Editing Diabase (section)

==Locations==
[[File:Dike diabase AZ.jpg|thumb|A diabase [[dike (geology)|dike]] crosscutting horizontal [[limestone]] beds in Arizona]]
[[File:Devil's Den 101215.jpg|thumb|Diabase boulders at [[Devil's Den]] on the [[Gettysburg Battlefield]], Pennsylvania, US]]
[[File:Doleritfelsen und Köcherbäume.jpg|thumb|Dolerite rocks and [[Quiver tree]]s near [[Keetmanshoop]] (Namibia)]]
[[File:Organ Pipes Mount Wellington.jpg|thumb|Dolerite forms tall vertical columns throughout [[Tasmania]]. These columns form steep vertical features through its alpine areas.]]

Diabase is usually found in smaller, relatively shallow intrusive bodies such as [[dike (geology)|dikes]] and [[sill (geology)|sill]]s. Diabase dikes occur in regions of [[crustal extension]] and often occur in [[dike swarm]]s of hundreds of individual dikes or sills radiating from a single [[volcanic]] center.

The [[Palisades Sill]] which makes up the [[New Jersey Palisades]] on the [[Hudson River]], near [[New York City]], New York, United States, is an example of a diabase sill. The dike complexes of the [[British Tertiary Volcanic Province]] includes Skye, Rum, Mull, and Arran of western [[Scotland]], the [[Slieve Gullion]] region of [[Ireland]], and dolerite dike swarms extending across northern [[England]] towards the Midlands, for example [[Rowley Rag]]. Parts of the [[Deccan Traps]] of India, formed at the end of the [[Cretaceous]], also include dolerite.<ref>[http://www.geokem.com/flood-basalts-1.html ''Continental Flood Basalts (and Layered Intrusions)'']</ref> It is also abundant in large parts of [[Curaçao]], an island off the coast of [[Venezuela]]. Another example of diabase dikes has been recognized in the [[Mongo, Chad|Mongo]] area within the [[Guéra Region|Guéra Massif]] of [[Chad]] in Central Africa.<ref>{{Cite journal|last1=Nkouandou|first1=Oumarou Faarouk|last2=Bardintzeff|first2=Jacques-Marie|last3=Mahamat|first3=Oumar|last4=Fagny Mefire|first4=Aminatou|last5=Ganwa|first5=Alembert Alexandre|date=2017-05-22|title=The dolerite dyke swarm of Mongo, Guéra Massif (Chad, Central Africa): Geological setting, petrography and geochemistry|journal=Open Geosciences|volume=9|issue=1|pages=138–150|doi=10.1515/geo-2017-0012|issn=2391-5447|bibcode=2017OGeo....9...12N|doi-access=free}}</ref>

In the [[Death Valley]] region of California, [[Precambrian]] diabase intrusions metamorphosed pre-existing [[Dolomite (mineral)|dolomite]] into economically important [[talc]] deposits.<ref>Miller, MB, and Wright, LA. 2007, "Geology of Death Valley National Park (Third Edition)", Kendall Hunt Publishing, p 19.</ref>

In the Thuringian-Franconian-Vogtland Slate Mountains of central [[Germany]] the diabase is entirely of [[Devonian]] age.<ref name="Deutsch2006">{{cite book | title=Einführung in die Geologie Deutschlands | publisher=Spektrum Akademischer Verlag | first1=Dierk | last1=Henningsen | first2=Gerhard | last2=Katzung | year=2006 | edition=7th | location=Munich | page=69 | isbn=3-8274-1586-1 | language=de}}</ref> They form typical domed landscapes, especially in the [[Vogtland]]. One [[Geotourism|geotourist]] attraction is the ''[[Steinerne Rose]]'' near [[Saalburg-Ebersdorf|Saalburg]], a natural monument, whose present shape is due to the typical weathering of lava pillows.

===Gondwanaland and Australia===
A [[geological event]] known as the [[Oenpelli]] Dolerite intrusive event occurred about 1,720 million years ago in western [[Arnhem Land]], in the [[Northern Territory]],<ref>{{cite web|url=https://geoscience.nt.gov.au/gemis/ntgsjspui/bitstream/1/74562/1/EL5893_2008_P_01.pdf|title=Wellington Range Project Northern Territory EL 5893 Relinquishment Report|publisher=Cameco Australia Pty Lt|date=August 2008 |series=Report No.: WR08-02 |first1=Cath |last1=Ranford |first2=Paul|last2= Melville |first3=Craig|last3= Bentley|access-date=5 Oct 2020}}</ref> forming curved ridges of Oenpelli Dolerite stretching over {{convert|30,000| km2}}.<ref>{{cite web | website=Australian Stratigraphic Units Database|publisher= Australian Government. Geoscience Australia | title=Definition card for: Oenpelli Dolerite| url=http://dbforms.ga.gov.au/pls/www/geodx.strat_units.def?strno=14496&stratname=Oenpelli%20Dolerite | access-date=5 October 2020}} [[File:CC-BY icon.svg|50px]] Text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/3.0/au/ Attribution 3.0 Australia (CC BY 3.0 AU)] licence.</ref> Further west, on the northern coast of Arnhem Land, a "subsurface radial dyke swarm" known as [[Galiwinku]] Dolerite, taking its name from the [[Aboriginal Australian|Aboriginal]] name for Elcho Island, occurs on the [[Gove Peninsula]] and continues under the [[Arafura Sea]] and on [[Wessel Islands]], including Elcho and [[Milingimbi Island]]s.<ref>{{cite web | website=Australian Stratigraphic Units Database|publisher= Australian Government. Geoscience Australia | title=Definition card for: Galiwinku Dolerite| url=http://dbforms.ga.gov.au/pls/www/geodx.strat_units.def?strno=77145&stratname=Galiwinku%20Dolerite | access-date=5 October 2020}} [[File:CC-BY icon.svg|50px]] Text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/3.0/au/ Attribution 3.0 Australia (CC BY 3.0 AU)] licence.</ref>

