Nipissing sills: Difference between revisions

[[File:Ungava magmatic event.png|thumb|right|250px|alt=This sketch shows the features associated with the Ungava magmatic event.|Nipissing sills associated with Ungava magmatic event]]

 

The '''Nipissing sills''', also called the '''Nipissing diabase''', is a large 2217– to 2210–million year old group of [[sill (geology)|sills]] in the [[Superior craton]] of the [[Canadian Shield]] in [[Ontario]], [[Canada]],<ref>[http://www.largeigneousprovinces.org/06may.html Ancient LIPS Reconstructed (2.50, 2.45, 2.22 & 2.10 Ga): The Utility Of Precise Magmatic “Barcodes” And “Piercing Points” In Matching Ancient Continental Fragments]</ref> which intrude the [[Huronian Supergroup]].<ref name=palmer>{{cite journal|doi=10.1139/E06-096|title=Magnetic Fabric Studies of the Nipissing sill province and Senneterre dykes, Canadian shield, and Implications for Emplacement|author1=Palmer, H. C.|author2=Ernst, R. E.|author3=Buchan, K. L.|journal=Canadian Journal of Earth Sciences|volume=44|issue=4|date=April 1, 2007|pages=507–528|publisher=NRC Research Press|bibcode = 2007CaJES..44..507P }}</ref> Nipissing sills intrude all the Huronian sediments and older basement rocks in the northern margin of the [[Sudbury Basin]];<ref name=siddom>{{cite thesis|title=Differential Uplift of the Archean Basement North of the Sudbury Basin: Petrographic Evidence from tahe Matachewan Dyke Swarm|author=Siddom, James P.|degree=submitted in conformity with the requirements for the degree of M.Sc. Graduate Department of Geology University of Toronto|year=1999|url=http://google.com/scholar?q=cache:zlfnuPgaVsAJ:scholar.google.com/+Nipissing+sills&ht=en&as_sdt=2000|accessdate=June 12, 2010}}</ref>{{rp|25,67}} they were emplaced after the [[fault (geology)|faulting]] and [[fold (geology)|folding]] of Huronian rocks, and are [[hornblende]] [[gabbro]] of [[tholeiitic basalt]] composition.<ref name=siddom/>{{rp|25}} In the [[Greater Sudbury|Sudbury]]&ndash;[[Elliot Lake]] area the Nipissing diabase is deformed; outcrops are parallel to the fold axes of the Huronian sedimentary rocks.<ref name=palmer/> Nipissing diabase intrusions are east-northeast trending and are no wider than {{convert|460|m|ft|abbr=on}}.<ref>{{cite journal|title="Sudbury Breccia" at Whitefish Falls, Ontario: Evidence for an Impact Origin|author1=Parmenter, Andrew C.|author2=Lee, Christopher B.|author3=Coniglio, Mario|journal=Canadian Journal of Earth Sciences|volume=39|issue=6|pages=971–982|year=2002|doi=10.1139/E02-006|url=http://article.pubs.nrc-cnrc.gc.ca/ppv/RPViewDoc?issn=1480-3313&volume=39&issue=6&startPage=971|accessdate=June 12, 2010|bibcode = 2002CaJES..39..971P }}</ref>{{rp|972}}

 

The Nipissing sills in the Southern Province of the Superior craton are thought to originate from a radiating [[dike swarm]] area {{convert|1300|km|mi|abbr=on}} to the northeast.<ref name=ernst>{{cite book |chapter=Large Igneous Provinces in Canada Through Time and Their Metallognic Potential |last1=Ernst |first1=Richard E. |date=January 1, 2007 |url=http://gsc.nrcan.gc.ca/mindep/synth_prov/lip/pdf/ernst_lips.pdf |access-date=June 12, 2010 |editor-last=Goodfellow |editor-first=W. D. |title=Mineral Deposits of Canada: A Synthesis of Major Deposit-Types, District Metallogeny, the Evolution of Geological Provinces, and Exploration Methods |publisher=[[Geological Association of Canada]], Mineral Deposits Division |number=Special Publication No. 5 |pages=929-937 |archive-url=https://web.archive.org/web/20110605012808/http://gsc.nrcan.gc.ca/mindep/synth_prov/lip/pdf/ernst_lips.pdf |archive-date=June 5, 2011}}</ref>{{rp|3}} The mantle source for the Nipissing sills did not come from the mantle beneath the Southern Province that had generated the 2500– to 2450–million year old [[Matachewan dike swarm]].<ref name=ernst/>{{rp|3}} The 2217– to 2210–million year old [[Ungava magmatic event]] &ndash; located under the [[Labrador Trough]] &ndash; fed the Nipissing sills;<ref name=ernst/>{{rp|3,5}} evidence shows the sills were laterally fed from a [[mantle plume]] center {{convert|1500|km|mi|abbr=on}} away via the 2216–million year old Senneterre dikes which form part of the radiating dike swarm.<ref>{{cite journal|title=Mapping Flow Patterns in Nipissing sills of the Southern Province, Canadian shield: a Magnetic Fabric Study|journal=AGU Spring Meeting Abstracts|volume=2004|pages=GP34A–04|author1=Palmer, H.C.|author2=Ernst, R.E.|author3=Buchan, K.L.|publisher=American Geophysical Union, Spring Meeting 2004, abstract #GP34A-04|bibcode=2004AGUSMGP34A..04P|year=2004}}</ref>

 

==See also==

==References==

{{reflist}}

 

[[Category:Igneous petrology of Ontario]]