Bravo Lake Formation

{{Short description|Large igneous province on Baffin Island, Nunavut, Canada}} The '''Bravo Lake Formation''' is a [[mafic]] [[volcanic belt]] and [[large igneous province]]<ref>[http://www.encyclopedia.com/doc/1G1-124343378.html Igneous rock associations in Canada 3. Large Igneous Provinces (LIPs) in Canada and adjacent regions: 3] Retrieved on 2007-01-10</ref> located at the northern margin of the [[Trans-Hudson orogeny]] on central [[Baffin Island]], [[Nunavut]], Canada. It is exposed along a nearly continuous east–west passage for {{convert|120|km|mi|0|abbr=on}} and changes in stratigraphic thickness from 1 to 2.5 kilometers.<ref name="SI">[http://gsc.nrcan.gc.ca/baffin4d/proj/p21_e.php Central Baffin Island 4-D Project - Projects] {{webarchive|url=https://web.archive.org/web/20090416021920/http://gsc.nrcan.gc.ca/baffin4d/proj/p21_e.php |date=2009-04-16 }}: Paleoproterozoic mafic magmatism in central Baffin Island. Retrieved on 2007-10-18</ref> The [[Formation (geology)|formation]] is a rare alkaline-suite that formed as a result of submarine [[rift]]ing during the [[Paleoproterozoic]] period.<ref>[https://web.archive.org/web/20090415162029/http://gac.esd.mun.ca/gac_2004/search_abs/sub_program.asp?sess=98&form=10&abs_no=280 Volcanology and geochemistry of the Bravo Lake Formation, Baffin Island, Nunavut]. Retrieved on 2007-10-18</ref> The Bravo Lake Formation is surprisingly undeformed by the Himalayan-scale forming event during the Trans-Hudsonian orogeny.

The [[stratigraphy]] of the Bravo Lake Formation starts with a basic section of iron-oxide rich [[sandstone]]s, [[psammite]]s, and semi-[[pelite]]s which cover a series of deformed [[pillow lava]]s which expand in viscosity towards the west, and volcanic/clastic deposits and [[ultramafic]] [[Sill (geology)|sills]]. The lower volcanic section is covered by [[garnet]] and [[diopside]] bearing [[Calc–silicate rock|calc–silicate]] layers and finely layered metasediments composed of coarse-grained [[actinolite]], [[hornblende]] and [[biotite]] followed by pelites and semi-pelites that are intruded by separate sills. In the [[Ridge Lake]] area, the volcanic belt includes an interlayered series of [[amphibolite]], [[gabbro]], [[Banded iron formation|iron formation]], sulfidic [[schist]] and metasediments.<ref name="SI"/>

Geochemical results of [[pillow lava]]s and chill boundaries along five transects across the volcanic belt suggest the existence of three chemically different [[magma]] types within the Bravo Lake Formation.<ref name="SI"/>

Lavas of the [[volcanic belt]] display [[Geochemistry|geochemical]] characteristics similar to modern ocean-island–basalt groups. They range from moderately to intensely fractionated. [[Rare-earth element|REE-profiles]] are similar to those from [[tholeiitic basalt]]s to extremely [[alkaline]] lavas in [[Hawaii]].<ref name="SI"/>

==See also== *[[List of volcanoes in Canada]] *[[Volcanism of Canada]] *[[Volcanism of Northern Canada]] *[[Geography of Nunavut]]

==References== {{reflist}}

==External links== *[https://web.archive.org/web/20110706190020/http://gac.esd.mun.ca/gac_2003/search_abs/sub_program.asp?sess=98&form=10&abs_no=439 Paleoproterozoic alkaline magmatism of the Bravo Lake Formation of central Baffin Island, Nunavut]

{{coord|68|31|N|073|18|W|type:landmark_scale:1000000_region:CA-NU|display=title|name=Bravo Lake Formation}}

[[Category:Volcanic belts]] [[Category:Large igneous provinces]] [[Category:Volcanism of Nunavut]] [[Category:Proterozoic volcanism]] [[Category:Geologic formations of Nunavut]] [[Category:Baffin Island]]