In the [[Yilgarn craton]] of [[Western Australia]], a [[Proterozoic]] {{convert|200| km |adj=on}} long dolerite dike, the [[Norseman-Wiluna greenstone belt]]<ref>Hill R.E.T, [[Sarah-Jane Barnes|Barnes S.J.]], Gole M.J., and Dowling S.E., 1990. Physical volcanology of komatiites; A field guide to the komatiites of the Norseman-Wiluna Greenstone Belt, Eastern Goldfields Province, Yilgarn Block, Western Australia., Geological Society of Australia. {{ISBN|0-909869-55-3}}</ref> is associated with the non-alluvial [[gold]] mining area between [[Norseman, Western Australia|Norseman]] and [[Kalgoorlie]], which includes the largest gold mine in Australia,<ref>{{cite journal|doi=10.1144/1467-7873/07-132|author1=O'Connor-Parsons, Tansy |author2=Stanley, Clifford R. |title=Downhole lithogeochemical patterns relating to chemostratigraphy and igneous fractionation processes in the Golden Mile dolerite, Western Australia|year=2007|journal=Geochemistry: Exploration, Environment, Analysis|volume=7|issue=2|pages=109–27|bibcode=2007GEEA....7..109O |s2cid=140677224 }}</ref> the [[Super Pit gold mine]]. West of the Norseman–Wiluna Belt is the [[Yalgoo-Singleton greenstone belt]], where complex dolerite dike swarms obscure the volcaniclastic sediments.<ref>{{cite journal|author1=Wanga Q. |author2=Campbella I. H. |year= 1998|title= Geochronology of supracrustal rocks from the Golden Grove area, Murchison Province, Yilgarn Craton, Western Australia |journal=Australian Journal of Earth Sciences|doi=10.1080/08120099808728413|volume=45|issue=4|pages=571–77|bibcode = 1998AuJES..45..571W }}</ref> Large dolerite sills such as the Golden Mile Dolerite can exhibit coarse-grained texture, and show a large diversity in petrography and geochemistry across the width of the sill.<ref name="Travis_etal_1971">{{Citation|last1=Travis|first1=G.A.|last2=Woodall|first2=R.|last3=Bartram|first3=G.D.|chapter=The Geology of the Kalgoorlie Goldfield|editor-last=Glover|editor-first=J.E.|title=Symposium on Archaean Rocks|pages=175–190|publisher=Geological Society of Australia (Special Publication 3)|date=1971}}</ref>

The vast areas of mafic volcanism/[[plutonism]] associated with the [[Jurassic]] breakup of the [[Gondwana]] supercontinent in the [[Southern Hemisphere]] include many large diabase/dolerite sills and dike swarms. These include the [[Karoo]] dolerites of [[South Africa]], the [[Karoo-Ferrar|Ferrar Dolerite]]s of [[Antarctica]], and the largest of these, the most extensive of all dolerite formations worldwide, are found in [[Tasmania]]. Here, the volume of [[magma]] which intruded into a thin veneer of [[Permian]] and [[Triassic]] rocks from multiple feeder sites, over a period of perhaps a million years, may have exceeded 40,000 cubic kilometres.<ref>[[David Leaman|Leaman, David]] 2002, "The Rock that Makes Tasmania", Leaman Geophysics, {{ISBN|0-9581199-0-2}} p. 117.</ref> In Tasmania, dolerite dominates much of the landscape, particularly alpine areas, with many examples of [[columnar jointing]].

[[Early Jurassic]] activity resulted in the formation of [[Prospect dolerite intrusion|dolerite intrusion in Prospect]] in [[Sydney]],<ref>Jones, I., and Verdel, C. (2015). Basalt distribution and volume estimates of Cenozoic
volcanism in the Bowen Basin region of eastern Australia: Implications for a waning mantle plume. Australian Journal of Earth Sciences, 62(2), 255–263.</ref> and [[quarrying]] of [[basalt]] for [[roadstone]] and other building materials has been an important activity there for over 180 years.<ref name="Johnson1989">{{cite book|author=Robert Wallace Johnson|title=Intraplate Volcanism: In Eastern Australia and New Zealand|url=https://books.google.com/books?id=4NBOn7ecZeAC&pg=PA4|date=24 November 1989|publisher=Cambridge University Press|isbn=978-0-521-38083-6|pages=4–}}</ref><ref>Wilshire, H.G. (1967) The Prospect Alkaline Diabase-Picrite Intrusion New South Wales, Australia. Journal of Petrology 8(1) pp.97-163.</ref>