Nipissing sills
![This sketch shows the features associated with the Ungava magmatic event.](http://upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Ungava_magmatic_event.png/250px-Ungava_magmatic_event.png)
The Nipissing sills, also called the Nipissing diabase, is a large 2217– to 2210–million year old group of sills in the Superior craton of the Canadian Shield in Ontario, Canada,[1] which intrude the Huronian Supergroup.[2] Nipissing sills intrude all the Huronian sediments and older basement rocks in the northern margin of the Sudbury Basin;[3]: 25, 67 they were emplaced after the faulting and folding of Huronian rocks, and are hornblende gabbro of tholeiitic basalt composition.[3]: 25 In the Sudbury–Elliot Lake area the Nipissing diabase is deformed; outcrops are parallel to the fold axes of the Huronian sedimentary rocks.[2] Nipissing diabase intrusions are east-northeast trending and are no wider than 460 m (1,510 ft).[4]: 972
The Nipissing sills in the Southern Province of the Superior craton are thought to originate from a radiating dike swarm area 1,300 km (810 mi) to the northeast.[5]: 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.[5]: 3 The 2217– to 2210–million year old Ungava magmatic event – located under the Labrador Trough – fed the Nipissing sills;[5]: 3, 5 evidence shows the sills were laterally fed from a mantle plume center 1,500 km (930 mi) away via the 2216–million year old Senneterre dikes which form part of the radiating dike swarm.[6]
See also
[edit]References
[edit]- ^ 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
- ^ a b Palmer, H. C.; Ernst, R. E.; Buchan, K. L. (April 1, 2007). "Magnetic Fabric Studies of the Nipissing sill province and Senneterre dykes, Canadian shield, and Implications for Emplacement". Canadian Journal of Earth Sciences. 44 (4). NRC Research Press: 507–528. Bibcode:2007CaJES..44..507P. doi:10.1139/E06-096.
- ^ a b Siddom, James P. (1999). Differential Uplift of the Archean Basement North of the Sudbury Basin: Petrographic Evidence from tahe Matachewan Dyke Swarm (submitted in conformity with the requirements for the degree of M.Sc. Graduate Department of Geology University of Toronto thesis). Retrieved June 12, 2010.
- ^ Parmenter, Andrew C.; Lee, Christopher B.; Coniglio, Mario (2002). ""Sudbury Breccia" at Whitefish Falls, Ontario: Evidence for an Impact Origin". Canadian Journal of Earth Sciences. 39 (6): 971–982. Bibcode:2002CaJES..39..971P. doi:10.1139/E02-006. Retrieved June 12, 2010.
- ^ a b c Ernst, Richard E. Large Igneous Provinces in Canada Through Time and Their Metallognic Potential (PDF) (Report). Retrieved June 12, 2010.
- ^ Palmer, H.C.; Ernst, R.E.; Buchan, K.L. (2004). "Mapping Flow Patterns in Nipissing sills of the Southern Province, Canadian shield: a Magnetic Fabric Study". AGU Spring Meeting Abstracts. 2004. American Geophysical Union, Spring Meeting 2004, abstract #GP34A-04: GP34A–04. Bibcode:2004AGUSMGP34A..04P.