonite lava in this region is the Capo Secco lava shield near <a href="/facts/Vulcano/QYgRaTEv">Vulcano</a>.<a class="footnote-ref" id="fnref:10" href="#fn:10">10</a> Late <a href="/facts/Cretaceous/nwKtFtKx">Cretaceous</a> <a href="/facts/Puerto_Rico/jVStMyG4">Puerto Rican</a> volcanism is interpreted to have occurred in a similar <a href="/facts/Tectonic/jPcFacFP">tectonic</a> setting.<a class="footnote-ref" id="fnref:11" href="#fn:11">11</a>
In places, shoshonitic and high-potassium calc-alkaline magmatism is associated with world-class hydrothermal gold and copper-gold mineralization. Examples include:<a class="footnote-ref" id="fnref:12" href="#fn:12">12</a>

Ladolam gold mine, <a href="/facts/Lihir_Island/WHeJe3hD">Lihir Island</a>, <a href="/facts/Papua_New_Guinea/RLaVlhFC">Papua New Guinea</a>;
<a href="/facts/Bingham_Canyon_Mine/GThqCwIf">Bingham copper-gold mine</a>, <a href="/facts/Utah/te7zUyBX">Utah</a>;
<a href="/facts/Grasberg_mine/mHnjqDvY">Grasberg copper-gold mine</a>, <a href="/facts/Indonesia/vQnWU3IW">Indonesia</a>;
<a href="/facts/Oyu_Tolgoi_mine/Q9sq2aG5">Oyu Tolgoi copper-gold mine</a>, <a href="/facts/Mongolia/ogQzUcQb">Mongolia</a>.

<h2 id="references">References</h2>

<ol>
<li id="fn:1">Le Maitre, R.W. (editor) (2002). Igneous Rocks — A Classification and Glossary of Terms (2nd ed.). Cambridge: Cambridge University Press. p. 141. ISBN 0-521-66215-X. {{cite book}}: |author= has generic name (help) <a href="0-521-66215-X" target="_blank">0-521-66215-X</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></li>
<li id="fn:2">Gest, D. E. and A. R. McBirney, Genetic relations of shoshonitic and absarokitic magmas, Absaroka Mountains, Wyoming, Journal of Volcanology and Geothermal Research, Vol 6; issues 1-2, Sept 1979. pp 85-104 <a href="#fnref:2" class="footnote-back-ref">↩</a></li>
<li id="fn:3">Shoshonite: Webster's Online Dictionary Archived 2009-11-27 at the Wayback Machine <a href="http://www.websters-online-dictionary.org/sh/shoshonite.html" target="_blank">http://www.websters-online-dictionary.org/sh/shoshonite.html</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></li>
<li id="fn:4">Prostka, Harold J., Hybrid Origin of the Absarokite-Shoshonite-Banakite Series, Absaroka Volcanic Field, Wyoming, 1973 GSA Bulletin February, 1973 v. 84 no. 2 p. 697-702 abstract <a href="http://bulletin.geoscienceworld.org/cgi/content/abstract/84/2/697" target="_blank">http://bulletin.geoscienceworld.org/cgi/content/abstract/84/2/697</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></li>
<li id="fn:5">Morrison, Gregg, 1980, Characteristics and tectonic settings of shoshonite rock association, Lithos, 13, 97-108 <a href="/wiki/Lithos_(journal)" target="_blank">/wiki/Lithos_(journal)</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></li>
<li id="fn:6">Morrison, Gregg, 1980, Characteristics and tectonic settings of shoshonite rock association, Lithos, 13, 97-108 <a href="/wiki/Lithos_(journal)" target="_blank">/wiki/Lithos_(journal)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></li>
<li id="fn:7">Müller D., Groves D.I. (2019) Potassic igneous rocks and associated gold-copper mineralization (5th ed.). Mineral Resource Reviews. Springer-Verlag Heidelberg, 398 pp <a href="#fnref:7" class="footnote-back-ref">↩</a></li>
<li id="fn:8">Joplin, Germaine A., The shoshonite association: A review, Journal of the Geological Society of Australia, v. 15, #2, 1968, pp 275-294 DOI:10.1080/00167616808728699 <a href="/wiki/Germaine_Joplin" target="_blank">/wiki/Germaine_Joplin</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></li>
<li id="fn:9">Morrison, Gregg, 1980, Characteristics and tectonic settings of shoshonite rock association, Lithos, 13, 97-108 <a href="/wiki/Lithos_(journal)" target="_blank">/wiki/Lithos_(journal)</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></li>
<li id="fn:10">Peccerillo, Angelo (2017). Cenozoic Volcanism in the Tyrrhenian Sea Region (2nd ed.). Springer. p. 239. ISBN 978-3-319-42489-7. <a href="978-3-319-42489-7" target="_blank">978-3-319-42489-7</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></li>
<li id="fn:11">Morrison, Gregg, 1980, Characteristics and tectonic settings of shoshonite rock association, Lithos, 13, 97-108 <a href="/wiki/Lithos_(journal)" target="_blank">/wiki/Lithos_(journal)</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></li>
<li id="fn:12">Müller D., Groves D.I. (2019) Potassic igneous rocks and associated gold-copper mineralization (5th ed.). Mineral Resource Reviews. Springer-Verlag Heidelberg, 398 pp <a href="#fnref:12" class="footnote-back-ref">↩</a></li>
</ol>

Shoshonite open-in-new

Shoshonite